BEST PRACTICE GUIDE FOR BUSINESSES IN GEORGIA

BEST PRACTICE GUIDE FOR BUSINESSES IN GEORGIA

ENERGY EFFICIENCY AND RENEWABLE ENERGY



I

TABLE OF CONTENTS

LIST OF ABBREVIATIONS X

DEAR READER 1

WHO IS THIS GUIDE FOR? 2

HOW TO USE THIS GUIDE 3

THE EBRD AND ITS SUPPORT FOR SUSTAINABLE ENERGY 4

1. ENERGY EFFICIENCY ESSENTIALS 61.1 Definitions 61.2 Benefits of Energy Efficiency 61.3 Steps to Investing in Energy Efficiency Projects 81.4 Energy Efficiency Investment Opportunities 11

2. CASE STUDIES 15

3. ENERGY EFFICIENCY FOR GENERAL UTILITIES AND SERVICES 563.1 STRATEGIC ISSUES AFFECTING ENERGY USE 563.1.1 Heat and power supplied separately or together? 57

3.1.2 Steam- or hot water-based systems and heat recovery 57

3.1.3 Security of supply 58

3.1.4 Changing fuels 58

3.1.5 Changing voltage / supplier 59

3.1.6 Managing demand for energy 59

3.1.7 Central or local supply 60

3.1.8 Renewable energy resources 61

3.2 INDUSTRIAL HEAT GENERATION AND DISTRIBUTION 623.2.1 Boilers 62

3.2.2 Furnaces and kilns 69

3.2.3 Cogeneration 74

3.2.4 Steam distribution 82

II

ENERGY EFFICIENCY & RENEWABLE ENERGY

3.3 INDUSTRIAL REFRIGERATION AND COOLING 89

3.4 COMPRESSED AIR 102

3.5 ELECTRICITY FOR INDUSTRIAL USE 107

3.5.1 Electricity distribution 107

3.5.2 Motors and drives 110

3.5.3 Reactive power 114

3.6 PROCESS CONTROL SYSTEMS 1183.6.1 Instrumentation 118

3.6.2 Energy Efficiency Management System (EEMS) 120

3.6.3 Process Integration 125

3.7 ENERGY EFFICIENCY IN BUILDINGS 1273.7.1 The building shell 127

3.7.2 Heating and hot water systems 134

3.7.3 Air-conditioning 141

3.7.4 Ventilation systems 147

3.7.5 Lighting 153

3.7.6 Building management systems (BMS) 158

4. SAVING ENERGY IN DIFFERENT BUSINESS SECTORS 1624.1 INDUSTRY 1624.1.1 Mining and metals processing 162

4.1.2 Wood processing 168

4.1.3 Pulp and paper 171

4.1.4 Ceramic brick production 177

4.1.5 Cement production 182

4.1.6 Glass production 189

4.1.7 Plastics processing 195

4.1.8 Pharmaceuticals 201

4.1.9 Food and beverage processing 206


III

4.2 AGRICULTURE 211

4.3 HEAVY TRANSPORT AND CONSTRUCTION VEHICLES AND FARM EQUIPMENT 215

5. RENEWABLE ENERGY RESOURCES 2215.1 SMALL HYDRO PROJECTS 2215.1.1 Introduction 221

5.1.2 Components of a SHP 222

5.1.3 Efficiency-capacity factors 226

5.1.4 Small hydro power project development 227

5.1.5 Small hydro project potential in Georgia 228

5.2 SOLAR ENERGY 2305.2.1 Solar electricity 230

5.2.2 Solar heating 235

5.2.3 Solar cooling 238

5.2.4 Solar energy potential in Georgia 239

5.3 BIOMASS 2405.3.1 Introduction 240

5.3.2 Biomass combustible fuel 242

5.3.3 Biogas 243

5.3.4 Biomass energy potential in Georgia 246

5.4 GEOTHERMAL 2475.4.1 Electricity generation 247

5.4.2 Geothermal heat pump (GHP) 248

5.4.3 Geothermal energy potential in Georgia 250

ACKNOWLEDGEMENTS 251IPA Energy + Water Economics 251

LDK Consultants 251

IV


TECHNICAL GLOSSARY 253

LIST OF TABLESTable 1. Typical thermal efficiencies for common industrial furnaces 70

Table 2. Typical characteristics of CHP technologies 80

Table 3. Types of insulation materials and their applications 84

Table 4. List of refrigerants’ replacement 93

Table 5. List of typical refrigerants found in most applications 93

Table 6. Typical COP of different refrigeration types 94

Table 7. List of fan motrs typical efficiencies 100

Table 8. Comparison between compressor types 103

Table 9. Typical EU U Values (for different climatic conditions) 127

Table 10. Impact of the energy saving measures on different types of walls 129

Table 11. Examples of how double glazing can save energy 130

Table 12. Heat losses due to infiltration 133

Table 13. Outline of the basic AC types 143

Table 14. Lamps characteristics 155

Table 15. Energy savings by using more efficient lamps 156

Table 16. World’s Best Practice Final Energy Consumption 163

Table 17. Energy requirements for the production of sawn timber 168

Table 18. Breakdown of energy use in pulp and paper making industry 173

Table 19. SEC in bricks and tiles manufacture 178

Table 20. Breakdown of energy used on cement industry 184

Table 21. Thermal Energy Balances to Produce Clinker in Process Kilns 186

Table 22. Approximate specific consumption of energy use in the glass production process 191

Table 23. Table Energy consumption allocation in pharmaceuticals 203

Table 24. SEC benchmarks in food industry- in final energy 206

Table 25. Typical Turbine Efficiencies for SHPs 226

Table 26. Typical CAPEX and OPEX costs of hydro plants 228


V

Table 27. Distribution of SHPP potential in Georgia 228

Table 28. Typical CAPEX and OPEX costs of solar PV and CSP 234

Table 29. Solar potential in Georgia (kWh/m2) 239

Table 30. Biomass key technology options 241

Table 31. Typical CAPEX and OPEX costs of biomass plants 243

Table 32. Costs of feedstock for biomass plants 243

Table 33. Biogas (methane) output from agricultural wastes 245

Table 34. Typical CAPEX and OPEX costs of biogas plants 246

Table 35. Typical CAPEX and OPEX costs for Geothermal power plants 248

Table 36. Typical CAPEX and OPEX costs for Ground source Heat pumps 250

LIST OF FIGURES

Figure 1. Losses allocation from a boiler 63

Figure 2. Condensing boiler and cross-section 64

Figure 3. Boiler Efficiency vs boiler return water temperature 64

Figure 4. Gas composition and efficiency vs excess air 65

Figure 5. View of an economiser 66

Figure 6. Furnace layout and incurred losses 70

Figure 7. Furnace efficiency versus load 72

Figure 8. Cross flow recuperative burner 72

Figure 9. Regenerative burner 72

Figure 10. CHP with steam turbine 76

Figure 11. CHP with reciprocating engine 76

Figure 12. CHP with gas turbine 77

Figure 13. Mini-CHP 78

Figure 14. The principle of an absorption cooling machine 79

Figure 15. Energy savings through CHP 81

Figure 16. Steam system 82

Figure 17. Economical thickness of insulation 85

VI


Figure 18. Typical condensate recovery system 87

Figure 19. Temperature gradient across heat transfer barriers 87

Figure 20. Mechanical vapour compression system 90

Figure 21. Vapour absorption system 90

Figure 22. Cold room heat gains 95

Figure 23. Ice bank system 96

Figure 24. Heat recovery through a de-superheater 97

Figure 25. Refrigerant leak detector 98

Figure 26. Multi stage compression & Refrigeration Cycle 99

Figure 27. Sankey diagram of the energy balance in an industrial compressed air system 102

Figure 28. Electricity transmission/distribution 107

Figure 29. Electromechanical and Electronic Meters 109

Figure 30. Motor losses 110

Figure 31. VSD beside a boiler control panel 113

Figure 32. Induction load 115

Figure 33. Power factor increase in motors 117

Figure 34. Control loop system 119

Figure 35. Weekly fabric production against energy consumption 121

Figure 36. Cumulative difference 122

Figure 37. Combustion analyser 124

Figure 38. Pinch point determination 126

Figure 39. Indicative numerical figures of heat losses from a commercial building 128

Figure 40. Layout of wall insulation 129

Figure 41. PVC double frame with thermal break 131

Figure 42. Window with rotating panel 132

Figure 43. Major components of a gas-fired LTHW boiler 135

Figure 44. Panel and column radiators 135

Figure 45. Direct gas-fired water heater 137

Figure 46. Electric water heater 137

Figure 47. Storage calorifiers fed from boiler 137


VII

Figure 48. Solar water heaters in a commercial building 140

Figure 49. Centralised air conditioning system 141

Figure 50. Packaged unit 142

Figure 51. Split systems 142

Figure 52. Chiller 142

Figure 53. Large AHU 147

Figure 54. Axial fan diagram 148

Figure 55. Centrifugal fan diagram 149

Figure 56. Cross-flow plate heat exchanger within an AHU 150

Figure 57. VSDs in a dual duct system 152

Figure 58. Incandescent lamps 154

Figure 59. Fluorescent lamps 154

Figure 60. Discharge lamps 154

Figure 61. Ceiling mounted photocell switch 157

Figure 62. Time switch compared to optimum time control 159

Figure 63. Basic BMS arrangements 160

Figure 64. VSDs application in mining industry 165

Figure 65. Efficient process heating in furnaces 166

Figure 66. Energy Conservation in the Wood-Furniture Industry 170

Figure 67. Pulp and paper manufacturing flow diagram 172

Figure 68. Paper-making machine 175

Figure 69. Ceramic brick production process 177

Figure 70. SEC for firing in ceramic industry 178

Figure 71. CHP in ceramic industry 179

Figure 72. Cement production process 182

Figure 73. Thermal and electricity SEC in clinker production 184

Figure 74. Glass production process 190

Figure 75. Glass batch preheating 192

Figure 76. Oxy-fuel furnace 193

VIII


Figure 77. SEC versus proportion of cullet in batch 194

Figure 78. Overview of plastics production process 196

Figure 79. Average SEC for plastics manufacture 197

Figure 80. Plant energy consumption in injection and extrusion 198

Figure 81. Energy use in injection moulding 199

Figure 82. Heat recovery in a bakery oven 209

Figure 83. Plastic bubble wrap insulation at north side and open greenhouse roofs 213

Figure 84. Heavy duty road transport vehicle 215

Figure 85. Maxitrans ecoFridge 217

Figure 86. Construction vehicles 218

Figure 87. Tractor with a fork-lift 219

Figure 88. Run-off river small hydro plant 221

Figure 89. Resevroir hydro plant 222

Figure 90. Powerhouse, high and medium head 224

Figure 91. Horizontal Axis Francis turbine 225

Figure 92. Double regulated Kaplan turbine 225

Figure 93. Two nozzles horizontal Pelton 225

Figure 94. Potential Hydropower Sites in Georgia 229

Figure 95. PV installation 230

Figure 96. PV principle 231

Figure 97. Installed PV capacity 231

Figure 98. The relative efficiency of alternative commercial PV modules 232

Figure 99. View of CPV tracker panels on tracker 233

Figure 100. Molten-salt power system diagram 234

Figure 101. PV modules learning curve 235

Figure 102. Typical thermo-siphon system with selective surface collectors 236

Figure 103. Vacuum tube operation principle 237

Figure 104. Vacuum tubes collector 237

Figure 105. Diagram of a solar cooling system 239


IX

Figure 106. Solar energy potential in Georgia (in average daily solar irradiation – kWh/m2) 240

Figure 107. Biomass power generation technology status 241

Figure 108. Pellets/ pellet boiler with flues gas condensation 242

Figure 109. Schematic of a biogas plant 244

Figure 110. Biogas storage facility 245

Figure 111. Biogas burner 245

Figure 112. Dry steam power plant 247

Figure 113. Flash steam power plant 247

Figure 114. Binary cycle power plant 248

Figure 115. GSHP open loop systems 249

Figure 116. GSHP horizontal and vertical ground closed loop systems 249

X


LIST OF ABBREVIATIONS

AC Air Conditioning

AC Alternating Current

AD Anaerobic Digestion

AHU Air-Handling Unit

AMT Automated Manual Transmission

ASHRAE American Society of Heating, Refrigerating and Air-Conditioning Engineers

BMS Building Management Systems

Capex Capital Expenditure

CAV Constant Air Volume (hoods)

CAS Compressed Air Systems

CDM Clean Development Mechanism

CFCs Chlorinated Fluorocarbons

CFLs Compact Fluorescent Lamps

cfm Cubic Feet per Minute

CHCP Combined Heat, Cooling and Power Production

CHP Combined Heat and Power

CO Carbon Monoxide

CO2 Carbon Dioxide

COP Coefficient of Performance

CPV Concentrated Photovoltaic

CSP Concentrating Solar Power

CUSUM Cumulative Sum

DCS Distributed Control Systems

DHW Domestic Hot Water

EBRD European Bank for Reconstruction and Development

EE Energy Efficiency

E-P Energy versus Production

ESR Energy Savings Ratio

EU European Union


XI

GDP Gross Domestic Product

GHP Geothermal Heat Pump

GT Gas Turbines

GWh Gigawatt Hour

HCFCs Halogenated Chlorofluorocarbons

HE High Efficiency

HEM High Efficiency Motor

HID High Intensity Discharge (lamps)

HRSG Heat Recovery Steam Generator

HV High Voltage

HVAC Heating, Ventilation and Air Conditioning

Hz Hertz

IRR Internal Rate of Return

kPa kilopascal

kW Kilowatt

kWe Kilowatt (Electrical)

kWh Kilowatt Hour

LCOE Levelized Cost of Energy

LPS Low-Pressure Sodium (lamps)

lt/s Litres per second

M&T Monitoring and Targeting

MWe Megawatt (Electrical)

MWh Megawatt Hour

MWhe Megawatt Hour (Electrical)

MWth Megawatt (thermal)

NPV Net Present Value

O&M Operations and Maintenance

Opex Operating Expenditure

PAR Project Assessment Report

PB Participating Bank

PLCs Programmable Logic Controllers

XII


PV Photovoltaic

R&D Research and Development

RE Renewable Energy

SCADA Supervisory Control and Data-Acquisition

SEC Specific Energy Consumption

SEC-P Specific Energy Consumption versus Production

SEFF Sustainable Energy Financing Facility

SEI Sustainable Energy Initiative

SHP Small Hydro Plant

SME Small and Medium-Sized Enterprise

SON High-Pressure Sodium (lamps)

SOx Sulphur Oxide

TDS Total Dissolved Solids

TWh Terawatt hour

USD United States Dollar

VFD Variable Frequency Drive

VSD Variable Speed Drive

VVVF Variable Voltage, Variable Frequency Drive


1

DEAR READER

Energy efficiency and renewable energy investments can be remarkably profitable, generating returns of over 25%, reducing energy consumption, cutting costs and improving an enterprise’s competitiveness and profitability. They are generally of low technical risk, can improve product quality and are fast to implement. Of wider benefit, they reduce greenhouse gas emissions and can stimulate economic activity.

This Best Practice Guide on Energy Efficiency and Renewable Energy for Businesses in Georgia is designed to help you learn more about energy efficiency and renewable energy and how they might help you to save money. This Guide is for everyone in business, not just those of you who work in industry but also those of you who manage commercial and public buildings.

This Guide has been produced by a team of experts working for the Sustainable Energy Financing Facility (SEFF) line of credit for Georgia. Financed by the European Bank for Reconstruction and Development (EBRD), the SEFF for Georgia trades under the EnergoCredit brand name (www.EnergoCredit.ge).

This Guide draws upon five years’ experience of identifying and reviewing financially viable projects for Georgian banks and therefore reflects the realities and practicalities of doing business in Georgia today. It is directed at the country’s most prominent economic sectors and contains a number of Case Studies which illustrate the team’s experience – the Case Studies are projects which have been evaluated favourably and recommended for financing.

This Guide recognises that there is little material currently available in the Georgian language on energy efficiency or the use of renewable energy. It is therefore aimed at raising awareness and constitutes a working tool for managers and engineers to assist them in the identification of Energy Efficiency and Renewable Energy opportunities in different business sectors.

2


WHO IS THIS GUIDE FOR?

This Guide is very different from previous energy efficiency-related material that you might have seen – it is driven by practical experience of real energy efficiency projects that have been implemented in Georgia and provides you with the information required not only to identify potential technical opportunities for energy efficiency measures but also to make an educated assessment of whether those opportunities are financially viable.

This Guide has been created with the following audience in mind:

Managers of private and public sector entities;

Representatives of banks, Chambers of Commerce and industry associations;

Providers of advisory services to small and medium-sized enterprises (SMEs);

Government and municipal officials and other decision-makers involved in the energy, transport and environmental sectors;

Engineers and energy managers involved in both the supply and consumption of energy;

Educational institutions, especially those providing courses for engineers and energy managers;

Journalists interested in promoting energy efficiency and renewable energy technologies.


3

HOW TO USE THE GUIDE

This Guide is presented as one book made up of five Chapters. However, it has been designed so that you don’t need to read all the Chapters sequentially, from start to finish. It has been designed so that you can quickly identify and go to the areas of most interest to you, whether you are the owner of a business, its financial director or a technical director.

The five chapters can be divided into two broad areas:

Chapter 1 contains an introduction to energy efficiency and sets out the benefits of improving your use of energy, while Chapter 2 includes a number of Case Studies which illustrate how these benefits have been captured in Georgia.

Chapter 3, Chapter 4 and Chapter 5 are more technical and are intended to be used as a reference resource for engineers and technicians. They identify the main areas where energy is wasted and set out what can be done to reduce that waste, describing the energy efficiency technologies most relevant to industries and buildings in Georgia. They also provide a framework which allows you to assess the applicability of energy efficiency and renewable energy initiatives to your business and buildings.

This Guide is also available to download as a pdf file from the EnergoCredit website (www.EnergoCredit.ge).

4


THE EBRD AND ITS SUPPORT FOR SUSTAINABLE ENERGY

The production of this Best Practice Guide was funded by the European Bank for Reconstruction and Development (EBRD), using resources from the United Kingdom Sustainable Energy Initiatives Funds, the Canadian International Development Agency, the EBRD-Special Shareholders Fund and Early Transition Countries Funds.

The EBRD is owned by 63 countries and two intergovernmental institutions (the European Union, EU, and the European Investment Bank). It was established in 1991 to provide finance to mainly private sector organisations whose needs could not be fully met by the market and thereby foster the transition towards open and democratic market economies in Central and Eastern Europe.

The EBRD provides financing to banks, industries and businesses, both new ventures and existing companies. It also works with publicly owned companies. As well as providing loan and equity finance, guarantees, leasing facilities and trade finance, the EBRD manages donor programmes which give local businesses access to consultant experts.

The EBRD currently operates in 29 countries in a region which stretches from central Europe and the Western Balkans to central Asia – it is the largest single investor in the region.

The EBRD’s Sustainable Energy Initiative (SEI) was launched in 2006 to address the twin challenges of energy efficiency and climate change in the region. Since then, it has invested €9.8 billion in 538 projects across 30 countries, with the total value of the projects equalling €55 billion1. The SEI has focused on a number of business areas: energy efficiency in the power sector, with large-scale industry and in the provision of municipal infrastructure; renewable energy; the provision of sustainable energy financing facilities through financial intermediaries; and the provision of carbon market support. Phase 3 of the SEI was launched in early-2012 – it sets a financing target for the next three years of €4.5 billion to €6.5 billion of EBRD funds with a total project value of up to €25 billion, and aims to reduce carbon emissions by 26 to 32 million tons of CO2 each year.

The EBRD’s Sustainable Energy Financing Facility2 (SEFF) is an important component of the SEI. It is a line of credit which has been specifically designed (i) to finance projects which improve the energy efficiency of commercial and industrial enterprises, (ii) to finance renewable energy projects and, (iii) in some SEFF countries, to implement energy efficiency measures in residential buildings. SEFFs are currently being implemented through about 67 local banks in 15 countries3, including Georgia where

1 Source: EBRD Sustainable Energy Initiative Factsheet, November 2012. http://www.ebrd.com/downloads/research/factsheets/sei.pdf2 Additional information on SEFFs are available on: www.ebrdseff.com3 Source: EBRD Sustainable Energy Initiative Factsheet, November 2012. http://www.ebrd.com/downloads/research/factsheets/sei.pdf


5

the EBRD’s SEFF operates under the brand name EnergoCredit. Under a SEFF, the EBRD provides credit lines to local banks that have decided to participate in the facilities. Each credit line is specifically dedicated for on-lending to industrial, commercial and residential borrowers for the implementation of energy efficiency and renewable energy investment opportunities. The local banks then use the credit lines to provide commercial loans, at their own risk, to borrowers with eligible investment opportunities.

Every credit line is supported by a comprehensive technical assistance package that underpins demand for the facility, helps potential borrowers to prepare loan applications and familiarises local bank officers with sustainable energy investment opportunities and credit appraisal methods. This assistance is provided free of charge by project implementation teams consisting of both local and international experts. These teams work together with the local banks to assess the technical eligibility of loan applications from potential borrowers. The local banks take lending decisions and the resulting financing is provided at commercial rates.

Loan amounts vary depending on the facility and the investment opportunity, but the average is about € 500,000 for loans to companies while loans to households are typically in the region of € 1,500.

In addition to the economic and environmental benefits of facilitating investment in energy efficiency and renewable energy projects, the EBRD’s SEFFs aim to transfer skills and expertise to the local markets in which they operate: not only do local bank staff become familiar with the particulars of sustainable energy investments and where to find them, but prospective borrowers also learn why sustainable energy projects make good business sense and how to finance them.

6


1. ENERGY EFFICIENCY ESSENTIALS1.1 DEFINITIONSSustainable Energy can be defined as the provision of energy such that it meets the needs of the present without compromising the ability of future generations to meet their own needs. It has two key components: energy efficiency and renewable energy.

Energy Efficiency (EE) improvements refer to a reduction in the energy used for a given service (heating, lighting, etc.) or level of activity. The reduction in energy used is usually associated with technological change, but not always since it can also result from better organisation and management or improved economic conditions in the sector (“non-technical factors”).

Energy Efficiency has a broader meaning for economists: it encompasses all changes that result in decreasing the amount of energy used to produce one unit of economic activity (e.g. the energy used per unit of GDP or value added). Energy efficiency is associated with economic efficiency and includes technological, behavioural and economic changes.

Renewable Energy (RE) is energy which comes from natural resources such as sunlight, wind, water, traditional biomass and geothermal heat, which are naturally replenished. It specifically excludes nuclear and fossil fuel energy.

1.2. BENEFITS OF ENERGY EFFICIENCY

OVERVIEWEnergy Efficiency in the industrial sector simply means producing the same output with less energy input, or a higher output with the same energy input. In effect, the amount of energy required to produce each unit of output falls, saving money.

Most of the EBRD’s countries of operation remain very energy intensive, typically with an energy intensity of more than three times the EU average (i.e. they require three times more energy per unit of GDP). This can be caused by a country’s economic structure, in particular when economic activity is concentrated in the energy intensive extractive and associated processing industries (such as mining and metals, chemicals, paper and wood products, and glass). It may also have been aggravated by the fact that previously low energy prices provided little incentive to conserve energy. In addition, it takes time for the full impact of economic transition to reach all sectors of the economy and many industries are still using out-dated equipment and technology (and they don’t have the resources to invest in new equipment).

With energy prices rising, energy efficiency investments provide the opportunity to modernise production facilities and to reduce costs – they can be considered a commercial initiative aimed at maintaining an enterprise’s profitability. At the same time, greater attention is being paid to an enterprise’s environmental impact, not only by regulators and environmental pressure groups but


7

also by investors – energy efficiency investments demonstrate commitment to reducing that impact.

For an enterprise, energy efficiency investments can result in:

Reduced energy costs, which will have a direct impact on its income statement;

Reduced exposure to fluctuations in energy prices, which allows for better planning;

Improved competitiveness, not just in the short-term in direct response to the investments, but also in the long-term as a result of changes to the enterprise’s cost structure;

An improvement in the quality and an increase in the volume of output, generating higher revenues;

Reduced CO2 emissions, improving the environment and the company’s reputation.

There are also wider benefits from energy efficiency investments:

For investors and beneficiaries, the reduction in operational costs due to increased energy efficiency is usually more than sufficient to repay any financing used to fund the investment, while the investment itself will increase the current and future competitiveness of the company;

For lenders, the well-documented savings from energy efficiency investments provide a degree of security which may allow them to offer more competitive loans;

Suppliers of energy efficient equipment face an expanding market, allowing them to increase revenues and staff numbers, thereby supporting economic development;

A country’s dependency on imported energy resources can be reduced, enhancing security of supply and meeting policy objectives;

Lower carbon emissions and reduced levels of pollution benefit the environment;

Aggregate social welfare is enhanced from reduced levels of pollution (which have a positive impact on health) and a stronger economy.

THE ECONOMICS OF ENERGY EFFICIENCY INVESTMENTSThe principal benefits from energy efficiency investments come from the reduction in electricity and natural gas costs that they can generate. The payback period for energy efficiency investments can vary widely depending on the type of project, but it typically lies between 1.5 and 6 years, which is a relatively short period compared to other capital investments – higher energy prices and higher energy savings per invested dollar can reduce the payback period. In general, the internal rate of return on energy efficiency investments is higher than the interest rate on the debt financing required for the investment. This means that any additional debt that a company uses to finance the investment has a limited impact on the company’s balance sheet, and that the ultimate financial effects of the investment is positive.

8


THE ECONOMICS OF RENEWABLE ENERGY INVESTMENTSThe principal benefit of investing in a renewable energy project is that the investment will continue to deliver cheap, clean and reliable energy for many years after the financing has been repaid. The life span of a renewable energy project can vary from around 15 years for biodiesel sets to at least 30 years for a small hydro project. Thus, if an investment is made in small hydro and the loan is repaid after seven years, the company would have more than another 20 years’ supply of reliable cheap energy to look forward to. Since many renewable energy investments have an internal rate of return significantly higher than the interest rate on the debt financing required, any additional debt that a company takes has a limited impact on the company’s balance sheet, and the ultimate financial effects of the investments are positive.

THE DECISION TO INVESTAlthough the benefits of investing in energy efficiency or renewable energy projects would appear to be clear, it is recognised that there are numerous reasons why enterprises have not made the decision to invest. The three most frequent causes of not investing are listed below:

First, companies in the early stages of their development are likely to be more focussed on investing in increasing their productive capacity and in raising revenues. As a result, they are likely to pay less attention to energy management.

Second, despite having highly qualified technical experts, technical departments are usually focussed on current operational routines which underpin a company’s output. They lack both time and human resources to conduct a systematic examination of energy efficiency issues and to investigate and carry out detailed analyses and evaluation of potential energy efficiency projects.

Third, the links between the technical, business planning and financial functions of an enterprise may be weak, as a result of which the potential benefits of energy efficiency investments may not be more widely recognised and they therefore are not included in the enterprise’s long-term financial planning.

Recognising that one of these causes has been used as a reason for not investing in energy efficiency projects should prompt an enterprise to re-examine those decisions.

1.3. STEPS TO INVESTING IN ENERGY EFFICIENCY PROJECTS

Many enterprises may believe that they can benefit from implementing energy efficiency measures, but will have little idea of where to start or how to proceed. There are numerous technological possibilities (see Chapter 3, Chapter 4 and Chapter 5 of this Guide), the implementation of which can lead to dramatic improvements in energy efficiency. However, it should be remembered that there are also other non-technological solutions (such as improvements to an organisation’s systems or logistical and managerial structures). To identify the optimal investment (or combination of investments), an enterprise needs to understand how it currently uses energy, the links between its operations and energy use, and the efficiency with which it uses energy. It also needs to know


9

where it wants to be in the future (not only in terms of its energy efficiency but also in terms of its corporate strategy). An enterprise can therefore be faced with a multitude of possible energy efficiency investment opportunities – these could include the replacement of existing boilers, the redesign of lighting systems, improving thermal insulation or the commissioning of renewable energy sources, as well as modifications to the way in which the enterprise operates or monitors and manages its use of energy.

The three key steps that are typically followed by enterprises as they investigate and try to exploit energy efficiency investment opportunities are summarised in the figure and described in greater detail below:

Energy AuditData CollectionData Analysis

Identification of Possible ProjectsAssessment of Possible ProjectsIdentification of Viable Projects

Implement Viable EE Projects

Manage and Monitor Energy Use

THE ENERGY AUDITAn Energy Audit is “a study to quantify cost-effective energy-saving opportunities in a building, process, manufacturing unit, piece of equipment or site over a given period of time”. It is made up of a number of steps:

Data collection, involving the gathering of basic data on energy use, preferable for specific areas which could benefit from the implementation of energy efficiency measures (for example, individual buildings or parts of a manufacturing process, or the heating or lighting circuits within a building);

Data analysis, the analysis of that data in order to identify the main areas of energy use and those areas where energy may be used relatively inefficiently, and to provide a focus for investigating energy saving opportunities;

The identification of possible energy saving investments, based on the results of the data analysis and involving the creation of technical and non-technical solutions to reduce inefficient energy use – this could involve a wide range of people within the enterprise, not just the technical experts;

10


The assessment of those projects, in order to determine their viability (which could be defined in terms of percentage reduction in costs, return on investment, NPV of the investment or payback period). The assessment process could also consider the wider costs and benefits to the enterprise of the investment, including any improvements to productivity or quality of product, reductions in greenhouse gas emissions, health and safety issues, and changes in the enterprise’s relations with the public, its employees or its shareholders. The assessment process is aimed at providing decision-makers with the information required to make the final investment decision.

The identification of the most viable project(s), drawing upon the results of the assessment process. The assessment process should allow the possible projects to be prioritised, which will facilitate the implementation of the most promising projects.

Carrying out regular Energy Audits is an important part of any enterprise’s efforts to manage its use of energy, the results from which can be used to identify the most promising energy efficiency investment opportunities.

PROJECT IMPLEMENTATION

The implementation of the most viable energy efficiency investments generated as a result of an Energy Audit can, depending on the nature of the investment, involve a wide cross-section of people or departments within an enterprise – they can range from a purely engineering-based change to an enterprise’s operations which affects only a manufacturing process to a change in management structure which crosses all parts of the enterprise. However, the investments can deliver a number of different inter-related benefits, such as:

Financial benefits, particularly in terms of reduced costs or increased profits;

Operational benefits, including improved productivity, comfort and safety, and security of energy supply;

Environmental benefits, such as sustainability, conservation of resources and emissions savings including greenhouse gas reductions.

MANAGEMENT AND MONITORING

The management and monitoring of an enterprise’s use of energy should be considered a key component of the management of its overall costs. They are also the means by which an enterprise can determine the effectiveness of energy efficiency investments, and whether targets for energy use have been met (allowing corrective action to be taken if not).

Energy Management can be defined as making the best possible use of the energy consumed by an enterprise through the implementation of an Energy Management System. An Energy Management System can include, inter alia, the establishment of relevant policies, procedures, action plans and targets for energy use; the creation of management structures and chains of responsibility for achieving energy efficiency savings; the provision of staff training, raising their awareness of and motivating them to save energy; and the installation of monitoring and data collection systems.


11

Energy Monitoring involves the regular recording of energy consumption and cost, and of the principal variables, such as outside temperature and occupancy, which affect them. It allows essential information on energy performance to be provided at the right time and in a useful form to those responsible for its control. Monitoring should be considered a continuous process, principally to ensure that there remains an incentive to improve. When use to determine the effectiveness of an energy efficiency investment, it can take place at the component, equipment or process level, depending on the nature of the investment.

1.4. ENERGY EFFICIENCY INVESTMENT OPPORTUNITIES

There are generally a number of opportunities to improve energy efficiency within any enterprise. These opportunities will differ in terms of the size of the required investment and in the rate of return achieved, and they may take different approaches – for example, technological or non-technological. However, if carefully identified, planned, financed and executed, they will make an enterprise more competitive, more profitable and more stable (in addition to there being other potential benefits).

However, it must be noted that all investments should be considered on their merits and that a strong interest in energy efficiency investments will not necessarily mean that those investments will be profitable and should be pursued. As the first step in assessing whether you should investigate energy efficiency investment opportunities in greater detail, you should answer the following questions:

Is your energy consumption and are your energy costs significant? For example, the value of the annual energy savings for enterprises which secured funding for energy efficiency investments under the EnergoCredit scheme ranged from a minimum of USD 26,000 to a maximum of USD 1.033 million, with a median value of USD 127,000.

Is your existing equipment outdated? For example, does it date from the Soviet era and is your enterprise continuing to deal with Soviet legacy issues;

Are there opportunities to improve the volume or quality of your output? Can you use the opportunity of investing in energy efficiency improvements to change / update your production processes in order to increase the volume of your output or improve its quality at the same time.

Are your buildings and production processes controlled manually? The introduction of automated monitoring and control systems is one of the most over-looked but can be one of the most effective means of improving use of energy.

If you can answer “yes” to all of these questions, then you should definitely investigate opportunities for energy efficiency investments in greater detail.

If you cannot answer “yes” to all of these questions, then there is less potential for energy efficiency investments being worthwhile. For example, if you have significant energy costs (“yes” to the first question) but have already invested in new equipment (“no” to the second question), additional investment is unlikely to be worthwhile.

12


A detailed technical description of possible energy efficiency measures and renewable energy opportunities is included in Chapter 3, Chapter 4 and Chapter 5 of this Guide. These Chapters also identify the key sectors where energy efficiency opportunities are likely to be found.

In order to help you identify the type of energy efficiency interventions which are most likely to generate savings in your enterprise’s area of activity, the results of the analysis contained in Chapter 3, Chapter 4 and Chapter 5 are summarised in the matrix below – this shows the most promising energy efficiency interventions by economic sector, and sets out the extent of the potential savings.

Sector

Energy Efficiency Intervention

Process-Specific Energy Efficiency Measures

Control Systems

Use of VSDS in Motors, Fans and Pumps

Energy Efficient Lighting

Mining and Metals Processing

25%-50% - Heat Recovery in Furnaces

5%-15% - Furnace Automation Systems

10%-30% 30%-60%

Wood Processing

30% - Improved Dust Collection System Efficiency

Up to 20% 30%-60%

Pulp and Paper

10%-50% - Heat Recovery from Pulp and Paper Drying Process

10%-20% - CHP up to 20% - Energy Efficient Boilers

C. 10% - Advanced Dryer Controls 5%-10% - Instrumentation and M&T Systems

10%-20%

Ceramic Brick Production

Up To 50% Reduction in Heat Losses Due to Better Design of Kilns

Up to 20% - Heat Recovery from Kilns 10%-20% - Cogeneration up to 10% - Optimising Drying Process

5%-10% 10%-30%

Cement Production

15%-40% - Switching from Wet to Dry Cement Process

3%-8% - Automatic Kiln Operations

10%-30%

Glass Production

20%-45% - Use of Oxy-Fuel Furnaces

12%-25% - Cullet/Batch Preheating

30%-60%


13

Sector

Energy Efficiency Intervention

Process-Specific Energy Efficiency Measures

Control Systems

Use of VSDS in Motors, Fans and Pumps

Energy Efficient Lighting

Plastics Processing

Up to 60%-80% - Use of Gas-Fired Dryers (As Opposed to Electrical)

25%-50% - EE Measures in Injection Moulding Process

Up to 50% Centralised Hydraulic System up to 50% - HVAC System

Up to 45% in Injection Moulding Machines

30%-60%

Pharmaceuticals40%-55% - Membranes for Water / Wastewater Separation

40%-60% - EE in HVAC, Including Heat Recovery Systems

5%-10% - Energy Management System

30%-60%

Food and Beverage Processing

5%-30% - Process Heat Recovery up to 30% - Energy Efficient Ovens

10%-30% 30%-60%

Agriculture

Up to 50% - Heating and Ventilation

10%-30% - Farm Equipment

10%-20% 30%-60%

Heavy Transport and Farm Equipment

Up to 15% - Reducing Aerodynamic Drag 10%-15% - Replacing Engines 5%-10% - Use of Lightweight Materials

Up to 8% - Tyre Pressure Monitoring Systems

Key:

Maximum savings: Up to 20%>20% and

<30%>30% and

<50%>50%

The experience of the last five years of operating EnergoCredit has identified a number of key types of investment which have consistently been found to be profitable. As a means of further helping you to identify potential energy efficiency investments, or the areas which you should first consider, these are listed below:

14


Type of Investment Potential Savings

Lighting:

�� Replacing Old Lamps with More Efficient Modern Ones

�� Redesign Lighting Systems

�� Installing Lighting Control Systems

15%-40% Electricity Savings

Buildings:

�� Improving Thermal Insulation

�� Replacing Windows and Doors

�� Installing Heating and Lighting Control Systems

�� Replacing Boilers, Pumps and Fans

10%-30% Fuel Savings; 20%-40% Heat Savings; 5%-20% Electricity Savings; 5%-10% Water Savings; 5%-15% O&M Cost Savings.

Utilities:

�� Repairing or Replacing Old and Defective Pipes and Pumps

�� More Closely Matching Pump Size to Load

�� Installing Variable Speed Drives and Control Systems

20%-40% Electricity Savings; 5%-20% Water Savings; 10%-30% O&M Cost Savings.

Industries:

�� Replacing Old Gas Boilers with New Condensation Boilers

�� Upgrading Steam Distribution and Delivery Systems

�� Utilising Process Heat

�� Installing Modern Cooling Systems

�� Using Variable Speed Electric Engines

10%-30% Savings in Thermal and Electrical Energy; Reduced Heat Losses; Lower Fluid Losses (Generates Air, Water, Gas and Electricity Savings); Improved Equipment Efficiency (Generates Electricity, Heat and Fuel Savings)

Renewable energy sources:

�� Geothermal Energy

�� Wind Power

�� Water Power

�� Solar Energy

�� Biofuels

IRR of 15%-75% Achievable.

Cogeneration:

Through the Use of Four Technologies:

�� Classical Steam Cycle

�� Combined Cycle Gas Turbines, With Capacity of 20MW-

�� Gas Turbine Plus Heat Recovery Boiler, 3MWe-40MWe Capacity

�� Reciprocating Engine Plus Heat Recovery Systems.

Substantial Financial Benefits due to lower electricity and heat production costs, but generally only economically viable if the simultaneous heat and electricity demand exceeds 6,500 hours/year. However, cogeneration can increase combined efficiency to 85% as opposed to an average of about 66% that would otherwise be achievable.

CASE STUDIES

15

2. CASE STUDIES

THE CASE STUDIESThe Case Studies included here are examples of energy efficiency projects that were screened by the GEEP Team and found to be eligible for a loan from the participating banks – the savings made from implementing the projects were found to be sufficient in themselves to repay the loans. However, for various reasons, some of the projects were not implemented – these are identified in the Table below.

LIST OF CASE STUDIESEE in industry

1. Installing a New Boiler and Steam Control System in a Juice Factory*

2. Redesigning and Replacing a Dairy Factory’s Refrigeration System*

3. Modernising a Refrigeration Warehouse

4. Installing New Energy Efficient Telecommunication Racks

5. Installing New Production Equipment at an Ice Cream Factory

6. Replacing Stone Crushing Equipment at a Mine

7. Replacing a Mine’s Dumper Trucks

8. Reconfiguring a Sugar Producer’s Electricity and Steam Supplies*

9. Improving Grain Loading / Unloading Facilities

10. Constructing a New Flour Mill

11. Replacing Old, Oversized Pumps at a Mining Company

12. Replacing Old Pumps for a Water Utility

13. Replacing Boilers and Improving Steam Control Systems at a Sugar Producer*

EE in buildings

14 Installing Energy Saving Systems at a University Building*

15. Incorporating Energy Efficiency Measures in the Design of a New Hospital Clinic

16. Installing a New Gas-Fired Boiler at a School

17. Installing a New Boiler and Improving Thermal Insulation at a Hospital Building

Renewables

18. Rehabilitating a Small Hydro Power Plant

19. Installing a Biogas System at a Poultry Farm*

20. Rehabilitating and Expanding a Small Hydro ProjectNote: * Projects screened by the GEEP Team and found to be eligible for a loan, but not implemented.

16


INSTALLING A NEW BOILER AND STEAM CONTROL SYSTEM IN A JUICE FACTORY

MEASURES WERE EXPECTED TO SAVE ENERGY AND REDUCE COSTSThe factory was established in the 1980s and has a production capacity of about 3,500 tons/year of concentrated fruit juice (mainly apple juice), all of which is exported to Europe under various long-term agreements. Energy accounted for a high proportion of production costs as a result of:

The continued operation of an old, inefficient steam boiler, which consumed large quantities of natural gas;

The use of an “open loop” steam circuit, which resulted in a substantial loss of steam in the production process;

The absence of any metering or control equipment in the plant;

Deteriorated pipe insulation, which caused significant heat distribution losses.

Under these conditions, the factory was consuming about 1.1 million m3 of gas per year, at a cost of around USD 520,000.

Energy Efficiency experts carried out an Energy Audit at the Company to identify key areas for energy efficiency measures. They recommended the installation of a new boiler and a new steam control system, and the closure of the “open loop” steam circuit. The recommended investments were expected to reduce gas consumption to about 800,000 m3/year, cutting costs by about 25% (saving some USD 130,000/year). However, the recommendations were not implemented.

CASE STUDIES

17

The Company

Main activities Fruit Juice Production

Region Gori, Georgia

Project Goal and Main Investments

Project goals

Main investments

back to the boiler

Investment size Approximately USD 300,000

Expected Results

Operational results

2 savings = 531 tons/year

Investment profitability

18


REDESIGNING AND REPLACING A DAIRY FACTORY’S REFRIGERATION SYSTEM

FACTORY WAS EXPECTED TO REDUCE ELECTRICITY COSTS BY ABOUT USD 40,000/YEARThe factory was designed in the 1970s to produce about 300 tons/year of dairy products (milk, yoghurt and cheese) and about 1,200 tons/year of ice cream. The factory consumes about 1.4 GWh/year of electricity, at an annual cost of USD 81,000.Energy Efficiency experts were deployed to carry out an Energy Audit of the factory. They found that it had a very high specific energy consumption, mainly because:

The factory was operating an old, inefficient ammonia-based refrigeration system; There was an imbalance in refrigeration capacity between shock freezing and post-production

storage;

No metering and control equipment had been installed in the plant. As a result, the operational parameters of the refrigeration equipment (e.g. temperature set-points) and its distribution system (e.g. ammonia leakage detection system, state of insulation) were not operating optimally.

In order to improve the plant’s energy performance, the Energy Efficiency experts recommended: Splitting refrigeration capacity between that used in production and that used for storage; Replacing the existing ice cream production line with a new, modern one; Replacing the shock freezer used in the production line; Replacing the storage freezing cells.

These investments were expected to halve electricity consumption, to around 700 MWh/year, and reduce costs by about USD 40,000/year. In addition, the replacement of the out-dated and inefficient equipment was expected to reduce O&M costs by about USD 30,000/year. However, the recommendations were not implemented.

CASE STUDIES

19

The Company

Main activities Ice cream, milk and yogurt production

Region Kutaisi, Georgia


Project goals

Main investmentscells


Expected Results

Operational results


20


MODERNISING A REFRIGERATION WAREHOUSE

ELECTRICITY CONSUMPTION IS HALVEDThe company was established in the 1990s and offers its customers refrigerated storage space in warehouses that date from the Soviet era. As part of its plans to expand its operations and construct a new refrigerated warehouse, the Company also wanted to modernize its existing facilities. Energy consumption in the old refrigerated warehouses is significant and accounts for a substantial proportion of the company’s operating costs (4.75 GWh/year at a cost of USD 265,000), principally because:

The old, inefficient refrigeration system uses ammonia as a refrigerant, which is expensive and toxic;

The compressor motors are oversized;

The central plant can only operate at one temperature, while storage temperature requirements vary;

The external surfaces of the warehouses are poorly insulated.

The existing refrigerated warehouse consists of eight 1,000 ton capacity refrigeration cells, each capable of storing products at temperatures of 0°C to -25°C. The proposed new refrigerated warehouse will include a new enhanced efficiency refrigeration system with well-insulated external cell walls, and individual refrigeration modules in each cell. Refrigeration is achieved through the use of a standard vapour-compression refrigeration cycle with R404 acting as the working refrigerant fluid. Cells that store goods at 0°C require two refrigeration units, while cells that store goods at -25°C require four. The installation of the new system is expected to halve energy consumption, reducing costs by some USD 135,000/year.

CASE STUDIES

21

The Company

Main activities The provision of refrigerated storage

Region Poti, Georgia


Project goals

Main investments

material and low heat-loss doors

modular units running on R404 in each cell

temperatures

Investment size Approximately USD 1.0 million

Expected Results

Operational results

GWh/year)

to meet customers’ requirements



22


INSTALLING NEW ENERGY EFFICIENT TELECOMMUNICATION RACKS

TELECOMMUNICATIONS COMPANY REDUCES ENERGY COSTS BY USD 50,000/YEAR The company offers fixed line telephone services in certain areas of Tbilisi and is also an internet service provider. It has the capacity to serve around 120,000 connections. At present, it operates an old digital telecommunication system of 40 racks which have an installed electrical capacity of 45 kW – these are installed in eight separate equipment rooms scattered throughout the company’s operating area. All the electricity consumed by the electronic racks is transformed into heat, which needs to be removed – the company’s equipment rooms are cooled by old, inefficient air-conditioning units which only add to its overall energy consumption.

In upgrading its telecommunication equipment, the company has installed eight new electronic racks – these consume only 5 kW of electricity (about 88% less than the existing racks) and are compatible with the rest of the telecommunication equipment used by the company.

CASE STUDIES

23

The Company

Main activities Fixed telephone lines and internet services

Region Tbilisi, Georgia


Project goalsservices

Main investments racks with more energy efficient ones which are also more reliable


Expected Results

Operational results



24


INSTALLING NEW PRODUCTION EQUIPMENT AT AN ICE CREAM FACTORY

FACTORY CUTS ENERGY CONSUMPTION BY 37% AND SAVES USD 46,000/YEAR This ice cream factory produces 1,600 tons/year of ice cream and supplies 20%-25% of national demand. The factory plans to upgrade existing production facilities during the winter (the season when demand is low), replacing the ice cream mixture preparation, boiling and cooling units in time for production to restart in the spring.

An Energy Audit was carried out in order to identify key areas in which energy use could be improved. Energy consumption and the associated costs were found to be higher than best practice because:

The ice cream mixture preparation, boiling and cooling equipment is old and inefficient;

The gas-fired ovens for wafer cups production are old and manually controlled;

The electrical MV/LV substation contains old and out-dated equipment.

The Energy Audit recommended that the ice cream mixture preparation, boiling and cooling equipment should be replaced completely – this would cost about USD 245,000 but would reduce energy consumption by 37% and operating costs by about USD 46,000/year.

CASE STUDIES

25

The Company

Main activities Ice cream production

Region Gurjaani, Georgia


Project goals

Main investmentsequipment


Expected Results

Operational results



26


REPLACING STONE CRUSHING EQUIPMENT AT A MINE

THE MINE CUTS AGGREGATE ENERGY AND O&M COSTS BY USD 700,000/YEAR This mining company is a major exporter and a leading contributor to Georgia’s balance of payments. However, its production facilities were installed in the 1970s and now are old and inefficient.

