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Comparison Between Landfill Gas and Waste Incineration for Power Generation in Accra, Ghana

Serwaa ANAGLATE

Syawalianto RAHMAPUTRO

Carlos RUIZ

Prof. Luis Rojas

PM3E

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Outline

Accra

Objective & Scope

RETScreen

Waste Characterization

Landfill Gas

Waste Incineration

Results

Social Impact

Conclusions

Outlook

3

Source: http://raklak.wordpress.com

Source: World Bank, 2010

Accra, Ghana

Source: World Bank, 2010

1,800 Daily Tons of Waste

Open Dump Sites

Insufficient Waste Collection

Insufficient Power Capacity Source: www.atokd.com

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Objective & Scope

Objective

Assess and compare landfill gas and waste incineration

Technical

Environmental

Economic

Social Impact

Scope

Total Electricity Exported

GHG Emissions Reduction

Approximate Costs

Financial Summary

Pre-feasibility Level

5

RETScreen®

Free Software

Clean Energy Project Analysis

Inexpensive Technical and Financial Feasibility Analysis

Energy Model

Cost Analysis

GHG Analysis

Financial Summary

Sensitivity & Risk

Analysis

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Waste Characterization

66%

17%

6%3% 3% 3%

2%

Organic Inert Paper Plastic Glass Metal Textile & Leather

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Landfill Gas

Source: Affiliated Engineers, 2010

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Landfill Gas Simulation

Assumptions: Constant Biodegradable Fraction in

Waste

50% of CH4 by Volume

75% Collection Efficiency

Climatic Conditions

Waste Composition

Amount of Waste

𝑄𝐶𝐻4=𝑘∗𝐿𝑜∗𝑚𝑖∗𝑒−𝑘𝑡

Input Parameter Value

Waste Disposal Rate (mi) 270,000 t/yr

Landfill Opening Year 2014

Landfill Closing Year 2044

Generation Constant (k) 0.06 yr-1

Generation Potential (Lo) 170 m3/t

6MW

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Waste IncinerationElectricityGeneration

Waste Incinerator

Flue GasTreatment

Receiving Area

Receiving Pit

Grate Furnace

Boiler

Source: www.valorena.fr

Pretreatment - Drying in the receiving pit.

Furnace - Moving grate furnace is the most robust.

Energy Recovery - Low-pressure steam boiler is convenient when energy recovery is designed for electricity use only (Haukohl, J., Rand, T., & Marxen, R. ,1999)

Energy Production - Rankine cycle with steam turbine, condenser, boiler, and pump for power generation.

Flue Gas Treatment - For 600 ton to 900 ton/day: SNCR, semi-dry scrubber, activated carbon, and a bag house filter are usually used (Kuo, Lin, Chen, Tseng, & Wey, 2011).

Source: www.sick.com

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Waste Incineration Simulation

1

2

3

Power Generatio

n

Fuel Potential

Waste Analysis

WASTE INCINERATION

Waste Feed Rate 270,000 t/yr

Dry Weight of Feed Waste

120,727.12 t/yr

Feeding Rate 13.78 t/hr

Lower Heating Value

15.854 GJ/t

POWER SYSTEM

Availability 8,401 hours

Back Pressure

5.6 kPa

Steam Temp. 380 °C

Return Temp. 90 °C

Steam Flow 68,600 kg/hr

Operating Pressure

80 bar

Turbine Efficiency

75 %

31%

55%

14%

Combustibles Moisture Ash

Combustibles

Moisture

Ash

Proximate Analysis

Ultimate Analysis

Predefined:• Udomsri, Petrov, Martin, & Fransson, 2011• Suggested values from RETScreen

Simulation:Energy Model

Fuel Potential 218.49 Gj/hr

Fuel Required 218 Gj/hr

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Results – Energy and Environment

WI energy output > 8 times that of LFG

GHG reductions are achieved in both technologies

LFG GHG reductions > 6 times that of WI

Technology

Emission Factor (Kg/GJ) Annual GHG Reduction (tCO2)CO2 CH4 N2O

Landfill Gas 0 0.0040 0.00010 273,657

Waste Incineration 29.43 0 0.00315 41,413.4

TechnologyLandfill Gas

Waste Incineration

Engine Power Capacity (kW)

6,000 16,505.24

Electricity Exported (MWh/yr)

48,000 138,658

Energy Mix in Ghana:• Hydro Power 67.6%• Thermal Power 32.4%

Source: www.siemenspowergeneration.com

Source: www.engineeringnews.co.za

Electricity Export Rate - $ 58.7

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Cost Breakdown Landfill Gas WI

Initial Cost

Engineering $ 1,050,000 $ 3,743,026

Power System $ 10,455,025 $ 7,512,749

Balance of System $ 3,630,152 $ 23,679,131

Total Initial Cost $ 15,135,177 $ 34,934,905

Annual Cost and Debt Payment

O&M $ 1,531,000 $ 5,460,225

Debt Payment (10 yr) $ 1,028,193 $ 2,373,267

Total Annual Cost $ 2,559,193 $ 7,833,492

Annual Income $ 2,817,600 $ 8,139,215

Results - Financial

Landfill Gas rendered better profitability

Since Ghana is a developing country, affordability is important

Financial Results

Landfill Gas WI

IRR 8.1% 4.8%

Payback Period 13.2 15.9 years

Annual Income $2,817,600 $8,139,215

Net Present Value (NPV)

$4,612,086 $826,358

Benefit-Cost Ratio 1.61 1.05

-20,000,000

-15,000,000

-10,000,000

-5,000,000

0

5,000,000

10,000,000

15,000,000

20,000,000

25,000,000

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

LFG Waste Incineration

Project Year

Cash

Flo

w (

US

D)

Accumulated Cash Flow

Inflation Rate – 3%

Discount Rate – 4.5%

Debt Interest Rate – 6%

Electricity Export Escalation – 2%

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Social Impact

Job Creation

Improvement of the City’s Image

Improved Sanitation

Productivity Increase

Source: www.rvg-ghana.com

Source: Schah Fekri, 2011

Source: Journalists for Human Rights, 2010

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Conclusion & Outlook

Both technologies are environmentally friendly and economically feasible.

Any solution would represent a great improvement.

LFG is preferred due to its outstanding environmental performance.

WI is more suitable in case of limited space.

Risk and sensitivity analysis are recommended.

Inclusion of carbon credits should be considered.

Further on-site tests should be carried out.

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Thank you.

Pictures in cover page courtesy of:•www.treehugger.com•Graham Turner (http://www.guardian.co.uk)•www.sick.com

Any Questions?