The term coal gasification refers to any process by which coal is converted into some gaseous form that can then be burned as a fuel. Coal gasification technology was relatively well known before World War II, but it fell out of favor after the war because of the low cost of oil and natural gas. Beginning in the 1970s, utilities showed renewed interest in coal gasification technologies as a way of meeting more stringent environmental requirements.

Traditionally, the use of fossil fuels in power plants and industrial processes has been fairly straight-forward. The fuel—coal, oil, or natural gas—is burned in a furnace and the heat produced is used to run a turbine or operate some industrial process. The problem is that such direct use of fuels results in the massive release of oxides of carbon, sulfur, and nitrogen, of unburned hydrocarbons, of particulate matter...