by

Alexis T. Belonio, MS, PAE, ASEAN Engineer

Affi l iate Professor

College of Engineering

Central Luzon State University

Science City of Munoz, Nueva Eci ja

UTILIZATION OF RICE HUSKS

IN THE PRODUCTION OF

RENEWABLE ENERGY

Lecture material during the Machinery Enterprise Training – Part 1:

PHILSCAT Rice Production and Postharvest Technologies for the Integrated

Rice Production and Processing Center (IRPPC) held at PHILSCAT Training

Room on December 3, 2014.

To acquire knowledge on the properties of rice husks and its

importance as an energy source;

To familiarize with the dif ferent methods of converting rice

husks into source of energy and power;

To acquire an in-depth knowledge on the present technologies

available in converting rice husks into heat and power,

especially for agriculture and rural applications; and

To be aware of the benefits of rice husk when used as source

of energy and power;

OBJECTIVES OF THE PRESENTATION

Introduction

What is Rice Husk?

Properties of Rice Husk

Energy Conversion Methods

Direct Combustion

Gasification

Pyrolysis

Rice Husk Energy Conversion Technologies

Rice husk stove and furnaces

Rice husk gasifier for heat and power

Carbonizers for char production

Social, Economic and Environmental Benefits

Concluding Remarks

References

TOPICAL OUTLINE

Renewable energy is becoming popular as an alternative source of energy worldwide as a result of increasing prices of crude oil coupled with the need for clean environment.

Biomass is one of the renewable energy sources that can have significant impact especially in agriculture and in rural sectors.

Among the different biomass which are readily available in the rural and farming areas is rice husks, which constitute a large parcel in rice producing regions.

Annually, there are around 115 mill ion metric tons of rice husk available worldwide.

In the Philippines, about 2 mill ion metric tons are available per year and is increasing with the introduction of high -yielding varieties and of rice mechanization.

With this scenario, harnessing biomass energy from rice residues can be an alternative to produce cheaper supply of fuel for heat and power especially in rice farming.

INTRODUCTION

35.5

24.6 9.7

7.8

6.3

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2.5

2.2 2.1

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1.2 1.1 1 0.8

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China India Indonesia Bangladesh Vietnam

Thailand Mayanmar Philippines Japan Brazil

USA Korea Pakistan Egypt Nepal

Cambodia Nigeria Sri Lanka Colombia Laos

Rest of the World

Average Annual Rice Husk Production of the World

Metric Tons

Philippines 1,932,846

CAR 39,064

Ilocos 168,125

Cagayan Valley 203,793

Central Luzon 341,191

Southern Tagalog 203,504

Bicol 149,098

Western Visayas 255,000

Central Visayas 38,004

Eastern Visayas 85,225

Western Mindanao 74,812

Northern Mindanao 78,019

Southern Mindanao 133,328

Central Mindanao 163,683

Annual Rice Husk Production of the Philippines (by Region)

Rice husk is a by -product from mill ing r ice.

I t constitutes around 20% of paddy.

At an average harvest of 4.5 tons per hectare of paddy, 900 ki los of r ice husk is made available.

At 6 tons per hectare, 1 .2 tons of r ice husk can be derived with the potential to provide enough heat and power not only for domestic rural application but also for propell ing r ice machines.

Studies have shown that 1 to 2 tons of r ice husks is enough to provide the energy requirement for cooking by a household for the whole year.

Also, r ice husk when used for heat and power for agriculture can provide the energy needed for water pumping, drying, and rice mill ing. Estimated rice husk consumption in per forming these operations is 800 kg per hectare.

RICE HUSK

Rice Husk Disposal Practices (Philippines)

There are 100 kg of rice husks per 1 cubic meter of space.

Good rice husk contains 9 to 14% moisture.

One kilo of rice husk can provide an energy of 3000 kcal.

Molecular hydrogen/carbon ratio is around 1.2 and 0.25 when gasified.

Proper combustion of rice husk requires 4.7 kilos of air per kilo.

Gas can be generated when burning rice husk at a rate of 1 .2 kg of air per kg of fuel.

When gasified, rice husk produces around 30 to 35% char. When subjected to pyrolysis, it provides 40 to 45% char.

Rice husk char can hold water 5 times its weight.

Ash content is around 20% containing high amount of sil ica, which is a good ingredient for the production of cement -fiber board, refractory cement, and geo polymer blocks.

PROPERTIES OF RICE HUSK

ρ = 100 kg/m3

MC = 9 to 14%

HVF = 3000 kcal/kg

Mol H/C = 1.2

Mol H/C = 0.25

Stoich Air = 4.7 kg

air/ kg of fuel

30 to 45 %

of RH

20% of RH WHC = 5Wrh

CHAR ASH

RICE HUSK

Direct Combustion – Burning rice husks with excess air to

produce heat and water. The product of combustion is CO 2.

Gasification – Partial burning of rice husks with 30 to 40% air

to produce combustible gases rich in CO, H 2 and CH4.

Pyrolysis – Burning of rice husks in an oxygen-starved

environment (10 to 30%) to produce primarily carbon and bio -

oil.

Carbonization – when carbon is primarily produced.

Bio-oil – when oil is primarily produced.

Torrefaction – is the process of upgrading the fuel quality of

rice husk by removing moisture and portion of the volatile

matter.