The company intends to upgrade its equipment and decided to examine the potential for financing the works through energy savings. Energy Efficiency experts carried out a detailed Energy Audit of the company’s facilities and recommended modifying and improving the stone crushing process.

Stones are currently reduced to about 25mm in size before being grounded to powder. The Energy Efficiency experts recommended the introduction of an additional stage into the crushing process, during which stone size would be reduced to 10-12 mm before the stone was pulverized. The cost of the new stone crushers was estimated at USD 2 million, but they would reduce energy consumption by 18-20% and maintenance costs by a further 18%, saving the company some USD 700,000/year.

CASE STUDIES

27

The Company

Main activities Copper and gold mining

Region Bolnisi, Georgia


Project goals

Main investments

Investment size USD 2.0 million

Expected Results

Operational results


28


REPLACING A MINE’S DUMPER TRUCKS

REPLACING THE EXISTING DUMPERS WITH NEW MODELS SAVES MINE USD 420,000/YEAR This mining company is a major exporter and a leading contributor to Georgia’s balance of payments. However, its production facilities were installed in the 1970s and now are old and inefficient.

The company intends to upgrade its equipment and decided to examine the potential for financing the works through energy savings. Energy efficiency experts carried out a detailed audit of the company’s equipment and recommended replacing five old dumper trucks with new, modern models.

The new dumper trucks cost USD 1.85 million but would reduce diesel consumption by 31% and maintenance costs by 44%, generating annual savings of about USD 415,000.

CASE STUDIES

29

The Company




Project goalsefficient and reliable equipment

Main investments


Expected Results

Operational results



30


RECONFIGURING A SUGAR PRODUCER’S ELECTRICITY AND STEAM SUPPLIESSUGAR PRODUCER SAVES USD 73,000/YEAR BY REDESIGNING ITS ELECTRICITY AND STEAM SUPPLIES The company is one of the largest sugar producers in the Caucasus region and is the only sugar producer in Georgia. Its factory at Agara supplies some 60% of the local market as well as exporting sugar throughout the region. The company wanted to completely replace the old on-site steam and electricity generation system that dated from the 1970s. Energy Efficiency experts carried out an Energy Audit of the company’s facilities and recommended:

The company abandon its existing gas-fired steam turbines and connects directly to the local high voltage (HV) network at a higher voltage, keeping a diesel-fuelled generator as back-up. This would improve reliability of supply and allow the production process to be run down safely in the event of a network power cut;

The installation of new steam boilers whose capacity matches the demands of the production process.

The measures would cost USD 3.24 million, but reduce gas consumption by almost 45%. The investment would also significantly improve specific energy consumption: steam and electricity used per ton of sugar produced would fall by 30% and 20% respectively. In addition, the investment was expected to show an IRR of over 50%. However, the recommendations were not implemented.

CASE STUDIES

31

The Company

Main activities White sugar production

Region Agara, Georgia


Project goals

Main investments


Expected Results

Operational results reduced from 81 kWh to 65 kWh, and from 1.7 t to 1.2 t respectively

2 savings = 13,500 tons/year


32


IMPROVING GRAIN LOADING / UNLOADING FACILITIES

GRAIN IMPORTER SAVES OVER USD 49,500/YEAR

In the past, Georgia has been a net exporter of grain. However, with the agricultural sector under severe pressure, the country has recently become a net importer of grain.

This company is one of Georgia’s biggest grain importers, supplying about 35% of the grain import market. It owns a grain storage elevator (silos) and flour mill in the Poti port area. However, the facilities were built in the 1940s and have now become out-dated and very inefficient.

The company plans to rehabilitate its loading/unloading facilities and exploit potential energy saving opportunities. The investment includes:

The replacement of existing loading/unloading equipment, and the construction of a new conveyer belt gallery;

The procurement of a new locomotive as a back-up mode of transport.

The total cost of the work and equipment was estimated at about USD 290,000 and it is expected to reduce energy consumption by 35%.

CASE STUDIES

33

The Company

Main activities Grain and oil seeds trading and milling



Project goals unloading facilities

Main investments


Expected Results

Operational results2 savings = 336 tons/year


34


CONSTRUCTING A NEW FLOUR MILL

GRAIN IMPORTER REDUCES ENERGY COSTS BY USD 200,000/YEAR

In the past, Georgia has been a net exporter of grain. However, with the agricultural sector under severe pressure, the country has recently become a net importer of grain.

One of biggest grain importers, with about 35% of the grain import market, owns a grain storage elevator (silos) and flour mill in the Poti port area. However, the facilities were built in the 1940s and have now become out-dated and very inefficient.

The company plans to expand its operations by milling imported grain in its own mill in Poti, either exporting the resulting flour or selling it the domestic market. It plans to demolish the existing flour mill and replace it with a new one. Energy Efficiency experts reviewed the proposed project and made a number of recommendations which would reduce electricity consumption by about 30% (saving about USD 200,000/year).

The total cost of the new flour mill was estimated at USD 1.0 million.

CASE STUDIES

35

The Company

Main activities Grain and oil seeds trading and milling



Project goals competitive product

Main investments


Expected Results

Operational results



36


REPLACING OLD, OVERSIZED PUMPS AT A MINING COMPANY

MINING COMPANY SAVES USD 54,000/YEAR IN ENERGY COSTS

This mining company is a major exporter and a leading contributor to Georgia’s balance of payments. However, it started operations in the 1970s and its production facilities and associated equipment have now become old and inefficient.

The company intends to upgrade its equipment and decided to examine the potential for financing the works through energy savings. Energy efficiency experts carried out a detailed audit of the company’s equipment and recommended replacing its old Soviet era pumps with four new, more efficient pumps.

The cost of the new pumps was estimated at about USD 250,000, but were expected to reduce energy consumption by 44% (1,160 MWh/year), saving the company some USD 54,000/year.

CASE STUDIES

37

The Company




Project goals

Main investments

Investment size USD 250,000

Expected Results

Operational results2 savings = 463 tons/year


38


REPLACING OLD PUMPS FOR A WATER UTILITY

WATER UTILITY SAVES ENERGY AND IMPROVES WATER SUPPLY SERVICEThis utility supplies water to a large city in Georgia. It has embarked upon a major rehabilitation program to improve its water supply system, network, pumping stations and reservoirs in order to reduce operating costs and to improve the quality and continuity of water supply.

The utility currently operates more than 80 pumping stations and consumes around 300 GWh of energy per year. The utility processes 1.6 million m3 of water per day for the city’s inhabitants. The large number of pumping stations is attributed to the hilly ground profile of the city. This, along with the use of old, inefficient pumps and high levels of leakage, has substantially increased the utility’s use of energy.

The project involves the replacement of old pumps with new, more energy efficient ones and the installation of automatic control systems. The existing two pumps have a total capacity of 2,320 m3/h and 915 kW but do not provide water around the clock. In order to optimise water pressure and provide water 24 hours per day, these will be replaced with three modern pumps, equipped with Variable Speed Drives, with a total capacity of 1,860 m3/h and power of 575 kW. Their installation is expected to reduce energy consumption by about 48% (saving about USD 210,000/year).

CASE STUDIES

39

The Company

Main activities Water supply



Project goalsday

Main investments efficient pumps with Variable Speed Drives


Expected Results

Operational results

pressure

0.21 kWh/m3



40


REPLACING BOILERS AND IMPROVING STEAM CONTROL SYSTEMS AT A SUGAR PRODUCER

FACTORY WOULD SAVE USD 2.65 MILLION/YEAR

The company is one of the largest sugar producers in the Caucasus region and is the only sugar producer in Georgia. Its factory at Agara supplies some 60% of the local market as well as exporting sugar throughout the region.

The company wanted to completely replace the old steam generation facilities on the site. Energy Efficiency experts carried out an Energy Audit of the company’s facilities and recommended installing new more efficient boilers to supply process steam at a lower temperature and a more consistent pressure. They also recommended making improvements to the steam condensate return circuit and to the instrumentation and control systems.

The investment was estimated to cost USD 2.1 million but would reduce natural gas consumption by 8 million m3/year, reduce energy costs by almost USD 2.7 million/year and reduce the volume of steam used per ton of sugar produced by 30%. However, the recommendations were not implemented.

CASE STUDIES

41

The Company

Main activities White sugar production

Region Agara, Georgia


Project goals

Main investments

superheated and high pressure steam


Expected Results

Operational results

year

one ton of sugar reduced from 1.7 t to 1.2 t



42


INSTALLING ENERGY SAVING SYSTEMS AT A UNIVERSITY BUILDING

UNIVERSITY EXPECTED TO REDUCE ENERGY COSTS BY AROUND 40%

This University in Tbilisi is a large consumer of energy. However, it found that its energy costs were increasing and becoming a more substantial drain on its resources.

It therefore decided to implement a project to improve its use of energy. This included the complete renovation of the existing building’s heating, cooling and ventilation systems using advanced energy efficiency technologies, as well as the installation of double glazing on all windows and the installation of a new Building Management System.

The investment was estimated to cost USD 550,000, but would reduce energy bills by about USD 83,000/year (about 40%). It would also contribute towards reducing Greenhouse Gas emissions, saving an estimated 420 tons of CO2 equivalent per year. In addition, students and staff would notice an improvement in working conditions, feeling more comfortable in both summer and winter, resulting in better learning condition. However, the recommendations were not implemented.

CASE STUDIES

43

The Company

Main activities University



Project goals environment

Main investments

Investment size USD 550,000

Expected Results

Operational resultsnew Building Management System



44


INCORPORATING ENERGY EFFICIENCY MEASURES IN THE DESIGN OF A NEW HOSPITAL CLINIC

CLINIC SAVES USD 20,000/YEAR IN ENERGY COSTSThe clinic was established in the 1990s in an old hospital near the centre of Tbilisi. It had a capacity of 30 beds and mainly offered cosmetic surgery and general pathology services. However, it had very poor basic facilities (poor electrical heating and lighting, no gas supply or ventilation). Therefore, in order to provide a better service to its patients and to allow it to expand, raising its capacity to 90 beds, the clinic decided to move to a modern, purpose-built facility outside the centre of Tbilisi.

Energy Efficiency experts were deployed to assist during the design process. They identified a number of measures that were included in the new building design in order to improve the clinic’s energy efficiency:

The addition of improved thermal insulation on the building envelope

The installation of energy efficient lighting with electronic ballasts

The installation of double glazing on all windows

These measures were estimated to cost about USD 140,000, but would result in energy savings of about 360 MWh/year, equivalent to USD 20,000, about 20% of projected energy consumption for a facility built following Georgian construction standards. The proposed measures would also have the effect of greatly improving the comfort of patients and staff.

CASE STUDIES

45

The Company

Main activities Clinic

Region Georgia


Project goals

Main investments


Expected Results

Operational results



46


INSTALLING A NEW GAS-FIRED BOILER AT A SCHOOL

SCHOOL REDUCES OPERATING COSTS BY USD 55,000/YEARAuthorized School #6 has been in operation since 2011. It currently has 250 pupils, but this number is expected to double in the next two years. The school is housed in a building which was constructed in 1917. In order to improve working conditions for both pupils and teachers, and to reduce costs, the school’s management decided to replace the old diesel-fired boiler with a modern, condensing, natural gas-fired boiler.

At present, the cost of diesel for the boiler comprises a significant part of the school’s operating expenses. This is due to the inefficiency of the existing boiler and has been aggravated by the rising price of diesel.

An Energy Audit conducted by Energy Efficiency experts indicated that replacing the boiler and changing the fuel supply would cost about USD 85,000. However, it would reduce energy consumption by 11%, cutting operating costs by around 35% (saving some USD 55,000/year).

CASE STUDIES

47

The Company

Main activities Education



Project goals system

Main investments


Expected Results

Operational results



48


INSTALLING A NEW BOILER AND IMPROVING THERMAL INSULATION AT A HOSPITAL BUILDING

HOSPITAL REDUCES COSTS BY ABOUT USD 150,000/YEARUnder the Government of Georgia’s health reforms, an insurance company is planning to take over and rehabilitate an existing hospital in Tbilisi. In doing so, it plans to renovate and extend the building to raise its capacity to 150 beds, investing in energy efficiency measures at the same time in order to reduce energy consumption (and thereby minimise costs).

Energy Efficiency experts carried out an Energy Audit of the company’s proposals and recommended implementing the following measures:

Insulating the building shell (using mineral-wool insulation and installing double-glazed windows);

Replacing existing boilers with enhanced efficiency boilers for heating and hot water supply;

Installing efficient refrigeration and air handling units to provide cooling and ventilation throughout the hospital building;

Installing Variable Speed Drives on fans;

Installing a Building Management System (BMS) to control and monitor the operation of the building’s HVAC systems.

These measures were estimated to cost about USD 1.2 million, but would reduce gas and electricity consumption by 37%, saving some USD 145,000/year in energy costs.

CASE STUDIES

49

The Company

Main activities Hospital



Project goals

Main investmentsand refrigeration systems

Investment size Approximately USD 1,022,000

Expected Results

Operational results



50


REHABILITATING A SMALL HYDRO POWER PLANT

ENERGY PRODUCTION DOUBLESThe company operates a small hydroelectric plant with a total capacity of 5 MW. The proposed investment involves the rehabilitation of almost all of the plant’s water supply system, as well as the rehabilitation of its electro-mechanical systems (turbines, generators and sub-station). By improving the water supply, eliminating losses and replacing the hydro turbine and power generator, the company will be able to start generating electricity again and increase energy output from designed 6 GWh to 13 GWh, thereby improve its financial position.

The work was expected to cost about USD 1.7 million. However, total electricity produced would generate income of some USD 1.4 million/year at current tariffs. At the same time, the project will reduce the country’s electricity imports by around 7 GWh, thereby helping to achieve the government’s policy objective of enhancing energy security.

CASE STUDIES

51

The Company

Main activities Electricity generation

Region Chkorotsku, Georgia


Project goalssupply system

Main investments


Expected Results

Operational results2 savings = 5,200 tons/year


valued at about USD 595,000/year

52


INSTALLING A BIOGAS SYSTEM AT A POULTRY FARM

FARM WOULD BECOME ENERGY SELF-SUFFICIENT USING BIOGAS PRODUCED FROM CHICKEN MANUREThe poultry farm has a population of around 500,000 egg-laying chickens and around 100,000 broilers. The resulting chicken manure (around 50 tons/day) is stored in lagoons on the site. The aim of the project is to make use of the chicken manure by installing a biodigester which would produce biogas that could be used in a special Combined Heat and Power (CHP) generator to supply the farm’s heat and electricity needs.

One tonne of manure fed into the biodigester produces 90 m3 of biogas with a calorific value of 6 kWh/m3. Burning this biogas in a CHP plant would generate about 2,500 MWh/year of electrical energy and 2,700 MWh/year of heat energy, making the poultry farm energy self-sufficient. In addition, no methane (which is 20 times more harmful that CO2) would be released into the environment. However, the project was not implemented.

CASE STUDIES

53

The Company

Main activities Production of chicken meat and eggs



Project goals waste

from the lagoon storage of the manure

Main investments


Expected Results

Operational results2 savings = 7,000 tons/year

Investment profitability automobiles and the remaining sludge as fertilizer

54


REHABILITATING AND EXPANDING A SMALL HYDRO PROJECT

INVESTMENT INCREASES REVENUE BY USD 1.5 MILLION/YEARThe company owns a small hydroelectricity plant that dates back to the 1940s. The plant has two sets of turbines, each with a capacity of 2.4 MW, but its turbines and electrical equipment all need to be completely rehabilitated. In an innovative move, the company decided to expand capacity by building a second plant on the same irrigation channel, thus avoiding additional environmental impacts.

The rehabilitation and expansion is expected to result in a 150% increase in capacity. The second hydro plant will have slightly less capacity than the existing plant but, together, the two projects will almost double the company’s overall electricity output (mainly due to longer operating hours as a result of increased reliability).

The company has also decided to use Chinese-produced turbines, thereby reducing equipment costs by 50%. However, in order to ensure quality control, it has been careful to choose experienced suppliers.

The Participating Bank asked an international hydro expert to evaluate the project. The resulting Project Assessment Report concluded that the investment would cost about USD 7 million but would increase revenues by around USD 1.5 million/year.

CASE STUDIES

55

The Company

Main activities Hydroelectricity plant

Region Kakheti, Georgia


Project goals while minimizing environmental impact of the expansion

Main investmentsexisting power plant) to generate more energy from the same water before it returns to the canal


Expected Results

Operational resultsreliability and fewer breakdowns



56


3. ENERGY EFFICIENCY FOR GENERAL UTILITIES AND SERVICES

Chapter 3, Chapter 4 and Chapter 5 of this Best Practice Guide describe in greater detail the technical solutions that can help you save energy, building upon the general advice contained in the previous Chapters.

The first part of this Chapter (Section 3.1) considers the broad strategic issues that businesses need to address in order to maximise the benefits associated with energy efficiency investments. The rest of this Chapter (Section 3.2 onwards) described energy efficiency investment opportunities by type of energy use (i.e. those measures which can be applied across different industries), while Chapter 4 considers the most promising opportunities by business sector and Chapter 5 considers the use of renewable energy resources.

3.1. STRATEGIC ISSUES AFFECTING ENERGY USE

When businesses start to examine their use of energy and, in particular, when they start to consider investing in energy efficiency measures, they all need to consider a number of key strategic energy-related issues. These issues are particularly important for new factories and buildings, which are not constrained by previous decisions and which can therefore act to minimise their future use of energy. However, for many businesses in Georgia, the manner in which they currently deal with energy-related issues and their ability to act to minimise future use of energy are constrained by past decisions. In particular, their current position may be due to:

Soviet legacy problems;

Failure to alter the way in which they are supplied with energy following changes to the volume or type of their output over the years;

Failure to replace equipment at the end of its life, and the lack of modern control, automation and instrumentation systems;

Failure to adopt modern energy management techniques, which has prevented them from being able to act to minimise their energy costs.

Given the current cost of energy and expectations that such costs are not going to fall, as well as the contribution of energy to overall business costs, many businesses now need to explicitly review the assumptions and decisions which underpin their current position. This may result in businesses being forced to consider significant changes to the way in which they operate and manage their demand for energy, but it does not necessarily involve significant costs.

Some of the key strategic issues that need to be considered both when upgrading or expanding an existing business and when planning a new business are:

Should heat and power be supplied separately or together?

Does the business need to use steam or could it switch to hot water, and can any of the waste heat used in its processes be recovered?


57

How can security of supply be ensured?

Should the business change fuel?

Could the business save money by changing the voltage at which it is supplied with electricity, or changing its supplier?

Can the business better manage its demand for energy?

Should a business secure energy from a central source or from individual sources for its different locations?

Could renewable energy resources be used to at least in part meet demand?

These issues are considered in greater detail in the rest of this Section.

3.1.1. HEAT AND POWER SUPPLIED SEPARATELY OR TOGETHER?

In most circumstances, in particular in or near larger towns in Georgia, businesses can purchase both their electricity and their gas supplies from a local utility company, whose supply will generally be cheaper and more reliable than self-provision. Purchasing energy from the local utility has the additional benefit that the business does not need to maintain any facilities.

However, for companies with large heat and power loads, especially for steam, it may be more convenient for them to generate the heat at the same time as producing electricity. This will depend on the size of both loads and whether the peak loads occur at the same time of day (or week or year). The technology is usually referred to as Combined Heat and Power (CHP) or cogeneration, and usually consists of steam boilers and turbines, or on a smaller scale, diesel or gas engines with heat recovery (more details on these technologies are found in Section 3.2).

In considering these options, a business must evaluate all of the costs (including the capital, the fuel and the O&M costs) of self-providing power and heat, and assess the differences in the reliability of supply between self-provision and being provided with energy by the local utility.

3.1.2. STEAM - OR HOT WATER-BASED SYSTEMS AND HEAT RECOVERY

In order to achieve desired heat levels, some industries need to use steam in their processes and therefore have to have steam boilers and distribution systems. Other industries, which do not need a similar quality of heat or heat supplied at as high a temperature, can use hot water-based systems (which can be cheaper to operate as there is no loss of water due to loss of condensate and blow-down, and there is no need for the water to be treated on a continuous basis). The opportunities to switch between steam-based and hot water-based systems are therefore limited, and will be dictated by the demands of the industrial processes.

However, in most cases (and this is particularly true in Georgia), industries can reduce their energy-related costs by modernising their systems, in particular by focussing on improving insulation, reducing steam leaks, correctly operating steam traps and improving condensate return (these measures are discussed in greater detail in Section 3.2.4).

58


An additional, and important, way of saving energy in steam- and hot water-based systems is to recover waste heat from processes and use it to preheat or precool input materials in other parts of the process. These “secondary” heat sources can be found in many places in buildings or industrial processes:

Heat from flue gases, which can be used to preheat feed water (e.g. by using economisers in steam boilers) or incoming air for combustion;

Water vapour in flue gases can be condensed and used to preheat the water being heated in boilers;

Heat can be recovered from the air and water used for cooling purposes, and recycled for heating or cooling elsewhere (e.g. from freezers in supermarkets);

The mixing of extract air and fresh air in ventilation systems, where energy can be exchanged between the two air streams (e.g. in kitchen ventilation systems);

Heat recovery from hot to cold streams can be tackled integrally within process integration techniques.

3.1.3. SECURITY OF SUPPLY

Ensuring security of supply will require a business to have at least two alternative energy sources in case one of them is disrupted. Common ways in which companies can enhance their security of supply include:

Dual fuel burners for boilers (e.g. gas and oil);

Dual pumps in water distribution systems within centrally heated (or cooled) systems;

Two separate connections from different parts of the gas or electricity supply network;

Diesel-fired standby generators for power cuts;

Battery backup supplies with trickle chargers for fire alarms.

The degree to which a company is prepared to invest in backup facilities will depend on a number of factors, including the level of security required, the likelihood of failure, and the impact of that failure.

3.1.4. CHANGING FUELS

Energy markets have changed so much in recent years that a company’s decision about which fuel it should use may be totally different today from a similar decision being made 30-40 years ago. Cleaner fuels, such as gas, are much more readily available and supplies are more reliable. Boilers and engines are smaller and more efficient than in the past. More automation, data logging and the use of computerised control systems have made operations and maintenance much simpler. Environmental


59

considerations have become much more important, meaning that it can be significantly more expensive to meet required environmental standards (e.g. emission standards) if a more polluting fuel is used.

3.1.5. CHANGING VOLTAGE / SUPPLIER

In the past, driven by government social policy objectives, industrial customers as a group tended to subsidise households and other consumers. However, with the liberalisation of energy markets, greater emphasis is now placed on the need for prices to reflect the cost of providing services to specific classes of customer. Given the additional distribution network costs of delivering electricity to the smaller consumer, the tendency is now for prices to increase as voltage is decreased.

This trend has been observed in Georgia where the electricity sector is being restructured, unbundled and privatised. As part of this process, the Georgian National Energy and Water Supply Regulatory Commission was established to regulate the country’s energy sector; the majority of the sector’s generating assets have been privatised (there are no state-owned thermal generating plants); and all of the three distribution companies are majority-owned by the private sector.

In addition, limited competition has been introduced in supply. Direct consumers can buy electricity directly from suppliers. Direct consumers are currently defined as those who consumer over 7 GWh per year of electricity (there were seven such consumers in 2011), but this cap is due to be reduced – to 3 GWh in 2013-2015, to 1 GWh in 2016-2017 and to 1 kWh in 2017 as part of the further liberalisation of the market.

Given the government’s energy policy objectives and the expected further liberalisation of the market, it can therefore make sense for an enterprise:

To investigate securing its energy supplies from the public network at a higher voltage level than in the past – the cost per kWh is lower and the required current (and hence cable size) is smaller. In addition, security of supply can be enhanced – HV networks are designed to minimise the probability and consequences of a failure.

To be prepared to discuss its specific electricity needs with potential suppliers as the market is further liberalised and they become defined as “direct consumers”. The incumbent supplier may no longer be the cheapest or provide the most appropriate service for an enterprise, and that enterprise should be open to investigating other suppliers.

3.1.6. MANAGING DEMAND FOR ENERGY

The key factors that will determine an enterprise’s energy costs are the amount of energy that it consumes over a specified period (be it 24 hours, a week or a peak season) and the voltage level at which it is supplied.

Although peak load charges are not currently applied in Georgia, they are applied in a number of other countries in which the market has been liberalised. In these instances, the supplier will charge a

60


consumer according to the level of its peak demand, but will often offer a lower tariff if peak demand can be shifted to a time of the day which is more beneficial for the utility (this is because the utility must also pay higher prices for peak energy).

As the electricity market is further liberalised in Georgia, the probability of peak load charges being introduced could be expected to increase. However, it should be noted that this will require the development of time-of-day tariffs and the introduction of smart meters, both of which are likely to take some time. Nevertheless, it remains sensible for an enterprise to make the necessary strategic decisions to reduce its peak load – this could be achieved by adding insulation and shading to buildings, or by shifting operating peaks to different times of the day or week in a factory.

3.1.7. CENTRAL OR LOCAL SUPPLY

A decision over whether energy should be supplied centrally or from a number of different sources will need to be made in two instances: when a single entity is responsible for a group of buildings or industrial sites, and when there are a number of end-consumers within a single building or site.

For groups of buildings or industrial facilities under the same management

A decision about whether to have a central plant supplying all of the buildings (or industrial processes) within a single site will depend on the scale and complexity of the requirements and the cost of distribution networks (and losses) on the site. It will also depend on the extent to which heat and power loads (compressed air, gas or steam) are spread over the week or the day, and whether demand can be balanced between the various buildings and processes to minimise the overall size of the required plant.

Whatever the decision, it will be necessary for such a large consumer of energy to monitor and manage energy use at each point of demand (for example, by installing local controls, instrumentation and metering) and attempt to minimise overall energy demand. Readings can be transmitted either wired or wirelessly, allowing energy use in different parts of the complex to be monitored centrally and permitting the operator to control central and local systems according to individual or zoned requirements.

For single buildings or sites with numerous end-users requiring individual control (e.g. large offices, shopping malls, large hotels and cold storage warehouses divided into cells)

Demand for energy from individual users within a multi-occupancy building will vary considerably. For example, hotel rooms may be empty or occupied; meeting rooms may be empty or full; shopping spaces within a mall may be rented by a range of different shops with different requirements (compare a shop selling electrical equipment with a restaurant); a cold store warehouse cell may store frozen meat or fresh vegetables, or be empty. In all these cases, energy supplies to the building will need to be able to respond to changes in demand.

The presence of people will mean that ventilation needs to be provided. Some buildings are provided with central ventilation systems, as well as central water-based cooling and heating systems. However, a lot of space is needed to distribute air throughout a building and different parts of a building may


61

require different amounts of fresh air at different times. Large air ducts passing through different parts of the building can cause fire risks and be difficult to accommodate within the building structure. In addition, it may be necessary to ensure that exhaust air does not mix with fresh air supplies (e.g. to prevent smells from kitchens and toilets being passed around a building). In many cases, the best option is to provide central water-driven heating and cooling systems (which supply the whole building), and to install user-specific ventilation systems (which can be smaller, simpler and better match user-specific demands).

3.1.8. RENEWABLE ENERGY RESOURCES

A company’s decision to use renewable energy sources will depend on a number of factors, including the availability of such resources and their cost (which will also be influenced by government policy towards the use of renewables and whether and how much it will subsidise / incentivise their use).

At present, the government has not yet adopted an integrated framework for the promotion of renewables (as can be found in EU countries). Such a framework could include the following elements:

An enabling legal framework;

The establishment of targets for renewable electricity or heating;

The provision of financial and / or fiscal incentives for investment in renewables;

The adoption of medium-term feed-in tariffs for the purchase of renewable energy;

The imposition of an obligation on power companies to secure a certain percentage of their supplies from renewable sources.

Nevertheless, there are a number of renewable energy resources that businesses in Georgia could consider, including:

Solar water heating;

Passive solar space heating for buildings;

Small hydro projects (of less than 15 MW);

Industrial or agricultural waste, which can be used as a fuel, or;

Manure, which can be processed in bio-digesters to produce biogas, either to supply a local community with gas or for use in a CHP engine to provide heat and power for a company’s own use or for sale.

Other renewable energy sources, such as geothermal heat, wind energy and solar PV, are generally considered to be too expensive or unproven in Georgia (apart from in remote off-grid locations).

These technologies are described in more detail in Section 5.

62


3.2. INDUSTRIAL HEAT GENERATION AND DISTRIBUTION

This Section sets out the potential energy efficiency improvements in industrial heat generation and distribution systems. It covers the production of hot water and steam (including boiler plants, and combined heat and power plants), high temperature industrial processes (including furnaces and kilns), and steam distribution systems.

3.2.1. BOILERS

DESCRIPTION - COMPONENTSBoilers convert fossil fuel energy into hot water or steam, which is used for process heating, space heating or to supply sanitary hot water. The boiler house is very often the largest single user of energy on a site. Boilers can be categorised based on:

Fuel used: Gas-fuelled boilers have much simpler fuel intake systems than those fuelled by coal (which needs to be transported and processed before burning) and oil (which needs to be stored, pumped and, possibly, heated before burning). Biomass also needs to be processed before burning. Waste materials can also be used as fuels (e.g. waste wood from sawmills and furniture making) in a Waste to Energy system.

Steam or hot water: Two different types of boiler systems are commonly used, depending on whether they produce hot water or steam. Steam boilers require additional features to those required in a hot water boiler – to treat intake water, to produce steam (steam drums) and to remove salts deposited during steam production (blow-down).

Waste heat recovery boilers recover heat from industrial processes, whenever waste heat source is available at medium or high temperatures to produce hot water, steam or hot air to be re-used in the process.

THE EFFICIENCY OF BOILERSThe operational efficiency of a boiler is measured in terms of the proportion of the fuel input energy that is delivered as useful heat output. The diagram below illustrates typical losses that occur when generating steam. Flue gas losses are the most significant, accounting in some cases up to 20% of the total losses, while other heat losses are due to moisture in the fuel and in the air, as well as radiation and blow-down losses. In total this example shows that about 75% of heat energy created goes to steam.


63

Hot water/steam outlet(1.08kg/sec 1700 C)

Flue gas outletLossos ( at 1950 C) = 18% Minimise by trim control and sequencing

Water feed(15,50 C) Maximise return of condensate Maximise temperature

Heat transfer gas and water side losses = 2%1 Minimise by online and offline cleaning Minimise by good water treatment

Insulated chamberRadiation losses = 2% Minimise by insulation Minimise by plantgood scheduling

Water outletBlowdown losses = 3% Minimise by good water treatment Minimise blowdown heat recovery

Shell boilerefficiency 75%

Figure 1. Losses Allocation from a Boiler (Source: (1)Carbon Trust)

MEASURING BOILER EFFICIENCYBoiler efficiency tests can help identify any decline in boiler efficiency and allow corrective action to be taken. Boiler efficiency is usually assessed by analysing the chemical composition of its flue gases: too much oxygen indicates “excess air” (which wastes heat), while too much CO indicates too little oxygen and incomplete combustion (which wastes fuel).

ENERGY SAVING MEASURESThe potential for implementing energy efficiency measures will depend on the fuel used, the size and type of the installation and whether the system produces hot water or steam. However, there is potential for implementing energy efficiency measures regardless of boiler type.

BOILER REPLACEMENTIn general, companies should consider replacing an existing boiler whenever its efficiency falls below 80%. They should also consider replacing boilers over 15 years old – such boilers are unlikely to be well insulated (losses due to poor insulation may be as high as 10% in older boilers compared with under 1% for more modern boilers) or possess many modern features (such as multiple-pass flue gas heat exchangers).

USE OF CONDENSING BOILERSA condensing boiler is a high efficiency modern boiler that incorporates an extra heat exchanger so that the hot steam is condensed to water and the heat recovered is then used to pre-heat the water

64


entering the boiler system – this can increase a boiler’s efficiency by as much as 10% to 12%. Thermal efficiency of up to 98% can be achieved in a condensing boiler, compared to 80%-85% for a conventional boiler.

Over a full year (i.e. taking account of seasonal variations), a condensing boiler can achieve about 90% thermal efficiency compared to about 80% thermal efficiency for a modern non-condensing boiler.

“Plume” at flue terminal

Sealed and corrosionresistant flue

Extra caseinsulation

Extra “SECONDARY”heat exchange area

Trap

Fan (either inducedor forced draught)

Return water

“PRIMARY”heat exchanger

Flow water

Figure 2. Condensing Boiler and Cross-Section (Source: GEEP & Carbon Trust (2))

The efficiency of condensing boilers depends on the return temperature to the boilers. The Figure below illustrates this relationship:

1009896949290888684828078

20 30 40 50 60 70 80 90 100 110

Dew Point

Condensing Mode

Boile

r Effi

cien

cy (G

CV)

Boiler Return Water Temperature

Figure 3. Boiler Efficiency Versus Boiler Return Water Temperature


65

INCREASE OF FUEL COMBUSTION EFFICIENCYThe correct mixture of fuel and air is critical to ensuring complete combustion (which means that, for example, when a hydrocarbon burns in oxygen, the reaction only yields carbon dioxide and water and there are no by-products). Modern burners are designed with this in mind. Achieving a high thermal efficiency (and thereby minimising fuel costs) requires that the amount of combustion air is equal to that required to ensure complete combustion of the fuel plus a margin of “excess air” to suit the particular combination of burner and boiler. Means to increase combustion efficiency are:

AIR CONTROLToo much air is the single most important cause of poor boiler efficiency – it increases the rate at which heat is lost to the flue, thereby raising operating costs. Likewise, too little air can cause a proportion of the fuel to remain un-burnt, producing smoke and possibly causing pollution regulations to be breached – again raising operating costs. Efficient gas-fired shell boilers typically require about 15% to 30% “excess air”, and the resulting flue gases contain 9% to 10% CO2 and 3% to 5% O2. Analysing the temperature and composition of flue gases can identify flue gas heat losses, which can then be addressed by reducing “excess air” to the minimum level required. However, if the air supply to a boiler is manually controlled, this process is likely to take time and be very inefficient. The graphs below indicate the concentration of gases and level of flue gas losses in exhaust air versus the level of excess air, showing the importance of keeping combustion close to the stoichiometric ratio. Digital combustion control systems can produce energy savings of about 5% (3).

Loss due tounburnt fuel

Zone ofmax.

efficiency

Loss due toheat in stack

% Excess air Excess Air %

Flue Gas Losses %

0 10 20 30 40 50 60 70 80 90 10012131415161718192021222324

NaturalGas

Coal

Oil

Figure 4. Gas Composition and Efficiency Versus Excess Air

PRE-HEATING COMBUSTION AIRThe thermal efficiency of a boiler plant can be increased by 1% if the temperature of the combustion air is raised by 20°C. The heat required to pre-heat combustion air can be drawn from a number of sources, including the boiler’s flue gases, air drawn from the top of the boiler house, and air drawn over or through the boiler casing. Rotary wheel type air preheaters are the most common type of heat exchangers used for this purpose.

66


FORCED AND INDUCED DRAUGHTForced or induced draught systems produce better combustion rates than natural draught systems, principally because the rate at which air is forced through the combustion chamber can be more closely controlled.

USE OF ECONOMISERSFlue gas temperatures of over 200°C are a sign of a significant opportunity to recover waste heat – this can be particularly important for steam boilers with large quantities of feed water. Economisers are heat exchangers which recover waste heat from boiler flue gases to preheat boiler feed water, and hence reduce respective energy demand. As an indication of the potential savings, an increase in the temperature of feed water from 10°C to 30°C can reduce a boiler’s fuel consumption by 4%-7%.

For a modern boiler with a flue gas exit temperature of 140oC, a condensing economiser would reduce the exit temperature to 65oC and increase the boiler’s thermal efficiency by 5%. However, economisers are usually only viable for boilers with a capacity of over 3 MW.

Figure 5. View of an Economiser (source: Cain industries)

IMPROVING CONTROLS

CONTROLLING BOILER LOADINGIn instances where more than one boiler is used, the operation of each must be coordinated and scheduled to ensure that they meet demand and they can be maintained on a regular basis. The quantity and profile of steam or hot water required by a plant throughout the day and week should be reviewed frequently, and the most efficient number of boilers required to meet this demand should be determined. This will involve balancing the fact that the optimum efficiency of a boiler occurs at about two-thirds of its full load, with the fact that boiler efficiency falls significantly if it operates under 25% of its full load. In many cases, therefore, it is more efficient to operate a smaller number of boilers at higher loads, than to operate a large number of boilers at lower loads.


67

Installing a Boiler Sequence Control system can generate significant fuel and energy savings in the operation of multi-boiler plant installations. These are fully automatic, microprocessor-controlled systems which monitor and sequence on/off operations of boilers and associated equipment according to steam or hot water demand.

REDUCTION OF BOILER STEAM PRESSURESteam is generated at a pressure which is normally determined by the highest pressure and temperature requirements of the specific process in which it is to be used. However, reducing these temperatures and pressures to as low a level as possible is an effective means of reducing fuel consumption (which can be cut by as much as 1% to 2%).

VARIABLE SPEED CONTROL FOR FANS, BLOWERS AND PUMPSIn general, if the load characteristics of a boiler are variable, it can be cost effective to replace existing dampers with a Variable Speed Drives.

SPECIAL CONSIDERATIONS FOR STEAM

AUTOMATIC BLOW-DOWN CONTROLWhen water is boiled and steam is generated, any dissolved solids contained in the water remain in the boiler. Above a certain level of concentration, these solids encourage foaming and cause “carry-over” of water into the steam. The deposits can also lead to scale formation inside the boiler, resulting in localized overheating and, eventually, boiler tube failure. The control of total dissolved solids in the boiler is achieved by the action of “blowing down” during which a certain volume of water is blown off and is automatically replaced by feed water. Boiler blow-down is necessary to remove sludge from precipitated salts, to prevent the scaling up of tubes and tube plates on the water side, and to avoid priming and “carry-over” into steam mains.

However, boiler blow-down also involves a loss of heat. In order to minimise heat losses, therefore, boiler blow-down should be kept to the lowest level possible to maintain the proportion of total dissolved solids within recommended limits.

There are a number of measures which could be implemented to save energy, including:

The replacement of simple manual or timer-based boiler blow-down controls with automatic systems which optimise blow-down quantities and which can reduce a boiler’s fuel consumption by up to 2%.

The installation of blow-down heat recovery equipment. This would comprise a flash vessel to collect flash steam and extract heat from it, as well as a heat exchanger so that heat within the residual hot water is transferred to process steam. Savings from blow-down heat recovery can be more than 3% (3).

Improving the quality of treated input water and / or increasing the proportion of returned condensate – both measures can reduce the amount of blow-down required.

68


INCREASE CONDENSATE RETURNThe heat content of the condensate return can be utilised to heat feed water, meaning that less steam is required to heat up the boiler feed water de-aerator. As the condensate is already treated pure water, less blow-down is required, further reducing the boiler’s fuel requirements.

CHECKLISTThe Figure below ranks alternative energy-saving measures in terms of their effectiveness in reducing energy consumption.

Reduction of boiler steam pressure (ESR: up to 2%)

VSDs for fans, blowers and pumps (ESR: up to 20% of electricity used; CAPEX: €150-€200/kW)

Feed water preheating with economizers (ESR: 4%-7%, up to 15% for condensing; CAPEX: about €30,000 600 kW boiler)

Excess air control (ESR: up to 5%; efficiency increases by about 0.5% for every 1% decrease in O2; CAPEX: about €10,000 for an average boiler)

Increase condensate return (steam) (ESR: up to 10%)

Boiler replacement (ESR: up to 20%; CAPEX: €20,000 for a 300 kW condensing boiler)

Controlling boiler loading – scheduling (ESR: up to 15%)

Radiation and convection heat loss avoidance (ESR: about 2%; CAPEX: about €20/m2)

Combustion air pre-heating (ESR: 1% for a 20°C increase in air temperature)

Automatic blow down (ESR: 2%-4%; CAPEX: about €15,000 for 10 t/h)


69

3.2.2. FURNACES AND KILNS

DESCRIPTIONA furnace is a device which is used to melt metals for casting or to heat materials in order to change their shape (e.g. rolling and forging) or properties (heat treatment). The type of fuel chosen for a furnace is important as the flue gases from the fuel come into direct contact with the materials being melted or heated. There are two broad types of furnace, characterised by the method used to generate heat: combustion furnaces, which use fuels, and electric furnaces, which use electricity. Furnaces can also, in theory, be further classified, according to mode of charging the materials, mode of heat transfer and mode of waste heat recovery. However, this classification tends not to be used in practice, because any given furnace may use more than one fuel type or charging method.

For most heating equipment, a large proportion of the heat supplied can be “lost” in the form of exhaust or flue gases – the extent of these losses depend on various factors associated with the design and operation of the heating equipment. Furnace heat losses include:

Flue gas losses: Defined as the heat that cannot be extracted from the combustion gases inside the furnace (caused by the flow of heat from the higher temperature to the lower temperature heat receiver).

Losses from moisture in fuel: Fuel usually contains some moisture and some heat is used to evaporate the moisture inside the furnace.

Losses due to hydrogen in fuel: this results in the formation of water.

Losses due to openings in the furnace: this includes: a) radiation losses from openings in the furnace enclosure – these can be significant, especially for furnaces and kilns operating at above 540°C. b) Losses caused by the infiltration of air – these occur because the draft within a furnace stack/chimney causes negative pressure inside the furnace, drawing in air through leaks or cracks or whenever the furnace doors are opened.

Furnace skin / surface losses, also called “wall losses”: caused when heat flows through the walls, roof or floor of a furnace. Once the heat reaches the outer skin of the furnace and radiates into the surrounding area or is carried away by air currents, it must be replaced by an equal amount of heat generated by the combustion gases.

Other losses: there can include losses due to the formation of scales, although they are often difficult to quantify.

The layout of a typical furnace and the areas in which losses are incurred are shown below:

70


Cooling air to waste( or dryers )

Under-carlosses

Flue gases

Latent Sensible

Structurallosses

Kilnfurniture

Kiln car

Heatto ware

Baseconduction

Leaks

Figure 6. Furnace Layout and Incurred Losses (Source: (4))

A furnace should ideally heat as much of the material as possible to a uniform temperature with the least possible expenditure on fuel and labour. The key to the efficient operation of a furnace lies in ensuring that the fuel is fully combusted and a minimum amount of “excess air” is used in the process. Furnaces operate with relatively low efficiencies (as low as 7%) compared to other combustion equipment such as boilers, principally due to their high operating temperatures. For example, a furnace heating materials to 1,200oC will emit exhaust gases at 1,200oC or more, resulting in significant heat losses through the chimney.

The thermal efficiency of common industrial furnaces is summarised in the Table below.

Table 1. Typical Thermal Efficiencies for Common Industrial Furnaces

Furnace Type Thermal Efficiency

Low Temperature Furnaces

540-980 °C (Batch Type) 20-30%

540-980 °C (Continuous Type) 15-25%

Coile Anneal (Bell) Radiant type 5-7%

Strip Anneal Muffle 7-12%

High Temperature Furnaces

Pusher, Rotary 7-15%

Batch Forge 5-10%


71

Furnace Type Thermal Efficiency

Continuous Kilns

Hoffman 25-90%

Tunnel 20-80%

Ovens

Indirect Fired Ovens (20-370 °C) 35-40%

Direct Fired Ovens (20-370 °C) 35-40%

ENERGY SAVING MEASURESTypical energy efficiency measures which can reduce energy consumption in industrial furnaces include:

OPTIMISATION OF COMBUSTION AIROptimising combustion air is one of the simplest and most economical means of conserving energy in a furnace: potential savings are higher in high-temperature furnaces. To ensure the complete combustion of fuel with the minimum amount of air, the operator of a furnace needs to control air infiltration, maintain the pressure of combustion air, ensure high fuel quality and monitor the amount of “excess air”. The air:fuel ratio must be controlled to eliminate the creation of excess carbon monoxide (usually defined as a concentration in excess of 30-50 ppm) and prevent unburned hydrocarbons occurring. These measures can generate savings of 5%-25% (5).

OPERATING AT OPTIMUM FURNACE TEMPERATUREIt is important to operate the furnace at its optimum temperature. Operating at excessively high temperatures can cause heat loss, excessive oxidation, de-carbonization and stress on refractories. Furnace temperature can be controlled automatically, a method which is preferred as it minimises the opportunity for human error. These measures can generate savings of 5%-10% (5).

CORRECT AMOUNT OF FURNACE DRAUGHTProper management of the pressure differential between the inside and the outside of a furnace is important to minimise heat losses and any adverse impact on products. Tests conducted on seemingly airtight furnaces have shown that air infiltration can be as high as 40%. To avoid this, a slight positive pressure should be maintained inside the furnace, but this should not be so high as to cause ex-filtration.

OPTIMUM CAPACITY UTILIZATIONOne of the most important factors affecting furnace efficiency is the load. This includes the amount of material placed in the furnace, its arrangement inside the furnace and the amount of time it spends inside the furnace. The furnace should be loaded to the optimum load at all times (although it is recognised that, in practice, this may not always be possible). Furnace efficiency increases in line with production, up to the design point, above which it declines rapidly – this is illustrated in the Figure below:

72


Furnace Efficiency

Total Consuption

Variable (Exhaust)

Fixed (wall, conveyor,radiation, storage)

Design HighLow

Production Rate (Units)

Ener

gy C

onsu

mpt

ion

per U

nit o

f Pro

duct

ion

High

Figure 7. Furnace Efficiency Versus Load (Source: US DOE (6))

WASTE HEAT RECOVERY FROM FLUE GASESFlue gases carry between 35% and 55% of the heat input to the furnace with them through the chimney. High-temperature heat recovery equipment can be used to recover heat from those gases – this equipment is usually based on one of two methodologies (although waste-heat recovery should only be considered when further energy conservation measures are not possible or practical):

�� Recuperation, which uses a gas-to-gas heat exchanger placed within the stack of a furnace. Recuperators are the most widely used heat-recovery devices.

�� Regeneration, which uses a high thermal mass matrix which is successively heated and cooled.

The differences between the two methodologies are shown below:

Flue

Air in

Pre-heatedair out

Furnace exhaust gases

Burner inexhaust mode

Burner infiring mode

Regenerator

Reversingvalve

Exhaust gas

Combustion air

Gas inlet

Regenerator

Ceramic bed

Figure 8. Cross Flow Recuperative Burner (Source: (7)) Figure 9. Regenerative Burner (Source: Best Practice Programme (4))

Typically, savings in the order of 10%-30% can be achieved with the use of heat recovery equipment in furnaces.


73

REDUCTION OF LOSSES FROM FURNACE SURFACE AND OPENINGS

Between 30% and 40% of the fuel used in intermittent or continuous furnaces is used to make up for heat lost through the furnace’s surfaces or walls. The extent of these losses will depend on the wall’s emissivity, the thermal conductivity of the refractories used and the thickness of the wall. The use of adequate and optimum insulation is a key energy savings action that should be provided and monitored.

Other measures to reduce heat losses through furnace openings include:

Keeping the openings as small as possible;

Opening the furnace doors less frequently and for the shortest period possible.

Such measures can reduce heat losses by between 2% and 15% of a furnace’s fuel consumption (5).

SELECTING THE RIGHT REFRACTORIESRefractories should be selected in order to maximise the performance of the furnace or kiln. Furnace manufacturers or users should consider the following points when selecting a refractory:

Type of furnace;

Type of metal charge;

Presence of slag;

Area of application;

Working temperatures;

Extent of abrasion and impact;

Structural load of the furnace;

Stress due to temperature gradient in the structures and temperature fluctuations;

Chemical compatibility with the furnace environment;

Heat transfer and fuel conservation

Cost.

