Biomass Energy Foundation

Here is a report on the recent micro gasifier camp in Honduras from Timothy Longwell

CO and PM Emissions from TLUD Cookstoves Presentation to 2009 ETHOS Conference, Kirkland, WA 23-25 January 2009 Paul Anderson, Biomass Energy Foundation, January 22, 2009

CO and PM in TLUDCO and PM in TLUD

Introduction Since 2005, high quality quantitative data on emissions from cookstoves have been accumulating. For data to be properly comparative, both a standardized cooking task and reliable emissions measurements are required. The principal test continues to be the standard five-liter Water Boiling Test (WBT), about which much has been written and debated. Equipment for reliable emissions measurements has been gathered, installed, tested, and accepted for operation at the Aprovecho Research Center (ARC) in Cottage Grove, Oregon, USA. No known equivalent site exists anywhere else in the world. Sincere thanks are given to the Shell Foundation, other financial donors, the ARC organization, and the numerous scientists who assisted in the establishment and operation of those emissions hoods. While the ARC facilitated the gathering of data presented here, the author is responsible for interpretations and any errors or omissions. Dozens of different stoves have been tested to various degrees with the ARC equipment and methodologies. Hundreds of separate test results have been collected. The two measured emissions are carbon monoxide (CO) and particulate matter (PM). This report is focused upon those emissions from four categories of cookstoves: 1. The traditional “three-stone fire,” which provides baseline data. 2. “Simple improved cookstoves” that utilize basic combustion that is confined in various stove structures made of ceramics, mud, or metal. 3. “Rocket stoves” that utilize clear principles and designs that provide significant control over the amount of wood in the area of combustion, with some restriction on the flow of air to the combustion area. 4. “TLUD (top-lit updraft) gasifier stoves” that essentially separate in time and location three processes of biomass burning (pyrolysis, char-gasification, and combustion). They also emphasize separate control of primary and secondary air supplies. Robert Flanagan, a TLUD stove developer in China, has coined the term “third-generation cookstoves” for these stoves that have the capability to easily create and save charcoal for use as a “biochar” additive to improve soil fertility (as in “terra preta”) and to remove permanently carbon from the atmosphere. See attached presentation

Palm Fronds as Fuel in a TLUD (Top Lit Updraft)
Micheal Trevor, Marshall Islands, December 7, 2008

Loaded Chopped FrondsLoaded Chopped Fronds

Remember in the rocket stove I am use very "pulpy" stuff.
In the TLUDS-- XL Woodgas and my tincanium ones--- they make charcoal. As for shell I have not tried it much yet in the TLUDS althought my son burned out the first XLWoodgas unit on it.

I think a mix of broken shell chips with the chopped frond piece may work very well.
The chopped frond pieces work well but the burn is rather short.

In industrial applications like a bakery I am sure shell would be fantastic if you could get enough.I think everyone else would get it first

Michael Trevor
Marshall Islands

Chopped Fronds for FuelsChopped Fronds for Fuels
Light OffLight Off
Nice BurnNice Burn

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.



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

TLUD Workshop being offered prior to ETHOS Conference
Hosted by Hydrovolts
Biomass Energy Foundation is offering a Workshop on the technical and practical concepts of its micro-gasification units. Dr. Paul Anderson aka “Dr TLUD” will provide an overview of the science and technology of the Top Lit Up Draft (TLUD) stove and its applications in meeting the cooking needs of local communities around the globe.
He will be assisted by Bob Fairchild, Christa Roth, and Kathy Nafie.

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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