Thursday, 2 July 2009

WoodGas stove demo

The following stove demonstration is by Mike Pepler, Technical Manager at the Ashden Awards.

One of the key issues in developing countries is changing the wood stoves people use for cooking so that they are more efficient and emit fewer harmful pollutants. Gasifying stoves are one area where research is still ongoing, and this demonstration is of a stove that uses a fan powered by two AA batteries. Being battery powered, this is not intended for use in developing countries, but is aimed at the outdoors and camping market in developed countries. However, some of the profits from its sale go to fund research on developing a similar stove for developing countries, but with a thermoelectric generator to power the fan.

Here's the details on how it works.
It's a WoodGas CampStove. What it does is "gasify" the wood, burning the gas produced in an efficient manner right under the cooking pot. Basically there's a cylinder inside it that you fill with small sticks:
If you look carefully you'll see some small holes at the base of this cylinder - these allow in a small amount of air to gasify the wood. Gasification means allowing the wood to partially burn, resulting in a mixture of gases, including hydrogen, methane and carbon monoxide (so don't use it indoors). These are all flammable gases, and as they rise up the inside of the stove they meet with more air injected through a ring of holes at the top of it:
The gas mixes with this additional air and burns. Right above it sits your cooking pot, resting on a simple but effective pot stand:
The air is drawn in through holes around the the outside of the base of the stove, which encloses a small fan. In the picture below you can see the two power sockets for the fan (high and low speed), and the air inlet holes:
The battery pack contains two AA rechargeable batteries (I reckon my 3200mAh batteries will run it for over 15 hours), and you plug it into the high or low speed socket depending on how much heat you want out of the stove. I charge my batteries from a solar panel.
Anyway, enough of the still pictures, it'll all be much clearer when you see it in action, so here's a video:

To see the range of stoves designed and used by past Ashden Awards winners, click here


This demonstration was originally published on Mike's personal blog.

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