Use of improved materials is reported to yield energy savings of up to 25% (5).

74



Operation at optimum furnace temperature (ESR: 5%-10%)

Waste heat recovery from flue gases (ESR: 10%-30%; CAPEX: about €80,000 per 500 kW)

Selecting the right type of refractory (ESR: 10%-20%)

Reduce losses from furnace surfaces and openings (ESR: 2%-15%; CAPEX: about €20/m2)

Optimum capacity utilisation (ESR: 5%-10%)

Optimisation of combustion air (ESR: about 5%; CAPEX: about €20,000 for a control system)

Correct amount of furnace draught (ESR: up to 5%)

References: (8), (9)

3.2.3. COGENERATION

DESCRIPTIONCogeneration, or Combined Heat and Power (CHP), is the simultaneous generation in one process of thermal and electrical energy, both of which are then used. It may include a range of technologies, but it will always include an electricity generator and a heat recovery system.

By utilising the heat, a cogeneration plant can achieve efficiencies of over 90%. In addition, as the electricity generated is normally used locally, transmission and distribution losses will be negligible.


75

Cogeneration can reduce primary energy consumption by as high as 20-30% (when compared with the supply of electricity and heat from conventional power stations and boilers).

Cogeneration technologies can be used in a wide range of applications, including:

Industrial

Buildings

Renewable Energy

Energy from waste

TECHNOLOGIESA cogeneration or CHP plant consists of four basic elements: a prime mover, an electricity generator, a heat recovery system, and a control system. The most important element is the prime mover (engine), which can be a steam turbine, a reciprocating engine or a gas turbine.

STEAM TURBINESSteam turbines are the most commonly used prime movers for CHP applications, particularly in industry and for district heating. They are typically used when very cheap fuel is available and when the steam can be used in a process after it has passed through the steam turbine. They also tend to be used when an existing steam generator needs to be replaced so that its costs need not be added

76


to that of the CHP installation but as a complement to an existing gas turbine/heat recovery generator to boost the electricity production of the CHP installation.

HP Stream

Boiler

Fuel

Condensate

Turbine

LP Steam

Process

Condenser

Figure 10. CHP with steam turbine (source: UNEP (10))

RECIPROCATING ENGINESReciprocating engines are generally employed in low to medium power cogeneration units – the largest gas-fired engines tend to have a capacity of about 10 MW, although diesel and heavy fuel oil fired engines can be larger. One of the principal advantages of reciprocating engines is that they are more electrically efficiency than other prime movers. They tend to be used when power and heat demand varies, when operations are intermittent and when low grade heat is also required (for example, hot water up to 110°C or hot gases up to 150°C).

Engine exhaust gases

Gas

Engineexhaust

Engine Generator

Controlpanel

Electricity

Cool waterreturn from site

Engine heatexchanger

Exhaust heatexchanger

Hot water supply to site

Figure 11. CHP With Reciprocating Engine (Source: (11))


77

GAS TURBINESGas turbines (GT) tend to be used when natural gas is available, when they are likely to be running continuously, when heat is consumed in the form of high pressure steam and when heat demand includes hot gases at 200°C or above. The actual power output of a GT varies with ambient conditions. The heat recovery steam generator (HRSG) is one of the major components of a GT CHP system: they are designed to produce process steam (or hot water) by recovering a large proportion of the energy contained in the exhaust gases.

Heat Source

Heat Exchanger

Compressor TurbineGenerator

Condensatefrom Process

Steam toProcess

Figure 12. CHP With Gas Turbine (Source: UNEP (10))

MICRO OR MINI-CHPMicro-CHPs are generally defined as plants with a capacity of up to 50 kWe (although plants with a capacity of between 5 kWe and 50 kWe are often referred to as Mini-CHP plants). They are typically used in the domestic market or in small commercial sites (such as leisure centres).

Most Mini-CHP installations are based on packaged complete units, and contain the prime mover, generator and heat recovery equipment, together with all the associated pipework, valves and controls.

Recently packaged micro-turbine technology has become available at sizes as small as 30 kWe. These units have comparable capital costs to those of a reciprocating CHP engine and claim to have lower maintenance costs as there are fewer moving parts. However, micro turbines have slightly lower electrical efficiency than reciprocating engines (around 25%) even when using a recuperator to pre-heat inlet air.

78


Figure 13. Mini-CHP (Source Capstone Turbines)

TRIGENERATIONIn countries with a warm climate, heating needs are limited to a few winter months, but there will be significant cooling needs during the summer months. In these cases, heat from a cogeneration plant is used to produce cooling via absorption cycles. This “expanded” cogeneration process is known as Trigeneration, or combined heat, cooling and power production (CHCP).

Cooling is generated by an absorption-cooling machine. At its simplest, the absorption machine consists of an evaporator, a condenser, an absorber, a generator and a solution pump. In the absorption cycle, instead of using a mechanical vapour compressor, an absorber compresses the refrigerant vapour, the solution pump and the generator in combination. Vapour generated in the evaporator is absorbed into a liquid absorbent in the absorber. The absorbent that has taken up refrigerant, and spent or weak absorbent, is pumped to the generator where the refrigerant is released as a vapour, which is condensed in the condenser. The regenerated (or strong) absorbent is then fed back to the absorber to pick up refrigerant vapour anew. Heat is supplied to the generator at a comparatively high temperature and rejected from the absorber at a comparatively low level, in the same manner as in a heat engine.


79

Condenser

Cold out

AbsorberHeat

exchenger

Evaporator

Orifice(expansion

mechanism)Separator

Generator

Heat in

Figure 14. The Principle of an Absorption Cooling Machine (Source: TRIGEMED project (12))

The refrigerant and absorbent in an absorption cycle form what is called a working pair. Although many pairs have been proposed over the years, there are two which have been most widely used: ammonia with water; and water together with a solution of lithium bromide in water.

The ammonia-water pair is found in most refrigeration applications with low evaporation temperatures, below 0°C. The water-lithium bromide pair is widely used for air-cooling applications, where temperatures above 0°C are needed. The pressure levels in the ammonia-water machine are usually above atmospheric pressure while the water-lithium bromide machines generally operate in partial vacuum.

The heat flows in the basic cycle can be summarised as follows:

Heat is supplied, and cooling is produced at a low temperature;

Heat is rejected in the condenser at an intermediate temperature;

Heat is rejected from the absorber, also at an intermediate temperature;

Heat is supplied to the generator at a high temperature.

Absorption cooling systems that use lithium-bromide as the absorbent and water as the refrigerant must be supplied with heat at a minimum temperature of 60°C-80°C, but can handle temperatures as high as 150°C. Ammonia-water based systems must be supplied with heat at a temperature of 100°C-120°C.

80


TYPICAL COSTSThe initial capital costs of a CHP system depend largely on the technology used and the ancillary costs associated with the installation (e.g. buildings and foundations). The costs also depend on whether a high pressure gas supply is available, whether gas compressors are required, and whether supplementary firing is to be used. The Table below presents some comparative characteristics of different cogeneration technologies and typical capital and maintenance costs (source: COGEN Europe).

Table 2. Typical Characteristics of CHP Technologies

Cogeneration Technologies

Fuels Power Range (MWe)

Electric Efficiency

Overall Efficiency

Average Capital Cost (USD/kWe)

Average Maintenance Cost (USD/

MWhe)

Steam Turbine Any 0.5-500 7%-20% 60%-80% 900-1,800 2.7

Gas Turbine with Heat Recovery

Gaseous and Liquid Fuels

0.25-50+ 25%-42% 65%-87% 400-850 4-9

Combined Cycle Gaseous and Liquid Fuels

3-300+ 35%-55% 73%-90% 400-850 4-9

Internal Combustion Engine

Gaseous and Liquid Fuels

0.003-20 25%-45% 65%-92% 300-1,450 7-14

Micro-TurbinesGaseous and Liquid Fuels

15%-30% 60%-85% 600-850 6-10

Stirling EngineGaseous and Liquid Fuels

0.003-1.5 About 40% 65%-85%In

DevelopmentIn Development

Fuel CellGaseous and Liquid Fuels

0.003-3+ 37%-50% 85%-90%In

DevelopmentIn Development

BENEFITS

The use of CHP facilities can produce substantial benefits compared with conventional sources of electricity and power:

Significant energy savings: depending on the conventional energy technologies used for comparison, CHP plants can reduce energy needs by as much as 30%. EC Directive 2004/8/EC defined high efficiency cogeneration as achieving primary energy savings of more than 10% compared with separate electricity and fuel consumption.


81

Power station anddistribution losses: 49

Power stationfuel input: 79

Boiler fuelinput: 60

Total primaryfuel input: 139

Boiler losses: 15

Total useful energy: 75

Primary energy savings: = 39/139 = 28%

Total primaryfuel input: 100

CHP losses: 25

30

Buildingservices

45

CHP fuelinput: 100

Electricity

Heat

Heat

Electricity

Figure 15. Energy Savings Through CHP (Source: Carbon Trust (11))

Additional revenue streams: if the CHP installation provides more electricity than is demanded, the excess electricity can be sold back to the grid, generating an additional revenue stream.

Reduced emissions: compared with conventional forms of energy generation, good quality natural gas CHP can reduce CO2 emissions by a minimum of 10%.

Cost savings: Cost can be cut by between 15% and 40% compared with electricity sourced from the grid and heat generated by on-site boilers.

Enhanced reliability of supply: small CHP stations connected to the electric network guarantee uninterrupted operation should the electricity supply network be interrupted. On a national level, decentralised generation reduces the need for large electric power stations. It also improves employment at local level.

82


3.2.4. STEAM DISTRIBUTION

DESCRIPTIONSteam is used in many industrial and commercial applications to provide space heat, process heat and motive power – it is chosen because:

Steam is efficient and economic to generate;

Steam can easily and cost effectively be distributed to the point of use;

Steam is flexible and easy to control;

Energy is easily transferred to the process;

The modern steam plant is easy to manage;

Steam should be available at the point of use:

In the correct quantity to ensure that a sufficient heat flow is provided for heat transfer;

At the correct temperature and pressure, or performance will be affected;

Free from air and incondensable gases which act as a barrier to heat transfer;

Clean, as scale (e.g. rust or carbonate deposit) or dirt have the effect of increasing the rate of erosion in pipe bends and the small orifices of steam traps and valves;

Dry, as the presence of water droplets in steam reduces the actual enthalpy of evaporation, and also leads to the formation of scale on the pipe walls and heat transfer surface.

STEAM DISTRIBUTION SYSTEMThe steam generated in a boiler must be conveyed through main pipes and then smaller branch pipes. Heat is transferred from the steam to the pipes, so the pipes network will start to transfer heat to the air. A typical steam circuit is shown below:

Condensate

Processvessel

Spaceheatingsystem

Make-upwater

Feed tankFeed pump

Figure 16. A Typical Steam System (Source: Spirax Sarco)


83

The distribution pressure of steam is influenced by a number of factors, including the maximum safe working pressure of the boiler and the minimum pressure required at the point of use. Pressure loss must therefore be taken into account in determining the initial distribution pressure. However, it must be remembered that generating and distributing steam at higher pressure offers three important advantages:

The thermal storage capacity of the boiler is increased, helping it to cope more efficiently with fluctuating loads and minimizing the risk of producing wet and dirty steam;

Smaller bore steam mains are required, resulting in lower capital cost for materials such as pipes, flanges, supports and insulation;

Smaller bore steam mains cost less to insulate.

There are three areas main where energy losses in steam distribution systems can be encountered and in which the potential for energy savings are high:

Steam leaks: leaks from flanges and valves are common and are normally caused by the expansion and contraction of pipe work during start-up and shut-down. Poor trapping arrangements and faulty steam traps can also lead to significant amounts of steam passing into the condensate system and the loss of its beneficial latent heat. Preventing leaks is one of the most straightforward areas for saving heat.

Pipework Surface Heat Losses: significant amounts of heat can be lost to the surrounding air from uninsulated pipes and vessels – it is important, therefore, to insulate all hot surfaces.

Condensate recovery: a major source of energy waste is unrecovered condensate or failure of steam traps. The overall efficiency of the steam distribution system can be improved by recovering flash steam and maximizing condensate return.

ENERGY SAVING MEASURESThere are many energy efficiency opportunities associated with steam distribution systems. The most important ones are:

1. Insulation of pipelines and equipment;

2. Correct operation of steam traps;

3. Flash steam recovery;

4. Use of correct steam pressure;

5. Improvements to condensate recovery;

6. Minimization of heat transfer barriers;

7. Housekeeping and maintenance: reuse low pressure steam, avoid steam leaks, provide dry steam for the process, utilize steam at the lowest acceptable pressure and utilise directly injected steam properly.

84


INSULATION OF PIPING AND EQUIPMENTA large amount of heat energy can be lost if there is no insulation or if insulation is inefficient or improperly installed. As well as reducing heat loss, thermal insulation has a number of other benefits:

It can help reduce fuel consumption;

It gives an enterprise better control over its processes as it helps maintain process temperatures at a constant level;

It can prevent corrosion, by keeping the exposed surface of a refrigerated system above dew point;

It helps protect equipment from fire;

It absorbs vibrations;

It improves staff working conditions – insulation protects staff members from exposure to hot surfaces and radiant heat and reduces noise levels.

The most commonly used types of insulating materials and their main applications are summarised in the Table below.

Table 3. Types of Insulation Materials and Their Applications

Temperature Application Materials

Low (<90oC)Refrigerators, Cold /Hot Water

Systems, Storage TanksCork, Wood, 85% Magnesia, Mineral Fi-bres, Polyurethane, Expanded Polystyrene

Medium (90 oC-325oC)

Low-Temperature Heating and Steam Generating Equipment, Steam Lines,

Flue Ducts

85% Magnesia, Calcium Silicate, Mineral Fibres

High (>325oC)Boilers, Super-Heated Steam Systems,

Oven, Driers and FurnacesCalcium Silicate, Mineral Fibre, Mica,

Vermiculite, Fireclay, Silica, Ceramic Fibre

Insulating pipes and equipment can generate energy savings of between 3% and 13% (13). However, there comes a point at which the installation of additional insulation is no longer economically justifiable. The thickness at which insulation gives the greatest return on investment is called the “economic thickness of insulation” – this is illustrated in the Figure below.


85

Insulation thickness

Cost

per

yea

r, $

Economicalthickness

Line BLost heat cost

Line AInsulation cost

Line A + BTotal cost

Minimum cost

Cost factors-HeatFuel costCapital investmentCost of moneyInterestDepreciationMaintenanceHours of operation

Cost factors-InsulationCapital investmentCost of moneyInterestDepreciationMaintenance

Figure 17. Economic Thickness of Insulation

CORRECT OPERATION OF STEAM TRAPSIt is important to ensure that steam traps are operated correctly as they provide a vital link between the steam and the condensate services. Steam trap failure in the closed position is usually reflected in poor plant performance, although it can go unnoticed on steam mains. Steam trap failure in the open position is also not always obvious. However, there are a number of ways in which the operation of steam traps can be monitored:

Visual inspection of the traps;

The installation of a sight glass or a test valve in a closed system – test valves can also be used to measure condensate return rates (and thereby estimate the steam consumption of specific equipment);

Measuring the difference in temperature between the steam side (e.g. upstream of the trap) and the condensate side of the trap – a significant temperature drop would indicate that the trap is working properly.

It is considered essential that an enterprise monitors the operation of its steam traps if it wants to realise the potential energy savings available – enterprises would normally adopt a combination of these three methods to do so.

Savings of 10%-15% can be gained from correct operation of steam traps (13).

86


FLASH STEAM RECOVERYFlash steam is released from hot condensate when its pressure is reduced. When steam is taken from a boiler and the boiler pressure drops, some of the water content of the boiler will flash off to supplement the “live” steam produced by the heat from the boiler fuel. If use is to be made of flash steam, it is helpful to know how much of it will be available. The quantity is readily determined by calculation, or can be read from simple tables or charts. Energy savings of up to 10% can be secured from flash steam recovery.

USE OF CORRECT STEAM PRESSUREThe overall efficiency of a heat distribution system is determined by steam pressure and the design of the pipework. Steam pressure at the system end points is determined by the temperature required by end-users. To minimise capital costs, steam should be conveyed to the end points via the shortest route and in the smallest diameter pipes. At the same time, the system has to be designed to minimise heat loss and pressure drop between the boiler outlet and the point at which the steam is used. In achieving these requirements, a number of contradictory factors have to be considered:

Higher pressure steam occupies a smaller volume – the same amount of heat can therefore be carried in a smaller pipe. However, the potential for leaks is greater and the pipe surface temperatures are higher, resulting in greater heat losses;

For any steam pressure, a smaller diameter pipe is cheaper to install but the pressure drop along its length will be greater (i.e. higher pressure needs to be developed at the boiler);

If a lower steam pressure is sufficient for process needs, boiler running costs will be lower but the larger diameter pipes will be more expensive.

IMPROVEMENT OF CONDENSATE RECOVERYAn efficient steam system will collect condensate and either return it to a de-aerator or a boiler feed tank, or use it in another process. Only when there is a real risk of contamination should condensate not be returned to the boiler. There are a number of reasons why the condensate should be recovered:

Condensate is a valuable resource and even the recovery of small quantities is often economically justifiable. Un-recovered condensate must be replaced in the boiler house by cold make-up water, which can be costly to treat and heat;

Colder boiler feed water will reduce the steaming rate of the boiler. The lower the feed water temperature, the more heat (and thus fuel) is needed to heat the water, thereby leaving less heat to raise steam.

Condensate is distilled water and, as such, it contains almost no total dissolved solids. As a result, returning more condensate to the feed tank reduces the need for blow-down and thus reduces the energy lost from the boiler.

An efficient condensate recovery system, which collects the hot condensate from the steam-using equipment and returns it to the boiler feed system, can generate savings of 1% in fuel for every 6% increase in boiler feed water. Such systems also tend to have very short payback periods (10).


87

Condensate

VatVat

Condensate

Processvessels

Spaceheatingsystem

Steam

Steam

Steam

Make-upwater

Boiler

Feed tank

Feed pump

Pan Pan

Figure 18. Typical Condensate Recovery System (Source: Spirax Sarco (14))

MINIMISATION OF HEAT TRANSFER BARRIERSLayers of scale, condensate and air can impede the transfer of heat and thereby reduce the efficiency of a steam distribution system (this is illustrated in the Figure below).

Steamtemperature1210C

Steam at 1 bar g

Air film

Condensate film

Scale

Metal heating surface

Scale

Product film

Product

990CProducttemperature

Figure 19. Temperature Gradient Across Heat Transfer Barriers (source: Spirax Sarco))

An enterprise should therefore act to minimise the development of these barriers:

Scale: regular cleaning of the surface on the steam side may increase the rate of heat transfer by reducing the thickness of any layer of scale;

Condensate film: as the steam condenses to give up its enthalpy of evaporation, droplets of water may form on the heat transfer surface. These may merge together to form a continuous film of condensate. The condensate film may be between 100 and 150 times more resistant to heat transfer than a steel heating surface, and 500 to 600 times more resistant than copper;

88


Air film: the most efficient means of air venting is with an automatic device. Air mixed with steam lowers the mix temperature. This enables a thermostatic device to vent the steam system.

IMPROVEMENT OF HOUSEKEEPING AND MAINTENANCEIt is considered essential to maintain a steam distribution system on a continual basis in order to minimise energy losses, in particular in steam traps. However, it is not unusual to find steam systems that have operated for several years without any maintenance at all. It has been found that, without adequate maintenance, some 15%-30% of steam traps stop operating or are left in the open position, meaning that steam passes through the condensate system and is wasted. Energy efficiency improvement of about 10% can be achieved by adopting an active programme of maintaining a system’s steam traps.


Use of correct steam pressure (ESR: up to 10%)

Insulation of pipelines and equipment (ESR: 3%-13%; CAPEX: about €10/m for a 2’’ pipe)

Correct operation of steam traps (ESR: 10%-15%)

Flash steam recovery (ESR: about 10%; CAPEX: about €30,000 for a 5 t/h 8 bar system)

Condensate recovery (ESR: about 5%, or 1% for 6° increase in feedwater temperature)

Improving housekeeping and maintenance (ESR: 2%-10%)

Minimisation of heat transfer barriers (ESR: up to 5%)

References: (15), (16)


89

3.3. INDUSTRIAL REFRIGERATION AND COOLING

DESCRIPTIONRefrigeration systems are used widely in industry, logistics, storage and trade. They account for a large proportion of electrical energy costs, particularly in the food industry where they can account for as much as 70% of total energy costs (for example, in ice-cream production and frozen product processes). In addition, with the peak industrial cooling load usually coinciding with the hottest weather conditions, enterprises may face additional peak demand charges (where applicable).

A cooling yield of between 60°C and -100°C may need to be achieved by a cooling process. The higher temperatures are typically required when cooling oil and other working fluids; the medium-range temperatures (of 0°C-10°C) are typically required when cooling air (in HVAC systems) or storing sensitive food products (such as vegetables and dairy products); while temperatures below 0°C are mainly used in the frozen food industry and in chemical processes.

Although mechanical cooling is the predominant technology utilized nowadays, it is possible to cool without using refrigeration, by using large volumes of cold water or air. However, these techniques have limited application when temperatures below 0°C are required, where there are space constraints or when there are environmental concerns. As a result, industries tend to use refrigeration to meet their cooling needs.

Refrigeration plants are not only costly to build, but they are also expensive to operate, primarily due to their high energy consumption. Typical refrigeration systems may have a lifetime operating cost seven to ten times greater than their initial investment cost.

The most common types of refrigeration systems use the reverse-Rankine vapour-compression refrigeration cycle (absorption heat pumps are used in a minority of applications).

Cyclic refrigeration can be classified as:

Vapour cycle;

Gas cycle (the working fluid is a gas that is compressed and expanded but doesn’t change phase – this is not very efficient and tends not to be used).

Vapour cycle refrigeration can further be classified as:

Vapour-compression refrigeration;

Vapour-absorption refrigeration.

The majority of refrigeration systems are driven by a machine which compresses and pumps refrigerant vapour or liquid around a sealed circuit. Heat is absorbed and rejected through heat exchangers.

A simplified diagram of a single stage, mechanical vapour compression refrigeration system with its four major components is shown in the Figure below:

90


Condenser may bewater-cooled orair-cooled

Outside AirFridge side

VaporCompressor

Vapor

Condenser

Fan

Evaporator

Warmair

Coldair

Expansion

Liquid + VaporValve

Liquid

TYPICAL SINGLE-STAGEVAPOR COMPRESSION REFRIGERATION

Figure 20. Mechanical Vapour Compression System

ABSORPTION COOLINGAbsorption coolers are heat-driven machines which follow the absorption refrigeration cycle and use two highly mutually soluble fluids – typically a refrigerant and an “absorber”.

The basic difference between an electric system and an absorption system is that an electric chiller uses an electric motor to operate the compressor used to raise the pressure of the refrigerant vapours, while an absorption chiller uses heat to compress the refrigerant vapours to a high-pressure. Most commercially available absorption chillers use either ammonia and water or water and lithium bromide.

Condenser

Generator

Absorber

ThermalCompressor

Expansionvalve

Evaporator

Pump

Qout

Qin

Win

Qout

Qin

Figure 21. Vapour Absorption System


91

Absorption cooling systems can, for example, be driven by waste from CHP systems, in which instances significant energy savings can be realised.

REFRIGERATION LOADThe “refrigeration load” is the heat that the refrigeration system is required to remove. It is generally specified by the industrial process, but is influenced by additional heat sources on the “fridge side”, such as lights, motors, and leakages when doors are opened. Damaged or inadequate insulation in cold rooms will result in heat gains through the walls, adding to the refrigeration load on the system and thus requiring additional energy to run the plant.

COMPRESSORSCompressors are the main consumers of power in a refrigeration system, hence the selection of the most appropriately sized compressor can minimise energy use. There are two basic compression technologies:

Positive Displacement (or Volumetric): pressure is increased by reducing the volume of the space where the gas is contained;

Dynamic: gas velocity is increased and the velocity energy is then converted in pressure energy.

REFRIGERATION CHILLER COMPRESSOR

POSITIVE DISPLACEMENT DYNAMIC

RECIPROCATING (Pistons) ROTARY CENTRIFUGALS

SCREW SCROLL

Most compressors are of the volumetric type (although dynamic compressors are used in some specific applications): volumetric compressors tend to be simple to construct, easy to use, and they come in a wide range of sizes.

EVAPORATORSEvaporators are heat exchangers designed to remove heat from the product or area requiring cooling. The cooling capacity of an evaporator is related to:

The difference in temperature between the material being cooled and the refrigerant;

The rate of heat transfer between the refrigerant and the cooled medium;

The quantity of refrigerant flowing through the evaporator.

92


Evaporators can also serve as chillers, providing a circuit of chilled liquid (usually water) for circulation to other heat exchangers where cooling is required (for example, for fan coils in buildings).

CONDENSERSCondensers are heat exchangers and are often similar in construction to evaporators. Either air or water can be used to cool the refrigerant and reject the heat to the external environment.

AIR COOLED CONDENSERIn an air-to-air condenser, passing air picks up heat from the refrigerant and the temperature of the high pressure refrigerant drops to a point where it condenses back into a liquid. In effect, the refrigerant enters the condenser as a high-pressure, high-temperature gas, and leaves in liquid form still under high pressure.

In a typical industrial refrigeration system, the warm liquid refrigerant coming out of the condenser goes into a reservoir called a receiver, and then through a sight glass. The sight glass is a troubleshooting aid that allows the liquid refrigerant to be observed, along with any bubbles of gas that might be present.

WATER COOLED CONDENSERA water cooled condenser operates using the same principles as an air cooled condenser – the only difference being that the heat is dissipated by water instead of air. This has the advantage that water temperatures remain relatively stable, dissipation is predictable and the heat exchange rate remains relatively constant throughout the year. This increases overall system efficiency and prevents damage to equipment when environmental conditions change significantly.

It must be noted that water cooled condensers are significantly more efficient than air cooled condensers – they can use about 50% of the energy of an air cooled condenser.

COOLING TOWERSAlthough a cooling tower can be considered a type of water cooled condenser, it is more of a hybrid solution for industrial cooling. It usually involves spraying water onto the condenser (rather than having a dedicated refrigerant / water heat exchange) which, along with the use of extractor fans, allows air to circulate, thereby causing the water to evaporate and the condenser to cool.

REFRIGERANTSA wide variety of refrigerants can be used in vapour compression systems, with the required cooling temperature largely determining the choice of fluid. The ideal refrigerant has favourable thermodynamic properties, is noncorrosive to mechanical components, and is safe (non-toxic, non-flammable and environmentally benign). The desired thermodynamic properties are a boiling point somewhat below the target temperature, a high heat of vaporization, a moderate density in liquid form, a relatively high density in gaseous form, and a high critical temperature.

Commonly used refrigerants belong to the family of chlorinated fluorocarbons (CFCs, also called Freon in the market although the word Freon is a trademark of the DuPont Company). They include


93

R-12, R-21, R-22 and R-502 (all of which have been discontinued); as well as R-134a, R-407c, R-410A. Old Soviet refrigeration systems use ammonia which, although an excellent low temperature refrigerant, can be dangerous (especially if it leaks) and is expensive to maintain – its use is therefore only recommended for special purposes. The Table below shows the primary replacements for the old refrigerants found in most developing countries.

Table 4. List of Refrigerants’ Replacement

ASHRAE1 Number Primary Replacement Reason for Replacement

R-12, R-500, R-502 R-134a, R-404A Ozone Depletion

R-22 R-407C, R417A Ozone DepletionNotes: 1 American Society of Heating, Refrigerating and Air-Conditioning Engineers

The Table below shows the refrigerants typically used for various applications.

Table 5. List of Typical Refrigerants Found in Most Applications

Refrigeration Application Typical Refrigerants Used

Domestic Refrigeration R-600a, R-134a

Commercial Refrigeration R-134a, R-404A, R-507

Food Processing and Cold Storage R-123, R-134a, R-407C, R-410A, R-507

Industrial Refrigeration R-123, R-134a, R-404A, R-407C, R-507, R-717

Transport Refrigeration R-134a, R-407C, R-410A

Electronic Cooling R-134a, R-404A, R-507

Medical Refrigeration R-134a, R-404A, R-507

Cryogenic Refrigeration Ethylene, Helium

It should be noted that R-600a is butane gas and that R-744 is CO2. Butane gas is used mostly in domestic applications but it is extremely flammable (which means that maintenance activities need to be carried out with great care). The use of CO2 has started to increase in recent years as technical constraints are overcome. It is considered an ideal refrigerant for sensitive products such as vegetables, meat and raw non-packed foods – it is non-toxic and cannot damage the product if it leaks (thereby helping to minimise product losses). In addition, there are no health risks if it leaks into crowded stores, such as super-markets or other retail stores.

CONTROL EQUIPMENTIn simple commercial refrigeration systems the compressor is normally controlled by a simple pressure switch, with the expansion performed by a capillary tube or simple thermostatic expansion valve. In more complex systems, including multiple compressor installations, electronic controls are typically used, with adjustable set points to control the pressure at which compressors cut in and cut out, and the temperature controlled by the use of electronic expansion valves.

94


In addition to these operational controls, separate high pressure and low pressure switches are normally installed to provide secondary protection to the compressors and other components of the system. In more advanced electronic control systems, the use of floating head pressure and proactive suction pressure control routines allow the operation of the compressor to be adjusted to more accurately meet differing cooling demands, thereby reducing energy consumption.

PIPEWORK SYSTEMGood insulation of pipe work and equipment is essential if a refrigeration system is to operate reliably and economically. It is particularly important in low evaporating temperature systems (which have long suction lines running through non-refrigerated areas) as any increase in the gas temperature entering the compressor will reduce its efficiency.

REFRIGERATION EFFICIENCY Refrigeration efficiency is determined by the refrigerant used and operating conditions. It is expressed as the Coefficient of Performance (COP), a measure of the ratio between the net cooling achieved and the total power consumed by the cooling system (including auxiliaries).

Typical COP values for different refrigeration systems are listed in the Table below:

Table 6. Typical COP of Different Types of Refrigeration

Type of Refrigeration COP RangeMechanical Compression refrigeration (Air Cooled Units) 2.0-5.0 (max)*

Mechanical Compression refrigeration (Water Cooled Units) 4.0-7.0 (max)

Absorption Refrigerationsingle Stage: 0.40-0.75 (max)

Absorption Refrigeration Double Stage: 0.8-1.0 (max)

NH3/H2O 0.65 (max)* For most industrial refrigeration installations based on mechanical vapour compression, the COP ranges between 2.0 for plants with Te = -40°C and 5.0 for plants with Te = 0°C.

It should also be noted that a system’s COP can change significantly when ambient weather conditions (temperature and humidity) and/or process conditions change.

ENERGY SAVING MEASURESConsiderable energy savings can be achieved through improvements to the design, operation and maintenance of refrigeration systems.

REFRIGERATION LOAD REDUCTIONWhen looking for savings in refrigeration plants, the first step is to try to minimise the load on the system. The total cooling load is made up of several components as described above.


95

Figure 22. Cold Room Heat Gains (Source: Carbon Trust (17))

The cooling load can be reduced by a number of means:

Cooling or pre-cooling without using refrigeration;

Improving the insulation of and reducing the ventilation in piping and in the building to be cooled;

Minimising the number of times that cold store doors have to be opened. If this is not possible, reducing the time that the doors remain open to a minimum. It is also possible to use automatically controlled doors or heat insulating curtains, or to establish an air-lock system at entrances.

Optimising transportation through the cold store;

Using more energy efficient lighting systems in the cooled rooms.

CHILLED WATER STORAGEGiven that the efficiency of an evaporator falls dramatically as it freezes, one of the easiest ways for a company to improve energy efficiency is for it to remove the layer of frost which forms on air blast coolers in refrigerating chambers.

Where there is a secondary chilled water circuit, demand on the compressor can be reduced by providing well-insulated chilled water storage which is sized to meet process requirements (this ensures that the chillers do not have to operate continuously). This arrangement is usually economical if small variations in temperature are acceptable – it has the added advantage of allowing the chillers to be operated at periods of low electricity demand (thereby reducing peak demand charges).

Low tariffs offered by some electric utilities for night-time operation can also be exploited by using a storage facility. An added benefit is that a lower ambient temperature at night lowers condenser temperature and thereby increases the system’s COP.

96


Figure 23. Ice Bank System (Source: Hafner Muschler (18))

CONDENSER - HEAT RECOVERYImplementing measures to recover heat from a refrigeration system is recommended when there is demand for hot air or water close to the refrigeration site and when that demand coincides with the working time of the cooling plant. Some options include:

Direct heating of air in the condenser. This is the most efficient form of energy recovery, but it often cannot be used because of the distance between the condenser and the point of demand for the heated air. However, heat recovered from the condenser at 25°C-35°C through heating air or water can be used to heat offices or dry air.

Recovering heat from a “de-superheater” installed between the compressor and the condenser. This heat can vary in temperature from 60°C to 90°C. The heat exchanger uses the refrigerant on one side and the fluid to be heated on the other side – it “de-superheats” the refrigerant and thereby reduces the amount of cooling water or air needed by the condenser. A de-superheater is typically sized to meet the demand for hot water, although it is possible to install storage systems if that demand fluctuates.


97

Out In

Heat rejection

Expansion valve

Condenser

Evaporator

CoolingCompressor

Heat exchanger(de - superheater)

Figure 24. Heat Recovery Through a De-superheater (Source: Carbon Trust (19))

Another way of recovering condenser heat is to use a heat pump1 - this can generate temperatures of up to 120°C in air or water. Installing a heat pump is recommended when running times are high (for example, at over 2,000 hours per year) and when the temperature differences are limited to 45°C-55°C.

In larger refrigeration plants that use screw compressors, recovering heat from oil coolers can generate water at 35°C-40°C. However, only 10% to 25% of the heat discharged in the condenser is recovered using this technique.

When fitting heat recovery equipment to an existing refrigeration plant, the amount of energy recovered can be up to 30% of the cooling capacity. However, the installation of such equipment isn’t really viable below a compressor electrical load of 30 kW (20).

IMPROVING SYSTEM CONTROLSIt is also possible to increase energy efficiency by improving control of a system, for example:

By not part-loading compressors, especially screw compressors;

By increasing temperature levels on the cold side and reducing temperature levels on hot side – each degree change in temperature can reduce electricity consumption by 2%-5%;

By using a storage facility to exploit low tariffs offered by some electric utilities for night-time operation. This has an additional benefit in that a lower ambient temperature at night reduces condenser temperature and thereby increases a system’s COP.

1 To obtain the greatest heat recuperation from the condenser in combination with a heat pump, the heat pump should be placed in cascade with the refrigeration plant so that the condenser of the cooling machine is also the evaporator of the heat pump.

98


REDUCING REFRIGERANT LEAKAGERefrigerant leakage may reduce a system’s efficiency and its COP. Leaking systems can therefore contribute twice to climate change: first, through the loss of the refrigerant itself, and second, through an increase in emissions associated with higher electricity consumption.

However, it is possible to install automated permanent leak detection systems to minimise possible leaks. These are available with single or multi-point sensing devices which can monitor up to 16 locations. Leak detection systems can save up to 15% of energy costs for refrigeration (17). A refrigerant leak detector is pictured below.

Figure 25. Refrigerant Leak Detector (Source: Carbon Trust)

MULTI-STAGE REFRIGERATIONThe capacity of a simple single stage refrigeration system is limited by the maximum pressure differential that a single compressor can sustain – a single stage system generally cannot efficiently achieve temperatures of below -26°C. Multi-stage refrigeration systems are therefore used when ultra-low temperatures are required. However, they need to maintain very high compression ratios which can:

Reduce compression efficiency;

Increase the temperature of the refrigerant vapour from the compressor;

Increase energy consumption per unit of refrigeration production.

There are two types of such systems: multi-stage and cascade. A multi-stage system uses two or more compressors connected in series in the same refrigeration system.


99

Comp.#1

Comp.#2

Mix

FlashDrum

Evaporator

ExpansionValve #1

ExpansionValve #2

Condenser

UpperCycle

LowerCycle

Multi - Stage Vapor - Compression Refrigeration Cycle

12

34

56

7 8

9

Multistage V-C Refrigeration Cycle

Upper Cycle

Lower Cycle

Figure 26. Multi Stage Compression & Refrigeration Cycle (Source: Learn Thermo.com)

Multi-stage systems are generally preferred because they are more efficient and less expensive than cascade systems: mixing the saturated vapour from the flash drum with the effluent from the second compressor (in a multi-stage system) is a more efficient way of transporting energy than using a heat exchanger (as in a cascade system).

HIGH-EFFICIENCY COMPRESSORS Several technologies exist to increase the efficiency of compressors. High efficiency reciprocating and scroll compressors, which often incorporate variable-speed motors, are found in some refrigeration systems. These compressors have higher efficiencies over a wider operating range than the traditional reciprocating compressors commonly used in small, self-contained commercial refrigeration equipment.

Modern high efficiency compressors are usually designed so that they have lower suction gas pressure losses, smaller valve clearance gaps, less heating of the suction gas within the compressor shell, lower pressure drop through the discharge valve, and lower mechanical losses. Improving a compressor to raise its overall efficiency to 60% would result in a 20% reduction in the electric load.

Scroll compressors compress gas in a fundamentally different manner from reciprocating compressors – between two spirals, one fixed and one orbiting. High efficiency reciprocating compressors are as efficient, or more efficient, than scroll compressors. However, they have some disadvantages when compared to scroll compressors, including being noisier, more costly and less reliable,.

There are three basic types of high efficiency compressors:

Vapour Injection;

Electronically Commutated Permanent Magnet (ECM) Compressor Motor;

Variable Capacity Compressor (Compressor Modulation).

The choice of compressor will depend on the use to which it will be put – detailed investigation is required to determine the best choice on a case by case basis.

100


HIGH EFFICIENCY FAN MOTORSFan motors move air across the evaporator or condenser coil and typically run at a single speed. The fan manufacturer will generally, during the design stage, match motor size and blade to the coil to meet the expected load under most operating conditions. However, this may not prove to be the optimum solution, in particular if the fan is operated partially loaded or if atmospheric conditions differ from those anticipated in the design study.

Single-phase induction motors require separate starting windings to ensure proper start rotation and sufficient starting torque. The type of start-up differentiates the three main types of single phase induction motors: the shaded pole motor, the permanent split capacitor motor (PSC), and the electronically commutated permanent magnet motor (ECM).

Shaded-pole motors are less efficient than other types of motor, but they are electrically simple and inexpensive.

A PSC motor contains a smaller, start-up winding in addition to the main winding and a capacitor. The capacitor causes the current to the start-up winding to be cut off as the motor reaches a steady state. As a result, PSC motors are more energy efficient than shaded-pole motors. They are also produced in large quantities and are relatively inexpensive and they offer a 50% to 60% reduction in wattage.

The electronically commutated permanent magnet (ECM) motor (also known as a brushless permanent magnet motor) is more energy-efficient than either the shaded-pole or PSC motor. However, ECM motors are more complex, particularly when used in commercial refrigeration applications, as they are internally powered with DC power. The power supply therefore has to be converted from AC to DC, and control electronics are required to handle the electronic commutation.

The efficiencies of the alternative types of fan motors are listed in the Table below.

Table 7. Typical Efficiencies of Fan Motors

Rated

Shaft Output

(W)

SPM

Power Input (W)

PSC

Power Input (W)

ECM

Power Input (W)

373 (1/2 hp) - 530 450

249 (1/3 hp) - 370 304

125 (1/6 hp) 329 202 155

50 (1/15 hp) - 90 65

37 (1/20 hp) 110 70 49Source: US DoE, Energy Savings Potential and R&D Opportunities for Commercial Refrigeration


101

GOOD HOUSEKEEPING OF REFRIGERATION PLANTSGood housekeeping is also important in maintaining energy efficiency in a refrigeration system. A neglected or poorly maintained cooling tower can reduce chiller efficiency by 10% to 35%, while a dirty coil condenser within an air cooled chiller can reduce efficiency by between 5% and 15%. In addition, cleaning the inside of the condenser and evaporator heat transfer surfaces with chemicals can reduce energy use by between 5% and 10%.


Load reduction (ESR: up to 10%; CAPEX: about €1,000 per evaporator for intelligent defrost controls; about €35,000 for door insulation and dehumidification)

Heat recovery (ESR: up to 30%; CAPEX: €3,000-€6,000 for a small site)

Use of high efficiency motors (ESR: up to 20%)

Use of automatic leak detection systems (ESR: up to 15%)

Multi-stage refrigeration systems (ESR: increase of COP by up to 10%)

Chilled water storage (ESR: mostly reflected in cost savings; Energy efficient if combined with system replacement / expansion, thereby allowing fewer, smaller,and/or more energy efficient chillers)

Good housekeeping (ESR: 5%-15% depending on the condition of the plant)

Absorption cooling (ESR: depends on system being replaced; mostly reflected in cost savings if gas prices are lower than electricity prices; CAPEX: about €300-€500/kWcool)

Improving controls (ESR: 2%-5%)

References : (21), (17), (22), (23)

102


3.4. COMPRESSED AIR

DESCRIPTIONCompressed air systems (CAS) are widely used across industrial sites, mostly to control processes but also for cleaning purposes. Compressors are one of the most energy intensive pieces of equipment in an industrial process. The overall efficiency of compressed air systems is very low: only about 5% to 8% of the electrical energy input is converted into useful energy. Companies should therefore strive to minimise their use of compressed air, using it only when it is absolutely necessary and when it cannot be replaced by a different form of energy. Typically, 20% of a factory’s electricity bill can be attributed to the production of compressed air and, in many instances, air compressors use more energy than any other single piece of equipment.

COMPRESSED AIR EFFICIENCYThe energy balance of a compressed air system is shown below: over two thirds of the input energy is lost through waste heat and other losses, and through leakage.

Waste Heat and otherLosses 3221 kWh/day

Leakage432kWh/day

Actuation62kWh/day

Conveying1092kWh/day

Blow(including

cleaning, purging,cooling, sealing,

filter pulsing)415kWh/day

Tools (airhoist, air gun)

58kWh/day

Com

pres

sed

Air

Gen

erat

ion

5280 kWh/day

Figure 27. Sankey Diagram of the Energy Balance in an Industrial Compressed air System (Source: http://www.sankey-diagrams.com).

ENERGY SAVING MEASURES

ENERGY EFFICIENCY IN COMPRESSORSThe key options for improving energy efficiency in compressors include:

Choosing the most energy efficient model (at both full load and partial load);


103

Designing the air intake carefully and reducing intake pressure;

Using variable speed drives, not throttling, to control the production of compressed air;

Introducing heat recovery mechanisms into the cooling system.

CHOOSING THE MOST ENERGY EFFICIENT MODELAlthough it may be considered desirable that a company should choose the most energy efficient compressor, it has to be recognised that a number of other factors will influence the decision-making process (including price, noise, maintenance requirements, the quantity of air required and the pressure at which the air is required). As a result, a company can be expected to choose the compressor which best meets its overall needs, even though it not be the most energy efficient model.

For example:

Reciprocating piston compressors often provide equal, or better, specific energy consumption to that of rotary compressors, but their performance suffers as their parts begin to wear, raising maintenance costs as a result. They are more often used for small industrial applications.

Centrifugal compressors and rotary screw compressors tend to be used in applications requiring a high volume of air. Rotary screw compressors are more efficient at flow rates of up to 1,000 litres/minute, above which centrifugal compressors are more efficient.

The key characteristics of alternative compressor types are listed in the Table below.

Table 8. Comparison Between Compressor Types

CriteriaPositive Displacement Type Dynamic

Reciprocating Rotary Vane Rotary Screw Centrifugal

Energy Efficiency Fully Loaded

High, Especially Multi-Stage

Medium to High High High

Energy Efficiency Partially Loaded

High Poor Below 60% LoadPoor Below 60%

LoadPoor Below 60% Load

Noise Level Noisy Least Noisy Quiet if Enclosed Least Noisy

Size Least Compact Compact Compact Least Compact

Oil Carry-OverModerate, Except with

Oil “Free” ModelsLow to Medium Low Medium

Vibration High Almost None Almost None Medium

Maintenance Many Wear Parts Few Wear Parts Very Few Wear PartsVery Few Wear

Parts

Capacity Low to High Low to Medium Low to High Medium to High

Pressure Medium to Very High Low to Medium Low to High Low to High

104


DESIGN AIR INTAKE CAREFULLY AND REDUCE INTAKE PRESSUREThe quality of intake air can have a significant impact on compressor performance. Contaminated or hot intake air can impair compressor performance and result in excess energy use and increased maintenance costs. Moisture, dust or other contaminants present in the intake air can build up on a compressor’s internal components (including valves, impellers, rotors and vanes) and cause premature wear and reduce compressor capacity. As a result, it is important to design a compressor’s air intake with care.

For every 1 kPa (or 1%) reduction in intake pressure between the atmosphere and the point of entry to the compressor’s inlet valve, a 0.5% increase in power is required to maintain the same level of output.

Every 4oC reduction in intake temperature reduces the compressor’s energy consumption by 1%.

As a result, intake air should be as cool as possible and the compressor’s intake ducts should be as short as possible, have a large cross-sectional area, smooth internal surfaces and large radius bends.

USE OF VARIABLE SPEED DRIVES (VSDS)Variable Speed Drives (which are also referred to as Variable Frequency Drives) are a type of adjustable-speed drives used in electro-mechanical drive systems to control AC motor speed and torque by varying motor input voltage and frequency.

When a VSD supplies power to an AC motor, it provides a voltage at a frequency which can range from less than 1 Hz to about 120 Hz, with the speed of the motor dependent on the frequency. The output torque of the motor will be determined by the ratio of voltage supplied to the frequency and failure to maintain the proper volts-per-hertz ratio will affect motor torque, temperature, speed, noise and current draw. It is therefore necessary to control both the voltage and the frequency of power supplied in order to ensure that the motor produces its rated torque at variable speeds.

A compressor’s capacity is usually regulated by throttling, a method which restricts the performance of the compressor while it continues to run at full speed. However, the use of a VSD is a more efficient way of regulating a compressor’s output in that power consumption more closely matches output. The energy savings deriving from the use of a VSD can therefore only be realised when there are variations in motor load. Furthermore, although two motors may have the same horsepower rating, their torque capability (in terms of breakaway torque, pull-up torque, peak torque and full-load torque) may differ, depending on their classification. As a result, the appropriateness of using a VSD can only be determined following a detailed study, taking account of the motor’s usual loading factor, its type of operation (VSDs are prone to failure in dusty environments) and its condition.

VSDs can be used in compressors when air requirements vary over time of day and days of the week (if fluctuations in demand for air are low, it is unlikely that the electricity savings would justify the cost of the investment). However, it has been demonstrated that VSDs can be used cost-effectively in a range of applications across a number of sectors, including the metal, food, textile, pharmaceutical and chemical industries. (24).


105

WASTE HEAT RECOVERYMost of the electrical energy used in a compressed air system is converted to heat which is released to the environment. However, air-cooled compressors can provide hot air at up to 60°C continuously, or at up to 80°C intermittently; while water-cooled compressors can heat water up to 90°C depending on the compressor load. Heat can be recovered either directly (for example by ducting warm air to heat an adjacent space) or indirectly (via a heat exchanger) – it is possible to recover up to about 80% of the energy consumed by a compressor. A typical 47 lt/s (100 cfm) capacity air compressor consumes about 22 kW at full load, almost 20 kW of which could therefore be recovered as heat.

