Charcoal burning conversion kits, which are really wood gas generators, enjoyed a brief civilian and military niche market in England, Germany, Australia, the United States, and other countries up to and during World War II. Wood gas generators were used to power taxis in Korea as late as 1970.

A charcoal burner actually burns the gases produced by heated wood. The burner is a two part system: a closed chamber with chunks of wood in it, and a charcoal burner to heat the closed chamber and make the wood generate gases by a process called pyrolysis.

Flammable gases produced by pyrolysis are then routed to a carburetor （化油器）of sorts, mixed with air, and burned in the engine’s combustion chambers. Once the wood in the closed chamber has produced gases and turned to charcoal, it is transferred to the charcoal burner to heat the next load of wood. Some charcoal-fueled cars were designed to be started on gasoline, and would then be switched to charcoal once the vehicle was underway.