Envirofit and BP Stoves
Tom Reed,, August 29, 2008
Envirofit and BP StovesEnvirofit and BP Stoves

On Fri, Aug 29, 2008 at 6:38 AM, Thomas Reed wrote:
Dear Stovers:

I am attaching [the image above]that may be of interest to the stovers.

Here is an unsolicited commentary on our new XL WoodGas Stove, available at
Woodgas stoveWoodgas stove
along with our gasification books.

We have recently learned that BP is manufacturing a VERY similar stove
and selling them (only in India) in their equivalent of Walmart. I hear
they have already sold 100,000. Sounds like we are well on the way to
getting a "Billion Improved Stoves" out to the developing world.

If you cover the combustion air holes with aluminum flashing or sheet
metal screws the stove also makes a good gasifier.



Dean Still, August 9, 2008

WoodGas vs Wood Combustion
Tom Reed, Biomass Energy Foundation, April 2006

As a longtime proponent (since 1973) of biomass gasification and moderator of the gasification REPP group, let me define "gasification" a little more widely than the discussion below
Coal pyrolysis produces typically 80% fixed carbon, 20% gas and volatiles. The principle step then for coal gasification is getting that carbon to be a gas with either oxygen, CO2 or water

2C + O2 ==> 2 CO
C + CO2 ==> 2 CO
C + H2O ==> CO + H2

The first reaction is exothermic, while the last two are endothermic.
So pass air/oxygen, CO2 and H2O through coal and you produce CO + H2.
Coal gasification was the principle form before 1940 and was practiced at a large scale because of the need to remove sulfur and ash. During WW II however, biomass was the fuel of choice for small gasifiers to run cars, trucks and buses.


Biomass is typically 80% gas plus volatiles plus 20% fixed carbon. So the main problem is to convert the volatiles to CO + H2.

Pyrolysis typically occurs at 300-500C. Conventional bottom lit updraft gasifiers burn charcoal on a grate to produce hot CO-H2 which then pyrolyzes the incoming biomass to make VERY tarry gas. *(I call this a "char burning, tar making gasifier")*.

But if you pass air through a mass of biomass the temperature is 700-1000 C, and we call that "flaming pyrolysis". FP produces mostly CO
+ H2, CO2 and H2O and small amount of condensibles (tars). These then
pass through the remaining charcoal where most of the volatiles are destroyed. At the high end the condensibles are typically < 100 ppm.
At the low end, more like 2000. *(I call this a "tar burning, char making gasifier").
I call the Flaming Pyrolysis process "PYROLYTIC GASIFICATION". It occurs at a continuum of temperatures from 700-1000C, depending on air/fuel ratio. At the low end, 700C, very little of the charcoal is gasified and the toplit updraft stoves produce 5-25% charcoal, depending on the moisture content of the fuel. At the high end up to 1000C the gas is VERY low tar and useful for operating engines for power and transportation and for synthesis of methanol and diesel. .

If secondary air is added to the gases after they are generated you have a very clean and hot flame. This is VERY different from direct combustion and I classify our WoodGas Campstove as a close coupled pyrolytic gasifier and combustor.

We now are selling WoodGas Campstoves at our website store along with our books on gasification ( and I recommend getting one and pondering the profound difference between the gasification and direct combustion of wood for cooking. While we have made the campstove, the principles can be applied at all scales for apartment and
field cooking around the world. We hope they will be.

Yours truly,

The Biomass Energy Foundation

T. B. Reed and Ron Larson

*Presented at the "Developments in Thermochemical Biomass Conversion" Conference, Banff, Canada, 20-24 May, 1996.

Introduction -

A.The Problem

Since the beginning of civilization wood and biomass have been used for cooking. Over 2 billion people cook badly on inefficient wood stoves that waste wood, cause health problems and destroy the forest. Electricity, gas or liquid fuels are preferred for cooking - when they can be obtained, but they depend on having a suitable infrastructure and are often not available in developing countries. In the last few decades, many improved wood stoves have been developed (the Chula, the Hiko, the Maendeleo, the Kuni Mbili, etc.), but the new wood stoves are often more difficult to manufacture, often more heat goes to the stove than to the food, and they do not offer good control of cooking rate. They are not always accepted by the cooks for whom they are developed.[1] Because of the problems of wood cooking, people often cook over charcoal. However, charcoal manufacture is very wasteful of energy and very polluting, so the problems of the wood stove are externalized but not solved.


Gas is preferred for cooking wherever it is available. Gas can be made from wood and biomass in gasifiers developed in this century, but these gasifiers are generally too big for home use. A downdraft stove for domestic cooking is now being manufactured in China.[2] We have developed a new "inverted downdraft gasifier" stove shown in Fig. 1. It operates using only natural convection. The rate of gas production and heating is controlled by the primary air supply to the gasifier. As an option, the gasifier can make charcoal with a 20-25% yield. The wood-gas stove consists of an "inverted downdraft gasifier" (shown in Fig. 2) plus a burner to mix air and gas and burn cleanly (Fig. 3). These sections are discussed below. The stove has been started and operated indoors with no exhaust fans and no odor of burning wood. However, we believe that there is still much work to be done in optimizing the stove for various fuels, adapting it to various cooking situations and developing other uses. For that reason we are publishing our preliminary results and hope that others will help adapt these principles to improve world cooking and wood conservation.

The C-H-O Fuel Map
Thomas Reed, Biomass Energy Foundation, October 4, 2007

Calculating the LHV for Biomass and Coal
Thomas Reed, Biomass Energy Foundation, October 1, 2007 to the Biomass Cooking Stoves List

Domestic Woodgas Cooking
Tom Reed, Biomass Energy foundation (BEF), June 1, 2007


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