AIR DISTRIBUTION SYSTEM

MONITOR AND REPAIR AIR LEAKAGESReducing leaks is one of the most important ways of saving energy as leaks affect all compressed air systems. In a well-maintained system, under 10% of capacity should be lost due to leaks. As a rule of thumb, every 10 l/s of compressed air leakage increases energy use by about 7,000 kWh per year – this is equivalent to a single 2.5 mm diameter hole in a 700 kPa system. It is therefore important that production staff not only identify but also label leaks so that they can be easily and quickly repaired. Preventive maintenance programmes, including leak detection tests, should therefore be an integral part of operating any compressed air system. Leaks can be repaired by tightening connections or by replacing faulty equipment (such as couplings, fittings or pipe sections).

KEEP INTAKE AIR DRY AND CLEANKeeping intake air as dry as possible can also help to reduce energy costs. Water can mix with oil carry-over and dust particles to form a sludge which will increase pipe pressure drop and raise energy consumption. The sludge can also cause corrosion (which will increase maintenance costs). However, the installation of water separators and automatic drain valves can minimise this problem. At the same time, ensuring that intake filters are kept clean will maintain compressor efficiency.

CONTROLS

CONTROL A COMPRESSOR’S OPERATING TIMES Reducing the number of hours that a compressor operates will reduce its energy consumption (if a compressor operates outside normal production hours then it will only be supplying air leaks). It is also possible to install air isolation valves for specific production areas which operate on a part time basis, closing those valves when those areas are not being used.

CONTROL PRESSUREThe higher the pressure within a compressed air system, the greater the energy used. Reducing air pressure can therefore reduce energy consumption, provided that the demand for air continues to be met. A pressure regulator can be fitted onto the supply pipe for each item of equipment, with the pressure set at a level which is as low as possible but which still permits that item of equipment

106


to operate satisfactorily. A reduction in operating pressure from 700 kPa to 600 kPa will reduce a compressor’s consumption of energy by about 8%.

Further savings can be achieved by installing solenoid valves on equipment so that its supply of air is switched off when its power is turned off.

CONTROL VELOCITYAs a general rule of thumb, air velocity in distribution mains should not exceed 6 m/s; while it should not exceed 10 m/s in branch lines. A 50% increase in air velocity will increase energy use by 2%.

THE END-USE EQUIPMENTGood housekeeping practices are vital in controlling energy use as compressed air is a very inefficient form of energy. In addition, an enterprise may want to examine whether it should change its operating processes – for example, it may be more effective and efficient to use sources of energy other than compressed air to clean machinery parts, to cool or to agitate liquids (all of which are typical uses of compressed air).


Use of controls (ESR: up to 12%; CAPEX: about €30,000 for a typical industrial system)

Waste heat recovery (ESR: up to 80%; CAPEX: €8,000 for a 130 kW compressor to preheat boiler water)

Reduce air leakage losses (ESR: up to 20%; CAPEX: about €5,000-€10,000 for leak detection instrumentation)

Use of VSDs (ESR: up to 30%, with an average of 15%; CAPEX: €150-€200/kWe)

Improve O&M practices (ESR: up to 5%)

References (25), (26), (10)


107

3.5. ELECTRICITY FOR INDUSTRIAL USE

3.5.1. ELECTRICITY DISTRIBUTION

The purpose of electricity distribution networks is to deliver electricity from generating stations to industrial, commercial and domestic users, through transmission systems and distribution networks. The components of an electricity distribution network are shown in the Figure below.

Color Key:Black: GenerationBlue: TransmissionGreen: Distribution

Generating Station

Generating Step Up

Transformer

Substations

Transmission lines6, 10, 35, 110, 220, and 500 kV

SubstationsStep Down

TransformerIndustrial Users

35 kV, 10 kV, 6 kV and 400 V

Commetial Users6 kV, 400 V and 220 V

Residential Users400 V and 220 V

Figure 28. Electricity Transmission/Distribution

After electricity is generated and transmitted at high voltage, step-down transformers located in distribution substations reduce the voltage so it can be carried on smaller cables or distribution lines to the final consumer. The boundary between a utility’s distribution system and a customer’s electricity system on an industrial site is normally set at the utility’s step-down transformer (where a meter will also normally be located).

QUALITY OF VOLTAGE AND POWER SUPPLYThe reliability and quality of the incoming supply will be important to an industrial customer, some of whom, for security of supply reasons, may also have more than one connection to the network.

An electricity supplier is normally obliged to maintain voltage and frequency within certain limits in order to protect customers’ installations from fluctuations in that supply (imbalances and fluctuations in the supply voltage can, for example, seriously affect the performance of electric motors).

ON-SITE GENERATIONCustomers may maintain their own on-site power generation for a number of reasons, including:

As back-up: for example, in a hospital or at an industrial facility where the unexpected loss of power could have a significant impact on the organisation’s activities;

To exploit on-site renewable energy resources: it is possible that an on-site generator may be an industry’s main source of supply, with surplus power being exported to the public network and that network being used as back-up supply;

108


To exploit the availability of surplus high temperature heat which can be recovered through waste heat boilers;

To match demand for heat and power in order to make cogeneration economically viable.

POWER LINES AND CABLESPower lines (above ground) and cables (underground) distribute power around a site, and terminate in switchgear within each building. Ideally each building and / or major point of demand for electricity within a site should be metered.

TRANSFORMERSA transformer is a device that transfers electrical energy from one circuit to another through inductively coupled conductors – the transformer’s coils. By the appropriate selection of the ratio of turns within those coils, a transformer allows an alternating current (AC) voltage to be “stepped up” or “stepped down”.

Many transformers within consumers’ sites will be old and will lack modern features and switchgear. They will often be oversized, especially if an industry’s processes have become more energy efficient. At the same time, their age will make them less reliable and safe. For these reasons, customers should consider replacing them.

Reducing electricity losses from a company’s transformers can be achieved in a number of ways:

Ensuring that transformers are sized to meet demand (i.e. they are not over-sized) – this may involve replacing existing transformers with new transformers;

Replacing existing transformers with modern low-losses transformers;

Minimising the overall use of transformers across a site – this may require some transformers to be deactivated and their load shifted to adjacent transformers or transformers at the nearest substation;

Matching the use of transformers to demand, for example by disconnecting low-load substations or individual transformers over the weekend, on official holidays or at other times of low demand.

MOTORS AND DRIVESElectric motors account for about two-thirds of all the electricity used by industry and one half of all the electricity used by commercial facilities. The electric motor industry produces special energy efficient motors that are 2% to 8% more efficient than standard motors. However, a motor’s use of energy is dependent on a number of factors, including its inherent energy losses, its size (i.e. whether it is correctly sized) and the quality of voltage.

METERSAn electricity meter is a device that measures the amount of electric energy consumed by a residence, business or electrically-powered device. Electricity meters are usually calibrated in billing units,


109

typically the kilowatt hour (kWh), and they fall into two basic categories: Electromechanical meters and Electronic (smart) meters.

Effective energy saving depends on knowing the amount of energy that is consumed – this requires an electricity consumer to have a reliable and precise tool for measuring consumption.

In many developed countries, utility companies are starting to use smart meters. These are essentially electronic meters with additional features that enable them to measure, store, integrate electricity parameters and communicate the information on at least a daily basis to the utility company for monitoring and billing purposes. Smart meters enable two-way communication between the meter and the central system, and may be capable of performing simple control routines (e.g. peak shaving, tariff band changes and alarms).

The ability of smart meters to gather data for remote reporting can help consumers understand load profiles and thereby manage their demand, helping them to reduce their electricity bills and cut greenhouse gas emissions.

Figure 29. Electromechanical and Electronic Meters (Source: greencollareconomy.com)

SWITCHGEARAnother important part of an electricity distribution system is the switchgear as it directly affects the safety and reliability of electricity supply. At small substations, switches may be manually operated, but at important switching stations on the distribution network all devices have motor operators to allow for remote control.

Switchgear can be located on both the high voltage and the low voltage side of a large power transformer. The switchgear on the low voltage side of a transformer may be located in a building, with medium-voltage circuit breakers for distribution circuits, along with metering, control, and protection equipment.

110


REACTIVE POWERCompensation of reactive power is an important organizational-technical measure for the control of electricity consumption, and for limiting maximum end-user loads.

ELECTRICAL HEATINGThe use of electricity for heating should generally be reduced unless there is no convenient alternative. However, some industrial processes (e.g. furnaces) can be efficient users of electricity.

BUILDING ENERGY CONSUMPTIONElectricity consumption can account for up to half of a building’s energy consumption, especially when conventional lighting and air conditioning are used.

3.5.2. MOTORS AND DRIVES

DESCRIPTION-COMPONENTSElectric motors account for about two-thirds of all the electricity used by industry and one half of all the electricity used by commercial facilities. The electric motor industry produces special energy efficient motors that are 2% to 8% more efficient than standard motors. However, a motor’s use of energy is dependent on a number of factors, including its inherent energy losses, its size (i.e. whether it is correctly sized) and the quality of voltage.

However, the electric motor itself is usually the most efficient element of any drive system. It may, therefore, be more effective to concentrate on improving the overall efficiency of the drive system rather than concentrating on the motor alone.

TYPICAL EFFICIENCYBetween 75% and 80% of the energy supplied to a motor system is usually transmitted to end-use. Energy losses generally occur across five areas, split between two major categories: fixed losses (which are independent of the motor loading) and variable losses (which are dependent of the motor loading):

Figure 30. Motor Losses

Losses Detail Cause

Fixed Core Losses Magnetisation of the Motor Core (Iron Losses)

Frictional and Windage Losses Bearing and Air Friction

Variable Stator Losses Resistance of The Stator Winding (Copper Losses)

Rotor Losses Resistance of The Rotor Winding (Copper Losses)

Stray Load Losses Leakage of Magnetic Flux Induced by Load Current


111

ENERGY SAVING MEASURESElectric AC motors are designed to rotate at or close to their synchronous speeds. However, in practice, many motor applications require a change in motor speed to meet changes in motor loads. Engineers therefore use a number of techniques to control the speed of electric motors, including belts, gears and VSDs – VSDs are a very effective tool for reducing energy use (and therefore costs).

Depending on a motor’s running time, the annual cost of operating a motor can be between five and ten times the original purchase price of the motor.

Given that the life of an electric motor can be more than 20 years, a small improvement in motor efficiency can generate substantial energy savings, exceeding the premium paid for these types of motors.

The most important methods of improving energy use include:

OPTIMISING MOTOR SIZEHighest efficiency is achieved when motors are loaded to their maximum capacity and, where possible, they should be run at that capacity. The direct replacement of like-for-like oversized electric motors is not considered sensible, in which case energy savings can be achieved by:

Replacing over-sized motors with smaller motors that operate close to full load;

Optimising operations. For example, in a system where a pump constantly removes liquid from a tank it might be better to install a header tank with a simple on/off control to switch the pump on at the defined critical point. The pump will then operate only at full load, only for part of the time;

Installing motor controllers. These are optimizers (they are also known as power factor controllers) that can be attached to motors which operate with small loads (generally of less than 40% of capacity) – they reduce the average voltage / current required by the motor and thereby save energy.

Determining the correct size of motor. It is common practice for engineers to oversize motors in order to provide a margin for safety. However, this can result in higher capital costs, a poor power factor as a result of running the motor at lower than nominal capacity, higher energy costs due to lower efficiency, and higher costs of electrical supply equipment due to higher kVA and kVAR requirements. Motors should be sized to run at over 75% of their rated load most of the time (motor efficiency tends to fall significantly when it operates at less than 40% of full load).

USE OF HIGH EFFICIENCY MOTORSA company should consider installing a High Efficiency (HE) motor when it needs a motor to run at a high load for long periods of time. As well as being designed to reduce motor losses, high ef-ficiency motors also have higher power factors during their operation. They may be between 10% and 30% more expensive than standard motors, but since a motor can use several times its initial cost in electric energy over its lifetime, there is still significant energy saving potential.

112


The energy losses of a typical standard and high efficiency motor (5 HP, 4-pole, 3-phase) are shown in the Table below:

Stator Losses Rotor Losses Core Losses Friction LossesStray Load

LossesTotal

Type % W % W % W % W % W % W

Standard Motor Efficiency (85.2%)

40% 267 25% 160 20% 131 5% 32 10% 62 100% 652

HE Motor Efficiency (90%) 190 75 102 27 8 402

% Losses Reduction -29% -53% -22% -16% -87% -38%

For larger motor sizes, HE motors are generally 2% to 4% more efficient than standard motors; for motor sizes below about 5.5 kW, HE motors are often 4% to 7% more efficient.

THE USE OF HE MOTORSStandard motors operating for more than 3,000 hours per year are good candidates for replacement with HE motors when they fail;

The option of using a HE motor should always be assessed when installing or replacing any equipment fitted with a motor;

It is usually more economic to replace small (less than 10 kW) motors with new motors when they fail;

Large (above 10 kW) burnt-out motors can be rewound or replaced with a new standard or HE motor. However, the efficiency of a rewound motor is usually at least 2% less than its original efficiency, a factor that must be taken into account (along with the rewinding costs) in any economic assessment of its replacement.

Maintaining HE motors in stock eliminates the lead-time required to import new HE motors (although there is a cost associated with this);

For centrifugal pump and fan applications, it is essential to ensure that the speed of the HE motor is identical to that of the motor it will replace;

Operational standard motors should not be replaced with HE motors unless they operate for over 6,000 hours/year. The decision to replace an operational standard motor with a HE motor should be supported with a detailed economic analysis;

Increasing the efficiency of electric motors in a plant is a gradual process that will take years to complete.

USE OF VARIABLE SPEED DRIVES (VSD)The use of Variable Speed Drives (VSDs) should be considered when a motor needs to run at variable speeds (for example, with fans, pumps, winders and precision tools). A VSD allows a machine to run at a speed which more closely matches the desired optimum speed than is possible with a fixed speed motor.


113

There are two types of VSD systems:

Mechanical VSDs, which include hydraulic clutches, fluid couplings, and adjustable belts and pulleys;

Electrical VSDs, which include eddy current clutches, wound-rotor motor controllers and variable frequency drives.

The most commonly used type of Electrical VSD is a frequency converter used in conjunction with an induction motor – a frequency converter is often referred to as an inverter (which is only part of the converter system), a variable voltage, variable frequency drive (VVVF), or a variable frequency drive (VFD).

There are a number of significant advantages associated with using a VSD, including:

Improvements to process control, as small variations in flow can be corrected more quickly;

Improvements to system reliability, as a result of reduced wear to pumps, bearings and seals;

A reduction in capital and maintenance costs, as control valves, bypass lines and conventional starters are no longer required.

Its “soft starter” capability – VSDs allow the motor to have a lower start-up current.

VSD installations can increase energy efficiency on average by 10%-20%. However, in some cases, depending on the operational profile of the motor, savings can exceed 50%.

Figure 31. VSD Beside a Boiler Control Panel (Source: Carbon Trust (27))

114


INSTALLATION OF SOFT STARTERSMotors draw very high currents when starting – these can generate significant heat, increase energy consumption, increase wear and reduce a motor’s life expectancy. Soft starters limit the current to a motor during start-up, allowing a smoother start and also allowing a higher maximum number of starts per hour (very useful for motors that are subject to frequent starts and stops).

INSTALLATION OF AUTOMATIC CONTROLSAutomatic controls (which switch a motor on and off automatically) can also help to reduce energy consumption. For example, a timer can be used to switch motor-powered equipment on or off at specific times during the day. Interlocks can be used to link the operation of one piece of equipment to that of another (so that, for example, both are operating at the same time). Load-sensing devices can also be used to sense when there is no load on the motor, allowing it to be switched off after a suitable period of time, thereby saving energy.


Optimisation of motor sizing (ESR: up to 10%)

Use of VSDs (ESR: on average about 20%; CAPEX: €150-€200/kW for a medium sized motor)

Use of soft starters (ESR: 3%-15%)

Use of high efficiency motors (ESR: 3%-7%; CAPEX: about €80/kW)

Introducing automatic control (ESR: up to 10%)

Improve housekeeping and maintenance (ESR: 5%-10%)

References (28), (29), (30)

3.5.3. REACTIVE POWER

DESCRIPTIONElectric motors, fluorescent lamps, induction ovens, AC arcs or resistance welders consume active power as well as a considerable amount of reactive power. Compensation of reactive power is an


115

important technical measure for the control of electricity consumption, and for limiting maximum end-user loads.

Reactive PowerActive Power Apparent

Power

Inductive loads require two kindsof power to function properly:

Active Power (kW) Actually performs the work

Reactive Power (kvar) Maintains the electro-magnetic field

MOTOR

Figure 32. Induction Load (Source: www.galco.com)

Practically all indices of voltage quality depend on how much reactive power is consumed by industrial loads. A decrease in the amount of reactive power consumed allows the end-user to:

Reduce heat loss in transformers and distribution equipment;

Prolong the life of distribution equipment;

Stabilize voltage levels; and

Increase system capacity.

The main industrial consumers of reactive power are:

Asynchronous motors (45% to 65%);

Electrical ovens (8%);

Rectifier transducers (10%);

Transformers (20% to 25%)

The aim of reactive power compensation equipment is to reduce the reactive current flowing on the lines and the subsequent losses.


REACTIVE POWER COMPENSATIONReactive power is usually compensated by devices such as synchronous motors, capacitors and filter compensation devices placed within the end-user’s network. The aim of reducing the reactive power is to limit a receiver’s impact on the supply network by influencing the receiver itself. Examples of such measures include:

1. Raising the load on technological units to match their capacity:

116


Raising the load of asynchronous motors (raising the operational current increases the power factor);

Ensuring that the capacity of a transformer is close to the required load (transformer loads should be 30% less than their rated capacity).

2. Raising operational times within process plants, for example by using limit switches during the idle operation of asynchronous motors and welders;

3. Replacing asynchronous motors with synchronous models (this, however, increases power losses and O&M requirements);

4. Using transducers with a large number of rectifying phases to artificial switch gates and limit content of higher harmonics in the consumed current;

5. In-turn and asymmetrical control of thyristor transducers.

Given the cost involved, decisions on how to compensate reactive power should only be made following a comprehensive techno-economic analysis. The option chosen must be financially viable, in that the cost of reducing the losses must not exceed the cost of the equipment purchased to achieve the savings. In considering ways of reducing reactive power, it is first necessary to reduce the end-user’s reactive power and then to consider technical means to compensate for this.

The following compensation devices can be used:

Rotational compensators (synchronous motors of light design with unloaded shafts);

A set of capacitor batteries;

Static capacitors (e.g. reactors and capacitors controlled and switched by thyristors);

Thyristor sources of reactive power.

The type, capacity, location and principle of controlling compensation equipment should be selected to achieve the most desirable effect while respecting all technical requirements. The following principles should be taken into account:

Placing the compensation device close to the electrical receiver may achieve the largest economic impact;

Individual compensation is effective and sensible for big electrical receivers, but causes both the compensation device and the consumer to be switched off.

MAXIMISE POWER FACTOR OF ELECTRIC MOTORSThe power factor of an electric motor can be maximised in several ways:

By adjusting the induction current in synchronous motors to deliver or receive reactive power. Existing motors can thus be used to optimise the power factor in a factory.

By using additional idle synchronous motors with an overexcited field to maximise the power factor. Power factor corrected in this way may be more economical in larger size motors (e.g. above 50,000 kVAr) than static capacitors.


117

By installing static capacitors close to a single load (e.g. a motor) with many operating hours – this reduces the current losses for the complete electrical network to the load. These can also be installed for a group of electrical systems with a different load profile.

Without Capacitor Reactive PowerActive PowerAvalable ActivePower

With Capacitor

Utility

Utility

Motor Motor

Motor Motor Capacitor

Figure 33. Power Factor Increase in Motors (Source: www.galco.com)


Raising the utilisation factors

Increase in the load of technological units (ESR: about 10% during start-up of motors)

Replacing asynchronous motors with synchronous models (ESR:2%-3%)

Maximising the power factor of electric motors (good practice billing)

In-turn and asymmetrical control of thyristor transducers (ESR: 1%-2%)

Use transducers of larger no of phases to reduce harmonics

Note: importance rated based on the average share each respective component holds with regards to reactive power consumption

118


3.6. PROCESS CONTROL SYSTEMS

Reducing energy use at an industrial site requires a structured approach based on sound, accurate and timely measurement of energy consumption and the ability of energy managers to access and utilise this information. Nowadays, it is possible for energy users to automatically collect and analyse this data.

This Section discusses Instrumentation, Energy Efficiency Management Systems (EEMS, a software and hardware based information administration system which allows users to both monitor and control energy use) and Process Integration.

3.6.1. INSTRUMENTATION

A closed-loop control system is the basic building block of any system designed to control a process – a system controlling the operation of a plant can include hundreds of individual closed-loops. A closed-loop system consists of:

1. The measurement device – usually a sensor that measures a particular physical property (such as temperature or flow rate) and a transmitter that converts the sensor’s output into a standard control signal which is sent to the controller.

2. The controller, which is usually located in a protective enclosure in a central equipment room. The controller compares the measured value against its set point (the set point is the value required for the efficient and proper operation of the process) and, if there is a difference, adjusts the process parameter to return the measured value to its set point. For example, the controller could measure the actual flow rate of liquid through a process and compare it with the set flow rate. If there is a difference, the controller would set in motion appropriate changes, such as adjusting the speed of the pump, until the flow rate returns to the desired rate.

3. The regulator which controls process throughput. The most common type of regulator consists of a control valve that adjusts the flow in response to commands from the controller (for example, control valves are used to regulate the flow of water around a heating coil to maintain a chemical process at the required temperature). A variable speed pump could also control the flow of the fluid – it has the additional benefits of being more energy efficient, providing more accurate control of the flow and eliminating the problem of sticky valves.


119

Controller

Set-point or desired value

RegulatorProcessMeasurement device

Figure 34. Control Loop System (Source: Carbon Trust(31))

There are various types of process control systems:

Single-loop controllers – electronic relays and simple on-off controllers are used to sequence, for example, valve movements and carry out other mechanical operations involved in process start-up and shut-down.

Sequence controllers – such as programmable logic controllers (PLCs). PLCs have a modular design so that they can be expanded to cover more aspects of process operation. PLCs can carry out a sequence of actions and incorporate single-loop controllers along with more advanced types of controller.

Distributed control systems (DCS) – DCS control large and complex processes, and can sequence process start-up and shut-down operations. They enable operators to adjust the set points of many individual controllers from a central control room. The central supervisory control unit monitors the operation of all other controllers, enabling the production of high-quality products.

Supervisory control and data-acquisition (SCADA) systems – SCADA systems are software packages designed to run on a computer workstation and control a wide range of industrial processes. Some advanced SCADA systems also include fault diagnosis and production scheduling systems.

Process control systems are generally very cost-effective. While directly accounting for only a small proportion of the energy used on an industrial site (typically less than 3%), they have an enormous influence on the overall consumption of energy within that site as they control the operation of all processes and utilities.

Adopting best practice in process control can result in energy savings of between 5% and 15%, depending on the quality of existing process control systems and the nature of the process.

120


3.6.2. ENERGY EFFICIENCY MANAGEMENT SYSTEM (EEMS)

Energy Monitoring and Targeting (M&T) is the collection, interpretation and reporting of information on energy use. M&T is a management approach that helps companies to eliminate waste and reduce their current use of energy (and other consumables) by providing timely and relevant information on their use. It also provides the incentive for further improvement by presenting concrete evidence of successful performance improvements, from which the economic benefits are evident.

An Energy Efficiency Management System (EEMS) is an energy-related M&T system that is reinforced by managerial support and the adoption of appropriate energy conservation-related policy measures.

Energy Monitoring and Targeting is made up of a number of key elements:

Measuring energy consumption over a specified period of time;

Relating energy consumption to a measure of output (e.g. production quantity) in order to define an energy consumption standard;

Setting targets for reduced energy consumption;

Regularly comparing actual consumption against target consumption;

Reporting variance in energy consumption; and

Taking actions to correct variances.

Energy performance monitoring is used initially to document the current situation. After some historical data has been collected, it will be possible to establish challenging but realistic targets for improving performance. At the same time, it will be possible to continue monitoring progress towards achieving those targets. More data will, in turn, lead to a better understanding of an enterprise’s energy performance and allow further targets to be developed.

In addition to measuring devices, a M&T system usually includes a computerised user-friendly interface which allows all data to be monitored in real time – it may also allow manager to intervene in the operation of major pieces of equipment (e.g. to shut down an air compressor or alter temperature set points). The system should be capable of reporting on actual energy consumption and energy consumption trends, helping to define KPIs and set targets, and facilitating comparative analysis.

An M&T system’s software is a crucial element in the successful monitoring and evaluation of data – it must be able to produce basic energy efficiency graphs and reports, thereby helping the site energy manager to identify energy waste and energy saving opportunities.

SETTING THE TARGETCentral to the success of a M&T system is the establishment of “accountable centres” for which targets can be set. A centre can consist of an individual machine, a process department or even the entire site. A nominated individual should be given responsibility for operational achievements at each centre. Tying the consumption of resources and the generation of emissions to those responsible


121

for operational achievement at each centre is a key factor in any M&T system since it focuses attention on those with the authority to effect improvements in performance. It is also essential that those responsible for each centre have all the information required to be able to make decisions and take action to improve performance, and to assess that performance.

Targets can be set using a detailed engineering analysis of operations. Alternatively, they can be developed using historical data. For example, graphs of Energy versus Production (E-P) and Specific Energy Consumption versus Production (SEC-P) will reveal the occasions when energy efficiency has been particularly high – a challenging but attainable target could then be set based on best historical performance (or something close to that). When there has been limited monitoring and comprehensive data is not available, an initial target could be set at, say, 5% to 10% better than current performance. This target could then be modified as more data is collected and more experience gained. In all cases, the target can only be set following full discussion between all the parties involved, including operations, accounting, energy and environmental staff.

An example of an Energy versus Production graph is shown below (for a fabric producer).

y = 1825,9x + 4E + 07R2 = 0,4686

Weekly Fabric Production (kg)Wee

kly

Ener

gy C

onsu

mpt

ion

( kJ)

Figure 35. Weekly Fabric Production Against Energy Consumption (Source: LDK Consultants)

CHECKING PERFORMANCEHaving established a target, plant performance needs to be monitored continually to determine if that target is being met. The evaluation of plant performance is best done by regularly comparing actual performance against the target – “regularly” should be interpreted to mean at least monthly, it certainly does not mean annually. In assessing energy use, it is necessary to take account of variations in production levels – relying on a simple comparison of specific consumption is not enough.

For example, using historical data, regression techniques can be used to develop an equation for estimating future energy consumption. This equation – or an “adjusted” equation which incorporates an enhanced performance or “target” – can then be used to compare actual energy consumption in any month with predicted consumption using the CUSUM (cumulative sum) method. The CUSUM

122


chart – which should be updated every month – will indicate if performance is proceeding towards the target or not.

An example CUSUM chart is shown below:

Week Number

Cu

mu

lati

ve D

iffer

ence

(kJ)

Figure 36. Cumulative Difference (Source: LDK Consultants)

In this way, the data generated by the monitoring activity forms the basis for continuous performance evaluation and control. First, it will indicate if and where deficiencies have occurred and trigger the necessary remedial action and, second, it will provide quantified evidence of exactly how successful any improvement measures have been (from better operating management to implementation of a major equipment investment).

However, it is recognised that maintaining the momentum of an M&T programme may be difficult. It is therefore important for an enterprise to carry out a periodic evaluation of the operation of the system, not only to determine if targets are being met, but also to measure the relative success of the techniques used to reach the targets and to identify opportunities for further progress.

To maintain interest, training should be given to plant personnel at all levels – this will equip them with the skills and knowledge necessary to operate the plant efficiently, to understand and participate in target development, and to move towards achieving those targets.

MEASUREMENTSEnergy metering is the most important step in determining energy consumption within a plant or facility. All plants already have basic metering systems installed: these provide the basis for monthly billing by the electricity and gas utilities. The measurement of energy in its different forms is of prime importance to energy conservation effort. A variety of fixed and portable energy measuring devices may be needed to provide the various measurements required to improve energy efficiency. However, there exists a broader rationale for their use: most processes could not operate without instrumentation. In addition, these devices can play a vital role in maintaining product quality by allowing process parameters to be monitored. Finally, they are necessary for monitoring equipment conditions and ensuring the safe operation of process equipment.


123

However, many plants in Georgia lack basic instrumentation. Most do not have sufficient instruments installed to monitor energy flows to or from major energy-consuming pieces of equipment. Some plants may have installed the measuring devices, but they have often fallen into disrepair. Some plants may have adequate instrumentation, but they don’t use them for measuring or monitoring energy consumption or energy efficiency.

For any energy consumer, there are two basic measurements:

1. Energy Consumption

This includes total plant consumption (which is readily obtainable from monthly electricity, gas, oil and other energy bills) as well as energy consumption within individual areas, units or processes. These measurements allow a company to determine energy costs as a proportion of production costs, and energy costs per unit of production. They can also allow the company to identify areas of high energy consumption and (potentially) waste within the plant.

Much of the instrumentation used to measure energy consumption can be automated. This can range from simple automatic control techniques to complex process automation systems (the most appropriate system for a particular plant will need to be determined by a separate study). However, by eliminating human involvement in the measurement, decision-making and modification of a process, automation can improve energy efficiency. Process automation can also improve productivity and product quality which can, in turn, further reduce energy consumption. If the basics of energy measurement and instrumentation are understood, automatic control and process automation are logical next steps in many process applications.

Sub-metering, or measuring energy consumption in different areas of a facility, is an effective way of obtaining energy consumption information for those areas. Sub-meters also can provide a good check on the utility meters and monthly bills. Examples of energy metering or sub-metering applications include:

Electricity: Electricity consumption (kWh) meters can be placed on feeders to important areas within a facility. They are usually mounted in the local distribution panels where they can be easily read;

Natural Gas: Gas meters should be installed on individual pieces of equipment that are large energy consumers (boilers, ovens, furnaces). This is especially true when there is more than one large user within a facility. Installing individual meters on two furnaces, for example, could help identify which (if either) is more efficient, something which might not be clear from examining the facility’s total monthly consumption;

Fuel Oil: Flow meters on diesel or furnace oil pipes supplying boilers, engines or other equipment are commonly used to determine consumption relative to output. At the very least, regular measurement of levels in storage tanks or day tanks should be carried out to provide a gross estimate of consumption rates;

Steam: A steam flow meter at the generation point can be used to estimate generation efficiency. It can also be used to determine a facility’s total steam requirements. Additional flow meters should be used to determine consumption in different areas of the facility;

124


Water: Water meters can be used to measure boiler feed water consumption when the cost of a steam meter cannot be justified. Equipment or processes that use large quantities of water should also be metered. Water is a scarce commodity and its pumping and distribution require energy. Excessive water use may also adversely affect energy consumption within particular processes (for example, requiring removal of moisture in a dryer).

2. Energy Efficiency

This includes the measurement of the efficiency of individual machines or processes (boiler or dryer efficiency, process temperature, electric motor load or power factor). It also includes measurements which can be used to quantify energy inefficiencies (steam, water and fuel leaks, the waste of hot condensate and the energy content of hot exhaust air). These measurements can generate specific energy saving recommendations, and usually allow accurate estimates of potential energy savings. Maintenance and operational checks and measurements are also included in this category.

Figure 37. Combustion Analyser (Source: TESTO)

Direct and indirect measurements of efficiency complement energy metering data, and can help pinpoint where energy may be being wasted. Efficiency measurements cover all measurements that provide some information on the relative efficiency of energy use in a process or piece of equipment. Examples of efficiency measurement include:

Combustion Efficiency: The measurement of combustion efficiency in all fuel burning equipment can be carried out using portable or on-line gas analysis equipment. For most applications, portable analysers are sufficient and they are equally useful for boilers, furnaces and other equipment. Large boilers may warrant on-line combustion analysis and control equipment;


125

Boiler Total Dissolved Solids: The measurement of Total Dissolved Solids (TDS) in boiler water, boiler feed water and boiler blow-down water provides the basis for computing blow-down rates (which affect boiler efficiency). It also allows an operator to set the level of blow-down required to prevent scaling and the deterioration of boiler efficiency;

Dryer Exhaust Humidity: The humidity in dryer exhaust air indicates the amount of air used in the dryer, and thus provides a measure of dryer efficiency. If the humidity is very low, for example, large amounts of air are passed through the dryer relative to the amount of moisture evaporated – the heating of this excessive air indicates low dryer efficiency and the wastage of energy;

Process Temperature: The temperature in a process (e.g. furnace temperature, hot water temperature or food pasteurization temperature) must remain within a narrow band above the minimum required for that process. Excessive temperatures not only endanger process quality but also increase energy consumption, reducing process efficiency;

Surface Temperature: The surface temperature of any equipment or material (insulation, piping, steam trap, boiler and process equipment) provides a direct indication of heat loss. This, in turn, directly affects the efficiency of that piece of equipment;

Compressed Air Pressure: As with process temperature, compressed air pressure must be maintained within a narrow band above the minimum level required for the proper operation of equipment. Compressing air to pressures beyond that required causes unnecessary power consumption, thereby reducing efficiency. This also applies to steam pressure, with the added consideration that distribution heat losses increase for higher-pressure steam:

Power Factor: The power factor in an electrical system is a measure of the efficiency of the use of the electric current provided. A low power factor usually corresponds to higher distribution losses and lower efficiency.

3.6.3. PROCESS INTEGRATION

Process Integration can be defined as the selection and interconnection of processing steps in order to create an optimum manufacturing solution. It is based on a non-mathematical approach to thermodynamics and enables the process designer to define inevitable and avoidable thermodynamic losses, and to set practical (as opposed to idealistic) performance targets.

Process Integration involves the use of mathematical simulation methods and expert-system-based approaches with the application of pinch concepts within a three stage methodology:

1. Defining a target for energy use or capital expenditure;

2. Using simple screening techniques to eliminate sub-optimal operations;

3. Determining critical components of a process in which key design considerations can have a major impact on overall energy performance.

As a process develops over time, the energy consumption per unit of production will decline as new plants are built using the accumulated experience gained from existing plants. Modifications to the

126


flow sheet through the application of process integration enable the traditional learning curve to be dispensed with and this can encourage the designer to achieve the optimum practical target for energy consumption.

Process Integration can also help to reduce overall capital cost as the cost of equipment decreases with an increased temperature gradient. In addition, improved heat recovery reduces steam and cooling water requirements, which can also help to reduce capital and operating costs.

One of the most important analytical techniques used by process engineers is pinch point analysis – this matches heat exchangers with process streams and allows the effects of changing operating procedures to be assessed. The method is driven by the minimum number of heat exchangers, the minimum required thermal load and the minimum required cooling load. In practice, the method:

Links cold and hot processes in the most thermodynamically advantageous way;

Starts with an analysis of heat processes – hot-cold flows are presented in the form of T-h diagrams;

The streams are separated by a minimum temperature difference;

Derived curves indicate the total availability of heat, as well as the demand for heat;

The point at which the hot and cold flows are closest is defined as the pinch point.

The pinch point divides the process into two regions: a high temperature or heat source region, and a low temperature or heat sink region – this is illustrated in the Figure below. Pinch point analysis has played an important role in identifying and correcting inefficiencies in heat exchange in complex industrial processes – it has been particularly useful in the petrochemical, chemical, pulp and paper, food and beverages industries.

Heat load H (heat units)

Tem

pera

ture

T (t

empe

ratu

re u

nits

)

Heat recovery4 units

Hot compositecurve

Hot utility target4 units

Cold compositecurve

Cold utility target3 units

PinchHot stream T = 600Cold stream T = 500 Tmin = 100

Figure 38. Pinch Point Determination (Source: Best Practice Programme(32))

3.7. ENERGY EFFICIENCY IN BUILDINGS


127

3.7.1. THE BUILDING SHELL

DESCRIPTIONThe building envelope (comprising a building’s walls, windows and roof) strongly affects a building’s demand for and consumption of energy since it regulates heating and cooling loads and the availability of daylight within the building. In general, it is possible to generate significant energy savings by renovating and refurbishing a building’s envelope.

Typically, two-thirds of the heat generated in a building is lost through the building fabric itself. The rest is lost through gaps, cracks and vents in the fabric of the building – these allow warm air to leave and cold air to enter the space. The lost heat has to be made up again by the heating system, which can be expensive. The rate at which heat is lost depends on:

The temperature difference between the inside and outside of the building;

The insulation properties of the building fabric;

The amount of fresh air entering the building, either by controlled ventilation or through poorly fitting windows, doors and joins in walls.

The main parameter used to evaluate the performance of a building’s fabric is Thermal Transmittance, or U Value – this is defined as the heat power per unit of surface area that is transmitted in to/out of the building for each degree difference in temperature. It is expressed in watts per square metre per Kelvin [W/(m2K)]. Typical U values for the various components of a building’s envelope are shown below (as currently found in the EU):

Table 9. Typical EU U Values (for Different Climatic Conditions)

U Values (W/m2K)

Components Passive and Low Energy Buildings

Severe Standards (North and Central EU)

Weak Standards (South EU)

Outer Walls U<0.15 0.15<U<0.4 0.4<U<0.65

Windows/Doors U<0.7 1.25<U<2.5 2.5<U<3.25

Roof/Ceiling U<0.15 0.22<U<0.45 0.45<U<0.9

Floor/Basement U<0.15 0.15<U<0.4 0.4<U<0.65

(Source: (33))

128


Roof22%

Windows26%

Walls9%

Floor8%

Ventilation andair infiltration

35%

Figure 39. Indicative Numerical Figures of Heat Losses from a Commercial Building (Source: the Carbon Trust 2).

ENERGY SAVING MEASURESDepending on the current performance of a building envelope, it is possible to reduce its energy consumption by up to 50%, either by acting collectively on the various components of the building envelope or by completely renovating the building’s façade.

THERMAL INSULATIONThe most important factor in reducing a building’s energy consumption is thermal insulation. The higher the quality of the insulation or thermal resistance of the parts of the building exposed to ambient temperature, the higher the potential energy and cost savings in heating and cooling the building.

WALL INSULATIONEnergy flows through a building’s walls are related to the thermal resistance characteristics of the material making up the wall (such as brick, stone masonry or concrete). Losses are inevitable without insulation. The thermal properties of walls are roughly related to the thickness of the material used in the wall – brick walls tend to be 38-64 cm thick while large panel concrete walls are about 30-35 cm thick. Achieving the same high thermal insulation standard for a brick wall would require it to be 1.5 m thick; while a lightweight concrete wall would need to be 65 cm thick. However, as this is not practical, additional insulation materials must be used to achieve the same thermal insulation standard.

2 Depends on surface of openings


129

To improve the insulation of existing buildings, it is possible to fix an additional layer of insulation onto the building’s walls – this layer can be attached to either the outside or the inside of the building. Attaching additional insulation to the exterior of a building has a number of advantages, including:

The whole wall is insulated (importantly, no heat is transferred through the joints, as would be the case if insulation had been installed on the inside of the wall);

The building will be protected from the damage caused by the seasonal variations of temperatures and moisture;

Exterior insulation does not reduce the size of the living area.

1. Anchor mechanism

2. Insulation e.g. 5 cm EPS

3. Plaster

4. Glass fibre Mesh

5. Final coloured stucco /(plaster)

6. Typical installation elements in external walls thermal insulation

Figure 40. Layout of Wall Insulation

Improved insulation can reduce heating/cooling costs by between 15% and 35%, depending on the technology used. The thermal insulation of a building’s walls can not only improve the thermal resistance of the walls, but also reduce the heat transfer rate – the same effect is realised when a building’s basement or ground floor is insulated.

The impact on heat lost through a wall following the implementation of energy saving measures is shown below for different types of wall.

Table 10. Impact of the Energy Saving Measures on Different Types of Walls.

Before Rehabilitation After Rehabilitation

Wall Fabric Thickness, cmThermal

Resistancem2°C/W

Heat LossesGJ

m2/y

Thickness of a Silicate Cotton Layer,

mm

Thermal Resistancem2°C/W

Heat LossesGJ/m2/year

Annual SavingsGJ/m2/y

Brick

38 0.63 0.48 50 1.69 0.18 0.30100 2.30 0.13 0.35

51 0.79 0.38 50 1.62 0.19 0.19100 2.46 0.12 0.26

64 0.95 0.32 50 1.78 0.17 0.15100 2.62 0.12 0.20

Ceramsite concrete

30 0.89 0.34 50 1.72 0.18 0.16100 2.56 0.12 0.22

35 1.01 0.30 50 1.85 0.16 0.14100 2.68 0.11 0.19

130


ROOF INSULATIONIt is also important to insulate a building’s roof, especially in a low-rise building. In Eastern Europe and post-Soviet countries, where attics tend not to be heated, this usually involves insulating the attic floor. Unlike walls, installing additional insulation on an attic floor is a relatively easy exercise.

Bulk insulation or insulating boards are usually used to insulate an attic floor. Mineral wool mats and other insulation materials laid on a floor can be up to 200 mm thick (including an upper protective layer). Bulk insulation, such as keramzit gravel, is usually over 250 mm thick. However, the insulating layer close to the outside wall should be 30mm to 50 mm thicker. It is possible to reduce heat losses by up to 20% by doubling the heat transfer resistance value of an attic floor in a one or two-storey cottage. However, the same measure applied in a nine-storey building will only reduce heat losses by some 3.5%.

ENERGY EFFICIENT GLAZINGGlazing systems and transparent facades are critical elements of the building envelope because they permit daylight and solar radiation to enter the building directly (although there is a risk of overheating in the summer). Up to half the heat supplied by the heating system of a multi-storey residential building can be lost through its windows. Glass elements of the building envelope should therefore have low thermal transmittance values (and at the same time continue to allow daylight to enter the building).

Replacing old single glazed frames with double glazed windows will usually incur savings of up to 15%. Double glazed windows which are a perfect solution for moderate climates, are generally manufactured with PVC or aluminium frames, anodized in a variety of colours. Wooden frames can increase the level of insulation, but they are more expensive and only tend to be used when restoring traditional style buildings which are protected by municipal by-laws. Although expensive, triple glazing is recommended for the most severe climates – it also provides the best soundproofing. Double-glazing with 10 to 12 mm air space between the panes can significantly reduce heat losses – the U-value of a double glazed window with a 12 mm air space is around 3 W/m2K, compared with a value of 5 W/m2K for a single glazed window.

Table 11. Examples of how double glazing can save energy

Type of glazing Inside surface TThermal

resistanceHeat

lossesHeat Savings per year

°C (m2°C)/W GJ/m2/year GJ/m2/y kWh/m2/y

Double glazed wooden windows

6 0.39 0.792 - -

Triple glazed wooden window 10 0.55 0.562 0.230 58

Double-glazing with heat reflecting coating

9 0.54 0.572 0.220 55

Double-glazing filled by argon 11 0.69 0.448 0.344 86

Double-glazing with two heat resisting coatings

12 0.78 0.396 0.396 100


131

While energy losses can be significantly reduced by installing double glazed windows with enhanced frames, care should also be taken to ensure that the joints between the window frame and the wall itself are insulated.

Figure 41. PVC Double Frame with Thermal Break (Source: archiexpo.com)

SHADING DEVICESWhenever there is a significant difference between the external and internal temperatures, both in summer and in winter, external shading is the most effective means of reducing glare and heat from the sun through exposed windows.

Installing shades, such as shutters or airtight blinds, to the outside of a building can prevent direct summer sun entering the building, thereby reducing uncomfortable heat and glare. Shading could also be angled to allow winter sun to enter the building, maximising the use of natural daylight and solar heat gain during those months. Up to 10% savings can be expected for good shading in tertiary sector buildings (34).

132


Figure 42. Window with Rotating Panel (source: (35))

Various technologies have been developed to provide effective solar protection, as follows:

Movable devices: these have the advantage in that they can be controlled both automatically and manually in response to changes in the sun’s position and other environmental factors. They include:

Internal Blinds A common method of window protection.

Easy to install.

Mainly used to help control the level and uniformity of lighting.

Ineffective in reducing summer heating load.

If well designed and combined with spectrally selective glazing that can (in some situations) help to control solar radiation transfers.

External Blinds They stop solar radiation before it enters the building – they are the most effective means of controlling solar radiation flows.

They should be made out of low heat storage materials with reflective finishing.

The movement of air between the blinds and the window can help to remove the energy absorbed by the blinds.

They can be harder to maintain and may have shorter lifetime.

New smart designs that are resistant to high wind speeds are available on the market.

Blinds Between Two Layers of Glass

Efficient in blocking both direct and diffuse radiation, as well as allowing winter sun to enter the building (as the slats can be tilted).

Medium efficacy in preventing undesired solar gains.

Vapour condensation can occur between the two layers of glass in winter.

Permanent devices: these are designed for a specific building and are less flexible than movable devices. Special care needs to be taken with fixed shading systems so that they don’t reduce potential solar heat gains in colder seasons – charts and specialized software can be used to optimize the


133

geometry of these devices so that they not only create summer shade but also don’t reduce winter gains.

Overhangs Relatively widespread in hot climates.

Advantages: if positioned correctly, they admit direct radiation when the sun is low in winter while blocking it in summer (they also block part of the diffuse radiation).

Disadvantages: appropriate only for south-facing windows. East- and west-facing windows have low and variable sun angles, thus other (vertical) device have to be used; they can also interfere with the air flows inside as well as outside a building.

Light shelves A device that combines both daylighting and shading. The light shelf is a horizontal reflective surface placed quite high through the window or just outside it.

By its positioning and by its interaction with overhangs, it shades the main part of the window but light can reach the back of the room as it is reflected off the top of the shelf.

Louvres Can be either fixed or movable devices. If movable, they can be used to block summer radiation while allowing winter sun to enter a building. If fixed, they can also improve a building’s security.

Disadvantages: affect view (especially if they are permanent) and means that artificial lighting has to be used within the building. Maintenance may be difficult if access to the louvres has not been incorporated into the design of the building.

They may modify air movements (either facilitate or hinder natural ventilation), depending on their geometry, their inclination and the building’s environment (36)

OVERCOMING INFILTRATIONInfiltration is the penetration of ambient air through gaps in the building envelope. Some of this air may be needed for ventilation, but gaps in the building envelope mean that a lot more air than is needed purely for ventilation purposes generally enters a building (remember that it is impossible to insulate windows completely). The volume of air entering a building will depend on the size of those gaps and the difference between internal and external air pressure. Sufficient infiltration is considered to be provided if half the volume of air in a room is changed every hour. In practice, however, due to gaps in window joints, three to four times this amount of air is typically changed every hour.

Table 12. Heat Losses due to Infiltration

Loss of Heat (per year)

Air Changes per Hour* Infiltration GJ of Fuel Oil kg Fuel Oil

0.5 Minimum 5.2 131

1.0 Permissible 10.4 262

1.5 Exceeding 15.6 393

2.0 Detriment 20.8 524

* Defined as cubic metres of air infiltrated per cubic metre of building volume.

