PREFACE (By Paul S. Anderson, to Alexis T. Belonio's "Rice Husk Gas Stove Handbook" 2005)
The importance of this “Handbook” and the work of Engr. Alexis Belonio should not be underestimated. I have been given the honor to write this Preface, and my intent is to illustrate the importance of this work.
The search for technology for clean combustion of low-value dry biomass in small stoves suitable for residential cooking has been ongoing for hundreds, if not thousands, of years. One relatively new technology was identified and initiated in 1985 by Dr. Thomas B. Reed. He originally called it “Inverted DownDraft” (IDD) gasification, but recently we have also called it “Top-Lit UpDraft” (T-LUD) gasification, a name that more clearly denotes what is actually happening in this combustion technology. The terms “gasifier” and “gasification” refer to having any type of combustible gases from dry biomass created distinctly separate from the combustion of those gases, even if the separation is only a few millimeters and/or milliseconds.
Developments and adaptations of Dr. Reed’s IDD or T-LUD technology during the past twenty years have been slow, mainly without commercial products, but discussed and shown occasionally as a combustion curiosity on every inhabited continent. At one conference/workshop in Thailand in 2003, someone from Sri Lanka gave a demonstration seen by Engr. Belonio.
Alexis Belonio is an Agricultural Engineer who specializes in rice husks and had previously made other stoves. For him there was only one question: Could rice husks be meaningfully combusted in one of these small gasifiers? For three years he worked in virtual isolation, but not in secrecy. He simply did not have awareness of what others were doing and writing.
When I first contacted him by e-mail in October 2005, I introduced him to the specialized literature and to the terminology of IDD and T-LUD gasification, which he has readily accepted as applicable to his rice-husk stove.
By not having the prior literature, he was unaware that what he was trying to do had been determined by Dr. Reed, myself and others as not being possible in a viable T-LUD stove. He did not even know that he should have been highly surprised that he has succeeded where others have stopped short of success. Therein reside the three most important aspects of his work!!!!
A. The Belonio Rice Husk Gas Stove is the first (and currently only) TLUD gasifier that can utilize a small-particle fuel. This stove will pass primary air upward through a thirty-five centimeter column of dry rice husks, allowing the pyrolysis and char-gasification processes to consistently descend through the fuel column. This means:
1. the ability to use raw unprocessed abundant rice husks as a fuel for residential cooking, and
2. the positive prospects for accomplishing similar T-LUD gasification for other small-particle fuels such as sawdust, husks from cacao and soybeans, and uniformly coarse (not powdery) by-products from other agricultural and industrial products, perhaps even sugar cane bagasse.
B. The Belonio Rice Husk Gas Stove provides a final flame for cooking that is distinctly more blue (with the higher quality gases of H2, CO, and CH4) than in the other variations of Reed’s IDD technology with mainly yellow flames from burning tars and other long hydrocarbons released in pyrolysis. This means:
1. probably even cleaner combustion than what has been very favorably measured for Reed’s “WoodGas CampStove” and Anderson’s “Juntos B” T-LUD Gasifier, and
2. favorable prospects for replicating that blue-flame combustion in other small gasifiers using other fuels.
C. The Belonio Rice Husk Gas Stove can operate with remote combustion (as opposed to the “close-coupled combustion” used in all other T-LUD gasifier stoves). In other words, the top of the gasifier can be closed and the gases can be piped to remote burners, undergo cooling, and still produce a wonderful clean blue flame in traditional LPG stove burners. This
1. the batch-fed small-scale T-LUD technology has fully entered the world of the larger and standard-setting gasifiers, and
2. the gases could probably be cooled, filtered and stored for use-on-demand, possibly including use in high-value tasks like lighting or fueling internal combustion (IC) engines for mechanical power or electricity generation.
These three results alone are sufficient to mark Engr. Alexis Belonio as easily one of the world’s top-ten developers of stoves using the IDD / TLUD technology. Such stoves form a small “pond” without many “fish,” but he is already a big fish in that small pond which could someday become a lake or even an ocean for improved cookstoves.
Not everything is perfect. Much work still needs to be done. Already Dr. Reed, Engr. Belonio, and myself have agreed to close collaboration for further advances, and all others who are interested are invited to join with us.
The tasks include:
Fuels: greater varieties of fuels and assurance of adequate supplies,
Combustion: further work on both forced-air and natural-draft versions, plus larger and smaller versions,
Applications: appropriately designed structures for cookstoves, for space heating, for small heat-use industry, and the high-value tasks of lighting and IC engines,
Human factors: reduction of cost of the various devices, designs for specific populations, gaining acceptance by the users, relations with governments and NGOs for rapid dissemination, and more.
We will be working on these and other issues as fast as we can. But we will not be waiting for perfection before dissemination of the results. As an example of this, I have encouraged Engr. Belonio to make minor changes in the draft of this document and then proceed to release this “Handbook” as soon as possible. This is his work, he deserves recognition for it, and the information should not be delayed while awaiting a re-writing. His future work is likely to include co-authors with a blending of ideas, styles, and credits. Let him be recognized now for the major work he has accomplished with so little outside influence.
The year 2005 is the Twentieth Anniversary of Dr. Tom Reed’s initial revelation and experimentation about inverted downdraft (IDD) or top-lit updraft (T-LUD) combustion. Two major causes for celebration are the Belonio Rice Husk T-LUD Gas Stove and the independent testing at the Aprovecho Research Center that reveals the higher quality (lower emissions) of the T-LUD combustion technology. Therefore, we look forward to 2006 when the innovative IDD / T-LUD technology “comes of age” (21 years old) with expressions and applications in various countries around the world.
Paul S. Anderson, Ph.D. 10 November 2005 Developer of T-LUD gasifier stoves Associated with Dr. Reed’s Biomass Energy Foundation (BEF)
Note: For those wanting to accompany the developments of T-LUD gasifier technology, the best single source is to visit the Stoves website at: http://stoves.bioenergylists.org/ and then search “Contributions by List Members” seeking the names of the authors, or by searching for the keywords like T-LUD and IDD and gasifiers. Also, consider joining the Stoves List Serve (via the same website address) and participate in the wide-ranging discussions and developments of all types is stoves for developing societies and our resource-challenged world.
Rice Husk Gas Stove Handbook (3.6 MB) The document in .pdf format is 3.6 meg, 155 pages long, with many photographs.