page_title: Wood gas
section_title: Internal combustion engine
hierarchical_section_title: Wood gas / Usage / Internal combustion engine
caption_attribution_description: English: Wood gasifier on a Ford converted to EPA tractor.
context_page_description: Wood gas is a syngas fuel which can be used as a fuel for furnaces, stoves and vehicles in place of gasoline, diesel or other fuels. During the production process biomass or other carbon-containing materials are gasified within the oxygen-limited environment of a wood gas generator to produce hydrogen and carbon monoxide. These gases can then be burnt as a fuel within an oxygen rich environment to produce carbon dioxide, water and heat. In some gasifiers this process is preceded by pyrolysis, where the biomass or coal is first converted to char, releasing methane and tar rich in polycyclic aromatic hydrocarbons.
context_section_description: Wood gasifiers can power either spark ignition engines, where all of the normal fuel can be replaced with little change to the carburation, or in a Diesel engine, feeding the gas into the air inlet that is modified to have a throttle valve, if it didn't have it already. On Diesel engines the Diesel fuel is still needed to ignite the gas mixture, so a mechanically regulated Diesel engine's "stop" linkage and probably "throttle" linkage must be modified to always give the engine a little bit of injected fuel, often under the standard idle per-injection volume. Wood 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, African and Asian countries, because the war prevented easy and cost-effective access to oil. In more recent times, wood gas has been suggested as a clean and efficient method to heat and cook in developing countries, or even to produce electricity when combined with an internal combustion engine. Compared to World War II technology, gasifiers have become less dependent on constant attention due to the use of sophisticated electronic control systems, but it remains difficult to get clean gas from them. Purification of the gas and feeding it into natural gas pipelines is one variant to link it to the existing refuelling infrastructure. Liquefaction by the Fischer–Tropsch process is another possibility.
  Efficiency of the gasifier system is relatively high. The gasification stage converts about 75% of fuel energy content into a combustible gas that can be used as a fuel for internal combustion engines. Based on long-term practical experiments and over 100,000 kilometres (62,000 mi) driven with a wood gas-powered car, the energy consumption has been 1.54 times higher compared to the energy demand of the same car on petrol, excluding the energy needed to extract, transport and refine the oil from which petrol is derived, and excluding the energy to harvest, process, and transport the wood to feed the gasifier. This means that 1,000 kilograms (2,200 lb) of wood combustible matter has been found to be equivalent to 365 litres (96 US gal) of petrol during real transportation in similar driving conditions and with the same, otherwise unmodified, vehicle. This can be considered to be a good result, because no other refining of the fuel is required. This study also considers all possible losses of the wood gas system, like preheating of the system and carrying of the extra weight of the gas-generating system. In power generation, reported demand of fuel is 1.1 kilograms (2.4 lb) wood combustible matter per kilowatt-hour of electricity.
  Gasifiers have been built for remote Asian communities using rice hulls, which in many cases have no other use. One installation in Burma uses an 80 kW modified Diesel-powered electric generator for about 500 people who are otherwise without power. The ash can be used as biochar fertilizer, so this can be considered a renewable fuel.
  Exhaust gas emission from an internal combustion engine is significantly lower on wood gas than on petrol. Especially the hydrocarbon emissions are low on wood gas. A normal catalytic converter works well with wood gas, but even without it, emission levels less than 20 ppm HC and 0.2% CO can be easily achieved by most automobile engines. Combustion of wood gas generates no particulates, and the gas renders thus very little carbon black amongst motor oil.
caption: A Wood gas generator fitted to a Ford truck converted into a tractor, Per Larsen Tractor Museum, Sweden, 2003
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