134



Shading devices (ESR: up to 5%; CAPEX: up to€600/m2 for mechanical with automation)

Thermal insulation in external walls (ESR: 15%-35%; CAPEX: €30-€50/m2)

Thermal insulation of roofs (ESR: 5%-20%; CAPEX:€20-€40/m2)

Double glazing (ESR: up to 15%; CAPEX: €150-€250/m2)

3.7.2. HEATING AND HOT WATER SYSTEMS

HEATINGThe aim of a heating system is to increase the temperature in an indoor space. Indoor heating in buildings can be provided by a number of means:

BOILERSThe type of boilers most commonly found in houses and commercial premises are low temperature hot water (LTHW) boilers that produce hot water at around 90°C. The hot water is distributed via a pipe network to “wet” heating systems and hot water storage tanks. LTHW boilers are usually gas-fired, but can also be run on oil or LPG, particularly in areas with no natural gas supply. However, oil and LPG are more expensive than gas and emit more CO2 to the atmosphere.

Biomass boilers, using wood or pellets, are becoming more popular. These emit very little net CO2, but are more expensive and the availability and storage of fuel can be difficult.

The main components of a gas-fired LTHW boiler are shown in the Figure below.


135

Major components in a typical gas hot water boiler

Draft hood

Water feed

Hot water outlet

Temperature andpressure controls

Circulating pump

Drain

Insulated metal enclosure

Gas burners

Exhaust gases

Flue

Heat exchanger

Gas valve andburner controls

Gas inlet

2

8

1

7

10

11

3

9

6

5

4

Figure 43. Major Components of a Gas-Fired LTHW Boiler (Source: (37))

TERMINAL UNITSThere are a variety of terminal units that can be used with LTHW boilers, each of which offer different opportunities for energy savings. The most frequently used terminal units in smaller buildings are radiators and under floor heating.

Radiators - Effective temperature control and low maintenance make radiator systems a popular choice for many consumers. There are a number of different types of radiators available, including panel radiators, column radiators and convectors. Heat emissions from panel radiators and column radiators come mainly from radiation and partly from convection. Convectors, on the other hand, draw room air in through a casing and warm it by passing it over a covered hot water pipe. They have a low surface temperature making them popular in schools and hospitals. Compared with panel column radiators, they have a greater heat output per unit size and a faster heat-up time. However, they are more expensive to maintain.

Figure 44. Panel and Column Radiators

136


Under-floor heating - Consists of a network of hot water pipes embedded between the floor finish and the main concrete floor slab. The main advantages of under floor heating over radiators and convectors are that it is “invisible” and that it provides greater flexibility in the use of a space (for example, in the positioning of furniture).

HEAT PUMPSHeat pumps can provide an alternative to electric heating and cooling systems and, particularly if the heat sink is the ground, they can reduce energy consumption significantly. In winter these devices use electricity to transfer heat from the ground into a building for space heating. In summer they transfer heat from the building to the ground for cooling. Heat pumps can produce up to four times more heating or cooling than the energy it takes to drive them.

Heat pump efficiency depends on the temperature of the source from which it draws the heat. By using the relatively constant temperatures found underground as the heat source, it is possible to achieve high heat pump efficiencies all year round.

HOT WATER PREPARATIONHot tap water (HTW) is usually used for cleaning, hand washing, cooking and showers. Hot water can be produced from centralised or decentralised systems:

CENTRALIZED SYSTEMSThese consist of a centrally-located hot water production unit and a pipe distribution system which distributed HTW to consumers. The installation of a pump on the distribution system ensures that hot water is always available.

DECENTRALIZED SYSTEMSThese involve the installation of small hot water production units at the places where the water is consumed. Gas and electric water heaters can be used to heat the water (electric water heaters are by far the most expensive option).


137

Figure 45. Direct Gas-Fired Water Heater (Source: (38)) Figure 46. Electric Water Heater (Source: (38))

There are two main types of water heater: instantaneous and storage.

Instantaneous - This type of heater only heats as much water as needed, when it is needed. Turning on the tap, cold water flows through a heat exchanger, igniting a gas burner or switching on an electric element. Therefore, there are no heat losses. As long as there is gas or electricity, hot water is available.

Storage - The water is heated to a relatively high set temperature (usually between 60oC and 70oC) and kept ready for use in a storage tank. Hot water is drawn from the top of the tank and replaced by a similar amount of cold water at the bottom. The temperature drop is sensed by a thermostat, which turns on the heater at the bottom of the tank. Although the tank is insulated, it will be constantly losing energy.

For large-scale applications, the most cost effective option is to place the water heater as close as possible to the point at which the hot water is used.

Figure 47. Storage Calorifiers Fed from Boiler (Source: choice.com.au)

138



HEATINGThere are a number of factors that can increase the energy efficiency of heating systems, including:

Heat recovery – Condensing boilers: In a conventional boiler, the heat contained in the exhaust gases is lost to the atmosphere. However, if it is not possible to replace an existing boiler with a condensing boiler, then this heat can be recovered through the use of a heat exchanger – the heat can be used to pre-heat the return water or the combustion air.

Replacing an existing boiler with a condensing boiler can, however, generate greater energy savings. A condensing boiler is a high efficiency modern boiler that incorporates an extra heat exchanger so that much of the hot exhaust gases are used to pre-heat the water in the boiler system. The use of a condensing boiler can raise efficiency by as much as 10% to 12%, depending on the water return temperatures allowed.

Insulation of boilers, pipe work and valves: Heat losses through the boiler, pipe work and valves will reduce efficiency. As a result, all businesses should check the insulation of their systems – well insulated boilers should have a surface temperature of 35oC-40oC. Energy savings of between 4% and 9% can be achieved by increasing the amount of insulation on boilers and hot water pipe work.

Flue dampers: On larger boilers, the flue can cause air to flow through the boiler even when it is not firing. This cools the boiler and valuable heat is lost to the atmosphere. This is referred to as “standing losses”. A flue damper can be used to close off the flue automatically when the boiler is not firing, thus preventing this loss of this energy.

Variable speed drives (VSDs) and pumps: On forced/induced-draught boilers, a VSD can be installed on the fan, enabling it to operate at lower speeds when less airflow is required. A reduction in fan speed of just 10% can result in fan energy consumption savings of around 20%. This is particularly relevant for big boiler systems.

Burner controls: Burner controls manage the fuel-to-air ratio which is critical to the efficient operation of the boiler: too little air and there will not be enough oxygen for complete combustion to occur (which can cause a build-up of potentially dangerous CO in the flue), while too much air can result in energy being wasted in heating the excess air. The fuel-to-air ratio is normally set on the burner controls and will be based on the boiler manufacturer’s recommendations. Proper control of this ratio will ensure that the boiler is operating as efficiently as possible.

Boiler interlock: Boilers can continue to fire even when there is no demand for heat (called dry-cycling). When this occurs, all of the heat energy will be lost to the flue. Linking the boiler controls with the heating system controls (such as room thermostats) via a boiler interlock ensures that the boiler does not operate when there is no demand for heat, thus preventing dry-cycling. This can be done using standard wiring between the boiler control and the main heating control, or can be achieved through the installation of a specialized integrated controller. Interlock control is appropriate for all types of boiler.


139

Sequence control: When there are two or more boilers, it is advisable to install a “Sequence Control” system. Good sequence control ensures that only the minimum number of boilers required to meet the demand for heat actually fire, and that those boilers are used to their full capacity rather than operate part-loaded. Good sequence control could save 5%-10% of the overall energy consumption of the boiler plant.

Optimized start/stop control: An optimizer is a sophisticated time switch linked to internal and external thermostats that switches the boiler on at exactly the right time to ensure that the building reaches the required internal temperature in time for occupation. An optimiser can reduce energy consumption by 5%-10%.

Direct weather compensation control: To achieve more savings, the temperature of the hot water produced by a boiler can be regulated according to the outside temperature. In milder weather, the flow temperature is reduced, thus saving energy. This is done through the use of a compensator linked to internal and external thermostats. This form of control is particularly useful in condensing boilers as it allows lower return water temperatures to be achieved, thus ensuring that maximum condensation occurs within the boiler, thereby increasing efficiency.

HOT WATERMaintenance: A well-maintained system is an efficient system. This implies that the HTW tank should be cleaned on a regular basis, the HTW temperature should be kept low (at between 50°C and 60°C), pipe insulation should be inspected and maintained on a regular basis, and the difference in the supply and return HTW temperatures should be kept to 5°C.

Proper Start / Stop of the recirculation pump, so that it only operates when there is a demand for it to operate. For example, as there is no demand for HTW at night or during the weekends in an office building, it is unnecessary for a recirculation pump to operate during these periods. The adoption of this policy will not only reduce heat losses from pipes but also cut demand for electricity for the pump. Thermostatic valves can be installed in the return of recirculation pipes to keep the temperature low (e.g. at 50°C).

Use of solar water heating systems: Solar heat supply is one of the most widely used practical applications of solar energy. Heat from solar radiation can be used for domestic hot water needs and heating, and for air cooling in residential, public and industrial buildings. Solar irradiance in Georgia can reach 1,400 kWh/m2 – this is considered to be sufficient to allow solar collectors to be used for HTW preparation.

140


Figure 48. Solar Water Heaters in a Commercial Building (Source: LDK Consultants)


Recover heat from exhaust gases (ESR: up to 10%)

Use of solar heating and ground source heat pumps (ESR: 50%-80% of DHW demand; CAPEX: €300-€400/m2 solar collector, €3,000-€4,000/kW for GSHP)

Use condensing boilers (ESR: 10%-12%; CAPEX: about €10,000 for a 150 boiler)

Install VSDs (ESR: up to 20%; CAPEX: €150-€200/kW)

Boilers sequence control (ESR: 5%-10%)

Improve insulation of boilers, pipe work and valves (ESR: 4%-9%; CAPEX: about €10/m2)

Optimising start/stop control (ESR: 5%-10%)


141

3.7.3. AIR-CONDITIONING

DESCRIPTION - COMPONENTSAir conditioning (AC) systems use the same operating principles and basic components as refrigerators (i.e. they cool using evaporators and release the absorbed heat to the external environment via a condenser). A compressor moves a heat transfer fluid (or refrigerant) between the evaporator and the condenser. Cooling systems are typically very energy intensive and are almost always fuelled by electricity. In addition, they tend to operate during peak hours of the day. Cumulatively, these systems are estimated to account for about 40% of the energy (both electricity and gas) used in commercial buildings – reducing their use of energy can therefore have a significant impact on a building’s energy costs.

Cooling towerCentral air-handing plant

Centralplant

Distributionsystem,ductworkandpipework

Centralplant

Variable airvolumeterminal unit

Extract airthroughlight fitting

Terminalunit withreheat

Chilled water

Chilled plant Boiler

Condensed water

Hot water

Fancoilunit

Figure 49. Centralised Air Conditioning System (Source: (39))

TYPESThere are three “families” of AC equipment on the market: “packaged units” (which are all-in-one units), “split systems” (made up of one outdoor unit which contains the condenser and the compressor and which is connected to one or more indoor units composed of evaporators and fans), and “chillers” (water cooling equipment). The main difference between the three systems is the carrier by which the “cold” is transported in cooled areas: this can be air for packaged units, refrigerant for split systems, or water for chillers. In a typical packaged system, all components are located in a single outdoor unit that may be located on the ground or roof; while in a split system the condenser and compressor are located in an outdoor unit and the evaporator is mounted in the air-handling unit.

142


Figure 50. Packaged Unit (Source: goodmanmfg.com)

Figure 51. Split Systems (Source: approvedcomfort.com)

Figure 52. Chiller (Source: york.com)

Whatever carrier is used, air has to be cooled at the end of the pipe and has to be introduced into the areas to be cooled. Air-cooling can be done either locally (in each area) or centrally (before distribution to each area), using an air-handling unit (AHU). Local AHUs need extra-ventilation systems, while centrally-located AHUs allow for the controlled renewal of the air.


143

Table 13. Outline of the Basic AC Types (Source (33))

System Description

Packaged Unit All in one units that can be installed either in the area to be cooled or outside. They can be cooled by fresh air (fed in through ducts) or by water. They can manage the renewal of the air by blowing in fresh air.

Rooftop Packaged Units: A type of packaged unit located on the roof which is generally air-cooled and which supplies fresh air through air ducts (this allows internal air to be renewed).

Smaller packaged air conditioning systems tend to use water as the heat transport medium to cool the indoor air directly. Their evaporators take the form of an air cooling coil (direct expansion or DX coils), and they tend to use an air cooled condenser.

Split System The installation is split between one outdoor unit (compressor and condenser) and one or more indoor units (evaporator and fan). Each indoor unit is linked with the condensing unit by two cop-per pipes and can be managed independently. Sometimes, in order to manage the renewal of the air, the indoor units are linked to an AHU.

VRF: A split-system that allows longer networks and more indoor units, and which permits heat-recovery by carrying the refrigerant in liquid phase and expanding it locally. Each indoor unit is fed refrigerant via a loop.

Chiller A water-cooling unit. The cold water is typically supplied into a loop at 6°C and returned at about 12°C. It can be used either locally by fan coil units or centrally with AHUs that can manage the renewal of the air.

CENTRAL OR LOCAL AC UNITSLocal air conditioners are movable units that can be used to cool a specific region of a building. Local AC units provide a cleaner looking end product, which may allow installation in areas with limited space, and are generally easier to install.

Central air conditioning is a system that either uses ducts to distribute cooled and/or dehumidified air to more than one room, or uses pipes to distribute chilled water to heat exchangers in more than one room. The installation of a central AC system is more complex than using local ACs – the use of a central AC system is best considered during the design of a building (in order to avoid costly remodelling later).

MODERN TYPES OF AIR CONDITIONINGThroughout the second half of the 20th century, nearly all air conditioners used chlorofluorocarbons (CFCs) as their refrigerant. However, CFCs damage the Earth’s ozone layer and they are no longer produced. As a result, nearly all AC systems now use halogenated chlorofluorocarbons (HCFCs) as a refrigerant. However, these are also being gradually phased out (all production of HCFCs is expected to be stopped by 2030).

Modern air conditioners use 30% to 50% less energy to achieve the same level of cooling as air conditioners made in the mid-1970s. Even if an air conditioner is only ten years old, replacing it with a newer, more efficient model can reduce energy consumption by 20% to 40%.

144



ENERGY EFFICIENT MOTORSReplacing existing electric motors that are used extensively throughout the year with energy efficient motors can save energy. However, it is important to ensure that they are sized according to the level of demand. Their operation can also be controlled according to the time of day, and to take the ambient air temperature into account. The use of VSDs (which enable a motor’s speed to match demand) can result in further energy savings. Although VSDs are more expensive, they can be a cost-effective option depending on many case-specific variables (such as voltage level, hourly loads, electricity tariffs and the design of control systems).

EVAPORATIVE COOLINGEvaporative cooling exploits the fact that as water evaporates it absorbs heat from its surroundings. This can be used for direct and indirect cooling:

In direct cooling systems, water is sprayed directly into the air supply. It can, alternatively, be sprayed into the exhaust air, which is then passed through an air-to-air heat exchanger to cool the supply air (this avoids altering the humidity of the supply air).

In indirect cooling systems, the airstream is separated from the evaporating water by a heat exchanger. This can take the form of a cooling tower, from which water can be used as chilled water. This method is preferred as it avoids possible microbiological contamination of the supply or exhaust air.

The drawback of evaporative cooling is that performance is lowest when it is needed the most, that is on hot, humid summer days when the outdoor air is least able to absorb the evaporated moisture. Although the system is not particularly effective in peak conditions, it can be used to offset mechanical cooling for most of the rest of the year.

NATURAL VENTILATION AND FREE COOLINGNatural ventilation and free cooling refer to the exploitation of the natural airflows between openings on opposite sides of a room or building, or the replacement of rising warm air with cooler air sucked in through windows or vents. This technique relies on moving air through a building using the forces caused by outside wind pressure and temperature differences. Good levels of natural ventilation can be provided in this way, enabling mechanical ventilation systems to be switched off or turned down, thereby saving energy. Chillers are also available which incorporate a “free cooling” coil – the coil operates when the outside air temperature drops below the temperature of the water returning from the system. The use of free cooling can save up to 10% of electricity consumption.

WATER LOOP HEAT PUMP SYSTEMThis type of system is made up of several reversible, small capacity heat pumps which are located in each treated area and which operate on a water loop. Each unit operates independently and is able to heat or cool the air in its immediate area. The key benefit of this system is its ability to save energy


145

by transferring heat from an area where it is not needed to an area where it is needed, via the piped water circuit. It is most beneficial in buildings where there are zones which have different heating and cooling periods.

USE OF GROUND SOURCE HEAT PUMPSThe use of ground source heat pumps (which use the ground for cooling or heating) can reduce energy consumption by 25%-50% (40).

OPERATION AND MAINTENANCE CONSIDERATIONSThe adoption of systematic maintenance procedures (for example, ensuring that the system is cleaned on a regular basis) can ensure the efficient operation of a cooling system, and can also help to identify any potential problems with the system. In addition, the proper operation of a system (e.g. by setting thermostats to 24°C-25°C in the summer and to 17°C-19°C in the winter) van provide optimal comfort and save energy – it is estimated that every 1°C reduction in temperature in winter will reduce energy consumption by 5%-6%.

DESIGN CONSIDERATIONSDecentralization

In smaller installations, the replacement of a chiller and chilled water system by a self-contained packaged air conditioner, which uses a DX cooling coil, can save energy.

Correct sizing of networks and choice of auxiliaries

In some installations, auxiliaries (such as fans and pumps) can account for a significant proportion (over 50%) of the energy bill. It is therefore important that air, water and refrigerant networks are sized correctly in order to reduce pressure drops and hence consumption of auxiliaries. The most efficient auxiliaries which meet system requirements should therefore be chosen.

146



Decentralisation and correct sizing of cooling systems (ESR: Up to 20%)

Use energy efficient motors and VSD (ESR: up to 20%)

Use of ground source heat pumps (ESR: 20%-50%; CAPEX: €3,000-€4,000/kW)

Evaporative cooling (ESR: up to 50%)

Water loop heat pump system (ESR: up to 20%; CAPEX: about €100/kW)

Improve operation and maintenance (ESR: up to 15%)

Natural ventilation and free cooling (ESR: average 10%)


147

3.7.4. VENTILATION SYSTEMS

DESCRIPTIONVentilation systems are used to distribute heat and cold throughout a building. They usually comprise air handling units (with fans powered by electric motors) connected to distribution air ducts (which can have different cross-sections) and air intake and air exhaust terminals. Air handling units generally contain air volume control dampers, filters, cooling coils and the supply air fan (all within an insulated metal housing). They can be factory built or customized on site and, depending on their configuration, may also contain a heating coil. Only well designed and properly sized equipment will be able to respond to variations in space cooling loads and maintain temperatures at the required level within their zones and do so efficiently.

Figure 53. Large AHU (Source: (38)

COOLING COILSCoils in air conditioning applications are constructed from a number of tubes expanded through sheets of aluminium or copper to form fins which fixed into a housing. The tubes are connected to form circuits that are joined by a common connection called a header. The cooling fluid enters and leaves the coil through the headers.

They use either a refrigerant or chilled water as the cooling medium to remove heat from the air supplied to a space. Cooling coils used in both comfort cooling and in building process cooling applications are typically dehumidifying coils (i.e. the coil removes both sensible and latent heat from the air stream passing through it).

148


FANSThere are two different types of fans used in air conditioning and ventilating systems:

Centrifugal fans, with either forward curved, backward curved or aerofoil blade impellers; and

Axial fans, with either propeller or aerofoil blades.

Intelflare

Impellerhubfairing

Impeller Impellerhousting

Fan casingand motor supports

Drivemotor

Figure 54. Axial Fan Diagram (source: Action Energy (41))

Some mixed flow fans are used in special applications but they are not common.

Axial fans with aerofoil blades are used when ductwork is connected to the fan – they are suitable for low pressure applications (of the order of 375 Pa). Axial fans with propeller blades deliver high volumetric air flow rates against very low pressures (i.e. to suit applications where no ductwork is connected to the fan or pressures are limited). In air conditioning applications, axial fans are often used as return air fans.


149

Intelcone

Dischargecasing

Impeller Casingclosingplate

Rotor bearing supportsand baseplate

Drivemotor

Figure 55. Centrifugal Fan Diagram (source: (41))

Centrifugal fans generally have high efficiencies (50% to 60% for aerofoil and backward curved blades, and about 40% for forward curved blades). They deliver a high total pressure for a given volumetric flow rate. The air stream is delivered parallel to the direction of the fan discharge.

Fans used in supply and exhaust ventilation systems discharge air at constant volumetric flow rates, while variable volumetric flow rates are achieved by either using dampers on the fan to restrict the airflow or by adjusting the fan speed (this is generally more energy efficient).

Energy can be wasted in a ventilation system in a number of ways:

Due to the infiltration of air – this can be minimised by reducing door opening periods, by using lock chambers or plastic curtains, or by other means;

Due to air leaks from ventilation ducts (which will increase the load on the fans). Air leak losses due to badly riveted square ducts can be significant;

When the capacity is not adjusted to the load;

Through the exhaust system, especially in winter and in buildings where the air exchange ratio is high. Due to different technological needs, this can sometimes reach several exchanges per hour. In such cases, the use of air recuperation technologies which minimize energy losses should be considered.


EXHAUST AIR HEAT RECOVERYExhaust air from industrial and civil buildings can contain significant levels of energy. When recovering heat from exhaust air, both sensible heat and condensed heat from the water vapour in the air (i.e. latent heat) can be exploited, provided that the exhaust air is cooled below the dew point.

150


For example, assuming that exhaust air is extracted at 25°C, relative humidity is 60% and incoming air has to be cooled to 20°C, then about 7 kW of heat can be obtained for every thousand cubic metres of air cooling (without considering the condensation heat of water vapours).

The amount of heat recovered will depend on the initial moisture content of the exhaust air, the initial temperature of the supply air and the effectiveness of the heat recovery system. Reducing the moisture content of the supply air by condensing water vapour can generate more heat – a reduction of 3-5 g/kg in water vapour will, on average, generate more than 3 kW of additional heat. As a result, this will raise the total amount of heat recovered from a thousand cubic metres of exhaust air to 10 kW.

To be able to recover heat from exhaust air, efficient heat recovery equipment is required. This equipment must take into account the relatively small temperature difference between the two coolants in this heat transfer process, the possibility of condensation and the need for its rapid evacuation, and ensure protection against corrosion. A recuperator is the most common technology used for air-to-air heat recovery, using rotating or cross-flow type heat exchangers. In addition, since the two air streams are separated from each other, recuperators are suitable for industrial applications where contamination could be a problem.

Air-to-air heat exchangers can reduce energy consumed in exchanging the air by up to 50%. This can reduce a building’s total energy consumption by 2%-9% (42).

Figure 56. Cross-Flow Plate Heat Exchanger within an AHU (Source(19))


151

OPERATION AND MAINTENANCE ACTIVITIESSystematic maintenance, including cleaning, is important in maintaining the energy efficiency of a ventilation system. It can increase, or at least maintain, the performance, availability and reliability of such a system – it can also help to reduce operating costs. Some critical O&M practices which can increase the efficiency of ventilation and cooling systems are:

Minimizing thermal losses by improving insulation;

Checking:

Pressure losses. Air friction loss in ducts can be reduced by 75% if their internal diameter is increased by 50%. In addition, velocities of above 10 m/s should be avoided.

If capacity is currently controlled by the throttling of a damper, it may be more efficient to control capacity by installing several small fans in parallel (which would be switched on or off as required);

Changing the rotational speed of fans can improve the efficiency of the control, especially when a ventilation system is working at a low load. If capacity is constantly too high, it may be possible to modify the belt drive ratio. However, some key rules should be remembered:

��Doubling the speed will double capacity;

��Doubling the speed will quadruple the pressure; and

��Doubling the speed will increase power input eight times.

ENERGY EFFICIENT MOTORSReplacing electric motors which operate for a large number of hours during a year with energy efficient motors can result in significant energy savings. The use of High Efficiency (HE) Motors and Variable Speed Drives (VSD) can also save energy, while energy consumed in fan systems can be reduced by:

choosing a high efficiency fan (which will be determined by blade geometry and casing shape);

designing the ventilation system so that losses are minimised at its expected load. This will influence the length and position of ducts, the type of regulation devices and the shape of its cross-section;

choosing the best fan for the application;

choosing the best type of control to regulate the fan’s speed and cross-section.

152


InverterVSD

control

SupplyAHU

Hotsupply Cold

supplyDual duct

mixing box

VAVcontroller

Dual ductmixing box

VAVcontroller

Extract

Figure 57. VSDs in a Dual Duct System (Source(38)


Exhaust air heat recovery (ESR: about 50% of energy for air change losses; CAPEX: €5,000-€7,000 for a 5,000 m3/h AHU)

Use energy efficient motors (ESR: up to 20%; CAPEX: €80-€120/kW for HE motors)

Optimisation of operation and maintenance (ESR: up to 10%)


153

3.7.5. LIGHTING

DESCRIPTION - COMPONENTSGood lighting is needed in working places to facilitate accurate work and provide a safe and pleasant working environment. The term “lighting” is defined to include both natural daylight and artificial light sources (such as lamps).

Daylight (which enters a building through windows and skylights) is often the main source of light during daytime hours given its high quality and low cost;

Artificial lighting is most commonly provided by electric lights.

Lighting systems provide many opportunities to save energy and, in many instances, lighting can be improved and operating costs can be reduced at the same time. More specifically:

Lighting improvements are an excellent investment in most commercial buildings – lighting can account for between 20% and 45% of a building’s total energy costs;

Energy used in lighting may represent only 3% to 10% of the total energy used by an industrial facility, but it is usually a cost-effective means of improving energy efficiency as lighting improvements are often one of the easiest changes to make.

LAMP TYPESIncandescent: Incandescent lamps have a filament which is heated until it glows white-hot, producing light. They are the most commonly found type of lamp. They emit light across the whole spectrum, giving them good colour rendering properties. They are inexpensive, and the absence of lamp control gear means that they can easily be switched on and off and easily dimmed using lighting control systems. They can be divided into General Light Service (GLS) lamps and tungsten halogen lamps – the latter are filled with halogen gas and last longer.

Fluorescent

Fluorescent lamps use an electrical discharge to ignite mercury vapour gases inside a tube. The resultant light is emitted mainly in the ultra-violet region of the spectrum and is converted into visible light by the phosphor coating on the inside wall of the tube. Fluorescent lamps also require an electronic ignitor or switch start (glow starter) and ballast (which can be of an electronic or standard type) to ignite the mercury vapour gases. It is generally recommended that triphosphor lamps are used for new and retrofit installations.

154


12v Capsule Lamp Par 38

Par 20Dichroic MR16

Linear Tungsten Halogen

Linear Fluorescent Circular Fluorescent

Compact 2DCFL 2 - Tube

Figure 58. Incandescent Lamps (Source: (43)) Figure 59. Fluorescent Lamps (Source: (43))

High Intensity Discharge (HID) Lamps

HID lamps produce light in a similar way to fluorescent lamps. A high voltage is introduced at the electrode inside the arc tube of the lamp by an ignitor. The gas and chemical mixture inside the tube is ignited, producing visible light. The type of lamp and the chemicals used (sodium, metal halides or mercury) determine the performance of the lamp. All HID lamps require lamp control gear, including a starting mechanism (ignitor) and ballast (which regulates current and voltage). HID lamps take several minutes to reach full light output and cannot be dimmed easily using lighting control systems.

SON Double Ended SON Elliptical Coated SON Tubular

Metal Halide Single Ended Metal Halide Tubular Metal Halide Clear Elliptical

Mercury Vapour Elliptical Mercury Vapour Elliptical Mercury Vapour Reflector

Figure 60. Discharge Lamps (Source: (43))

The Table below sets out the key characteristics of different types of lighting.


155

Table 14. Lamps Characteristics

Incandescent Fluorescent High Intensity Discharge

Incandescent Filament

Tungsten Halogen

Fluorescent Tube

Compact Fluorescent

Mercury Vapour

Metal Halide

High Pressure Sodium

Installation Cost

Low Low Low Low ModerateModerate to

HighModerate to High

Efficacy (Lumen/Watt)

8-17 20-30 60-100 50-85 40-70 60-100 60-120

Wattage Range

Up to 1,500 WUp to

1,000 W8-120 W 7-20 W

40-10,000 W

70-200 W 35-1,000 W

Lamp Life (Hours)

Less than 1,000 2,000-3,000 6,000-8,000 6,000-8,0006,000-24,000

8,000-10,000

14,000-24,000

Replacement Costs

Low Medium Low Medium Low High High

Colour Rendering

Excellent (100)Excellent

(100)

Medium to Good (50-

98)

Medium to Good (50-80)

Poor (15-50)Medium to Good (60-

90)Poor (40-60)

Best Applications

Where Lighting for Short Periods Task Lighting or where Colour

Rendering Important

Low Wattage for Spot Lighting

High Wattage Linear for Security Lighting

Areas Where Lighting is for Long

Periods and Height Below

5 M Exterior

Lighting for Small Areas

Small Rooms

Exterior Lighting and Lighting in Factories

and Warehouses

where Colour

Rendering Not

Important

Lobby Lighting,

Office and Shops where

Height is Greater than

4 M

Exterior Lighting and Lighting in Factories and

Warehouses where Colour Rendering

Not Important and Ceiling Height

Above 4 M

(Source: (44))

High-pressure sodium lamps (SON) and metal-halide lamps are preferred for high-bay lighting. The SON lamps have excellent life expectancy (of 12,000 hours), a modest colour rendering factor and are energy efficient and are thus the most popular. Metal halide lamps may have a better colour rendering but have a shorter life. Low-pressure sodium (LPS) lamps have an increased efficacy (of 100-200 lumens/Watt) but produce the poorest quality of light and therefore tend to be used for security, street lighting or indoor low wattage applications where colour quality is not critical.


HIGH EFFICIENCY LAMPS AND LUMINAIRESThe replacement of existing fittings by modern ones can often significantly improve lighting levels and be a cost-effective option. The right choice of illumination, the right definition of the number and rating of the bulbs, and the height and location of lamps are crucial in lamps selection. As a general principle:

Ordinary light bulbs which are likely to be used for over 4,000 hours per year should be replaced with a more efficient lighting system. For example, an ordinary light bulb will use six times as much electricity as a fluorescent light to produce the same amount of light.

Ordinary light bulbs which will are likely to be used for over 3,000 hours per year should not be used in cold stores or other rooms with space cooling.

156


T5 lamps (16mm diameter) should be used instead of T8 lamps – they are shorter and more efficient than T8 lamps.

Compact fluorescent lamps (CFL’s) should be used in corridors, reception areas, stairwells and toilets.

Low-pressure and high-pressure sodium (HPS) and metal halide lamps should be used instead of fluorescent light tubes if the fixtures are installed at heights above 5 m. Metal halide lamps can be used when colour rendering is not critical, since they have higher efficacy.

Mercury lamps should be replaced with sodium or argon lamps whenever it is technically possible.

Metal halide lamps can be used in place of mercury / sodium vapour lamps. They provide a high colour-rendering index and would be selected for colour critical applications where higher illumination levels are required, for example in assembly lines, inspection areas and painting shops.

Simple light tube fixtures which are likely to be used for over 5,000 hours per year should be equipped with reflectors – reflectors can double light emission and thus halve the number of lamps needed.

Substantial electricity savings (of as much as 80%) are obtainable by replacing incandescent lamps with LED lamps. Recent advances in the technology have led to a new generation of LEDs which offer better colour properties than previous models. The lifetime of LED lamps can be as high as 50,000 hours.

The Table below sets out potential energy savings associated with the use of more efficient lamps.

Table 15. Energy Savings by Using More Efficient Lamps (Source UNEP(10))

Potential Savings From Lamps Replacement

Replaced by

Existing Lamp CFL HPMVMetal Halide HPSV LPSV

Slim tube (Krypton)

GLS Incandescent 38%-75% 45%-54% 66% 66%-73%

Standard Tube (Argon) 9%-11%

Tungsten Halogen 54%-61% 48%-73% 48%-84% 31%-61%

HPMV 37% 34%-57% 62%

Metal Halide 35% 42%

HPSV 42%

HPMV High Pressure Mercury Vapour

HPSV High Pressure Sodium Vapour

LPSV High Pressure Sodium Vapour

CFL Compact Fluorescent Lamps

The savings associated with these measures can be enhanced by installing Lighting Management


157

Systems which provide the user with the ability to control any light, group of lights, or all lights in a building from a single point – they can also include automatic time and occupancy switching and dimming.

LIGHTING MANAGEMENT SYSTEMSThe most cost-effective method of reducing lighting costs is to switch off lights when they are not needed. Manual switching may be inconvenient, but lighting management systems can automatically switch or dim lighting circuits using one or more of the following control elements:

Switching: time-, localised-, daylight- and occupancy-switching; sensors can achieve up to 30% energy savings (45);

Dimming: daylight or voltage control dimming;

Switches can be manually reset by staff;

Zone switching, which allows a single switch to control several lights.

Lighting management systems are more cost-effective when fitted to a new or completely refurbished lighting installation – they can reduce energy consumption by between 20% and 30%.

Figure 61. Ceiling Mounted Photocell Switch (Source (46))

ELECTRONIC BALLASTSIn high frequency fluorescent lighting, an electronic ballast converts the 50 Hz power supply to 28,000-30,000 Hz, reducing both lamp and ballast requirements and increasing lamp and ballast life. A single ballast can drive several lamps. There are no stroboscopic effects. The ballast starts lamps instantly and cuts out automatically if a lamp fails, eliminating flickering. High frequency lighting has a higher power factor, lower sensitivity to voltage variations, and less light level depreciation with age than systems using standard ballasts. With a daylight control system, dimmable ballasts can dim down to 10% of full power with slim line tubes reducing artificial lighting levels and saving energy.

158


Electronic high frequency ballasts are therefore recommended when buying new fluorescent light tube systems which are likely to operate for more than 5,000 hours per year. The total (ballast and lamp) savings achieved by using high frequency fitting instead of:

Fitting with standard ballast and 38 mm lamps - 30%.

Fitting with standard ballast and 26 mm lamps - 25%.

GENERAL RECOMMENDATIONSGood housekeeping activities that can improve energy efficiency include:

Improving the use of natural light so that less electric lighting is required;

Regular cleaning and wiping of lighting appliances;

Regular cleaning and wiping of glass covers;

Switching off sources of artificial light in the daytime when there is enough natural light.


Improve housekeeping and maintenance (ESR: up to 5%)

Use of high efficiency lamps and luminaires (ESR: up to 80%, e.g. from T12 to T8 by ca. 30%; CAPEX: about €4/Wfor LED; about €0.5/W for CFL)

Implement modern lighting management systems (ESR: up to 30%, e.g. for occupancy sensors 10-20%; CAPEX: about €4/lamp for dimming; about €15for occupancy sensor)

Use electronic ballasts (ESR: 10%-30%; CAPEX: €15-€20/pc for a T8 lamp)

3.7.6. BUILDING MANAGEMENT SYSTEMS (BMS)

DESCRIPTION - COMPONENTSBuilding Management Systems (BMS) are computer-based control systems installed in buildings that control and monitor the building’s mechanical and electrical equipment (including its ventilation, lighting, power, fire and security systems). BMS are critical to managing a building’s power demand as systems linked to them typically account for 40% of a building’s energy usage (or close to 70% if lighting is included). BMS can be linked to access control or other security systems (such as closed-circuit television and motion detector systems). Fire alarm systems and elevators are also sometimes linked to a BMS.


159

There are three main types of control features within a BMS:

Controlling by time — time controls vary in complexity from simple 24 hour on/off timers, to sophisticated seven-day timers. Upgrading existing time controls to enable services to be switched on and off to better match daily and weekly requirements can result in substantial energy savings.

Controlling by occupancy — building services can be altered to accommodate changing staff working times. For example, intermittently occupied spaces will often have lights left on unnecessarily. These are areas that could be better served using controls that switch lights off when no one is around. Occupancy controls are generally used for quick response services like lighting and individual ventilation fans. They are rarely appropriate for slower response services like heating and cooling across a whole building.

Controlling by condition — building services can be controlled by environmental conditions such as temperature (for heating, cooling and ventilation systems), day-lighting (for lighting and shading systems), humidity (for ventilation systems and air conditioning systems), and even carbon dioxide levels (for ventilation systems).

Time (hours)

Inte

rnal

tem

per

atu

re 0

C

Potential energy savings

Time switchset for 6am

Typical settings

Maximum heat-upperiode.g. 6am to 9am

Normal occupancyperiode.g. 9am to 5pmOptimised

start

Figure 62. Time switch compared to optimum time control (source: (47))

160


A BMS is a central computer controlled system which can be used to manage three basic operations: controlling, monitoring and optimising.

Sensors

Userinterface

Actuators

Controllers

Figure 63. Basic BMS Arrangements (Source(47))

A BMS will include hardware (such as sensors, actuators and controllers) and software elements.

Key features of the hardware elements of a BMS include:

Sensors: These provide information to the system on their surroundings. There are three principal types of sensor:

Digital inputs – to show, for example, whether a boiler is on or off, or if a pump is running or stopped. These sensors can monitor the conditions of any device which has two possible states;

Analogue inputs – these provide information on indicators such as temperature, humidity and light levels which can exhibit a range of values;

Pulse inputs – these act as counters, usually providing information on consumption through interfaces with meters and similar devices.

Actuators: These are the action element of a system and fall into two categories:

Digital outputs — these control any device which has two possible states, for example switch equipment on or off;

Analogue outputs — these adjust devices to a specific position, for example altering the speed of a variable speed drive.


161

Controllers: The basic building blocks of a BMS are the controllers (or outstations), which also determine the capacity of the system. Controllers include:

Internal clocks and microprocessors, which contain the control and network communication software but which are also capable of operating on a stand-alone basis;

Integral power supplies;

Interfaces to sensors and actuators — collectively known as “points”.

The connection of the controllers to the BMS enables their operation to be simplified and their capability to be enhanced. It also allows performance data to be widely published.

BENEFITSThe benefits of using a BMS include:

Effective monitoring and targeting of energy consumption – the installation of a BMS can reduce energy consumption by 5%-10%, although it should be noted that the actual level of savings will depend on human factor such as the proper operation and exploitation of the system’s capabilities;

Control and scheduling of indoor temperature, lighting and humidity patterns (which can improve comfort);

Possibility of controlling individual rooms;

Possibility of controlling lights and air conditioner units in offices, allowing them to be switched on or off when they are not required (either when there is no one in the office or it is after office hours);

Possibility of scheduling an optimal sequence for lighting and air conditioning start-up (leading to energy savings);

Better maintenance planning (which can reduce overall maintenance costs);

Possibility of having local controls in occupied areas and automatic controls in unoccupied areas (improving overall efficiency);

Integrated systems can be used to increase the efficiency of related systems, such as access control systems; and they also allows for the remote monitoring of equipment;

Improved responsiveness to Heating, Ventilation and Air Conditioning (HVAC) related complaints and, as a result, increased employee productivity.

162


4. SAVING ENERGY IN DIFFERENT BUSINESS SECTORS

4.1. INDUSTRY

4.1.1. MINING AND METALS PROCESSING

DESCRIPTION - PROCESSESThe mining industry in Georgia is involved in the production of a number of minerals including coal, manganese, copper and gold. Iron is also produced from scrap. Following their extraction, metals tend to be exported in a semi-processed state.

Energy, consumables and the movement of waste account for a large proportion of operating costs in the mining and metals processing industries, with the principal energy-intensive processes as follows:

MININGEnergy consumption is important at every stage in mining operations:

Extraction: Energy is used in ventilation, blasting, drilling, digging and dewatering;

Materials handling: Service and dump trucks consume diesel, while electricity is used by conveyors and pumps to transport materials;

Processing: Crushing, grinding and separation are all highly energy-intensive processes – grinding is usually the largest single energy consuming process within mining operations, accounting for as much as 40% of total energy consumed.

METALS PROCESSINGEnergy use within the metals processing industry is very dependent on the specific industry. However, in general, the most energy-intensive processes are:

Melting and holding: Furnaces for melting and holding use huge quantities of energy. The type of metal, the moulding process and the quantity of castings required will determine working practices. However, the amount of energy consumed by the furnaces will depend on variable parameters such as their design, shift patterns, burner design, production capacity, charging temperature of the stock and insulation. Furnaces can be powered by electricity or other fuels, with their design very much dependent on the metal being processed.

Hot rolling: The energy required for the motor-driven rollers depends on the degree of deformation, the temperature of the work piece and hardness of the material.

Cold rolling: Energy is required in mill stands, emulsion, hydraulics and oil management for drives, fans and pumps.

Annealing: Electrical energy is required for drives and heating; mixed gas for the HNX3-hoods and natural gas or LPG for the hydrogen-high convection hoods.

3 Hydrogen-nitrogen mixtures


163

Given significant differences in production processes, broad-based energy consumption data for the metals processing industries are of limited use. However, according to the IEA, 90% of the global steel industry uses between 14 GJ and 30 GJ of energy per tonne of steel produced. Specific energy consumption for each step in the alternative steel making processes are summarised in the Table below.

Table 16. World’s Best Practice Final Energy Consumption (Source: LBNL (49))

Blast Furnace-BOF

Smelt Reduction-BOF

Direction Reduced Iron-Electric Arc

Furnace

Scrap-Electric Arc Furnace

GJ/t GJ/t GJ/t GJ/t

Material Preparation

Sintering 1.9 1.9

Pelletizing 0.6 0.6

Coking 0.8

Iron Making Blast Furnace 12.2

Smelt Reduction 17.3

Direct Reduction Iron 11.7

Steel Making Basic Oxygen Furnace

-0.4 -0.4

Electric Arc Furnace 2.5 2.4

Refining 0.1 0.1

Casting and Rolling

Continuous Casting 0.1 0.1 0.1 0.1

Hot Rolling 1.8 1.8 1.8 1.8

Sub-total 16.5 19.5 18.6 4.3

Cold Rolling and Finishing

Cold Rolling 0.4 0.4

Finishing 1.1 1.1

Total 18.0 21.0 18.6 4.3

ENERGY SAVING MEASURESKey energy efficiency opportunities in the mining and metals processing industries can be summarised as follows:

Area Measure

A. Measures Related to General Utilities

Compressed Air System improvements and optimisation, including leak reduction

Electricity Rehabilitation of power distribution systems; the use of HE motors, with VSDs and soft start for all pumps, fans, lifting and transport systems.

Process Control Systems Instrumentation and M&T systems.

Lighting EE in lighting and the use of lighting controls.

164


B. Process-specific measures

Mining – EE in Exploration Use of non-invasive technologies in exploration.

Mining – EE in Transport Rehabilitating excavation and transport vehicles; switching from gasoline/diesel to gas; and better fleet management.

Mining – Cooling Use of chilled water in mine cooling systems.

Mining – Milling of Ore Use of HE motors and VSDs in motors.

Metals processing – Easte Heat Recovery

Installation of recuperators or regenerators in furnaces to recover heat from flue gases.

Metals Processing – Furnaces Reduction in furnace shell losses by installing insulation and minimising losses from seals and openings.

Metals processing – Optimised furnaces operation

Optimising furnaces operations through scheduling and control of combustion.

Metals Processing – Optimised Furnaces Type

Switch from electricity to fuel-based direct heating.

Energy efficiency opportunities related to general utilities are discussed in greater detail in Chapter 3; process specific opportunities are described in greater detail in the rest of this Section.

PROCESS-SPECIFIC MEASURESMINING

USE OF NON-INVASIVE TECHNOLOGIES IN EXPLORATIONThe use of non-invasive technologies, such as remote sensing, can minimise energy used in exploratory digging and drilling. In particular, modelling with 2-D and 3-D technologies combined with better satellite imaging and instant scanning of the mine surface in open pit mining can improve geological, geochemical and geophysical characterization, replacing the need to drill.

ENERGY EFFICIENCY IN VEHICLES USED FOR MININGDepending on the state of the transport vehicle fleet, significant energy savings can be obtained by:

Rehabilitating or replacing vehicle engines can reduce fuel consumption by 10%-15% and reduce maintenance and service costs;

Switching from gasoline/diesel to gas or to a dual fuel system which enables a diesel engine to run primarily on gas can reduce fuel consumption by up to 10% (and have a significant impact on CO2 emissions);

Improving management of the vehicle fleet, for example by minimising km or ton-km travelled, by adopting predictive maintenance strategies, or by improving driver skills.

USE OF CHILLED WATER IN MINE COOLING SYSTEMSSpaces in underground mines are often cooled by transporting air cooled at the surface to those spaces via a system of fans and ducts, which can be quite energy inefficient. However, using chilled water transported via a system of insulated pipes and pumps to fan/coil heat exchangers located in


165

the mine takes advantage of gravity to move water into and out of the mine and, with water able to contain 55 times more energy per unit of volume than air, can be significantly more energy efficient method of cooling.

USE OF HIGH EFFICIENCY MOTORS AND VSDSConveyors and mills used to transport and mill ore require large motors – the use of more efficient motors with better controls, VSDs and “soft start” systems (which temporarily reduce the load and torque in the motor’s power train during start-up) can reduce energy consumption and O&M costs. The optimisation of milling particle size (for example, through the use of a number of mills linked in series) can also save power.

Figure 64. VSDs Application in Mining Industry (50))

METALS PROCESSINGAs very large consumers of energy, melting and reheating furnaces provide significant energy saving opportunities:

WASTE HEAT RECOVERY FROM FURNACESWaste heat can be recovered through flue gas recuperators or regenerators and used to pre-heat feedstock4. These burners incorporate heat recovery and therefore result in substantial energy savings from reduction of flue gas temperature. Energy savings can reach 25-50% from the use of these burners (51). In addition the installation of air-to-air heat exchangers for heat recovery can also result in significant savings, these systems can be fitted to more than one furnace if operate in parallel. The installation of evaporative skid cooling systems can also be mentioned in this area, which incorporates the use of heat lost to the skid cooling system to produce steam.

4 Recuperation is an effective energy-reduction technology, involving preheat of combustion air usually between 300-400 °C

166


Heat GenerationReduce excess air and

control the air-fuel ratioin a typical aluminum

melting furnace* tosave up to $ 170,000

per year.

Waste Heat RecoveryUsing preheated combustion air in atypical aluminum melting furnace couldsave more than $ 350,000 per year.

HeatContainmentStopping air leakagethrough furnaceopenings can save asmuch as $ 225,000per year in a furnacewithout pressurecontrol

EnablingTechnologies

Use sensors andcontrols, process control

methods, advancedmaterials, and design

models and tools to optimizethe four process areas.

HeatTransfer

Cut energy use by5-20% with improved

charging or loadingpractices and through

enhanced heattransfer.

Figure 65. Efficient Process Heating in Furnaces (Source: DOE-Office of EE and RES)

REDUCTION IN FURNACE SHELL LOSSESA substantial amount of heat can be lost through a furnace’s surfaces and its openings. Minimising the number of seals and openings and ensuring that a furnace’s external surfaces are properly insulated can result in savings of up to 5% of fuel consumed.

OPTIMISING A FURNACE’S OPERATIONSThis can include the design and management of a furnace, including:

Improving the scheduling of a furnace’s operations;

Optimising the air/fuel ratio used in the process;

The installation of new control systems for blast furnaces and hot blast stoves;

Optimising furnace door design.

According to the IPPC, these Interventions can produce energy savings of 5%-15%.


