6. How much energy is
out there?
432,039 metric tons of rice consumed / year
x 0.6 milling rate
x 12 GJ / metric ton
/ 1.3 MJ to cook a meal
2 billion meals / year
Saturday, January 29, 2011
7. Properties of Rice Husk
• Energy Content
• Chemical Composition
• Angle of Repose
• Thermal Conductivity
• Air Flow Resistance
Saturday, January 29, 2011
8. Properties of Rice Husk
or Understanding a Really Strange Fuel
• Energy Content Low
• Chemical Composition High in Silicates
• Angle of Repose Causes Bridging
• Thermal Conductivity Can Put Out Fires
• Air Flow Resistance Darn High
Saturday, January 29, 2011
9. Energy Content
Hull 3000 kcal / kg
Char
Ash
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13. Thermal Conductivity
Test Results from ASTM testing by
R&D Services of Cookville,
Tennessee (Courtesy Dr. Paul
Olivier)
Saturday, January 29, 2011
14. Dr. Paul Olivier http://www.esrla.com/
Saturday, January 29, 2011
15. Resistance to Air Flow
• Pressure drop higher
than that generated by
stack effect in a natural
draft cook stove
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16. Summary, courtesy of
Eldon Beagle
“The high percentage of silica in rice hulls and the
peculiar silica-cellulose structure impede uniform
and thorough burning of the hulls in a combustion
process.”
“Eldon Beagle set a pile of rice hulls 300’x500’x50’ on fire
and they burned for six months.”
“However, husk cannot be burnt easily or cleanly with
excess air, and energy recovery is very low as the heat
produced cannot be utilized in a beneficial manner.”
Beagle (1978), p. 8. ,Velupillai (1996), p. 18., Ibid., p. 24. , Ibid., p. 25.
Saturday, January 29, 2011
18. Gasification
• Two-stage
• Cleaner burn
• More fuels
• Air-controlled
Saturday, January 29, 2011
19. Power Generation
$34 / kW
30-300 kW
• Fluidised bed
• Projects around the
world
Dr. Alexis Belonio
Saturday, January 29, 2011
20. Forced Air Batch Gasification
$113
0.8 kW
• Requires a fan and
electricity
• Blue flame
• Easy to control
Dr. Alexis Belonio
• Batch operation
Saturday, January 29, 2011
28. Future?
• TEG (or thermopile) to power fan
• More autonomous continuous stove
• Blue flame on natural draft stove
• More options for cooking surface
construction
Saturday, January 29, 2011
30. Sources
• IRRI World Rice Statistics http://beta.irri.org/solutions/index.php?
option=com_content&task=view&id=250
• Chemical Analysis of Rice Husk Ash: http://www.scribd.com/doc/3085035/Chemical-Analysis-of-
Rice-Husk-Ash
• Rice and Straw Properties (Rice Knowledge Bank) http://www.knowledgebank.irri.org/rkb/
index.php/rice-milling/contributions-and-references-milling/further-information-byproducts/
husk-and-straw-properties
• “No other plant offal even approaches the amount of silica found in rice husks.” Beagle, E.C.
1978. FOA Agricultural Services Bulletin 31, p. 8.
• Kaupp, A. (1984). Gasification of Rice Hull: Theory and Praxix.
Federal Republic of Germany:
GATE/GTZ. 303pp.
• http://gasifiers.bioenergylists.org/content/continuous-flow-rice-husk-gasifier-thermal-application
• Sawdust stove image: http://www.motherearthnews.com/Do-It-Yourself/1974-11-01/How-To-
Sawdust-Stove.aspx
•
Saturday, January 29, 2011
