Wood gas

Wood gas, also known as producer gas, is the mixture of gases that results when wood or other organic materials are heated in an environment with little or no oxygen. Wood gas mainly consists of molecular nitrogen (N₂), carbon monoxide (CO), molecular hydrogen (H₂), carbon dioxide (CO₂), and methane (CH₄). It is flammable because of the carbon monoxide, hydrogen and methane content.

Wood gas can be used to power cars with ordinary internal combustion engines if a wood gasifier is attached. This was quite popular during World War II in several European countries. In more recent times, wood gas has been suggested as a clean and efficent method to heat and cook in developing countries, or even to produce electricity when combined with a gas turbine.

A wood gasifier takes wood chips, sawdust, charcoal, coal or similar materials as fuel and burns these incompletely in a fire box, producing solid ashes and soot (which have to be removed periodically) and wood gas, but no smoke. The wood gas is then filtered, cooled and directed to the engine. There it takes the place of the gasoline/air mixture from the carburetor and burns with oxygen mainly to carbon dioxide and water.

The first wood gasifier was apparently built by Bischof in 1839. The first vehicle powered by wood gas was built by Parker in 1901. Around 1900, many cities delivered wood gas (centrally produced typically from coal) to residences. Natural gas began to be used only in 1930.

External links

• Food and Agriculture Organization of the United Nations: Wood Gas as Engine Fuel, 1986, http://www.fao.org/DOCREP/T0512E/T0512e00.htm. Detailed explanation of the theory and praxis of wood gasifiers, including dangers and downsides.
• Hans Hochwald: Wood gas producers, http://highforest.tripod.com/woodgas/woodgas. A schematic of a wood gasifier, and links.
• Report about an '85 Yugo car converted to wood gas by Igor and Anton Peterka: http://www.hszk.bme.hu/~oj002/yugo/wood-gas.htm
• Description of several wood gas stoves: http://journeytoforever.org/at_woodfire