Coal pollution mitigation emissions of sulfur dioxide or oxides of nitrogen associated with the utilization of coal in the generation of electricity." Before being adopted in this fashion, historically "clean coal" was used to refer to clean-burning coal with low levels of impurities, though this term faded after rates of domestic coal usage dropped. The term appeared in a speech to mine workers in 1918, in context indicating coal that was "free of dirt and impurities." In the early 20th century, prior to World War II, clean coal (also called "smokeless coal") generally referred to anthracite and high-grade bituminous coal, used for cooking
Bituminous coal sulfur, and other impurities as possible. The constituents of the coal should be as follows: Cannel coal is a coal which ignites easily producing a bright flame. The name derives from the Scottish pronunciation of "candle coal". It contains a high volatile content, is non-coking and was a source for coal oil in West Virginia during the mid-1800s. While the use of Cannel has greatly diminished over the past century, it is still valued by artists for its ability to be carved and polished into sculptures and jewelry. When used for many industrial processes, bituminous coal must first be "coked"