167

SWITCHING FROM ELECTRICITY HEATING TO FUEL-BASED DIRECT HEATINGUsing oxy-fuel burners, normal combustion air is replaced by industrial grade oxygen, reducing energy consumption and emission levels. In addition, the injection of oxygen helps to remove phosphorus, silicon and carbon from the steel bath (52). However, this option is best chosen when planning a new furnace or a major revamp of an existing furnace, particularly in the stainless steel sector (51).


Furnaces automation control (ESR: 5%-15%

Heat recovery in melting/reheating furnaces (ESR: 25%-50% of waste heat in flue gas; CAPEX: about €25,000 for a 5,000 ton furnace)

Replacement of vehicles engines (ESR: 10-15%; CAPEX: about €20,000/engine)

Use of VSDs for motor, fans and pumps (ESR: 10%-30% of electricity in motors)

Optimisation of exploratory digging and drilling

Improvement of furnaces insulation (ESR: 2%-5%; CAPEX: about €20/m2)

EE in compressed air systems (ESR: 10%-20% for electricity for leakage reduction and automation)

Energy efficient lighting (ESR: 30%-60% of electricity for lighting)

168


4.1.2. WOOD PROCESSING

DESCRIPTION - PROCESSESThe wood processing industry includes the processing of trees into timber products, as well as the subsequent transformation of the timber into furniture and other finished products. Strict environmental controls on the felling of trees means that few trees are now processed in Georgia. However, there are a number of firms that transform imported timber products into furniture.

Electricity is used by the industry for motors and lighting, while heat energy is used for process heating and drying as well as for conversion into secondary energy.

Energy consumption in the wood processing industry can be broadly split between three major areas:

Processing and materials handling;

Raw material and product drying;

Other Services, including compressed air, space heating and the lighting of premises.

Saws and planers are the most significant users of energy in the furniture manufacturing process (accounting for up to 30% of total energy consumption), followed by dust collector systems and compressed air systems. Typical specific energy requirements for the production of sawn timber, plywood and particleboard are shown in the Table below:

Table 17. Energy Requirements for the Production of Sawn Timber

Electrical Thermal Motor Fuel

(kWh/m3) (GJ/m3) (l/m3)

SAWN-TIMBER (air dried)

- Hardwood 30 - 5

- Softwood 20 - 4

SAWN-TIMBER (kiln dried)

- Hardwood 75 2.5 5

- Softwood 45 1.5 4

PLYWOOD

- Hardwood 230 6.0 4

- Softwood 150 4.0 3

PARTICLEBOARD 1

- Hardwood 160 3.0 3

- Softwood 120 2.0 3

1 Applicable for Plant of 100-500 m3/Day Capacity (Source: FAO 1983 – Sectorial Study)


169

ENERGY SAVING MEASURESKey energy efficiency opportunities in the wood manufacturing industry can be summarised as follows:

Area Measure

A. Measures related to general utilities

Heat Generation Energy efficient boilers.

Compressed Air System improvements and optimisation, including leak reduction.

Electricity Use of VSDs in motors in the dust collectors, bag houses and fans.



Utilisation of By-Products Maximising the recycling of cardboard, wood, fabric and other waste to be used to produce heat.

Cutting Technology Use of narrow band sawing technology to reduce energy consumption in the cutting process.

Dust C ollection Improve dust collection system efficiency by reducing the system’s air velocity.


PROCESS-SPECIFIC MEASURES

RECYCLING AND ENERGY PRODUCTION FROM WASTEThe three major waste streams produced by the wood / furniture industry are cardboard, wood and fabric, all of which can be recycled. In particular, wood waste can be used to generate energy. For example, it is often feasible to install a rotary grinder to grind the wood waste and then either use it internally to generate energy or sell it externally to generate additional revenues (which can be used to offset energy costs). However, the timing of the wood grinding activities must be carefully selected to ensure that the aggregate demand for energy is balanced (i.e. occurrence of sudden peaks is minimised).

USE NARROW BAND SAWING TECHNOLOGYThe energy required to make a cut is directly proportional to the width of the cut. The use of narrow kerf circular saws and band saws can reduce the amount of energy used in the cutting process by up to 15%, in addition to increasing yield and reducing the amount of sawdust produced (53).

IMPROVE DUST COLLECTION SYSTEM EFFICIENCY Dust collection systems are designed to maintain a consistent minimum air velocity so that the dust in kept in suspension as it is conveyed to the collection device. Operating a system at a velocity greater than the minimum velocity for the material being handled can lead to excessive electrical energy being consumed. Given that a 10% decrease in the velocity of the air within a dust collection

170


system can reduce power consumption by almost 30%, companies can potentially save significant quantities of energy by checking air velocity and ensuring that their systems operate at the minimum required air velocity.

Figure 66. Energy Conservation in the Wood-Furniture Industry (source: Mississippi State University, Industrial Assessment Centre)


Use narrow band sawing (ESR: up to 15%)

Improve dust collection system efficiency (ESR: up to 30%)

Recycling /energy production from wood combustion (ESR: depends on quantity of waste; CAPEX: €20,000 for a 300 kW boiler)

Use of VSDs for fans (ESR: up to 20%)

Optimising compressed air system (ESR: 5%-10% of total electricity consumption)



171

4.1.3. PULP AND PAPER

DESCRIPTION - PROCESSESPulp and paper is an energy-intensive industry, with energy accounting for about 16% of production costs on average (source IPPC-2010, from CEPI, 2007, (54)). However, the pulp and paper industry can also be a major producer and user of renewable energy (worldwide, around 50% of its primary energy consumption comes from biomass (source IPPC-2010, from CEPI, 2008, (54)).

The main raw materials used in the paper industry are either wood chips or recycled paper. There are a limited number of paper manufacturers in Georgia who tend to focus on producing paper and cardboard, while paper recycling is still at an early stage of development.

A typical paper-making process consists of five distinct stages:

1. Wood Chipping: The wood and / or bark is made into very small chips;

2. Grinding: The wood chips are ground into fibres;

3. Pulping: The wood chips are treated either chemically or mechanically to remove lignin (the binding material which holds the cellulose fibres together), producing a porridge-like pulp. Mechanical pulping is more energy intensive than chemical pulping.

4. Refining: After being diluted in water to 1%-5% consistency and mixed with other additives, the pulped paper stock is fed into refiners. These are two toothed plates – a stator and a rotor. The refiners macerates the fibres to the correct size and consistency depending upon the type of paper being produced (e.g. absorbent paper, general packaging paper, fine paper, strong packaging paper and transparent paper).

5. Papermaking: The papermaking stage consists of four sections: the wet end or forming section, the press section, the drier section, and the Calender and reel-up section. The refined pulp is poured on to a fabric mat at the wet end to form a layer of wet pulp, and some water drains away through the fabric. However, the web of paper leaving the forming section contains around 80% moisture – it then enters the pressing section where mechanical rollers squeeze more water out of the paper mat. On leaving the pressing section, the paper mat is dried by being passed through a series of steam-heated drying cylinders (which are heated to around 140oC with steam pressures up to 80 psig). The paper is then calendered (smoothed and reduced to a more uniform thickness, after which its moisture content has been reduced to about 6%), before being reeled-up for storage and dispatch. This is the most energy intensive process in papermaking.

172


A flow diagram of a pulp and paper manufacturing process is shown in the Figure below:

Wood Logs

Paper Making

Wood Preparation

Shredder

Waste chips

Round

De-barker

Chipper

PulpingDigester

Blow Tank

Washing/Filtering

Screening

Bleaching

Washing/Screening

Refiner

Clean/Screen

White Water

PulpForming Press Drying

WasteWater

Calender

Reel/Finishing

Paper Products

Exhaust

WhiteWater

Water/Chemicals

Water/ScreenRejects

BlackLiquor

Multipler-effect

Evaporators

Direct ContactEvaporator/

Recovery Furnace

Slaker/Causticizer

WhiteLiquor

Lime Kiln/MundConcentrator

FlueGas

Green Liquor

Con-densedVapor

FlueGas

Figure 67. Pulp and Paper Manufacturing Flow Diagram (Source (55))

The EU paper industry typically uses about 8 GJ of heat and 670 kWh of electricity per tonne of paper produced(56). Other sources suggest that the industry uses between 11.5 GJ (54) and 13.4 GJ5 per tonne of paper produced – this will vary depending on the type of paper (tissue and fine paper can require up to twice as much energy per tonne of paper produced). A breakdown of energy used in the paper-making process is contained in the Table below.

5 source: CEPI-Confederation of European Paper Industries


173

Table 18. Breakdown of Energy Use in Pulp and Paper Making Industry (Source: IEA, 2002 (48))

% of Energy Use

Process Steam Electricity Total

Raw Materials Preparation 0 8 2

Pulping

Mechanical 15 18 14

Chemical 0 15 3

Pulping from Recovered Paper 1 1 1

Chemical Recovery 8 4 7

Bleaching 19 2 19

Pulp Drying 2 1 2

Paper Making (Stock Preparation-Sheet Formation-Finishing) 55 36 47

Other Processes 6 4

Non Process (HVAC-Lighting etc.) 10 2

Total 100 100 100

During the paper-making process, steam is provided for drying, mechanical energy is provided by electrical motors for wood chipping, grinding, pulping (stirring), refining and reel-up, and hot water is provided for pulping.

ENERGY SAVING MEASURESKey energy efficiency opportunities in the pulp and paper industry can be summarised as follows:

Area Measure


Heat Generation Use of energy efficient boilers; boiler sequencing.

Cogeneration Use of black liquor boilers, combined cycle and biomass boilers.

Compressed Air System improvements and optimisation, reducing leaks.

Electricity Use of VSDs in pumps, fans and process equipment

Process Control Systems Instrumentation and M&T systems


B. Process-Specific Measures

Pulping – Digesters Increase energy efficiency of digesters by increasing yield of pulp and introducing computerise systems.

Pulping – Washing Improved brownstock washing: Replace conventional vacuum pressure units with pressure diffusion or wash presses.

Pulping – Recycling Increased use of recycled paper can result in substantial energy savings in the pulping process.

Paper making – Pressing Replacement of rotating cylinder in pressing: Use of concave shoe press instead of a rotating cylinder.

174


Pulping and Paper Making Heat recovery: Digester flash heat recovery and heat recovery from bleach effluents; heat recovery from steam or waste heat in paper drying; heat recovery from de-inking effluent.

Paper Drying Introduce advanced dryer controls to help optimise operations and increase EE in drying.


PROCESS-SPECIFIC MEASURESMost energy used in paper production is used in mechanical pulping and paper drying and these provide the greatest opportunities for the introduction of energy saving measures.

PULPING – EE IN DIGESTERS There are a number of areas in the pulping process in which energy efficiency can be improved, including:

The addition of chemical pulping aids in the pulping process can increase the yield of pulp and reduce specific energy consumption. Studies suggest that these measures can reduce energy consumption by 8%-10% (55).

Computerised control systems can optimize the operation of the digester, reduce production losses, reduce operating costs and lower environmental impacts, at the same time as increasing paper quality and quantity – such systems can be expected to generate savings of 1%-2% (55). In addition, automated chip handling and thickness screening can reduce steam consumption in the digester and evaporator – some studies suggest that digester yield can be increased by 5%-10%, although this can be offset by a higher volume of raw material screened out.

PULPING - IMPROVED BROWNSTOCK WASHING Replacing conventional vacuum pressure units with pressure diffusion or wash presses for brownstock washing can reduce electricity and steam consumption and reduce use of bleaching chemicals. Steam savings can be as large as 3 kWh/ton of production, while electricity savings can reach about 12 kWh/ton of production.

INCREASED USE OF RECYCLED PAPERThe production of recycled pulp consumes, on average, significantly less energy than that required to produce mechanical or chemical wood pulps. However, recycled pulp produces sludge that can be difficult to dispose of and there are limitations to the amount of recycled fibres that can be used for a given product. Each ton of recycled paper used can reduce energy consumption by about 10.9 GJ (source (IEA) (48).

Paper making – replace rotating cylinder in pressing: The use of a large concave shoe press instead of a rotating cylinder in the pressing process can increase the amount of water extracted from


175

the pulp and thereby reduce the demand for energy in the drying process. Reported energy savings are in the range of 2%-15%; capital costs are estimated at about USD 30/ton of paper producing capacity (55).

Heat recovery: there are a number of options for recovering heat in the pulping and paper making process:

Pulping: The installation of heat exchangers in effluent circuits can recover some of this heat for other uses, in particular from bleach plant effluents and from de-inking effluents produced by re-pulping installations.

Paper making – heat recovery in drying: Drying is an energy intensive process, and paper mill steam consumption can reach as much as 4 GJ/ton of product. Heat can be recovered from the humid exhaust gases that come out of paper dryers, which can then be used to pre-heat incoming air. These measures can reduce steam consumption by up to 50% (57) .

Advanced dryer controls: Available Advanced Process Control Systems can, for example, reduce the demand for steam in the dryer by improving drainage (thereby lowering specific energy consumption) and raise the productivity of the drier sheet – they are reported to have reduced dryer steam use by about 10% (58).

Figure 68. Paper-Making Machine (Source: pulpandpaper-technology.com)

176



Pulping-improved brownstock wash (ESR: up to 3%)

Use energy efficient boilers (ESR: up to 20%)

Heat recovery from waste heatt in pulping and paper drying (ESR: 10%-50%)

Introducing combined heat and power (CHP) (ESR (primary): 10%-20%)

Increase use of recycled paper (ESR: about 11 GJ/ton recycled paper)

Use of VSDs for motors, pumps, fans and process equipment (ESR: 10%-20%)

Paper making-replace rotating cylinder in pressing (ESR: 2%-15%)

EE in digesters (ESR: 5%-10%)

Advanced dryer controls (ESR: about 10%)

Instrumentation and M&T systems (ESR: 5%-10%)

References: (59)


177

4.1.4. CERAMIC BRICK PRODUCTION

DESCRIPTION - PROCESSESThe ceramic brick industry is very energy intensive – energy can account for up to 30% of production costs. However, the introduction of new technologies, together with greater use of natural gas, has helped to reduce energy use substantially over recent years.

A flow diagram of the various stages in the production of ceramic bricks is shown below:

Mining Storage Size Reduction ScreeningForming

and Cutting

Coating or GlazingDryingFiring

and CoolingStorage

and Shipping

Figure 69. Ceramic Brick Production Process (Source: American Brick Industry Association)

The main energy-consuming processes in the ceramics industry include:

Preparation of raw materials: including the use of electrical energy in motors (which has become more important with the increased mechanisation of the process);

Shaping: including the use of electrical energy in motors;

Drying: the process of removing excess moisture from the brick before it is fired – if this moisture is not removed, the water will burn off too quickly during firing, causing cracking. This can account of up to 50% of total energy consumed during the production of the brick.

Firing: the process of hardening and strengthening the brick. With this accounting for up to 30% of the cost of producing a ceramic bricks, improving the energy efficiency of kilns is essential to reducing overall production costs. Specific energy consumption (SEC) in the brick-making industry averages about 2 GJ/t of product, but this is highly dependent on the type of output produced (see Figure below). In Europe, the SEC of tunnel kilns ranges from 1.5 GJ/t-3.0 GJ/t but this can be significantly higher in intermittent kilns used in many developing countries (60).

178


SEC in MJ/kg

SEC vs. firing temperature

firing temperature in 0C

masonry bricks

roof tiles

facing bricks

stoneware pipes

sanitary ware

final firing / porcelain

Figure 70. SEC for Firing in Ceramic Industry (Source (61))

The SECs of producing different types of brick and tiles using alternative forms of energy are summarised in the Table below:

Table 19. SEC in Bricks and Tiles Manufacture (Source: IPPC-BREF (62))

Source Unit Masonry Bricks Facing Bricks Roof Tiles

Thermal Energy (Natural Gas) (AT) GJ/t 1.02-1.87 2.87 1.97-2.93

Electrical Energy (AT) GJ/t 0.08-0.22 0.27 0.23-0.41

Total Energy (ES) GJ/t 1.50-2.50 2.50-3.00 1.90-2.95

ENERGY SAVING MEASURESKey energy efficiency opportunities in the ceramic brick production industry can be summarised as follows:

Area Measure


Cogeneration To cover heat demand for kilns/dryers

Compressed Air Improving and optimising compressed air systems and reducing leaks

Electricity Optimising motor size; using VSDs in pumps, fans and motors for process equipment

Process Control Systems Instrumentation and M&T systems



179


Drying Optimising the drying process, including measures to recover heat from the kilns and to introduce automation control systems

Kilns – Design Improving kiln design and operating procedures to optimise operations; improving refractories-cars and minimising heat losses

Kilns – Heat Recovery Recovering heat to preheat combustion air

Ceramic bodies Introducing new materials, with the objectives of reducing drying and firing time

Dryer

Gas engineexhaust gas

c. 450 0C

Supplementaryfiring

Mixingchamber

Kiln exhaust gasc. 300 0C

Fresh airc. 40 0C

Kilns

c. 90 0C

c. 80 0C

Emergency cooler circuit

Cogeneration gas engine

Catalyst Sound insulator

Figure 71. CHP in Ceramic Industry (Source: (62))


180



OPTIMISING THE DRYING PROCESSCoupling the dryer and kiln is one of the key means of reducing energy consumption in the dryer. However, it is also important to improve working practices in the dryer to achieve best performance. In particular:

Using automatic controls to regulate humidity, air flow and temperature within the dryer;

Optimising loading density;

Redirecting airflows to improve consistency and reduce drying time;

Using software tools for drying process simulation and to link to control data;

Insulating the ducts which transfer air from kiln to dryers;

Using alternative drying systems: “airless drying” systems, which use a steam atmosphere, are reported to be able to reduce drying times by up to 80%, thereby generating significant savings (63).

Improved measurement and control in the dryer will typically result in fuel savings of about 5%-10%.

IMPROVING KILN DESIGN AND OPERATING PROCEDURESIdentifying improvements to kiln design and implementing better operating procedures can result in substantial energy savings. These can be achieved through:

The optimisation of kiln car loads according to weight and spacing;

The installation of seals (such as metal casing and sand or water seals for tunnel kilns and intermittent kilns) aimed at reducing heat losses;

The use of improved refractory kiln linings and kiln-car decks – which can reduce cooling downtime and associated heat losses;

The optimisation of firing speed (and therefore throughput);

The use of high velocity burners to improve combustion efficiency and heat transfer;

The replacement of old kilns, possibly with kilns with an increased tunnel;

The installation of interactive computer control of kiln firing regimes to reduce energy consumption and air pollution;

Minimising the time between dryer and kiln and using the preheating zone within the kiln to complete the drying process, thereby avoiding unnecessary cooling of the dried ware before the firing process.

Heat losses from modern process-controlled kilns can be up to 50% lower (or about 200 kJ/kg lower) than traditional kilns (64).


181

RECOVERING HEAT FROM THE KILNSSome processes employ heat exchangers to recover heat from kiln flue gases which is then used to preheat the combustion air – this can reduce losses by about 20%. However, possible corrosion problems caused by acid combustion gases and the fact that flue gas temperatures have tended to be too low mean that this option has limited applicability. However, excess heat from an afterburner can be used, either in the kiln or in the dryer.

NEW MATERIALS/MODIFIED CERAMIC BODIESThe use of low thermal mass materials and ceramic fibres can save energy as these materials can reduce heat-up times and, therefore, energy use by more than 20%. They can also increase kiln efficiency and reduce labour costs. They require less heat to reach the required temperature and can be heated and cooled quickly. They also allow for the use of low volume, rapid firing kilns such as roller hearth and moving Best Available Technologies type kilns (note that this does not apply to the production of bricks) (65).


Modification of ceramic bodies

Recovery of excess heat from kilns (ESR: up to 20% reduction in heat losses)

Cogeneration (ESR: 10%-20% in primary energy; CAPEX: about €1,000/kWel)

Improving design of kilns (ESR: up to 50%; less heat losses about 200 kJ/kg)

Optimising drying process (ESR: up to 10%)

Use VSDs for motors (ESR: 10%-20% of electricity in motors)

Introducing Energy Management System (EMS): (ESR: 5%-10%)

Optimising compressed air system (ESR: about 20% of electricity for CAS)

182


4.1.5. CEMENT PRODUCTION

DESCRIPTION - PROCESSESCement production is a highly energy-intensive industry. The two cement plants in Georgia produced about two million tons of cement in 20106. However, both plants are quite small by world standards.

Cement is made by heating limestone (calcium carbonate) with small quantities of other materials (such as sand and clay) to 1,450°C in a kiln to produce clinker, a hard granular material. The clinker is then ground with a small amount of gypsum into a powder to make ‘Ordinary Portland Cement’, the most commonly used type of cement.

A typical cement production process is shown in the Figure below:

Cement Production Process

Raw MillElectrostaticPrecipitator

Raw Meal Silo Suspension Preheater

Gypsum

Clinker Silo

Rotary Kiln

Cement Silo

Packing House

Cement Tanker

Cement Mill

Figure 72. Cement Production Process (Source: Lootahgroup)

Energy accounts for 20% to 40% of the total cost of producing cement. The most energy intensive element of the process is the production of the cement clinker, in particular in the grinding of the raw materials. However, significant quantities of electricity are also used to grind the finished cement.

The major components of the process are:

Raw material preparation: Grinding and milling account for about 6% of the energy consumed during the production process (Choate, 2003). As these processes operate at between 6% and 25% energy efficiency (US Department of Energy 2003), they provide a significant opportunity for energy savings.

6 Sakcement and Kartulicement factories. Source: HeidelbergCement)


183

Pyroprocessing: Converting the raw materials into clinker under a high temperature is the core process in the production of cement. Given that pyroprocessing is the most energy intensive stage in the production process, the most significant benefits in terms of reducing energy consumption in the industry will be obtained by improvements to pyroprocessing. Significant savings can be achieved by switching from the energy-intensive wet manufacturing process to the dry manufacturing process. Wet processing plants use water in raw meal grinding operations, and this water must be evaporated in the pyroprocessing area, using additional energy.

Fine crushing of clinker: The final stage in the cement production process is the crushing and mixing of clinker with other materials (such as gypsum) to produce cement. Although similar equipment is required to that used in preparing the raw materials, the fact that the final product is much finer means that this stage in the process consumes significantly more energy per tonne of output. It also therefore presents opportunities for energy savings.

Specific thermal energy consumption in the production of cement in Europe ranges from 3,000 MJ/ton to 6,000 MJ/ton depending on the type of process (wet or dry), with most plants being in the range of 3,300 MJ/ton to 4,000 MJ/ton. Specific electricity consumption ranges from 90 kWh/ton to 150 kWh/ton (13).

The distribution of global cement production capacity by thermal and electrical energy consumption is shown in the Figures below:

Spec

ific

ther

mal

en

erg

y co

nsu

mp

tio

n (G

J/t)

Production share (%)

Cumulative clinker production (Mtonnes/yr)

IndiaPacific Dev. Asia

ChinaGNR

SA EuropeME &

Africa

China Other NA

EIT

(for the activity level of 2007)

184


Spec

ific

elec

tri c

ity

con

sum

pti

on

(GJ/

t)Production share (%)

Cumulative cement production (Mtonnes/yr)

India

Pacific

ChinaGNR

SA

Europe

ME

EIT

(for the activity level of 2007)

150

125

100

75

50

0 500 1,000 1,500 2,000 2,500

0 25 50 75 100

Africa

LA Dev. Asia China Other

Figure 73. Thermal and Electricity SEC in Clinkerproduction (Source: (60))

The breakdown of energy consumption in the production of cement for the “world best practice” producer is summarised in the Table below:

Table 20. Breakdown of Energy Used on Cement Industry (Source: (49))

Electricity Heat Electricity Total

Process kWh/t Clinker GJ/t Clinker kWh/t Cement GJ/t Cement

Raw Materials Preparation 21.30 0.07

Solid Fuels Preparation 0.97

Clinker Making – Fuel 97.00 2.71

Clinker Making – Electricity 22.50 0.08

Cement Grinding 16.00 0.06

Total 2.92


185

ENERGY SAVING MEASURESKey energy efficiency opportunities in the cement industry can be summarised as follows:

Area Measure


Heat Generation Use of energy efficient kilns.

ElectricityUse of energy efficient fans; use of VSDs in order to control air inlet; use high efficiency motors and VSDs for motor conveyors.


Pyroprocessing Change from wet to dry manufacturing process

Pyroprocessing Optimising combustion efficiency in kilns

Pyroprocessing Automating kiln operations

Pyroprocessing Cogeneration: using heat from cooler exhaust gases

Raw Materials Replacement of traditional mills with roller and high pressure mills

Raw Materials Use of pre-crushers in ball mills

Raw Materials Improving the grinding media

Kilns Reducing cold air leaks

Cooler Reducing heat losses



CHANGE FROM A WET TO A DRY MANUFACTURING PROCESS Energy saving opportunities in kilns are likely to come from a combination of improved energy management, the upgrading of existing equipment (e.g. replacing wet kilns with dry kilns), and the installation of preheaters and precalciners. Simply switching from a wet to a dry kiln can reduce energy consumption by about 15%, while switching from a wet to a dry kiln with preheater can reduce energy consumption by about 40%.

Typical thermal energy balances for the major types of clinker producing kilns are summarised in the Table below.

186


Table 21. Thermal Energy Balances to Produce Clinker in Process Kilns

Wet Kiln Dry Kiln Preheater Kiln

Energy Use J/ton % J/ton % J/ton %

Theoretical Requirement 1,782,950 30.5% 1,825,150 36.6% 1,761,850 49.9%

Exit Gas Losses 752,215 12.9% 1,382,150 27.7% 496,905 14.1%

Evaporation of Moisture 2,236,600 38.3% 300,675 6.0% 235,265 6.7%

Dust in Exit Gas 11,288 0.2% 12,976 0.3% 1,287 0.0%

Clinker Discharge 56,706 1.0% 61,190 1.2% 65,832 1.9%

Clinker Stack 189,900 3.3% 590,800 11.8% 614,010 17.4%

Kiln Shell 677,310 11.6% 606,625 12.2% 175,130 5.0%

Calcination of Waste Dust 40,723 0.7% 18,426 0.4% 6,193 0.2%

Unaccounted Losses 89,179 1.5% 192,010 3.8% 173,020 4.9%

Total 5,836,871 100.0% 4,990,002 100.0% 3,529,492 100.0%

Alternative technologies also present opportunities for energy savings. However, although several large-scale (200 tons/day) fluidised-bed kiln projects have been trialled since the mid-1990s and have been found to be over a third more efficient that the average plant, the technology has not yet been widely adopted for commercial-scale operation.

OPTIMIZATION OF COMBUSTION EFFICIENCY IN KILNSImproper control of combustion in kilns can result in inefficiency and energy losses from poorly adjusted firing, unburned fuel with high CO concentration or excess air. Optimising combustion and reducing kiln gas losses can reduce energy consumption by 2%-10% - this can be achieved by:

Installing high conductive devices to enhance the transfer of heat from the gases to the materials (e.g. kiln chains);

Controlling combustion air input so that the process operates at optimal oxygen levels;

Optimising burner flame shape and temperature;

Improving or enhancing preheater capacity.

AUTOMATING KILN OPERATIONSHeat from the kiln may be lost through sub-optimal process conditions or process management. Automated computer control systems can help to optimize the combustion process and conditions which can, in turn, improve the product quality and grindability (e.g. reactivity and hardness of the produced clinker) and lead to more efficient clinker grinding. A wide variety of systems are used throughout the world, most of which use so-called “fuzzy logic”, expert control or rule-based control


187

strategies. Such systems do not use a modelled process to control process conditions, but try to simulate the best human operator, using information from various stages in the process. They can reduce energy consumption by 3%-8%, at the same time as improving kiln productivity.

REDUCTION OF MOISTURE OF RAW MEAL AND FUELSWith the use of preheaters/precalciners kilns avoid using energy to evaporate adsorbed moisture content in raw meal. This preheating is effected in a tall tower with multi-stage counter-current flow cyclones, within which multiple solid/gas cyclone heat exchangers swirl the raw materials with the hot exit gases from the kiln and heat them quickly and efficiently. Some preheater towers include a special preheater section which contains a fuel combustion chamber. These sections provide some of the precalciner energy.

Kilns have historically used the direct firing system – the fuel (primarily coal) is dried, pulverised and fed in a continuous stream into the kiln. However, most modern kilns tend to use an indirect firing technique – neither primary air nor fuel is fed directly to the kiln and all moisture is vented to the atmosphere. Between 5% and 10% less primary air is used in this process, which can reduce energy consumption by between 38 kWh/ton and 55 kWh/ton (9).

COGENERATIONThe cement industry has exploited the opportunity to use CHP to generate heat and cooling from the clinker cooler exhaust on a number of occasions, typically using the Organic Rankine Cycle or the steam cycle. For example, the ORC CHP plant at Lengfurt in Germany, which is used to recover low temperature heat from the cooler, has a capacity of 1.1 MWe and is reported to recover about 9 MW of the 14 MW of energy available from the exhaust gas and to be operational for about 97% of the time (66).

REPLACEMENT OF TRADITIONAL MILLS WITH ROLLER MILLS AND HIGH PRESSURE PRESSING MILLS The cement industry has traditionally used ball mills to grind raw materials. Ball mills use an established technology and offer certain advantages. However, they have higher energy demands. By using more efficient roller mill technologies, the industry could save energy without compromising product quality. There are a number of roller mill concepts which can be applied to cement manufacturing (67):

Vertical roller mills: In these mills materials are crushed between a rotating grinding table and two to six grinding rollers positioned slightly less than 90 degrees from the table surface and pressed hydraulically against it. The principal advantages of vertical roller mills are their relatively low power consumption (less than 10 kWh/t for medium raw material hardness and medium fineness), their ability to combine grinding, drying (using waste heat from kiln system) and separation, and their ability to manage larger variations in mass flow rates

Horizontal roller mills: Materials in this type of mill are crushed inside a rotating mill tube which also contains a grinding roller that is hydraulically pressed against the inside surface of the tube. Horizontal roller mills use 65%-70% of the energy used in ball mills.

188


Roller press (high-pressure pressing mills): In this technology materials are crushed between two counter-rotating rollers. These rollers are up to 2 metres in diameter and 1.4 metres long. High-pressure pressing mills use 50%-65% of the energy used in ball mills.

USE OF PRE-CRUSHERS IN BALL MILLSWhen it is not possible to replace ball mills, certain measures can be taken to improve their efficiency, in particular by using a pre-crusher (pre-crushers can be used in front of all mill types). A fine crusher machine is installed in front of the ball mill, reducing the particle size of materials and, thereby, reducing the grinding system load.

IMPROVE GRINDING MEDIA TO INCREASE THE GRINDING EFFICIENCYMore wear resistant materials can be introduced as grinding media in ball and vertical mills (68). Grinding media are usually selected according to the wear characteristics of the material. Raising the ball charge distribution, increasing the surface hardness of the grinding media and installing wear resistant mill linings have been shown to reduce both wear and energy consumption. Other improvements include the use of improved liner designs, such as grooved classifying liners. These measures have the potential to reduce grinding energy use by 5%-10% in some mills, which is equivalent to about 1.8 kWh/t cement.

LOWER CLINKER COOLER STACK TEMPERATUREThis can be achieved by:

Recycling excess cooler air;

Reclaiming cooler air by using it to dry raw materials and fuels or to preheat fuels or air;

Lowering kiln radiation losses by using the correct mix and more energy efficient refractories to control kiln temperature zones.

REDUCTION OF COLD AIR LEAKAGES: This can be achieved by:

Closing unnecessary openings;

Providing more energy efficient seals;

Operating with as high a primary air temperature as possible.


189


Replace traditional mills with roller mills and high pressure pressing mills (ESR: 6-7 kWh/t raw materials; CAPEX: about €4.3/t raw material)

Switching from wet to dry cement process / using a preheater (ESR: 15-40% of energy; CAPEX: €40-€80/t of clinker capacity)

Optimisation of kiln combustion (ESR: 2%-10% fuel savings CAPEX: about €0.8/t raw material)

Cogeneration with ORC (CAPEX: €0.8-€1.2 million/MWe)


Indirect firing systems (ESR: about 40-55 kWh/ton)

Use high efficient separators/classifiers (ESR: about 8% in specific electricity use; CAPEX: about €1.7/t raw material production)

Automation in kiln operation (ESR: 3%-8%)

Grinding media (ESR: about 1.8 KWh/ton)

References: (69).

4.1.6. GLASS PRODUCTION

DESCRIPTION - PROCESSESGlass production is an energy intensive manufacturing process. In Georgia glass production mainly consists in the production of glass for containers for the food industry, such as bottles and jars.

Soda-lime glass accounts for about 90% of manufactured glass. It is generally made from sand, limestone, soda ash and cullet (recycled glass) and contains 70% to 74% silica by weight. The use of recycled glass can save on raw materials and energy, but impurities in the cullet can lead to product and equipment failure.

190


A modern glass factory is made up of three parts: the batch house, the hot end, and the cold end. The batch house handles the raw materials; the hot end comprises the manufacturing process and includes furnaces, annealing ovens and forming machines; and the cold end involves the inspection and packaging of the final product.

Sand Soda Ash Lime Other Cullet

BatchPreparation

Melting andRefining

Conditioning

FormingInternal recycling

Annealing

Finishing

Internal recycling

Internal recycling

Glass Products

Cullet Crusher

Figure 74. Glass Production Process (Source: University of California)

The most important energy-consuming areas in the glass industry are:

Melting and refining: These are the most energy-consuming steps in the glass making process – about 2,000 kW are required to melt each tonne of glass. Both processes are therefore subject to a specific focus for energy efficiency measures, in particular in terms of ensuring proper control of combustion and oxygen content in the furnaces.

Annealing process: The uneven cooling of glass causes stresses which weaken the glass. The annealing process controls the rate at which the glass is cooled, ensuring that it is cooled evenly. Glass enters an annealing lehr at about 600°C, before passing through several temperature control zones and emerging as a final product to which coatings can be applied (for example, to improve scratch resistance).

Use of cullet: Cullet (i.e. recycled glass ground into pieces) makes up about 20% of the materials that go into glass making (cullet use can vary from 10% to over 90% in container glass manufacturing). The proportion of cullet used can have a significant impact on the energy used – because no chemical reactions take place in melting the cullet, energy consumption is reduced. In addition, raw materials use is reduced, energy in producing the raw materials will fall, and the life of the furnace will increase. However, it is important to control and guarantee the quality of the cullet (contaminants need to be removed and the cullet has to be separated on the basis of its colour).


191

Specific energy consumption for different types of glass is summarised in the Table below:

Table 22. SEC in the Glass Production Industry (Source: (70))

Average Specific Energy Consumption (GJ/ton)

Process Step Flat Glass Container Glass Speciality Glass Fiberglass

Batch Preparation 0.3 0.5 0.8 1.1

Melting and Refining 6.5 5.8 7.3 5-6.5

Forming 1.5 0.4 5.3 1.5-4.5

Post-Forming/Finishing 2.2 0.7 3.0 1-2

ENERGY SAVING MEASURESKey energy efficiency opportunities in the glass production industry can be summarised as follows:

Area Measure


Heat Generation Combustion performance improvements for furnaces: Minimising the use of excess air and the proper tuning and positioning of burners in the furnace.

Compressed Air Compressed air leakage repair programmes.

Lighting The use of energy efficient lamps for lighting, and the installation of sophisticated lighting controls

Electricity Effective load management through the use of, for example, an M&T system.


Melting Preheating the cullet/batch materials before they enter the furnace by filtering the raw materials through hot exhaust gases.

Melting Adding oxygen at specific points in the melting process enables hotter combustion temperatures to be achieved, thereby increasing process efficiency.

Raw Materials Increasing the proportion of cullet used in the raw materials can generate substantial fuel savings –0.25% for every 1% increase in the proportion of cullet.

Process Control The use of continuous gob monitoring systems can save energy and raw materials.

Annealing The installation of re-circulating systems; recirculation with high velocity burners without the use of re-circulating fans.

Controls The installation of hot end inspection systems can allow any faults in the production process to be identified (and rectified) earlier.


192



BATCH PREHEATINGOne of the most promising energy-saving measures adopted by the glass industry in recent years has been to preheat cullet before it enters the furnace. A cullet-preheater uses waste heat from the furnace to preheat the incoming cullet batch. They can be either direct or indirect preheaters: in a direct preheater, the cullet comes into direct contact with the flue gas and is heated to about 400°C (a bypass is available in case the preheater cannot be used); while in an indirect preheater, the cullet moves through cross-flow plate heat exchangers that preheat it to about 300°C.

Cullet preheaters are estimated to reduce energy consumption by between 12% and 20%, depending on the proportion of cullet used in the process and the pre-heating temperature. Significant fuel savings can be achieved by preheating cullet when it accounts for over 35% of the raw materials and, in theory, any system with uses over 50% cullet in the batch can install preheaters. However, batch-only preheaters are not considered a proven technology.

Batch preheating is more difficult than cullet preheating, as the clumping of incoming materials can affect product quality and the efficiency of the melter. However, it is estimated that this process could reduce fuel consumption and oxygen use by 25% in oxy-fuel glass furnaces, increase glass production by up to 25% and increase the life of the furnaces (US Energy Information Administration, EIA 2000).

Installing a preheater will also reduce NOx emissions; direct preheaters can also reduce SO2, HF and HCl emissions.

Figure 75. Glass Batch Preheating (Source: ZIPPE)

OXY-FUEL FURNACESAdding oxygen at specific points in the melting process enables hotter combustion temperatures to be achieved, thereby increasing the process’s energy efficiency (measured in terms of tons of output


193

per kW) – it has been reported that increasing the oxygen content of combustion air from 21% to 23% can raise glass production by 12%. However, the process must be carefully controlled as burning unnecessary oxygen is expensive and its combustion increases NOx and particulate matter emissions. It also increases wear and tear on the furnace, particularly the silica crown roof (see Figure below). About 20% to 25% of all glass furnaces operating today are oxy-fuel furnaces.

The energy savings of converting to an oxy-fuel furnace depend on the energy used in the current furnace, use of electric boosting, air leakage, glass type and cullet use. However, energy use can be reduced by between 20% and 45% (45% for replacing energy inefficient furnaces). Even for large efficient regenerative furnaces, savings can be between 5% and 20%. (70)

A new oxy-fuel furnace costs about 20% less than a recuperative furnace, and 30%-40% less than a regenerative furnaces. However, an on-site oxygen plant will account for about 10% of the capital costs of the plant. Oxy-fuel furnaces also benefit from reduced costs for flue gas treatment and significantly reduced maintenance costs. However, overall cost-effectiveness varies widely, and depends strongly on location-specific circumstances, such as the current system’s fuel efficiency, the cost of NOx emissions, and the cost of fuel and electricity. The technology is most effective when installed when replacing a furnace which has come to the end of its useful life.

NaOH

NaOH (vapor, eq)

Na2 O in glassment

H2 OV V

Figure 76. Oxy-Fuel Furnace (Source: European Container Glass Association - CGA)

INCREASING THE USE OF CULLETIncreasing the proportion of cullet used in the raw materials can generate substantial fuel savings – these savings are estimated at 0.25% for every 1% increase in the proportion of cullet (starting at 10%). The Figure below shows the relationship between specific energy consumption (SEC) and the share of cullet found in a benchmarking study of 130 glass furnaces.

194


6000

5500

5000

4500

40000 20 40 60 80 100

cullet in batch (wt%)

Spec

ific

prim

ary

ener

gy c

onsu

mpt

ion

(MJ/

ton)

Figure 77. SEC Versus Proportion of Cullet in Batch (Source Beerkens,2001)

INSTALLING CONTINUOUS GOB MONITORING SYSTEMSInstalling process control systems can save energy and raw materials. In particular, precise control of product weight is essential in the manufacture of glass containers to ensure that the containers remain within the customer’s specification. The continuous gob measuring system is an electronic system for measuring and controlling the length of each gob of melted glass as it leaves the forehearth. By monitoring the weight of the gob for every container manufactured, the system can alert the operator when containers are either underweighted or overweighed, allowing the operator to take immediate corrective action. Savings from this measure have reported to yield significantly low payback periods in the order of 18 months (source (70)).

IMPROVING THE ANNEALING PROCESSThe energy efficiency and operation of annealing lehrs can be improved by:

The installation of re-circulating systems that provide a high rate of air recirculation (which result in rapid heat transfer at low temperature differentials);

Recirculation with high velocity burners without the use of re-circulating fans;

Optimisation of insulation and elimination of air leakages from the furnaces;

Automation systems to control internal parameters.

HOT END INSPECTIONThe installation of hot end inspection systems allows any faults in the production process to be identified (and rectified) earlier. Products have traditionally been inspected at the end of the production process, just prior to packaging, but this is a long time after the defect has occurred. Earlier identification of a defect can reduce the volume of product that need to be recalled (thousands of bottles can be produced in the period before packaging).


195


Install continuous gob monitoring system (Payback period of about 18 months)

Oxy-fuel furnaces (ESR: 20%-45% of energy; CAPEX: 20%-40% lower than other furnace types, but need to add 10% of capital costs for an oxygen plant)

Cullet/Batch preheating (ESR: 12%-25% of energy; Payback period of 1-4 years)

Increase in the use of cullet (ESR: 0.25% for each 1% increase in proportion)

Minimise of excess air/proper burner position (ESR: up to 8% of fuel)

Improvement of the annealing process (ESR: 5%-15%)

Energy efficient lighting (ESR: 30%-60% CAPEX: €4/WLED; about €0.5/W for CFL)

Implement compressed air leakage repair (ESR: up to 20%; CAPEX: about €5,000-€10,000 for a leak detection system)

Hot end inspection (ESR: 2%-3% of plant energy through lower reject rates)

4.1.7. PLASTICS PROCESSING

DESCRIPTION - PROCESSESSome 230 million tons of plastics are produced each year throughout the world, about 25% of which is produced in Europe. The plastics manufacturing industry in Georgia focuses on plastic bottle making and is made up of “captive” facilities operated by food processors and beverage companies, and a number of independent producers.

The steps involved in the production of plastics are shown in the Figure below.

196


Raw materials

Distillation - cracking

Base chemicals

Chemickalreactions

Polycondensation

Monomers

Polymerization

ResinIntermediates

Polymerization

Resins(mainly

thermosetting)

Compounding

Paintsglues,

etc.

Mouldingpowders

Polymers(mainly

thermoplastics)

Compounding

Fillers,plasticiserspigments,

etc.

Machinery

ProcessingMoulding by:

compression/injectionblow mouldingextrusioncalenderingvacuum formingcoating, etc.

Finished products(such as mouldings, pipe, sheet, film, containers,

insulated cable, flooring and upholstery, foams, fibres)

Figure 78. Overview of Plastics Production Process (Adapted from 3rd Edition Encyclopaedia of Occupational Health and Safety – P.K. Law – T.J. Britton)

Electricity is the principal form of energy consumed in the plastics processing industry where it is used in the following activities:

The melting of raw materials;

Cooling (mould, gauges and oil);

Driving peripheral equipment, such as grinders, compressors, pumps, pre-driers and mixers;

Vacuum formation of semi-manufactured products.

The key piece of equipment in a plastics processing plant is the injection moulding machine (which typically has a hydraulic drive system). However, as the hydraulic pump runs throughout the injection cycle, these are relatively energy inefficient machine (they have an energy efficiency of 50%-60%).


197

Average Specific Energy Consumption for various plastic manufacturing processes in EU industries is shown below (expressed in kWh/kg of product):

SEC (kWh/kg/h)

0 1 2 3 4 5 6 7

Thermoforming

Rotational moulding

Compression moulding

Injection moulding

Profile extrusion

Film extrusion

Fibre extrusion

Compounding

Figure 79. Average SEC for Plastics Manufacture (Source: RECIPE project-2005)

Estimates of the distribution of energy use in the extrusion and injection moulding processes are shown in the Figures below:

Plant Energy Distribution-Extrusion

Plant; 10%Barrel heating; 7%

Extruder Drive;41%

Auxiliaryr; 42%

198


Plant Energy Distribution-Moulding

Mould clamping; 36%

Plant; 10%

Barrel hea ng; 19%

Extruder Drive; 18%

Compressed air; 2%

Machine cooling; 2%

Process chilling; 4%

Granulator; 2%

Material drying; 6%

Material Handling; 1%

Auxiliaryr; 16%

Figure 80. Plant energy consumption in injection and extrusion (Source:NRCAN (71))

ENERGY SAVING MEASURESThe principal energy efficiency opportunities in the plastics industry can be summarised as follows:

Area Measure


HVAC Improving ventilation in order to remove process heat; heat recovery measures

Refrigeration and Cooling Use of more efficient chillers and heat exchangers

Compressed Air Correct sizing of compressors and ensuring that they are staged; heat recovery in compressed air systems and the use of controls

Electricity Use of VSDs in injection moulding machines



Injection Moulding Use of a servo hydraulic drive instead of a hydraulic drive system; installation of baler insulation jackets

Extrusion Ensuring that the design of the system is optimal and that the appropriate operating parameters have been determined

Blow Moulding Improving controls and heat recovery

Drying and Polymerization Improving insulation and introducing automation systems in order to improve the operation of drying and polymerisation equipment

Hydraulic Systems Use of a single hydraulic system; incorporation of accumulators


199



ENERGY EFFICIENCY OPTIONS IN INJECTION MOULDINGA servo electric drive, which recovers energy during the braking period, is more efficient than a hydraulic drive system, generating energy savings of between 25% and 50%. In addition, electric machines which do not require hydraulic systems eliminate the need to cool the hydraulic coil and are thus less expensive to operate.

The installation of barrel insulation jackets can reduce the energy consumed by the heating elements of an injection moulding machine by as much as 50%. They can also reduce start-up times and reduce health and safety concerns associated with hot surfaces.

ENERGY EFFICIENCY OPTIONS IN EXTRUSIONMost of the energy used in extrusion is directly related to the operation of the extruder, mainly associated with the need to drive the extruder-screw motor. In addition, significant amounts of water may be used for cooling which is often recirculated. Specific energy efficiency measures include:

Optimising and controlling cooling water volumes and temperatures;

Setting die temperature at the lowest possible level;

Ensuring that motors and other equipment are sized to match extruder capacity (HE motors and VSDs can also be used);

Ensuring that the barrel is adequately insulated (with a potential for reducing energy use by up to 15%);

Use of direct drives which do not use the conventional gear systems.

A1

1

7

3

31

7

7

LOCAL EXHAUST HOOD TOATMOSPHERE

RAW MATERIALFEED

REGROUNDMATERIAL FROM

PROCESSPOWER FOR HOT

RUNNER MOULDS

PLATTEN

TO OPEN/CLOSE MOULD

COOLING

MOULDCOOLINGHEATING

HYDRAULICMOTOR

HYDRAULIC RAM

FEED

INJECTION UNIT

MOULDED PRODUCTEJECTED

Resources Used and Discharges: 1- Electricity 3- Cooling 7- Hydraulic Pressure A- Exhaust Air

Figure 81. Energy use in Injection Moulding (Source: Natural Resources Canada, 2007 (71))

200


ENERGY EFFICIENCY OPTIONS IN BLOW MOULDINGBlow moulding is the process used to manufacture hollow objects. There are two forms of blow moulding: extrusion blow moulding, in which the mould closes around a polymer tube which is expanded to match the shape of the mould by the injection of air, and injection blow moulding, where the resin is moulded into a perform which is then transferred to a blow mould where it is reheated and expanded by the injection of air. Energy efficiency opportunities in blow moulding focus on improving and optimising energy consumption:

Installation of control systems, which allow better monitoring of the manufacturing process, thereby enabling corrective action to be taken more quickly, thus leading to improved product quality as well as lower energy consumption;

Installation of a heat exchanger in the cold water network of hydraulic systems, both to control temperature and to recover waste heat;

The use of all-electric machines for moulding instead of hydraulic machines can generate savings of 30%-40% (72).

