Producer gas is fuel gas that is manufactured from material such as coal, as opposed to natural gas. In this respect it is similar to other types of "manufactured" gas, such as coal gas, coke oven gas, water gas and carburetted water gas. Producer gas was used primarily as an industrial fuel for iron and steel manufacturing, such as firing coke ovens and blast furnaces, cement and ceramic kilns, or for mechanical power through gas engines. It was characteristically low in heating value but cheap to make, so that large amounts could be made and burnt.
In the USA, producer gas may be wood gas produced in a gasifier and used to power cars, town gas, originally produced from coal, for sale to consumers, and syngas, used as a fuel source or as an intermediate for the production of other chemicals.
In the United Kingdom, producer gas, also called suction gas, specifically means a fuel gas made from coke, anthracite or other carbonaceous material. Air is passed over the red-hot carbonaceous fuel and carbon monoxide is produced. The reaction is exothermic and proceeds as follows:
- 2C + O2 + 3.73 N2 → 2CO+ 3.73 N2
The nitrogen in the air remains unchanged and dilutes the gas, giving it a very low calorific value. The concentration of carbon monoxide in the "ideal" producer gas was considered to be 34.7% carbon monoxide (carbonic oxide) and 65.3% nitrogen. After "scrubbing", to remove tar, the gas may be used to power gas turbines (which are well-suited to fuels of low calorific value), spark ignited engines (where 100% petrol fuel replacement is possible) or diesel internal combustion engines (where 15% to 40% of the original diesel fuel requirement is still used to ignite the gas ). During World War II in Britain, plants were built in the form of trailers for towing behind commercial vehicles, especially buses, to supply gas as a replacement for petrol (gasoline) fuel. A range of about 80 miles for every charge of anthracite was achieved.
In old movies and stories, when describing suicide by "turning on the gas" and leaving an oven door open without lighting the flame, the reference was to coal gas or town gas. As this gas contained a significant amount of carbon monoxide, it was quite toxic. Most town gas was also odorized, if it did not have its own odor. Modern 'natural gas' used in homes is far less toxic, and has a gassy odor added to it for identifying leaks.
- W. J. Atkinson Butterfield, "The Chemistry of Gas Manufacture, Volume 1. Materials and Processes", Charles Griffin & Company Ltd., London, 1907, page 72
- Staff (16 July 1941). "Producer gas for transport". Parliamentary Debates. Hansard. Retrieved 15 November 2008.
- Taylor, Sheila (2001). The Moving Metropolis. London: Calmann and King. p. 258. ISBN 1-85669-241-8.
- Mellor, J.W., Intermediate Inorganic Chemistry, Longmans, Green and Co., 1941, page 211
- Adlam, G.H.J. and Price, L.S., A Higher School Certificate Inorganic Chemistry, John Murray, 1944, page 309