ENERGY CONVERSION METHODS

Rice Husk

Direct Combustion

Gasification

Pyrolysis

Bio-Oil

Carbonization

Torrefaction

Heat

Power

Power

Stove

Furnace

Gasifier

Gasifier

Heat

Stove

Furnace

Heat

Energy Conversion Methods of Rice Husk into Heat and Power

Power

Direct

Combustion

Gasification

Pyrolysis

Burning of rice husks

at an air-fuel ratio of

> 30 to 40

Burning of rice

husks at an air-fuel

ratio of > 0 to 30

Burning of rice husks

at an air-fuel ratio of

> 40 to 100

Stoves for Domestic

Cooking

Multiple-Burner Stove for

Cottage and Institutional

Applications

Gasifiers and Furnaces

for Drying, Oven, etc.

Gasifiers for Water

Pumping

Gasifiers for Electricity

Generation

RICE HUSK ENERGY CONVERSION

TECHNOLOGIES

Conical-Grate Rice Husk Stove with Steam Injection

Rice Husk Furnaces for Paddy Drying

Rice Husk Gas Stove for Domestic Cooking

Multiple-Burner Rice Husk Gasifier Stove for Food Processing

Rice Husk Gasifier for Paddy Drying

Rice Husk Gasifier for Paddy Drying

Rice Husk Gasifier for Twin-Bed Paddy Drying

Rice Husk Gasifier for Flash Drying of Paddy

Rice Husk Gasifier for Water Pumping

Rice Husk Gasifier for Water Pumping

Rice Husk Gasifier for Electricity Generation

Rice Husk Gasifier for Electricity Generation

Pyrolyzer for Production of Carbonized Rice Husk

SOCIAL, ECONOMIC, AND

ENVIRONMENTAL BENEFITS

Cheaper source of fuel – cost of rice husks is very minimal

compares with crude oil and electricity.

Utilization can be either for heat, mechanical power, and/or

electricity generation.

Cleaner source of fuel for power farming.

Added income to farmers.

Creation of employment in the manufacture and distribution

of rice husk energy -generating devices in the locality.

Additional revenue to the local government units in terms of

taxes.

By-product can be used for:

Carbon capture and storage activity which can be traded off

internationally.

Soil restoration.

Rice Husk Char for Carbon Sequestration and Soil Restoration

Rice husk is good source of alternative energy for rural and

agricultural applications, especially in rice farming areas

where it is accessible.

Rice husk can provide a low cost source of fuel for heat

application and, when gasified, can provide energy to provide

power to propel stationary agricultural machines and

generator to produce electricity.

When converted via pyrolysis, rice husk can be a good source

of quality carbon and of bio -oil.

Aside from supply of alternative energy, rice husk is also a

material for carbon sequestration and soil restoration. Its ash

can also be used for the production of local construction

materials such as cement-fiber board, geopolymer, etc.

CONCLUDING REMARKS

Belonio , A .T. , Ramos, J .A . Regalado, M.J .C. , and V.B. Ocon. An Overview of the Downdraf t Rice Husks Gasi f ier for Thermal and Power Appl ications. Journal of Technology Innovat ions in Renewable Energy. 2013, Volume 2, p246 -258.

Belonio, A.T. , Orge, R.F. , Tado, J .C.M. Regalado, M.J.C., Taylan, V.T., Paras, F. O. , Amongo, R.M.C., and Tadeo , B.D. Renewable Energy Technologies for Rice Mechanizat ion. Paper presented at the ARF Annual Rice Forum 2013: Mechanizat ion in Rice Farming : Status, Chal lenges and Opportuni t ies held at BSWM Audi tor ium, SRDC Bldg. , Visayas Ave. corner El l ip t ica l Rd. Di l iman, Quezon Ci ty on November 22, 2013.

Belonio, A.T. Rice Husk Gasi f ier : Theory and Appl icat ions. Paper presented at the 25th Nat ional Rice R&D Conference held at the Phi l ippine Rice Research Inst i tute, Science Ci ty of Munoz, Nueva Eci ja , Phi l ipp ines on September 4 -6, 2012. .

Belonio, A.T. Rice Husk Gasi f ier : A Renewable Energy Technology for Poverty Al leviat ion. Paper resented at the Fi rs t (1 st ) Professional Summit held at the Mani la Hote l , Mani la on October 18 -19, 2012.

Orge, R.F. and J .E .O. Abon. Design Improvement of the Phi lRice Cont inuous-Type Rice Hul l Carbonizer for Biochar Product ion Toward Sustainable Agricul ture. OIDA Internat ional Journal of Sustainable Development 05:08 (2012). pp. 83 -96. (Ontar io Internat ional Development Agency. ISSN:1923 -6654. http://www.ssrn.com/link/OIDA -Int l - Journal -sustainable -Dev. html . )

REFERENCES

THANK YOU VERY MUCH AND

GOD BLESS!!!

Recipient, Betterment for Mankind Award 2011, Pauchon Research Foundation (Morgan Hill, California, USA)

Laureate, Economic Business Development, The Tech Awards 2010 (San Jose, California, USA)

Associate Laureate, Rolex Awards for Enterprise 2008 (Geneva, Switzerland)

Awardee, Seven Inspiring Young Filipino Heroes 2011 (Yahoo Southeast Asia)

Awardee, The Outstanding Young Filipino 1997 in Agricultural Engineering (TOYM and Roxas Foundation)

Awardee, Outstanding Professional in Agricultural Engineering 1993 (Professional Regulation Commission)