Improving the operation of compressed air systems (as they account for about 60% of total energy costs for blow moulding).

ENERGY EFFICIENCY OPTIONS FOR DRYING AND POLYMERIZATION EQUIPMENTThere are a number of opportunities to save energy, particularly in the operation of drying equipment:

The use of high efficiency electrical dryers (savings of up to 30%) as well as the use of modular gas fired dryers can substantially reduce energy consumption. The use of gas-fired dryers for high volume applications is reported to result to savings of 60%-80%, while the addition of dew point monitoring systems in dryers can reduce energy consumption by about 20% (71).

The installation of automated systems to control drying and ventilation levels;

Only using electricity if a temperature of over 100oC is required for drying purposes;

The use of infra-red heaters in the drying process instead of drying in resistant ovens (especially through-type ovens);

The selection and use of the most appropriate insulating materials (to ensure that the external surface temperature of the drying chambers and/or ovens do not exceed 40oC).

ENERGY EFFICIENCY OPTIONS IN HYDRAULIC SYSTEMSThere are a number of ways of reducing energy consumption in processes which use hydraulic systems (these can generate savings of up to 50%):

The use of accumulators, especially for injection moulding;

The use of a single central hydraulic system to power multiple hydraulic motors, especially across a group of injection-moulding machines, can reduce both energy consumption and maintenance costs. There might, however, be a need to add a load-sensing device if the pressure requirement is not continuous.


201

The use of two cylinders on injection presses: a small-diameter, long-stroke cylinder for mould transport and a large-diameter, short-stroke cylinder for clamping the moulds.


Use of VSDs in injection moulding machines (ESR: up to45% for electricity used in motors)

Injection moulding process (ESR: 25%-50%; CAPEX: all-electric moulding machines are 20%-30% more expensive than hydraulic moulding machines)

Drying equipment (ESR: 60%-80% for gas fired dryers; 20% for dewpoint control systems)

Centralised hydraulic system for multiple machines (ESR: up to 50%)

Extrusion (ESR: about 15% for insulation of extruder barrel; 20% for use of HE motors)

Use of energy efficient HVAC systems (ESR: up to 50% of waste energy from air losses)

Compressed air systems: (ESR: up to 20%)

Energy efficient lighting (ESR: 30%-60% of electricity used for lighting)

4.1.8. PHARMACEUTICALS

DESCRIPTION - PROCESSESThere are between 50 and 60 pharmaceutical manufacturers operating in Georgia at present. However, the two largest producers account for about 90% of the industry’s output. The industry is mainly involved in secondary manufacturing and packaging, although there is some primary manufacturing in herbal/natural medicines and bacteriophage products. Just under 40% of local production is exported, principally to neighbouring countries.

In general, there are three stages in the production of bulk pharmaceutical products:

Research and development;

Conversion of natural substances to bulk pharmaceuticals, and Formulation of the final product.

202


Bulk pharmaceutical substances are typically produced via chemical synthesis, extraction, fermentation, or a combination of these processes:

Chemical synthesis: which includes reaction, separation, crystallisation, purification and drying (as shown in the Figure below):

Reagent(s)

ChemicalReaction(s)

Separation Extraction Decanting Centrifugation Filtration

Crystalization

Purification Recrystalization Centrifugation Filtration

Drying

Product(s)

Product extraction: precipitation, purification and solvent extraction are used to recover active ingredients in the extraction process.

Fermentation: in this process microorganisms are fed into a liquid to produce pharmaceuticals as by-products of normal microorganism metabolism.

HVACFor most pharmaceutical manufacturing plants, Heating, Ventilation and Air Conditioning (HVAC) is typically the largest consumer of energy, accounting for over 50% of the total – HVAC is used to achieve the required operating temperatures and to ensure air quality standards are maintained. In particular, the need to maintain air quality in clean rooms and other “high purity” areas may necessitate a large number (up to 12) of air changes per hour – this will use a significant amount of energy but also presents energy saving opportunities for through better management and control of the HVAC systems.

The average distribution of energy use across the various elements of the pharmaceutical production process is shown in the Table below.


203

Table 23. Table Energy Consumption Allocation in Pharmaceuticals (Source: (73))

Area% Energy Overall

Processes Lighting HVAC

Total 100% 25% 10% 65%

R&D 30% Microscopes, centrifuges, mixers, analysis equipment. sterilisation processes.

Task and overhead lighting.

Ventilation for clean rooms and fume hoods; areas with 100% free air: chilled and hot water.

Offices 10% Office equipment Task, overhead and outdoor lighting

Space heating

Cooling ventilation

Bulk Manufacturing

35% Centrifuges, sterilisation processes, incubators, dryers, separation

Task and overhead lighting

Ventilation for clean rooms and fume hoods; areas with 100% fresh air: chilled and hot water

Formulation, Packaging and Filling

15% Mixers, motors Mostly overhead Particle control ventilation

Warehouses 5% Lifts, water heating Mostly overhead Space heating; refrigeration

Other 5% Overhead

ENERGY SAVING MEASURESKey energy efficiency opportunities in the pharmaceuticals industry can be summarised as follows:

Area Measure


HVAC Efficient design, monitoring and control, leakage repairs, VSDs and recovery of heat and cooling water; common heat recovery equipment include heat wheels and heat pipes.

Compressed Air System improvements, leak reduction, heat recovery for water preheating.

Electricity Use of high efficiency motors, use of VSDs.


Energy Management Building Energy Management Systems


Fume Hoods Heat recovery in R&D facilities to capture and expel hazardous gases demand large amounts of energy to heat and cool make-up air. EE opportunities also include heat storage and variable air volume hoods.

Clean Rooms Optimisation of HVAC operation; use of ultra-fine range filters

Drying Heat recovery; de watering of feed.

Water Separation Use of membranes for water and waste water separation in place of traditional techniques.


204


PROCESS-SPECIFIC MEASURES Pharmaceutical plants, which often include laboratory and office space, offer a number of energy saving opportunities.

EE IN FUME HOODSFume hoods are commonly installed in R&D laboratory facilities to capture, contain and expel hazardous gases generated by laboratory activities and industrial processes. The energy required to heat and cool make-up air for laboratory fume hoods can account for a significant proportion of laboratory HVAC energy consumption as they often operate at high air-exchange rates. Significant energy savings can often be realized by using low-flow fume hoods where appropriate and variable flow exhaust systems. These measures can generate savings of 10-20% in the electricity used for ventilation.

Fume hood sash openings can also be restricted in order to reduce the volumetric flow rate and lower energy consumption in variable flow hoods. Variable-air-volume hoods can offer considerable energy savings compared to constant air volume (CAV) hoods.

EE IN CLEANROOMSCleanrooms are areas in which ambient conditions (such as airborne particles, temperature and humidity) need to be strictly controlled, as a result of which they tend to consume more energy. However, there are a number of ways in which their energy efficiency can be improved, such as optimising the operation of their cooling and ventilation systems and controlling fresh air inlets. It is also possible to use high efficiency particulate air filters and ultra-low penetration air filters to filter make-up and recirculation air, while alternative filtration technologies that trap particles in the ultra-fine range (0.001-0.1 microns) can reduce energy consumption by lowering the need for reheating/re-cooling air. Low pressure drop filters can also reduce energy consumption.

EE IMPROVEMENT IN DRYINGPharmaceutical materials in powder, granular or crystalline form generally contain moisture or solvents which need to be removed through drying. However, the pharmaceuticals tend to be heat sensitive, requiring the use of specialised drying techniques: small volumes are generally dried using various types of tray dryers, fluidised bed dryers and vibratory conveyor dryers; large volumes are generally dried using rotary dryers, flash dryers, continuous circulation or a fluidised bed; while very sensitive products have to be dried in spray dryers, high vacuum tray dryers and freeze dryers.

Nevertheless, there are energy saving opportunities that can be exploited, including:

Heat recovery from exhaust air to preheat incoming air;

Proper mechanical dewatering of feed before it enters the dryer;

Online instrumentation and automatic feed forward controls;

Energy saving by optimising auxiliary equipment operation.


205

USE OF MEMBRANES Membranes can be used in the pharmaceutical industry in applications where separation is needed, for example in water and wastewater treatment. Membranes have a number of advantages over other methods of separation, including reduced maintenance and, therefore, lower O&M costs, as well as reduced energy consumption. For example, the use of ultra-low pressure thin film membranes instead of cellulose acetate can reduce energy consumption by about 50%. Membranes can also be used in the wastewater treatment process, replacing traditional methods like coagulation, flocculation, sedimentation and filtration.


Optimising compressed air systems (ESR: up to 20% of energy for CAS)

Energy savings in HVAC, including heat recovery (ESR: 40%-60% of heat wasted due to air losses)

Membranes for water/wastewater separation (ESR: 40%-55%; CAPEX: about €25,000)

Use of high efficiency motors and pumps (ESR: up to 20%)

EE in fume hoods (ESR: 10%-20% of electricity used for ventilation)

Energy Management systems (ESR: 5%-10% of total electricity and fuel consumption; CAPEX: about €100,000 for 50 metered points)

Energy Efficiency improvement in drying


206


4.1.9. FOOD AND BEVERAGE PROCESSING

DESCRIPTION - PROCESSESFood and beverage processing and manufacturing in Georgia covers a wide range of products, including meat and poultry, fruit and vegetables, seafood, dairy products, flour and cereals, bakery products, sugar, sugar confections, soft drinks and brewery products.

Although the food processing industry is not considered an energy intensive industry, energy still represents a significant cost of doing business and there are opportunities for improving the industry’s use of energy, in particular in:

Electrical energy – where power is required for mechanical processing (such as pumping, ventilating, mixing and conveying) and is used in mechanical compression coolers;

Thermal energy – for both high temperature processing (such as pasteurisation, cooking and evaporation) and low temperature processing (freezing and cooling).

Approximately half of all the energy consumed by the industry is used to change raw materials into products (process use) – this includes process heating and cooling, refrigeration, machine drive (mechanical energy), and electro-chemical processes. Less than 8% of the energy consumed by the industry is for non-process uses, such as facility heating, ventilation, refrigeration, lighting, facility support, on-site transportation and conventional electricity generation. Boiler fuel represents nearly one-third of consumption.

Studies have shown that processing accounts for 78% of electricity used in the food sector: 48% is used for machine drive and 25% for process cooling and refrigeration. Non-process activities account for 16% of electricity used by the sector: 12% is used for lighting, heating, ventilation and air-conditioning. Distillate fuel oil use is split mainly between boiler fuel (42%) and non-process uses (42%, of which on-site transportation is the most significant use), with just 9% used in processing (most of which is used in process heating). Natural gas was mostly consumed as boiler fuel (62%). (74).

Specific energy consumption varies across the sector, dependent on the particular type of industry. International SEC benchmarks for various food products are summarised in the Table below.

Table 24. SEC Benchmarks in Food Industry- in Final Energy (Source: (48))

Electricity (GJ/t) Heat (GJ/t) Total (GJ/t)

Dairy Sector

Butter 0.5 1.3 1.8

Cheese 1.2 2.1 3.3

Milk 0.2 0.5 2.7

Milk Powder 1.1 9.4 10.5


207

Meat and fish production

Dried Salted Smoked Fish 0.01 2.10 2.10

Fresh, Chilled Frozen Fish 0.60 0.01 0.61

Fish Meals 0.70 6.20 6.90

Carcass Beef, Sheep, Veal 0.30 0.50 0.80

Carcass Poultry 1.00 0.60 1.60

Carcass Pork 0.50 0.90 1.40

Other

Vegetable Oil 0.2 2.7 2.9

Sugar (Refined) 0.6 5.3 5.9

ENERGY SAVING MEASURESKey energy efficiency opportunities in the food and beverage processing industry can be summarised as follows:

Area Measure


Refrigeration Energy efficient chillers, automation and control in refrigeration equipment; use of CO2 as refrigerant.

Cogeneration The adoption of combined heat and power technologies can result in significant energy savings in many sub-sectors of the food industry, including dairy, milk and ice-cream, beverages, juices, brewing, and wine and spirits.

Air Conditioning Cooling and refrigeration efficiency can be improved by optimising head pressure controls, controlling air purges, installing a refrigerant gas heat recovery system and by reconfiguring the entire refrigeration system

Heat Generation Energy efficiency technologies can be used in steam generation and distribution systems

Compressed Air Repairing leaks and replacing inefficient equipment

Lighting The use of energy efficient lamps and installation of lighting control systems.

Renewable Energy Sources These can be used to lower temperature heat requirements

Electricity The use of energy efficient pumps, fan motors, grinders and mixers, as well as VSDs


Process Heating/Cooling, Pasteurisation, Evaporation

Process heat recovery: several options in many processes including pasteurization section in a milk packaging plant; Evaporation plants in the food industry; Process heating; Process Cooling

Kilns Installing thermal insulation on the doors and walls of the ovens; Double glazing oven doors; Installing individual deck controls on deck ovens; Installing combustion control systems; Reduce the thermal mass of baking tins.

Drying Improving insulation, mechanical dewatering, maintenance

208



PROCESS-SPECIFIC MEASURES A wide range of factors can affect the use of energy within the industry. For example, energy consumption will vary according to levels of production; more energy will be used for cooling in warm climates; more energy will be used for heating in cold climates; while some processes may be seasonal. These factors can make it harder to justify investment in energy efficiency measures.

However, there are two important process-specific measures which can reduce energy consumption on the production side, both of which are applicable to the industries operating in Georgia – these are process heat recovery (which is relevant for a large range of industries) and the use of energy efficient ovens (particularly attractive for industrial bakeries).

PROCESS HEAT RECOVERYAreas in which energy use can be reduced or heat can be recovered in the food industry include:

The pasteurization section in a milk packaging plant - In the dairy industry, the pasteurisation process provides significant opportunities for waste heat recovery. Currently, the most common method of pasteurization is by means of heat exchangers designed for the High Temperature Short Time (HTST) process. This process involves heating milk to a certain temperature and holding it at that temperature under continuous turbulent flow conditions for a sufficiently long enough time to ensure the destruction and/or inhibition of any hazardous microorganisms that may be present. To save energy, heat is regenerated (i.e. the chilled milk feeding the exchangers is heated by the pasteurized milk leaving the pasteurization unit (75)). Sterilisation, particularly bottle sterilisation, is another energy intensive process that allows for waste heat recovery.

Evaporation plants in the food industry – Evaporation, the process of converting a liquid to a vapour, typically involves boiling off water by applying heat and is used in the food industry to concentrate liquid solutions. Energy savings can be achieved by the use of membrane technology to pre-concentrate the liquid solution, thereby reducing the energy required in the heating stage of the process. Energy can be recovered from the vapour (through the use of mechanical vapour compression systems) and used, for example, to pre-heat the liquid solution.

Process heating – Process heating is the single most important area in which energy is consumed in the food industry, with heat usually being provided in the form of steam or hot oil or through direct firing. Process heating activities include the heating of feed materials to reaction temperatures, as well as the heating of pipe and storage vessels and kilns. Energy can be recovered, for example, from an oven’s flue gases and exhaust vents and then used for space heating. Energy can also be recovered and used for process cooling using absorption cooling systems (76). Another option is to use induction heating, which works by dissipating the energy generated when the secondary winding of a transformer is short-circuited. This instantly imparts heat to liquid circulating in a coil around the transformer core. Compared to boiler-based methods of liquid heating, these techniques are estimated to reduce energy consumption by up to 17%. (77)


209

Process Cooling – Savings in overall energy use can be achieved by pre-cooling. For example, the use of plate heat exchangers to pre-cool ice water with ammonia prior to its final cooling with a coil evaporator can result in substantial energy savings.

USE OF ENERGY EFFICIENT OVENSEnergy efficiency measures that can be adopted when installing new ovens include:

The installation of thermal insulation on the doors and walls of the oven: Substantial heat losses can occur if thermal insulation on the walls and doors of an oven are missing or inadequate;

Double glazing oven doors: Oven doors account for about 10% of the total surface area of the oven. Double glazing the doors can reduce heat loss significantly.

Installing individual deck controls on deck ovens: These provide the oven operator with the facility to switch oven decks on and off in response to demand, thereby minimising overall energy use.

Installing combustion control systems along with accurate temperature and humidity electronic controls.

Reduce the thermal mass of baking tins – which can be achieved either by reducing their weight or by using tins made from low thermal mass materials.

Direct fluegas outlet

Post heat exchangerflue gas outlet

Air damper

Flue gas fromthe oven

The oven(very hot)

Bread leavingthe oven

Bread enteringthe oven

Bread leavingthe proofing oven

Bread enteringthe proofingoven

From theproofing oven

Gravity-assistedwickless heat pipeheat exchanger

The proofing oven(warm & humid)

To theproofingoven

Figure 82. Heat recovery in a Bakery Oven (Source: Best Practice Programme (78))

210


ENERGY EFFICIENCY IN DRYINGThere are a number of measures that can reduce energy consumption in drying and dewatering equipment, particular in the fruit and vegetable industry:

Ensuring proper maintenance – inefficient maintenance of drying and dehydrating equipment can increase energy consumption by up to 10% (77).

Insulating the hot surfaces of drying equipment that are exposed to air, such as burners, heat exchangers, roofs, walls, ducts, and pipes.

Mechanical dewatering of fruits and vegetables prior to drying, through centrifugal, gravity and mechanical compression and the use of high velocity air. These can reduce the moisture loading on the dryer – for every 1% reduction in feed moisture, demand for energy in the dryer can be reduced by up to 4%. Direct fired dryers are generally more energy efficient than indirect heated dryers. They remove the inefficiency of first transferring heat to air and then transferring heat from air to the product.

The use of heat pumps and infra-red drying are emerging alternative technologies in this area.


EE in heat generation (ESR: 10%-30%)

Process heat recovery (ESR: 5%-30% of heat process energy)

Using energy efficient ovens (ESR: up 30%)

Optimising cooling (ESR: 10%-20%)


Optimising compressed air system (ESR: up to 20%; CAPEX: about €5,000-€10,000 for leak detection instrumentation)

Cogeneration (ESR: 10%-20% in primary energy; CAPEX: about €1,000/kWel)

Energy efficient lighting (ESR: up to 80%; CAPEX: about €4/WLED, €0.5/W for CFL)

Use of renewable energy sources-primarily solar water heat


211

4.2. AGRICULTURE

DESCRIPTION – PROCESSESAgriculture has a very long history in Georgia and the country has become well-known in particular for producing hazelnuts, wine and fruit. Georgia has over 21 micro-climates which allow a wide range of grain, vegetables, hard and soft fruits, and meat and dairy products to be farmed and produced.

Animal farming is not considered to be a highly energy intensive industry but, for farms located in remote areas where natural gas is not available, electrical energy is used for all processes and it can be a significant contributor to overall costs. Energy is principally used in building services, animal feeding systems, waste management and removal, and in emissions control.

ENERGY SAVING MEASURESConsumption of energy within agricultural establishments will vary according to a number of factors, including the type of farm and its size. For example, cattle sheds do not need to be heated, but poultry sheds require heating. In addition, demand for energy can be seasonal, which can make it difficult to justify investment in energy efficiency measures.

The most important areas in which energy saving measures could be implemented can be summarised as follows (process-specific measures are described in greater detail in the rest of this Section):

212


Area Measure


Improvements to Building shells

Shell fabric sealing (such as ventilation shutters and access doors) can help reduce heat losses.

Heating and Ventilation GSHP could be a viable option for farms located in remote areas. The installation of good control systems is a prerequisite for maintaining the right temperature in buildings and minimizing the use of energy, while overall efficiency can be enhanced by the use of VSDs on fans and other motors.

Motors and Drives Using HE motors with VSDs when replacing existing or installing new motors on feed or waste handling systems. It is estimated that motor running costs can be reduced by more than 30% with VSDs.

Lighting Use of fluorescent tubes or compact fluorescent lamps; installation of lighting controls.


Farm Equipment Replace old inefficient farming equipment.

Hot Water and Electricity Production

Consider the use of RES, particularly solar heating for hot water production and the use of biogas for heat and/or electricity production.

Greenhouses Good housekeeping and the use of EE equipment and natural ventilation can reduce energy consumption in greenhouses.



FARM EQUIPMENTMuch of the equipment used in farms in Georgia today is antiquated and very energy inefficient, and is thus a significant contributor to a farm’s overall energy cost. The procurement of modern farm equipment will, apart from improving a farm’s operations, also save energy (due to it having a lower SEC). More details on energy efficiency in farm vehicles are contained in Section 4.3.

USE OF RENEWABLE ENERGY RESOURCESThere are a number of key areas where agricultural enterprises could consider the use of renewable energy resources, including:

Anaerobic digestion: The use of animal waste to produce biogas for use in heat only boilers or CHP systems could also deliver energy savings for a farm. The feasibility of this technology will depend on a number of factors, including the size of the farm, the specific substrate and its mixing requirements – anaerobic digestion is discussed in greater detail in Section 5.3.

Biomass power generation: There are also opportunities to burn agricultural residues to generate heat or power. These can include the use of wood waste for small scale space heating, or the burning of straw on a larger scale.


213

Solar energy: Solar energy can be used to produce hot water, in greenhouses, and in crop drying systems, all applications of which will allow a farm to reduce energy costs.

ENERGY EFFICIENCY IN GREENHOUSESGood housekeeping as well as the use of energy efficient equipment and natural ventilation can reduce energy consumption in greenhouses

Savings can be realised by regularly monitoring crop level temperature and regulating the thermostat so that the desired temperature is maintained. Weather stripping on doors should also be checked on a regular basis as air leaks will reduce internal temperatures and thereby increase demand for heat and energy consumption.

An additional layer of covering (for example curtains or a polyethylene sub-roof) can be installed to minimise heat losses – it has been estimated that they can reduce energy consumption by between 20% and 30%.

Figure 83. Plastic Bubble Wrap Insulation at North Side and Open Greenhouse Roofs

(Source (79))

The addition of thermal blankets that can be extended inside the walls and roof have been proven to reduce fuel required for heating by up to 50%7, while the installation of movable benches that allow access to plants but increase usable bench space by as much as 85% are an effective means of increasing the number of plants that can be grown in the greenhouse, thereby reducing specific energy consumption per plant grown.

The use of energy efficiency measures in greenhocuse is constrained by the fact that greenhouses are built to maximise the transmission of light to the plants and they may therefore have limited insulating properties. It is possible, however, to improve a greenhouse’s insulation without affecting light transmission, for example by covering the inside of a glass clad north-facing wall with plastic bubble wrap.

Ventilation systems can be installed in greenhouse to help maintain temperature, humidity and

7 Source: California Farm Bureau Federation

214


carbon dioxide concentrations at levels which ensure optimal growing conditions (both in warm and cool seasons). These can include mechanical devices (such as horizontal airflow fans) and natural ventilation systems (such as open-roof greenhouses) – air-conditioning is far too expensive.


HE motors and VSDs on feeding and waste handling systems (ESR: 10%-20%)

EE heating and ventilation (ESR: up to 50% of energy for heating/ventilation; CAPEX: varies depending on technology used)

Biogas from manure (ESR: depends on feedstock quantity; CAPEX: €2,000-€4,000/kW)

EE measures in greenhouses, such as thermal blankets and moveable benches (ESR: up to 50%)

Energy efficiency in farm equipment (ESR: 10%-30%)

EE in refrigeration (ESR: up to 40% of electricity for refrigeration)

EE lighting systems (ESR: 30-60% in electricity for lighting)

EE in building shell (ESR: 2%-5% of energy for heating, for example in chicken halls)


215

4.3. HEAVY TRANSPORT AND CONSTRUCTION VEHICLES AND FARM EQUIPMENT

DESCRIPTIONTransport vehicles consume a significant part of the world’s output of petroleum products. The heavy transport vehicles operating in Georgia are generally old (dating from the Soviet era) and are driven by inefficient and polluting diesel fuelled engines.

The use of heavy transport vehicles is expected to increase in the future, in particular because the construction sector, an important part of the economy, is expanding – its growth is being driven by improvements to the country’s infrastructure, the construction of new buildings and the renewal of town centres. In addition, Georgia is an important transit link between the Black Sea and the Caspian Sea and, following improvements to the country’s road infrastructure, the use of those routes is increasing as trade within the region expands. At the same time, the mining and metal extraction industry and the agricultural sector, both of which are dependent on the use of heavy transport vehicles, are expanding.

These factors emphasise the importance of acting to improve the energy efficiency of the country’s heavy vehicle fleet.

There are about 1,500 kilometres of main or international highways in Georgia which are considered to be in good condition, as well as some 18,800 kilometres of secondary and local roads that are, generally, in poor condition.


HEAVY DUTY ROAD TRANSPORT VEHICLESThere are a number of modern energy efficient technologies that can be deployed to reduce the power needed to run a vehicle and thus improve the efficiency of its operations. These technologies, which particularly apply to heavy duty road transport vehicles, are described in the rest of this section.

Figure 84. Heavy Duty Road Transport Vehicle

216


ENERGY EFFICIENT ENGINES Modern engines last longer, are more reliable, need less servicing and are more efficient than older engines – their use can reduce fuel consumption by 10%-15%.

IMPROVED AERODYNAMICSThe higher the drag coefficient (a measure of the resistance of an object in a fluid environment such as air or water) of a vehicle, the higher the energy losses associated with its movement and the greater its consumption of fuel. Studies have found that over half of the energy consumed by a heavy vehicle at high speed is used to overcome aerodynamic drag – a reduction in aerodynamic drag can therefore generate significant fuel savings.

Aerodynamic drag can be reduced in heavy vehicles by fitting devices (commonly referred to as “fairings”) that target areas where drag is most prevalent, including the gap between the cab and trailer, the gap between the trailer and the road, and the rear of the trailer (where parasitic drag occurs). Implementing such measures can reduce fuel consumption by as much as 15%.

AUTOMATED MANUAL TRANSMISSIONAutomated Manual Transmission (AMT) is a system designed to improve the driving experience, especially in cities where congestion frequently causes stop-and-start traffic patterns. The system removes the need for a clutch pedal but the driver is still able to decide when to change gear. The clutch itself is actuated by electronic equipment that can synchronize the timing and the torque required to make gear shifts quick and smooth. It is estimated that such systems can reduce fuel consumption by up to 5% - they also reduce greenhouse gas emissions.

ENGINE EFFICIENCY MANAGEMENT SYSTEMSThrough the use of an intelligent controller that continually monitors an engine, engine efficiency management systems can adjust the engine’s performance to match its work state, thereby maximising fuel efficiency. This may be a new technology, but anecdotal evidence suggests vehicles will run smoother, use less fuel, provide greater power when most needed and emit less. The technology can be applied to a wide range of diesel systems and can be retrofitted to existing vehicles without affecting engine or vehicle warranties.

LIGHTWEIGHT MATERIALSMany lorry components are typically made of heavy steel. However, the use of aluminium, metal alloys, metal matrix composites and other lightweight components can reduce tare weight. When manufactured with lightweight materials, the weight of a truck’s tractor unit can be reduced by over 500 kg, while that of a trailer can be reduced by over 1,000 kg. This is important given that fuel consumption increases with vehicle weight. Studies have shown that a 10% reduction in vehicle weight can reduce fuel consumption by between 5% and 10%.


217

REFRIGERATION Small refrigeration transportation units tend to be powered directly from a vehicle’s engine, while large truck and trailer units tend to be powered by stand-alone independent diesel generators. The design, application and efficiency of a refrigeration unit can have a significant impact on fuel consumption. Greater fuel efficiency and lower emissions can be achieved by replacing old independent units with new, more efficient models. This can be enhanced by the use of alternative cooling systems, some of which claim to be quieter, to have lower maintenance costs (owing to fewer moving parts) and, in some cases, to be emissions free. In addition, new insulation material (such as vacuum insulated panels) can reduce heat load insulation. It is estimated that these systems can reduce energy consumption by 5%-10%. (79)

Figure 85. Maxitrans EcoFridge (Source: MAXITRANS)

TYRES The rolling resistance of a tyre determines the amount of energy that is required to get a tyre moving, and to keep it moving. Low rolling resistance tyres are designed to minimise the amount of energy needed to move a tyre. The replacement of traditional dual tyres on a truck with one single wide tyre can reduce rolling resistance and the weight of the tyres and wheels, thereby reducing engine load and fuel consumption.

Incorrectly inflated tyres on truck trailers increase drag and increase fuel consumption. These effects can be mitigated by the use of automatic tyre pressure monitoring systems that use the air compressor on the vehicle to automatically monitor and adjust tyre pressures to the optimum level for a given load and terrain. Studies have shown that fuel savings of up to 8% can be achieved with these systems.

CONSTRUCTION VEHICLESConstruction vehicles tend to use one of two source of energy: diesel or electricity. Trucks, dump trucks, graders, concrete mixers, excavators, loaders and others vehicles tend to use diesel, while cranes, lifts and elevators mainly use electrical energy. In general terms, the replacement of existing electrical motors with more efficient models equipped with soft start-stop and variable speed drives can improve energy efficiency.

218


Figure 86. Construction Vehicles (Source: itdunya.com, hankstruckpictures.com, science.howstuffworks.com).

Other measures that can reduce energy consumption include:

REPLACEMENT OF ENGINESNew, modern engines generally last longer, are more reliable, and need less servicing than older engines. The replacement of a vehicle’s engine can reduce fuel consumption by 10%-15%, reduce maintenance costs by about 40%, and reduce servicing costs.

THE INTRODUCTION OF DUAL FUEL SYSTEMS The installation of a dual fuel system on a diesel truck can reduce CO2 emissions by up to a quarter, and cut operating costs by up to 10% (79). A dual fuel system enables a diesel engine to run primarily on gas, although diesel is used to ignite the gas:air mixture (the engine can still run wholly on diesel). Up to 90% of the diesel can be substituted, depending on the level of system integration and the engine’s operating point.

OTHER MEASURESOther measures which can increase energy efficiency include:

Improved logistics (for example, minimising the distance travelled or the loads carried). Modern fleet management systems incorporating real time data have proven to be highly successful in planning/monitoring vehicle routes, leading to substantial fuel savings.

Training drivers in fuel-efficient driving techniques.

FARM EQUIPMENTThe use of machinery and on-site transportation dominate energy use on a farm. Whether tilling the fields with a tractor, moving crops with a fork-lift, or using a combine harvester or hay baler, the


219

average farmer spends around 12% of their total identified energy budget fuelling machines and farm vehicles to perform these tasks. Since the tractor is one of the most utilized and essential tools for farmers in Georgia, it is no surprise that the tractor is the machine that presents the greatest potential for saving energy. Fuel consumption varies widely, due to variations in soil moisture conditions, crop yields and other agricultural factors, as well as variations in tractor efficiency.

Figure 87. Tractor with a Fork-Lift

There are a number of ways in which a tractor’s consumption of energy can be reduced, including:

ENGINE UPGRADE / REPLACEMENTReplacing gasoline engines with diesel engines will improve fuel efficiency, as will the replacement of old diesel engines with newer ones that contain more advanced technology. For example, a modern tractor with a 180 kW engine can do the same work as an old tractor with a 250 kW engine, saving about 15,000 lt/y for every 1,000 hours/y of operation.

Fuel consumption can also be reduced by changing farming techniques, for example by adjusting crop planting patterns or by converting to no-till farming.

MAINTENANCEThe preventive maintenance of farm equipment can improve energy efficiency. This can include, for example, the regular tuning of engines, lubricating the equipment, cleaning or replacing air filters, cleaning electrical equipment and ensuring that tyres are inflated to the proper pressure.

MATCHING FIELD EQUIPMENT TO THE APPROPRIATE SIZED TRACTORIf too powerful a tractor is used for a job, fuel efficiency will decline. The use of too small a tractor will likewise cause fuel efficiency to suffer. A good rule of thumb is to select the smallest and lightest tractor for the job that needs to be done, not only to improve fuel efficiency but also to reduce soil compaction.

220


OPTIMIZATION OF TRAFFIC PATTERNSReducing the number of turns by travelling lengthwise across a field will save fuel and time, as will the planning of routes which minimise overlapping.


Use of lightweight materials (ESR: 5%-10%; CAPEX: about €15,000)

Reduction in aerodynamic drag (ESR: up to 15%; CAPEX: about €1,000-€3,500)

Replacement of engines with dual fuel engines (ESR: 10%-15%; CAPEX: about €20,000-€25,000

Use of alternative options for engine-powered refrigeration (ESR: up to 10%)

Monitoring systems for type pressure (ESR:up to 8%; CAPEX: about €12,000)

Automated Manual Transmission (ESR: 2%-5%; CAPEX: €3,500-€5,000, about €700 for a stop-start system)


221

5. RENEWABLE ENERGY RESOURCES

5.1. SMALL HYDRO PROJECTS

5.1.1. INTRODUCTION

Hydroelectricity is one of the more mature forms of renewable energy – it provides more than 19% of the world’s electricity consumption. Although some may not consider large hydro projects to be a sustainable energy source because of their potential adverse impact on human activity and the environment, this concern does not hold for small hydro plants (SHPs – in Georgia, small hydro plants are considered to be those with a capacity of up to 15 MW). Small hydropower projects are most suitable for rural electrification schemes – they can be stand-alone, grid-integrated or combined with irrigation systems.

Small hydro projects can generally be categorised as either “run-of-river developments” or “water storage (reservoir) developments”. In Georgia, reservoir water storage is used only for larger capacity power stations.

RUN-OF-RIVER DEVELOPMENTSRun-of-river hydro plants use only the water that is available in the natural flow of the river – they do not store water. Their power output therefore fluctuates in line with the hydrological cycle, and they are often best suited to providing energy to a larger electricity system. Run-of-river SHPs can involve the construction of a weir or small dam which diverts a river’s flow into the plant’s intake and takes advantage of the drop in elevation that occurs over a distance in the river.

Individually, SHPs do not generally provide much firm capacity. Therefore, isolated areas that use SHPs often require an additional source of energy. A run-of-river plant can only supply all of the electrical needs of an isolated area or industry if the river’s minimum flow is sufficient to meet that area’s peak power demand.

A typical run-of-river SHP is shown in the Figure below.

Power canal

Intake gates

Controlpanel

Turbine

Generator

Tailrace

Draft tube

Penstock

Powerhouse

Figure 88. Run-of-River Small Hydro Plant 8

8 Source: US DoE, EERE website

222


WATER STORAGE (RESERVOIR) DEVELOPMENTSThese plants, which are driven by water stored in one or more reservoirs, provide power on demand, either to meet a fluctuating load or to provide peak power. Unless a natural lake can be tapped, storage usually requires the construction of a dam and the creation of new lakes. This has both positive and negative impacts on the local environment, although the scale of development often magnifies the negative impacts. The creation of new storage reservoirs for SHPs is generally not financially viable, except possibly in isolated locations where the value of energy is very high. SHP storage is generally limited to small volumes of water in a new head pond or existing lake upstream of an existing dam.

A typical water reservoir SHP is shown in the Figure below.

Inside a Hydropower Plant

ReserviorDam

Generator

Powerhouse

Power LinesTransformer

Intake ControlGate

Penstock Turbine Outflow

Figure 89. Water Reservoir Hydropower Plant9

5.1.2. COMPONENTS OF A SHP

A SHP is made up of three main components: the river head, civil works and the powerhouse.

THE RIVER HEADThe river head and water flow rates determine a river’s suitability and capacity for a hydro power plant. The flow is the volume of water which can be captured and re-directed to turn the turbine generator, and the head is the distance the water will fall on its way to the generator. The larger the flow (i.e. the more water there is) and the greater the head (i.e. the higher the distance the water falls), the more energy is available for conversion to electricity.

9 Source: HowStuff Works website


223

Schemes are generally classified according to the size of the head as follows:

High head: over 100 metres

Medium head: 30 - 100 metres

Low head: 2 - 30 metres

Reservoirs can guarantee a constant flow of water to a hydropower plant. However, water flow is critical in determining the potential energy output of a run-of-river SHP – this is demonstrated through the relationship used to calculate the electrical energy produced by a SHP:

P=p*h*r*g*k

Where:

P is Power in watts;

p is the density of water (~1,000 kg/m3);

h is height in meters;

r is flow rate in cubic meters per second;

g is acceleration due to gravity of 9.8 m/s2; and

k is a coefficient of efficiency ranging from 0 to 1. Efficiency is often higher (that is, closer to 1) with larger and more modern turbines (it averages about 0.6)

CIVIL WORKSCivil works comprise the diversion dam or weir, and the water passages. The diversion dam or weir directs the water into a canal, tunnel, penstock or turbine inlet. The water then passes through the turbine, spinning it with enough force to create electricity in a generator. The water then flows back into the river via a tailrace.

THE POWERHOUSEThe powerhouse includes the SHP’s electrical and mechanical components – primarily its turbine(s) and generator(s). Although small hydro turbines can attain efficiencies of up to 90%, this is dependent on matching the type of turbine to a river’s characteristics: some turbines can only operate efficiently over a limited flow range (e.g. propeller turbines with fixed blades and Francis turbines). For most run-of-river SHP sites, where flows vary considerably, turbines that operate efficiently over a wide flow range are usually preferred.

HeadFlow

224


Transformer Grid

Inlet valve

Penstock

Turbine

Figure 90. Powerhouse, High and Medium Head (Source: ESHA)

TURBINESThe potential energy in water is converted into mechanical energy in the turbine by one of two different mechanisms:

The water pressure applies a force on the face of the runner blades which decreases as the water proceeds through the turbine. Turbines that operate in this way are called reaction turbines. The turbine casing, with the runner blades fully immersed in water, must be strong enough to withstand the operating pressure. Francis and Kaplan turbines belong to this category.

The water pressure is converted into kinetic energy before entering the runner. The kinetic energy is in the form of a high-speed jet which strikes buckets mounted on the periphery of the runner. Turbines that operate in this way are called impulse turbines. The most common form of impulse turbine is the Pelton.

The three major types of turbine are described below:


225

Francis turbines: reaction turbines which are generally used for low to medium head (from 25 metre to 350 metre) hydro plants. They can have vertical or horizontal axis. However, the admission of the water is always radial, while its exit is always axial. They are the most common type of water turbine in use today.

Figure 91. Horizontal Axis Francis Turbine (Source: ESHA)

Kaplan and propeller turbines: axial-flow reaction turbines which are generally used for low head (from 2 metre to 40 metre) hydro plants. They are generally used in schemes where both flow and head remain relatively constant, characteristics that make them unusual in SHPs.

Figure 92. Double Regulated Kaplan Turbine (Source: ESHA)

Pelton turbines: impulse turbines which are only used for high head (from 60 metre to over 1,000 metre) hydro plants. The efficiency of a Pelton turbine can range from 30% to 100% of the maximum discharge for a one-jet turbine, and from 10% to 100% for a multi-jet turbine.

Figure 93. Two Nozzles Horizontal Pelton Turbine (Source: ESHA)

GENERATORSGenerators can be manufactured with horizontal or vertical axis, independently of the turbine configuration. Small generators tend to have an open cooling system; larger units tend to have a closed cooling circuit provided with air-water heat exchangers.

226


SWITCHGEARSwitchgear must be installed to control the generators and to link them with the grid or with an isolated load. They provide protection for the generators, main transformer and station service transformer. The generator breaker (either air, magnetic or vacuum operated) is used to connect or disconnect the generator from the power grid. Instrument transformers, both power transformers and current transformers, are used to transform high voltages and currents down to more manageable levels for metering. The generator control equipment is used to control the generator voltage, power factor and circuit breakers.

5.1.3. EFFICIENCY-CAPACITY FACTORS

The efficiency of a turbine reflects its ability to exploit a site‘s hydrodynamic characteristics. It is defined as the ratio of the power supplied by the turbine (mechanical power transmitted by the turbine shaft) to the hydraulic power.

To estimate the overall efficiency of a hydro power plant, the turbine efficiency must be multiplied by the efficiencies of the speed increaser (if used) and the alternator. Typical efficiencies for SHP turbines are listed below:

Table 25. Typical Turbine Efficiencies for SHPs

Turbine Type Best efficiency

Kaplan Single Regulated 91%

Kaplan Double Regulated 93%

Francis 94%

Pelton n Nozzles 90%

Pelton 1 Nozzle 89%

Turgo 85%

Source: ESHA

The capacity factor of a SHP can vary considerably compared to other renewable energy resources, being determined mainly by the design of and the principal objectives set for each plant. For example, a SHP could have a high installed capacity and low capacity factor to provide electricity predominantly to meet peak demands and ancillary grid services. A SHP with a lower installed capacity and a higher capacity factor would, in contrast, have less flexibility to meet peak demands. Analysis of data from 142 CDM hydropower projects around the world found that their capacity factors ranged from 23% to 95%, with an average of 50% (80).


227

5.1.4. SMALL HYDRO POWER PROJECT DEVELOPMENT

The development of a SHP, from conception to final commissioning (which includes the required studies, design work, necessary approvals and construction), typically takes between two and five years. This process will typically involve carrying out a number of studies, including:

Topography and geomorphology of the site;

Evaluation of the water resource and its generating potential;

Site selection and basic layout;

Hydraulic turbines and generators and their control;

Environmental impact assessment and mitigation measures;

Economic evaluation of the project and financing potential;

Power purchase agreements;

Institutional framework and administrative procedures to attain the necessary consents.

VIABILITYThe technical and financial viability of each potential SHP are very site specific. Power output depends on water flow and head, with the amount of energy that can be generated dependent on the quantity of water available and the variability in its flow throughout the year.

In off-grid and isolated-grid applications, the value of the energy generated is generally significantly more than that generated by systems that are connected to a central grid. However, in these cases it might not be possible to use all of the available energy or to use the energy when it is available because of seasonal variations in water flow and variations in energy consumption.

A conservative “rule-of-thumb” is that the power (P) produced by a SHP is equal to seven times the product of the flow (Q) and the gross head (H) at the site (i.e. P = 7QH). Producing 1 kW of power at a site with 100 metres of head will require one-tenth of the flow of water than at a site with 10 metres of head. The size of a hydro turbine depends primarily on the flow of water it has to accommodate. Thus, the generating equipment required for higher-head, lower-flow installations is generally less expensive than for lower-head, higher-flow plants. The civil works components are related much more to the local topography and physical nature of a site.

OPERATION AND MAINTENANCEOnce constructed, SHPs require little maintenance over their useful life – this can be well over 50 years for mechanical and electrical equipment. Plants can be operated automatically without operating personnel except for routine inspection and the clearing of water channels.

In general, it may not be necessary to renovate the turbines and alternators in an older hydro station, but the replacement of old switchgear and control mechanisms can allow for the introduction of automation.

228


Investment and electricity production costs for hydro plants, as well as some indicative figures on operating costs, are presented in the Table below – these estimates are based on current technologies as well as future projections (81):

Table 26. Typical CAPEX and OPEX Costs of Hydro Plants

Value

Unit Large HPPs (> 1 MWe) Small HPPs (< 1 MWe)

Production Costs – State of the Art (2007) €2005/MWh 35-145 60-185

Production Costs – Projections for 2020 €2005/MWh 30-140 55-160

Production Costs – Projections for 2030 €2005/MWh 30-130 50-145

CAPEX €2005/kW 1000-2000 1500-4000

Capacity Factors % 25-90 20-95

O&M Costs €2005/kW/y 40-75 85-130

Lifecycle GHG Emissions tCO2/GWh 3.5-40 3.5-32

5.1.5. SMALL HYDRO PROJECT POTENTIAL IN GEORGIA

Georgia has 360 rivers with considerable energy potential. The total theoretical hydro energy potential has been estimated at between 137 TWh and 160 TWh per year, while the technically feasible potential has been estimated at between 81 TWh and 90 TWh per year. SHPs are estimated to account for 40 TWh/year of the total theoretical hydro energy potential, and 19.5 TWh/year of the technically feasible potential. The distribution of Georgia’s technically feasible SHP potential by region is shown in the Table below – this shows that some 70% (13.7 TWh) of that potential is located in the west of the country. (82)

Table 27. Distribution of SHP Potential in Georgia

Region No of Rivers Potential- Total Capacity (MW)

Potential Annual Energy Generation (GWh)

Abkhazia 64 752 4,374

Achara 25 244 1,425

Samegrelo-Svaneti 36 450 2,246

Guria 9 174 1,128

Racha-Lechkhumi 28 444 2,472

Imereti 42 677 2,036

Total West Georgia 204 2,741 13,681


229

Region No of Rivers Potential- Total Capacity (MW)

Potential Annual Energy Generation (GWh)

Kakheti 41 416 2,430

Kvemo Kartli 21 40 241

Mtskheta-Tianeti 38 270 1,613

Shida Kartli 26 146 835

Samtskhe-Javakheti 26 117 671

Total East Georgia 152 989 5,790

GRAND TOTAL 356 3,730 19,471

The Ministry of Energy has published a map identifying the possible locations for some 90 SHPs. This map, which also indicate the areas of the country with the highest hydro power potential, is shown below:

POTENTIAL HYDROPOWER SITES IN GEORGIA

Russian Federation

AzerbaijanArmeniaTurkey

Black Sea

25

75363739

3433

299126 742875

75731241

27

1771

22 2

6367

64

6166 60

7575

7682

7715

757561

876

30

316

401

5232 53

11

2155

2365

8586 5990

9491

47754746

64

204748

50515253

9 4

Figure 94. Potential Hydropower Sites in Georgia (source: Ministry of Energy)

230


5.2. SOLAR ENERGY

Solar technologies on the market (such as photovoltaic solar cells and concentrating solar power) are efficient and highly reliable, providing electricity and occasionally heat for a wide range of applications, including district heating systems, industrial processes, domestic hot water and, in some cases, space heating and cooling for residential and commercial buildings.

5.2.1. SOLAR ELECTRICITY

The conversion of solar energy to electrical energy takes place through two principal methods:

Photoelectric – solar energy is converted into direct current electrical energy using semiconductors that exhibit the photovoltaic effect.

Thermodynamic – solar energy is converted to steam which drives a turbine which generates electricity.

PHOTOVOLTAIC (PV) SYSTEMSPhotovoltaic (PV) power generation uses solar cells to convert light directly into electricity. The energy can be used or stored in chemically charged batteries. There are two main types of PV systems:

Grid-connected systems (on-grid systems) – these are connected and provide electricity to the grid; and

Off-grid systems – these are not connected to and operate independently of the grid (they are also known as autonomous systems).

More than 90% of existing PV systems are grid-connected systems. A typical PV installation is shown in the Figure below.

Figure 95. A Typical PV Installation (Source: Martifer)


231

DC to ACinverter AC

DC

circulit breaker boxes

battery system

DC outlets

chargecontroller

AC outlets

PV array

Figure 96. PV Power Generation Principles (Source: PV Solar Energy-Development and Current Research, EC, 2009)

The production of electricity from PV-based systems has grown rapidly in recent years. Between 2004 and 2009, global grid-connected PV capacity increased at an annual average rate of more than 60%. More than 30 GW of grid-connected capacity was added in 2011, increasing the existing total capacity to about 70 GW. This development is shown in the Figure below.

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

80

70

60

50

40

30

20

10

0

GW

Rest of World China North America Other APEC Japan European Union

Figure 97. Installed PV Capacity (source: IRENA (83))

232


There are three types of solar cell: wafer-based silicon cells, thin film technology cells, and concentrated photovoltaic cells. The first two are the most commonly used.

