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DIY Updraft Gasifier

A gasifier is a stove or boiler that converts wood or other biomass into gases. It consists of a perforated dual-walled metal container that is packed with wood chips, straw or grain husks for fuel. The fuel is ignited at the top and burns downwards in an environment of restricted oxygen supply. It smoulders, expels carbon monoxide, hydrogen and methane and heats the surrounding chamber. Heated air around the fire rises and creates an updraft that sucks in cooler air through perforations at the bottom of the container. The new air heats up in the fuel and burns it again. The cavity between the container̵7;s two walls acts as a chimney for waste gases to escape.

Things You'll Need

1-gallon metal can formerly holding paint or food
Smaller metal can to fit inside the large can
Safety can opener
Leather or canvas punch
Hammer
Hand drill
Dry wood waste
Candle wax, firelighters or white spirit
Water supply

Instructions

- 1
  Clean out the cans. Remove any remains of the can tops with the can opener. Use the can opener to remove the bottom of the larger can.
- 2
  Pierce two rows of holes around the sides of the larger can at its base with a punch and hammer. Space the holes about 1 inch apart. Drill the holes to one half-inch diameter.
- 3
  Drill between six and eight holes of 1/4-inch diameter in the base of the smaller can. Mark out and drill one row of holes of the same diameter in the side of the smaller can at its base. Repeat this process around the sides of the smaller can, 1 inch below its top. The holes allow air into the smaller can where the fuel burns.
- 4
  Place the smaller can into the larger can. Position the cans on a surface that cannot ignite. Fill the smaller can with wood chips or other biomass.
- 5
  Light the fuel at the top using candle wax, firelighters or white spirit to start the combustion. Once alight, the wood glows red hot and continues to burn downwards with little smoke production.

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