WAFER-BASED SILICON CELLS:Wafer-based silicon cells are made from thin slices (approximately 200 μm thick) cut from a single crystal of silicon (monocrystalline) or from a block of silicon crystals (polycrystalline). Their efficiency ranges from 11% to 19% and they are the most common technology on the market today.

THIN FILM TECHNOLOGY:Thin film modules are constructed by depositing extremely thin layers of photosensitive materials onto a low-cost backing such as glass, stainless steel or plastic. As the film is only 1-2 μm thick, thin film modules require significantly less active semiconducting material. Thin film solar cells can be manufactured at lower cost in larger quantities than wafer-based silicon cells, but they are less efficient (their efficiency ranges from 4% to 11%), meaning that a larger surface area and more materials are required to achieve a similar performance.

The Figure below shows the relative efficiency of current technologies.

Commercial Module Efficiency

Technology Thin Film

(a-Si)

4-8%

Source: EPIA 2010. Photon International, March 2010, EPIA analysis

Efficiency based on Standard test conditions.

~15m2 ~9m2 ~10m2 ~12m2 ~7m2 ~8m2

Cell efficiency

Module

efficiency

Area Needed

per KW

(for modules)

10-11% 7-11% 7-9% 13-19% 11-15%2-4% (LAB)

a-Si/�c-Si Dye s. cells Mono Muki(CdTe) Ci(G)S

Crystalline

Silicon

uo oDye s. ce s(a S ) a S /�c S(Cd e) C (G)S

Figure 98. The Relative Efficiency of Alternative Commercial PV Modules (Source: EPIA)

CONCENTRATED PHOTOVOLTAIC TECHNOLOGY:Concentrated photovoltaic (CPV) technology uses optics such as lenses or curved mirrors to concentrate a large amount of sunlight onto a small area of solar photovoltaic (PV) cells to generate


233

electricity. Compared to non-concentrated PV systems, CPV systems can save money as a smaller area of photovoltaic material is required.

However, the high cost of lenses or other parabolic materials makes them more expensive than normal PV technologies. Semiconductor properties allow solar cells to operate more efficiently in concentrated light, as long as the cell junction temperature is kept cool by a suitable heat sink (the efficiency of multi-junction photovoltaic cells currently being developed in research is upward of 40%).

Figure 99. View of CPV Tracker Panels on Tracker (Source: SolFocus)

It must be noted, however, that CPV technology works only with tracking systems as the exact position of the cells relative to the sun is crucial to achieving solar energy concentration.

CONCENTRATING SOLAR POWER SYSTEMSConcentrating Solar Power (CSP) Systems concentrate the thermal energy of the sun to drive a heat engine, which then drives a generator to produce electricity. The principal CSP technologies include:

LINE-FOCUS PARABOLIC TROUGHSParabolic-trough systems concentrate the sun’s energy through long rectangular, curved (U-shaped) mirrors. The mirrors are tilted toward the sun, focusing sunlight on a pipe that runs down the centre of the trough. Oil flowing through the pipe is heated (to about 400°C) and is used to boil water in a conventional steam generator to produce electricity. Trough system designs can include thermal storage – setting aside the heat transfer fluid in its hot phase – allowing electricity to be generated for several hours after sunset.

SOLAR POWER TOWERSThis technology involves an array of flat, movable mirrors which focus the sun’s rays upon a collector tower where a receiver is installed. Molten salt flowing through the receiver is heated, and the salt’s heat is then used to generate electricity through a conventional steam generator. Molten salt retains heat efficiently, allowing the heat to be stored for several days before it is converted into electricity (this means that electricity can be produced on cloudy days and after sunset).

234


Current solar power-tower technology takes the form of utility-scale, grid-connected plants providing electricity to the wholesale market. Numerous working fluids have been tested or considered for use in power-tower plants, including water/steam, air, sodium and molten salt.

System Boundary

Sunlight:2,7 MWh/m2/yr

Hot SaltStorage Tank Cold Salt

Storage Tank

Steam Generator

CondenserCooling TowerSteam Turbine

and Electric GeneratorSubstation

5650C 2900C

Figure 100. Molten-Salt Power system Diagram (Source: www.solarpaces.org)

Indicative investment costs for different types of solar power facility (PV and CSP) as well as levelized production costs (the Levelized Cost of Energy – LCOE) are contained in the Table below:

Table 28. Typical Capital and Operating Costs for Solar PV and CSP (83)

Plant Efficiency

Factory Gate Price of Module

Installed Costs O&M Costs LCOE

% €/W €/kW €/MWh €/kWh

Residential Installations:c-Si PV 11-19 0.65-0.95 1,500-2,500 0.14-0.40

Amorphous Si thin Film 7-10 0.65-0.72 2,500-3,000 0.20-0.45

Stand-Alone Installations:

c-SI PV with Battery Storage 11-19 0.65-0.95 3,500-4,500 0.28-0.55

Non-residential Installations:

CPV (85) 27-30 1.30-1.50 3,500-5,000 18-23 0.10-0.12

CSP Parabolic Trough – no Storage (84)

14-20 3,500 15-27 0.11-0.28

CSP Solar Tower - 6-7.5 h Storage 23-35 4,800-5,700 15-27 0.13-0.22


235

It should be noted that global prices for PV systems are declining and are expected to continue to decline in the future (as shown by the PV module learning curve below):

1979

1992 19982002

2004 2011$ 1.3-1.5

2015$ 1.082014$ 1.05

2010$ 1.52

100.00

10.00

1.00

0.101 10 100 1.000 10.000 100.000 1.000.000

Comulative production volume (MW) c-Si CdTe

Glo

bal M

odul

e av

eran

ge s

ellin

g pr

ice

(201

0 U

SD/W

p)

22% price reduction for eachdoubling of comulative volume

2006 c-Si price increasedue to polysilicon shortage

Figure 101. PV modules Learning Curve (Source: IRENA (83))

5.2.2. SOLAR HEATING

Solar heating is one of the most widely used practical applications of solar energy. Heat from solar radiation can be used for domestic hot water needs, and for heating and air cooling in residential, public and industrial buildings. Solar energy can also provide the heat needed in many industrial processes, such as food production and drying and the desalination of drinking water. While ordinary solar collectors typically generate temperatures of 60-100°C, concentrating solar collectors can produce temperatures of over 300°C. However, concentrating solar collectors are rarely found. The two main types of domestic hot water (DHW) solar heating systems are:

Flat collectors;

Vacuum tube collectors.

FLAT COLLECTORS:The flat collector is the main type of domestic hot water solar heating systems currently in use. It is made up of several components:

An absorber - usually a sheet of dark-coloured high-thermal conductivity metal, such as copper or aluminium, to which pipes are attached. Sunlight heats the absorber plate, changing solar energy into heat energy, which is then transferred to a liquid passing through the pipes attached to the

236


absorber plate. Modern applications have a coating that has a high thermal absorption factor and a low thermal emissivity factor (the coating is a complex combination of other coatings or materials inside the paint).

A metal box, which is insulated in order to reduce heat loss from its back and sides;

A glass or plastic cover (glazing), which allows sunlight to pass through to the absorber and which also insulates the space above the absorber;

A hot water tank, which tend to be located on top of the collectors (thermo-siphon type).

Figure 102. Typical Thermo-Siphon System with Selective Surface Collectors (Source: Bartec)

The advantages of a flat collector include:

Low cost solution;

Easy to install and maintain;

Simple to operate and generally require no other equipment required (such as pumps);

Proven technology with significant lifetime (more than 25 years);

Ideal for intermittent loads (e.g. houses, restaurants and small businesses).

The disadvantages of a flat collector include:

Lower efficiency compared to vacuum tube collectors;

Temperature range not ideal for solar cooling;

During extended winter periods, cannot compensate DHW load;

Sensitive to damage from extreme snowfall or hail.


237

VACUUM TUBE COLLECTORS:Technological advances have seen the development of vacuum tube (or evacuated tube) collectors. They are made up of several components:

Double-walled glass tubes and reflectors which heat the fluid inside the inner tube. The inner tube has a highly heat absorptive coating, while a vacuum between the two walls insulates the inner tube and ensures that it retains as much heat as possible. The fluid inside the tube (glycol mix) flows naturally and the tube is connected to a heat exchanger where its hot tip transfers the heat to water.

Heated Vapor Rise

s to th

e Top

Cooled Liquid Falls to Botto

m

Heat Absorbed byHeat Pipe

Solar Energy Absorbedby Solar Tube

Heat Transfer

Figure 103. Vacuum Tube Operation Principle (Source: SolarPanelsPlus.com)

A hot water tank, which is generally located on top of the collectors.

Figure 104. Vacuum Tubes Collector (Source: SOLCO project (85))

238


The advantages of vacuum tube collectors include:

Higher efficiency compared to flat collectors;

Ideal for high and constant loads (hotels, spa, swimming pools and gyms);

Ideal for solar cooling and heating;

Temperatures range from 50°C in winter to 120°C in summer;

Cover winter load, except in extreme conditions;

Not prone to damage from heavy snow or hail.

The disadvantages of vacuum tube collectors include:

They are a relatively expensive solution;

Not ideal for small DHW loads (such as houses);

Hot summer conditions may cause glycol pyrolysis if there is no constant consumption or water circulation (temperatures may rise above 130°C);

Prone to being damaged if used for intermittent loads;

Small electricity consumption due to the need for forced recirculation especially during the summer.

PASSIVE SOLAR SYSTEMS:The design and construction of passive solar buildings is one way of exploiting solar energy for heating purposes. The design aims to take advantage of the local climate, using a building’s windows, walls and floors to collect, store and distribute solar energy in the form of heat in the winter and to reject solar heat in the summer. It takes account of window placement and type of glazing, thermal insulation, thermal mass and shading, and is called passive solar design because it doesn’t involve the use of mechanical or electrical devices. Depending on the local climate, buildings constructed on this basis can reduce the amount of fuel used for heating by between 20% and 60%.

These techniques can also be used in the agricultural sector, in particular to dry agricultural products and to distil water for animals in desert areas. Farmers can also minimise their energy costs by ensuring that greenhouses are designed and built so that they utilise solar energy to the maximum.

5.2.3. SOLAR COOLING

Solar chillers use thermal energy to produce cold and/or dehumidified air. A typical solar cooling system consists of a common solar thermal system made up of solar collectors, a storage tank, a control unit, pipes and pumps, and a thermally-driven cooling machine. The chillers use the hot fluid in the storage tank to produce a cold fluid which is used in a normal cooling plant similar to an electric refrigerator. On a typical day, the thermal storage tank acts as a buffer and enables the optimisation of the asynchronous heat absorption during the hours of solar radiation and the cooling that may be needed during a different period of the day.


239

Thermal buffer Collectors

Air-conditioningsystem for minimumair supply

Cooling applicationin this case:cooling ceilings

Cold buffer Exhaust air

Supply air

AbsorberCooling agent vapour

Cooling agent (liquid)

Cooling agent vapour

High pressure

Low pressure

VaporiserCoolingtower

Condenser Expeller

Solution richin cooling agent

Solution low in cooling agent

Figure 105. Diagram of a Solar Cooling System (Source: (85), www.solcoproject.net)

5.2.4. SOLAR ENERGY POTENTIAL IN GEORGIA

Georgia has reasonably favourable conditions for the exploitation of solar energy. According to studies conducted by the Academy of Science of Georgia, direct and global radiation can reach up to 7.0 kWh/m2 per day in the most promising locations. Average monthly and annual total solar radiation for different locations in Georgia are summarised in the Table below:

Table 29. Solar Potential in Georgia (kWh/m2) (Source: Academy of Science of Georgia, “Energetic Resources of Georgia” 1992)

Month

StationElevation

(m)Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual

Tbilisi 428 58 65 94 114 143 174 175 172 137 111 64 54 1,361

Senaki 40 68 68 91 113 143 158 128 137 138 126 87 60 1,317

Telavi 568 76 69 79 100 129 166 178 165 131 109 79 68 1,349

Tsalka 1,457 98 98 109 106 125 149 150 142 120 117 83 88 1,385

Stepantsminda 3,653 124 135 158 150 149 151 143 124 170 131 131 131 1,697

Average 6.0% 6.1% 7.5% 8.2% 9.7% 11.2%10.9%10.4% 9.8% 8.4% 6.2% 5.6%

With realistic nebulosity conditions, the annual total in-take of solar radiation would average between 1,300 kWh/m2 and 1,700 kWh/m2. The highest volume of solar radiation is observed in the country’s mountainous areas. However, terrain and atmospheric conditions will dictate actual radiation and these need to be taken into account when selecting a location for and when designing a solar power plant. The share of direct solar radiation varies during the year: from 20% to 25% in November to February, to 75% to 80% in March to October. As a result, it is estimated that the total annual duration of operation of solar installations in Georgia would be in the range of 1,500-2,000 equivalent hours/year.

240


The locations with the highest solar energy potential in Georgia are shown in the map below:

3.5

3.8

4.2

4.5

5.3

Figure 106. Solar Energy Potential in Georgia (In Average Daily Solar Irradiation – kWh/m2- (Source: USAID (86))

5.3. BIOMASS

5.3.1. INTRODUCTION

Biomass is any organic matter – wood, crops, seaweed and animal waste – that can be used as a source of energy. Around 120 billion tons of dry organic substance is produced on earth every year by means of photosynthesis, equivalent in energy terms to more than 40 billion tons of oil.

Biomass can be used in a number of ways: it can be burnt directly, used to produce gas or used to produce ethyl alcohol. It accounts for about one seventh of world production of fuel, and is the third most important source of energy produced (with gas). In addition, using biomass as a fuel reduces the amount of other fuels that have to be purchased to meet energy needs, sometimes by as much as 50%.

Various biomass power generation technologies exist today, at a varying status of development. An overview of most important biomass technology options and corresponding end-uses, together with an indication of the technology status, is shown in the Figure and Table below.


241

Ant

icip

ated

Cos

t of F

ull-S

cale

App

licat

ion

Research Development Demonstration Development Mature Technology

Time

Integrated BiomassGasification - Fuel Cell

Bio-Hydrogen

Biorefineries

Hybrid Biomass-Solar/Geotherminal

PressurizedGasification

Torrefied Pellet Production

High-RateCofiring

AtmosphericBiomass Gasification

Refuse-Derived &Process-Ehgineered Fuels

100% Biomass Repowering Options

Pyrolysis

Medium-Rate Cofiring

MSWIncineration

Anaerobic DigestionLFG

CHP

Low-RateCofiring

Stoker/FBCSteam-Elektric

Combustion

Figure 107. BiomassPower Generation Technology Status (source IRENA (87))

Table 30. Biomass – Key Technology Options

Type of Resource Raw MaterialsConversion Technology

Product End-Use

Solid BiomassWood Logs, Chips and Pellets, Agricultural Residues

Combustion (Thermal)

Combustible Fuel Heat, Electricity

Solid BiomassWood Chips and Pellets, Agricultural Residues

Bioengineering Biogas or BiofuelHeat, Electricity, Transport Fuels

Wet BiomassManure, Sewage Sludge, Animal Litter

Anaerobic Fermentation (Biological)

BiogasHeat, Electricity, Transport Fuel

The technologies involved are generally well-developed and commercially available so that development of projects depends mainly on the availability of raw materials. For enterprises using their own waste materials, project lifetimes are certain while the enterprise continues its own production.

242


5.3.2. BIOMASS COMBUSTIBLE FUEL

Solid biomass is usually used directly as a combustible fuel – it has a calorific value that ranges from 10 MJ/kg to 20 MJ/kg. It can come in the form of wooden chips or waste, and be derived from municipal solid waste or the unused part of field crops. It can be burned in boilers to generate heat, electricity or both (cogeneration). Combustion is the main conversion option applied. A typical application is in medium and large-scale district heating with CHP, and process heating systems.

Boilers using biomass fuels require additional technology to manage automatic firing such as stoker-fired boilers, suspension-fired boilers, and fluidised bed boilers, with the latter becoming the preferred technology for power plants with a capacity of over 10 MWe because of their clean and efficient combustion characteristics.

Wood pellets are now becoming a more frequently used fuel – the pellets are generally produced from residues of wood processing industries. They are mainly used for heating and the production of electricity and are particularly suitable for small heating systems – they are easy to store and do not degrade, are relatively cheap when compared with fossil fuels, and produce very little ash and other emissions.

Feed water

Return

Flue gas path

Figure 108. Pellets/ Pellet Boiler with Flues Gas Condensation (Source: AEBIOM (88))

Smaller boilers (those with a capacity of 20-50 MWth) tend to have efficiencies of about 20%, a relatively low level caused by the lower heating values and higher moisture content of the wood fuel. As a result, the viability of investing in these types of projects depends on access to a large, reliable and cheap source of biomass (e.g. producers of furniture with access to waste wood, or farmers with access to straw).


243

Indicative capital costs, electricity production costs and operating costs for biomass electricity generating plants are summarised in the Table below (81):

Table 31. Typical CAPEX and OPEX Costs of Biomass Plants

Unit ValueProduction Costs – State of the Art (2007) €2005/MWh 80-195Production Costs – Projections for 2020 €2005/MWh 90-215Production Costs – Projections for 2030 €2005/MWh 95-220O&M Costs €2005/kW/y 135-260Fuel Prices10 €2005/toe 90-160Lifecycle GHG Emissions tCO2/GWh 20-40CAPEX

Stoker Boiler €/kW 1,450-3,200Fluidised Bed Boiler €/kW 1,700-4,300Stoker or Gasifier CHP €/kW 2,700-5,200

LCOE

Stoker Boiler €/MWh 45-160Fluidised Bed Boiler €/MWh 55-180Stoker or Gasifier CHP €/MWh 55-220

10

Table 32. Costs of Feedstock for Biomass Plants (Source: IRENA)

LHV Price

MJ/kg €/ton

Forest Residues 11.5 12-23

Wood Waste 19.9 8-38

Agricultural Residues 11.3-11.6 15-38

Energy Crops 14.3-18.3 30-46

5.3.3. BIOGAS

Biogas is a mixture mainly of methane and carbon dioxide, although it may also include some hydrogen sulphide, moisture and siloxanes. It is generally produced from landfill sites or from anaerobic digesters. It is a product that is viable in Georgia, either for large scale animal husbandry or small scale rural farmers. At the large scale, it can also help with the disposal of large quantities of animal manure, especially if strict environmental standards need to be met.

Biogas can be produced from a wide variety of waste, including that from the production of paper and sugar, from sewage and from animal waste. The waste has to be slurried and fermented naturally to produce methane. When a biogas plant has extracted all the methane that it can from the waste, the remains can sometimes be more suitable than the original biomass for use as a fertilizer.

10 Indicates average costs of raw material if purchased

244


Biogas can also be produced via advanced waste processing systems, such as mechanical biological treatment. These systems recover the recyclable elements of household waste and process the biodegradable fraction in anaerobic digesters. A typical biogas production facility will include the following elements:

Feedstock storage – the substrate loading system, which will include bunker, feeders and conveyors;

Hydrolysis – loading the substrate to a hydrolysis reactor, at the same time as heating it in order to maintain a constant temperature;

Digestion – the bacterial decomposition of the substrate to biogas. Retention time will depend on the anaerobic digestion process, but the system will be heated to maintain a constant temperature;

Gas conditioning unit – pumping and cleaning the biogas (removing H2S, soot and other impurities);

Separation unit – after it has been used in the biogas plant, the substrate is directed to the separation unit. Bio-fertilizer can be packed or granulated;

Gas flare system;

Gas holder – to collect the biogas. Pressure and temperature are maintained at constant levels within the gasholder, from which the biogas is fed into the combustion system;

Cogeneration – the biogas is used to produce electricity and hot water, which can then be used;

Heat recovery systems – which include heat exchangers and circulation pumps;

Auxiliaries – the electrical equipment required to connect to and operate the generator on a farm’s electrical network, or to connect the generator to the public electricity distribution network.

Reception tanks Reactor Secondary reactor

Blomass forfertilisation

Biogas forexplotation

Gas storageGas purification

Figure 109. Schematic of a Biogas Plant (Source: PlanEnergi).

Energy produced by the combustion of biogas can represent between 60% and 90% of the energy contained in the raw material. However, this can be difficult to determine, especially if the biogas is


245

produced from liquid mass, 95% of which is water. The characteristics of the biogas produced from various different types of organic farm waste are summarised in the Table below.

Table 33. Biogas (methane) output from agricultural wastes

Organic WastesCH4 Output,

(m3/kg of Dry Organic Substance)

Content of CH4(%)

Pig Manure 0.580 77.5

Milk Waste 0.625 82.0

Bull Manure 0.290 56.2

Bull Manure 50% + Molasses 50% 0.300 48.0

Bull Manure with Straw 0.220 52.0

Silo Maste 0.250 84.0

Chicken Manure 0.370 54.0

Turkey Manure 0.640 62.0

Milking Cows Manure 0.208 55.0

Biogas can be burned on-site to produce heat, or it can be transported by pipeline to end-users. The use of biogas in a CHP unit, usually a gas engine, is considered to be a very efficient way of producing energy. However, it can also be burnt directly, in natural gas burners.

Figure 110. Biogas Storage Facility (Source: Lemvigbiogas.com) Figure 111. Biogas Burner (Source: (89) Big-East Project)

Biogas can also be produced in landfills from organic domestic waste. The biggest organic waste landfill site in Georgia (at Rustavi) was completed in 2011. It is designed to process 100 t/day of municipal solid waste, and is equipped to collect biogas for its further utilization.

Indicative capital costs, operating costs and electricity production costs for biogas plants are summarised in the Table below (81): 11

11 Indicates average costs of raw material if purchased

246


Table 34. Typical Capital and Operating Costs for Biogas Plants

Unit Value

Production Costs – State of the Art (2007) €2005/MWh 55-215

Production Costs – Projections for 2020 €2005/MWh 50-200

Production Costs – Projections for 2030 €2005/MWh 50-190

O&M Costs €2005/kW/y 240-330

Fuel Prices11 €2005/toe 270

Lifecycle GHG Emissions tCO2/GWh 240

CAPEX

Digester €/kW 1900-4500

Landfill €/kW 1500-2000

LCOE

Digester €/MWh 45-115

Landfill €/MWh 70-90

5.3.4. BIOMASS ENERGY POTENTIAL IN GEORGIA

There is very little information on the potential use of biomass in Georgia. However, the potential annual electrical output from various forms of waste has been estimated as follows:

Wheat crop residues – 280 million kWh;

Corn crop waste – 750 million kWh;

Other corn and legume cultures – 270 million kWh;

Residues from farming and poultry breeding - 6.9 GWh.

The total energy potential from the first there sources would therefore reach some 1.3 GWh/year (equivalent to 112,000 toe per year); that from farming and poultry breeding would be equivalent to some 0.6 million toe.

The biogas potential from other waste residues has been estimated as follows:

Tbilisi and Kutaisi produce about 900,000 tons/year of residential waste, which could generate some 90 million m3 of biogas;

The Tbilisi sewage treatment works could produce some 160 million m3 of biogas per year, equivalent to about 1 GWh (86).


247

5.4. GEOTHERMAL

Geothermal energy is energy derived from the natural heat of the earth. The earth’s temperature varies widely, and geothermal energy is usable for a wide range of temperatures, from room temperature to over 420°C.

Geothermal reservoirs are generally classified as being either low temperature (<150°C) or high temperature (>150°C). Generally speaking, the high temperature reservoirs are the ones suitable for commercial production of electricity.

5.4.1. ELECTRICITY GENERATION

Three types of power plants are used to generate power from geothermal energy: dry steam, flash and binary.

Dry steam plants take steam out of fractures in the ground and use it to drive a turbine that spins a generator. Flash plants take hot water, usually at temperatures of over 200°C, out of the ground and allow it to boil as it rises to the surface. Steam/water separators are used to separate out the steam which is then run through a turbine.

Dry Steam Power Plant

GeneratorTurbine

Condenser

Water

Water

Water

Air

AirCoolingtower

Air and watervapor

Injectionwell

Geothermal ZoneSteamProduction

well

Air and watervapor

InjectionwellGeothermal Zone

Steam

Water

GeneratorTurbine

Flash Steam Power Plant

Water

Waste Brine

AirAir

Coolingtower

Productionwell

Steam

BrineDirect HeatUses

Figure 112. Dry Steam Power Plant (source: https://inlportal.inl.gov)

Figure 113. Flash Steam Power Plant. (source: https://inlportal.inl.gov)

In binary plants, the hot water flows through heat exchangers, boiling an organic fluid that spins the turbine.

248


Air and watervapor

Turbine

Air Air

Coolingtower

InjectionwellGeothermal Zone

Water

Binary Cycle Power Plant

Water

Cool Brine

Productionwell

Hot Brine

Pump

Heat Exchanger

Condenser

Iso-Butane

Iso-B

utan

e (v

apor

)

Generator

Figure 114. Binary Cycle Power Plant (Source: https://inlportal.inl.gov)

The condensed steam and remaining geothermal fluid from all three types of plants are injected back into the hot rock to pick up more heat.

Table 35. Typical Capital and Operating Costs for Geothermal Power Plants (source: (91), (92)

Plant Efficiency Installed Costs O&M LCOE

€/kW €/MWh €/kWh

Geothermal Power Plants 10%-23% (Depending on Plant Type and Geothermal Field)

3,500-4,500 15-26 ~0.052

5.4.2. GEOTHERMAL HEAT PUMP (GHP)

Geothermal heat pumps are very similar to ordinary heat pumps, but instead of using heat found in the outside air, they rely on the stable heat of the ground to provide heating, air conditioning and, in most cases, hot water.

Designing geothermal heat pump systems requires professional expertise: the length of the loop will depend on a number of factors including the type of loop configuration used, the heating and air conditioning load, local soil conditions and landscaping, and the severity of the climate. Typical loop configurations are:

Open loop systems

Closed loop systems (Horizontal type and Vertical type)


249

OPEN LOOP SYSTEMSOpen loop systems use water directly from underground reservoirs as the source of energy, especially when the water is of good quality, is available in sufficient quantities and is at a convenient depth for pumping. Ditches, ponds or streams, and the underground source reservoirs, are used for rejected water.

Water table

Pump

Prod

uctio

n w

ell

Inje

ctio

n w

ell

Figure 115. GSHP Open Loop Systems (Source EGEC)

HORIZONTAL GROUND CLOSED LOOPSHorizontal systems use geothermal heat exchangers, positioned parallel to the surface at a depth of between 1.2 metres and 1.8 metres. They usually contain one or more layers of tubes.

Connection in series

Connection in parallel

Manifold inside orat the building

Figure 116. GSHP Horizontal and Vertical Ground Closed Loop Systems (Source EGEC)

250


VERTICAL GROUND CLOSED LOOPSIn vertical ground closed loop systems, the geothermal heat exchanger is set vertically into the ground, in holes pierced by a drill and at depths ranging from 50 metres to 150 metres.

BENEFITS OF GHPSEnergy Savings: GSHPs use 25%–50% less electricity than conventional heating or cooling systems. According to the United States EPA, they can reduce energy consumption and corresponding emissions by up to 44% compared to air-source heat pumps and by up to 72% compared to electric resistance heating with standard air-conditioning equipment. GSHPs also improve humidity control by maintaining about 50% relative indoor humidity, making them very effective in humid areas.

GSHP systems are very flexible and can be installed in both new and retrofit situations. Because the hardware requires less space than that needed by conventional HVAC systems, the equipment rooms can be scaled down in size, freeing space for more productive use.

GSHP systems have relatively few moving parts and, because those parts are sheltered inside a building, they are durable and highly reliable.

Because GSHP systems have no external condensing units (like air conditioners), external noise is not an issue.

Table 36. Typical Capital and Operating Costs for Ground source Heat pumps (source: Carrier,(93), (94))

Plant Efficiency Installed Costs O&M (Incl. Electricity Cost) LCOE

COP €/kW €/kW/year €/kWh

Ground Source Heat Pump System

4.0 (Closed Loop) - 5.5 (Open Loop)

~1,300 (Horizontal)

~1, 500 (Vertical)~150-180 ~0.03

5.4.3. GEOTHERMAL ENERGY POTENTIAL IN GEORGIA

The total theoretical thermal capacity of all geothermal sources in Georgia was estimated at 300 MW of thermal capacity. Total achievable potential is estimated at 30%, or 100 MW, of thermal capacity. The temperatures of Georgia’s geothermal deposits are not particularly high and are mostly suitable for heating and hot water supply. At present, there are approximately 206 wells and four geothermal water springs with temperatures of between 30°C and 110°C found in 44 locations in Georgia. About 80% of this geothermal potential is located in West Georgia.


251

ACKNOWLEDGEMENTS

The production of this Guide would have not been possible without the valuable contribution of the following consultants:

IPA ENERGY + WATER ECONOMICSHelene Ryding

Simon Monk

Sylvia Beamish

David James

LDK CONSULTANTSSavvas Louizidis

Kyriakos Argyroudis

ENERGOCREDIT TEAM, GEORGIAGeorge Zurashvili

Murad Kharaishvili

Ana Mindorashvili

George Shikhashvili

George Khmaladze

Many thanks should be also extended to the designer of this book, translator and editor:

Zakaria Zalikashvili, Stromboli, Georgia

Giorgi Samadashvili

Michael Abramishvili

252


This Guide was produced by a consortium of the British firm IPA Energy + Water Economics and LDK Consultants of Greece.

IPA ENERGY + WATER ECONOMICSwww.ipaeconomics.com

Established in 1989, IPA Energy + Water Economics is recognised as a leading specialist practice for infrastructure economics, working across the Electricity, Gas, Renewables, Carbon and Water sectors. With experience in over 80 countries, IPA Energy + Water Economics’ principal services incorporate pricing and markets, trading and risk, regulation, project economics, financing and PSP. Energy efficiency is one of our core specialist areas. We advise Governments on the development of policy and targets for energy efficiency and the most appropriate mechanisms for disbursing support, and companies on the most effective means of reducing their carbon footprint and energy costs. IPA Energy + Water Economics is a member of the DAR Group (www.dargroup.com), one of the world’s top 15 international groups of professional service companies.

LDK CONSULTANTSwww.ldk.gr

LDK Consultants is one of the leading consulting firms in Greece, with over 30 years’ international experience in the areas of energy, environment, SMEs, planning, project management and communication/information dissemination. LDK offers consultancy and engineering services to both private and public sector clients in the fields of Energy and Environmental Consulting. LDK’s areas of specialisation in the energy sector include the development of energy efficiency and renewable energy projects; energy audits; energy management and conservation; power generation, transmission and distribution; energy policy advice, market liberalisation, restructuring and regulation; the reorganisation of electricity and natural gas utilities; feasibility studies, financial and socio-economic analyses, tariffs and training on planning and investment evaluation.


253

TECHNICAL GLOSSARY

Air Economizer – A ducting arrangement and automatic control system incorporating recovery of exhaust heat within a heating, ventilation and air conditioning (HVAC) system and allowing to preheat or pre-cool incoming air to the building1

Air Handling Unit – A device that includes a fan or blower which is used to condition and circulate air throughout a building as part of a heating, ventilation and air conditioning (HVAC) system. Efficiency can be improved through heat recovery and/or installing control systems.

Ballast - A device that provides starting voltage and limits the current during normal operation in electrical discharge lamps (such as fluorescent lamps).

Biomass - Energy resources derived from organic matter. These include wood, agricultural waste and other living-cell material that can be burned to produce heat energy. They also include algae, sewage and other organic substances that may be used to produce biogas through chemical processes.

Boiler - A vessel or tank where heat produced from the combustion of fuels (such as natural gas, fuel oil or coal) is used to generate hot water or steam for applications ranging from building space heating to electric power production or industrial process heat.

Boiler Rating - The heating capacity of a steam boiler; expressed in kcal/h or kW, or pounds of steam per hour.

Building Envelope – The physical separator between the interior and the exterior environments of a building.

Coefficient of Heat Transfer, or U-value - A value that describes the ability of a material to conduct heat – it measures the rate at which heat is transferred through a material of a given area under standardized conditions and is measured in W/(m2 K). The lower the U-value, the better a material is at keeping heat inside a building.

Coefficient of Performance (COP) - A ratio of the work or useful energy produced by a system compared with the amount of work or energy put in to the system, determined by using the same energy equivalents to measure energy in and energy out. COP is used as a measure of the steady state performance or energy efficiency of heating, cooling and refrigeration appliances – it is equivalent to the Energy Efficiency Ratio (EER) divided by 3.412. The higher the COP, the more efficient the device.

Cogeneration – The simultaneous generation of thermal energy (heat) and electrical and/or mechanical energy.

Condenser – a device or unit used to condense vapour into liquid.

254


Energy Efficiency – a ratio between the useful output of a machine (which may be electric power, mechanical work or heat) and the input (measured in energy terms).

Energy Efficiency Improvements – a reduction in the energy used to provide or produce a given service (for example heating or lighting) or level of activity. It is usually the result of technological, behavioural and/or economic changes.

Energy Savings – the amount of energy saved following the implementation of one or more energy efficiency measure.

Fan Coil - A heat exchanger coil in which a fluid such as water is circulated and a fan blows air over the coil to distribute hot or cool air to the room(s) supplied by the Fan Coil Unit.

Flue Gas - is the gas exiting to the atmosphere via a flue, which is a pipe or channel for conveying exhaust gases from a fireplace, oven, furnace, boiler or steam generator.

Fluorescent Lamp – A type of electric discharge lamp consisting of a glass tube filled with a mixture of argon and mercury vapour. A current of electricity causes the vapour to produce ultraviolet radiation which, in turn, excites a phosphor coating on the inside of the tube, causing it to fluoresce or reradiate the energy as visible light.

Geothermal Energy – Energy produced by the internal heat of the earth. Geothermal energy can be used directly for heating (for example in district heating systems, greenhouses or industrial process heating) or to produce electric power.

Ground Source Heat Pump (GSHP) - A type of heat pump that relies on the fact that the Earth (beneath its surface) remains at a relatively constant temperature throughout the year – warmer than the air above it during the winter and cooler in the summer. A Ground Source Heat Pump takes advantage of this by transferring heat stored in the Earth or in ground water into a building during the winter, and transferring heat out of a building and back into the Earth or ground water during the summer.

Heat Exchanger - A device used to transfer heat from one fluid (liquid or gas) to another fluid, where the two fluids are physically separated.

Heat Pump – An apparatus used for heating or cooling (for example a building) by transferring heat by mechanical means from or to an external reservoir (such as the ground or outside air).

Heating Load - The rate at which heat must be added to a space in order to maintain the desired temperature within the space, usually measured in Btu per hour.

Incandescent Lamp - An electric lamp in which a filament is heated by an electric current until it emits visible light.


255

Load Factor – The ratio of average energy demand (load) to the maximum demand (peak load) during a period.

Lumen - A measure of the amount of light emitted from a light source, equivalent to the light emitted by one candle.

Luminaire - A complete lighting unit – consisting of a lamp or lamps, the socket(s) and other parts that hold the lamp(s) in place and protect it/them, the wiring that connects the lamp to a power source and the parts which distribute or help direct the light.

Luminous Efficacy – the ratio of visible light produced by a lamp to the electrical power consumed, including ballast losses, measured in lumens per watt.

Lux – A unit of measurement of the intensity of light, equal to the illumination on a surface one square meter in area on which there is a luminous flux of one lumen uniformly distributed, or the illumination on a surface all points of which are at a distance of one meter from a uniform point source of one candela.

Passive Solar Energy – A term used to categorise techniques for harnessing the sun’s energy. Passive solar techniques include orienting a building to the Sun, selecting materials with favourable thermal mass or light dispersing properties, and designing spaces that naturally circulate air.

Photovoltaic Device - A solid-state electrical device that converts light directly into direct current electricity. The characteristics of the device’s output are a function of the light source, the materials used in the device and the design of the device. Solar photovoltaic devices are made of various semi-conductor materials including silicon, cadmium sulphide, cadmium telluride and gallium arsenide.

Renewable Energy – Energy which comes from natural resources which are naturally replenished. These include sunlight, wind, rain, tides, water flows and geothermal heat.

Reactive Power (KVAR) - This is the difference between the electricity supplied and the electricity converted into useful power. If the difference is large (i.e. there is a large amount of power being wasted), its puts an additional strain on the distribution network. The loss of power can be caused by kinetic energy (heat) or through defective machinery.

256


BIBLIOGRAPHY

1. Carbon Trust. Steam and high temperature hot water boilers - Introducing energy saving op-portunities for business CTV018. 2007.

2. —. How to implement condensing boilers - CTV021.

3. Sustainability Victoria. Energy Efficiency Best Practice Guide – Steam Systems, Hot Water Systems and Process Heating Systems. 2009.

4. Best Practice Programme. A manager’s guide to optimizing furnace performance GPG 253. 2001.

5. US DoE. Office of Industrial Technologies, Roadmap for Process Heating Technology. 2001.

6. —. Waste Heat Reduction and Recovery for Improving Furnace Efficiency, Productivity and Emissions Performance. 2004.

7. Best Practice Programme. Burners and their Control, GPG 252. 1998.

8. Bureau of Energy Efficiency Australia. Waste Heat Recovery.

9. Rodriquez, et.al. “Improve Efficiency of Furnaces and Boilers”.

10. UNEP. Energy Efficiency Guide for Industry in Asia . 2006.

11. Carbon Trust. Introducing Combined Heat and Power Technology Overview, CTV044. 2010.

12. EC, SAVE Programme. Promotion of tri-generation technologies in the tertiary sector in Mediterranean countries, Publication. 2003.

13. I., Fleming. Spirax Sarco Optimising steam systems Part I,.

14. Spirax Sarco. http://www.spiraxsarco.com/resources/steam-engineering-tutorials/condensate-recovery/introduction-to-condensate-recovery.asp.

15. Best Practice Manual. Fluid piping systems and insulation.

16. Fuhr P., US DoE. Easy Ways to Save Energy Now -Take Care of those Steam Traps.

17. Carbon Trust. Refrigeration systems, Guide to energy saving opportunities, CTG046. 2008.

18. Hafner Muschler. http://www.xn--industrieklteanlagen-kzb.com/en/ice-banks.html.

19. Carbon Trust. Heat recovery- A guide to key systems and applications-CTG057. 2011.

20. Carbon Trust . How to implement heat recovery in refrigeration-CTL056.

21. Carbon Trust. How to implement heat recovery in refrigeration-CTL056.

22. Roxburgh, Mark. Mercury Technologies Ltd, Industrial refrigeration – energy saving opportunities.

23. Carbon Trust. Refrigeration systems, Best Practice Northern Ireland - CTG024.

24. IPPC. Reference Document on Best Available Techniques for Energy Efficiency. June 2008.

25. Atlas Copco. Compressed Air Best Practices.

26. Carbon Trust. Heat recovery from air compressors, GPG230.

27. —. Variable speed drive on a boiler fan-GPCS452. 2005.

28. Rooks, J. Energy Efficiency of Variable Speed Drive Systems.

29. Carbon Trust. How to implement High Efficiency Motors.


257

30. Carbon Trust . Motors and drives introducing energy saving opportunities for business, CTV016. 2007.

31. Carbon Trust. Industrial process control Introducing energy saving opportunities for business, CTV030. 2007.

32. Best Practice Programme. Process Integration, GPG242. 1998.

33. IEE. THE EUROPEAN GREEN BUILDING PROGRAMME Air-Conditioning Technical Module. 2006.

34. Dubois, Marie-Claude. Solar Shading and Building Energy Use A Literature Review Part 1 .

35. Carbon Trust . Building fabric Energy saving techniques to improve the efficiency of building structures, CTV014.

36. IEE. THE EUROPEAN GREEN BUILDING PORGRAMME, Building Envelope Module. 2006.

37. Carbon Trust . Low temperature hot water boilers - Introducing energy saving opportunities for business-CTV-008. 2006.

38. Carbon Trust. HVAC - Best Practice Northern Ireland-CTG028. 2010.

39. —. Air Conditioning, CTG005. 2010.

40. US DoE. Guide to Geothermal Heat Pumps.

41. Action Energy . Energy savings in fans and fan systems-GPG383. 2004.

42. Liescheidt, Steven. Economizers in Air Handling Systems, CED Engineering.

43. Carbon Trust . Installers’ Guide to the Assessment of Energy Efficient Lighting Installations – CTV007.

44. Sustainability Victoria. Energy Efficiency Best Practice Guide Lighting. 2006.

45. Carbon Trust. Lighting - Bright ideas for more efficient illumination-CTV021. 2010.

46. Carbon Trust . Lighting - A guide to equipment eligible for Enhanced Capital Allowances, ECA763. 2009.

47. —. Building Controls, CTV032. 2007.

48. IEA. Tracking Industrial Energy Efficiency and CO2 Emissions. 2007.

49. Lawrence Berkeley National Laboratory. World Best Practice Energy Intensity Values for Selected Industrial Sectors. 2007.

50. TMEiC. Drive solutions for the Global Mining Industry.

51. IPPC. Reference document on BATs in the Ferrous Metals Processing Industry. 2001.

52. Lawrence Berkeley National Laboratory, Ernst Worrell, Paul Blinde, Maarten Neelis. , Eliane Blomen, and Eric MasanetEnergy Efficiency Improvement and Cost Saving Opportunities for the U.S. Iron and Steel Industry.

53. Efficiency Vermont. Reduce Energy Use at Lumber and Wood Processing Facilities. 2010.

54. IPPC. Draft Reference Document on Best Available Techniques in the Pulp and Paper Industry. 2010.

55. EPA,. Available and emerging technologies for reducing GHG emission from the pulp and paper manufacturing industry. 2010.

56. IPPC. Reference document on BATs in Pulp and Paper industry. 2001.

57. Carbon Trust . Energy Efficient Paper Drying, GPG353. 2004.

258


58. Austin et. Al. “Improved Energy Efficiency in Paper making through reducing dryer steam con-sumption using advanced process control”.

59. Carbon Trus. Industrial Energy Efficiency Accelerator - Guide to the paper sector, CTG059.

60. UNIDO. UNIDO, Global Industrial Energy Efficiency Benchmarking. 2010.

61. IEE CERAMIN Project . Energy saving concepts for the European ceramic industry CERAMIN – Public Final Report. 2009.

62. IPPC. Reference Document on BATs in the Ceramic Manufacturing Industry. 2007.

63. IEE. Energy saving concepts for the European ceramic industry CERAMIN- Tutorial about En-ergy saving, D&-Tutorial, 2009. . 2009.

64. EC DGXVII. Energy saving in the brick and tile industry, ICIE, OPET Network .

65. Tangram Technology. Energy efficiency in ceramics processing Practical worksheets for industry, .

66. European Commission . Best Available Techniques Reference Document for the production of Cement, Lime and Magnesium Oxide, Draft CLM BREF. June 2012.

67. Industrial Efficiency Technology Database. High-Efficiency Roller Mills, http://ietd.iipnetwork.org/content/high-efficiency-roller-mills.

68. —. Improved Grinding Media for Ball Mills, http://ietd.iipnetwork.org/content/improved-grinding-media-ball-mills.

69. Lawrence Berkeley National Laboratory, Ernst Worrell, Christina Galitsky and Lynn Price. Energy Ef-ficiency Improvement Opportunities for the Cement Industry. 2008.

70. Lawrence Berkeley National Laboratory, Ernst Worrell, Christina Galitsky, Eric Masanet, and Wina Graus. Energy Efficiency Improvement and Cost Saving Opportunities for the Glass Industry – An EN-ERGY STAR Guide for Energy and Plant Managers. 2008.

71. Canadian Industry Program for Energy Conservation c/o Natural Resources Canada. Guide to energy efficiency opportunities in the Canadian plastics processing industry. 2007.

72. IEE Programme. Low Energy Plastics Processing- European Best Practice Guide. 2006.

73. LAWRENCE BERKELEY NATIONAL LABORATORY . Energy Efficiency Improvement and Cost Saving Opportunities for the Pharmaceutical Industry. 2005.

74. ClimatetechWiki. http://climatetechwiki.org/technology/energy-saving-agri-food-industry.

75. Dairy Consultant. Milk Pasteurization, http://www.dairyconsultant.co.uk/si-milkpasteurisation.php.

76. US Department of Energy . Energy efficiency and Renewable Energy - Improving Process Heating System Performance – A Sourcebook for Industry.

77. Lawrence Berkeley National Laboratory, Eric Masanet, Ernst Worrell, Wina Graus, and Christina Galitsky. Energy Efficiency Improvement and Cost Saving Opportunities for the Fruit and Vegetable Pro-cessing Industry. 2008.

78. Best Practice Programme. Reducing Energy Costs in Industrial Bakeries-GPG309. 2002.

79. Erik Runkle, A. J. Both. Greenhouse energy conservation strategies. Nov. 2011.

80. AEA. Reduction and Testing of Greenhouse Gas (GHG) Emissions from Heavy Duty Vehicles – Lot 1: Strategy, 2011. 2011.

81. IRENA. Renewable Energy Technologies: Cost analysis Series, Volume I: Power Sector, Issue 3/5, Hydropower. 2012.


259

82. EC. Second Strategic Energy Review AN EU ENERGY SECURITY AND SOLIDARITY ACTION PLAN Energy Sources, Production Costs and Performance of Technologies for Power Generation, Heat-ing and Transport. 2008.

83. USAID. USAID, Georgia, Rural Energy Programme, Renewable Energy Potential in Georgia and the Policy Options for its utilisation. 2008.

84. IRENA. Renewable Energy Technologies : Cost analysis Series, Volume I: Power Sector, Issue 4/5, Solar Photovoltaics. 2012.

85. GTM Research. Roadmap for CPV Technology. 2011.

86. IRENA. Renewable Energy Technologies : Cost analysis Series, Volume I: Power Sector, Issue 2/5, Concentrating Solar Power. 2012.

87. IEE. SOLCO Project, SOLCO-Layout of solar cooling installations. .

88. USAID. Georgia, Rural Energy Programme, Renewable Energy Potential in Georgia and the Policy Options for its utilisation. 2008.

89. IRENA. Renewable Energy Technologies: Cost analysis Series, Volume I: Power Sector, Issue 1/5, Biomass for Power Generation. 2012.

90. AEBIOM. Pellets for small scale domestic heating systems. 2007.

91. IEE. Biogas Handbook, Big<East project. 2008.

92. US Department of Energy, NREL,. Renewable Energy Finance Tracking Initiative (REFTI): Snapshot of Recent Geothermal Financing Terms Fourth Quarter 2009 – Second Half 2011”. 2012.

93. All., Subir K. Sanyal et. Cost of electricity from enhanced geothermal systems. PROCEEDINGS, Thirty-Second Workshop on Geothermal Reservoir Engineering Stanford University. 2007.

94. University of Southampton, School of Civil Engineering & Environment, Prof A.S. Bahaj and Dr P.A.B. James. FUTURE ENERGY SOLUTIONS. 2009.

95. US Department of Energy, NREL. Ground Source Heat Pump Subprogramm Overview, Geother-mal Technologies Programm Peer Review. 2010.

96. ClimatetechWiki. http://climatetechwiki.org/technology/energy-saving-cement.

97. University of Southampton, School of Civil Engineering & Environment, Prof A.S. Bahaj and Dr P.A.B. James . FUTURE ENERGY SOLUTIONS. 2009.

260


Documents

BEST PRACTICE GUIDE FOR BUSINESSES IN GEORGIA