Coal is an abundant and relatively inexpensive fuel on a dollar per BTU basis in North America. Fifty-five percent of the United States' utilities' net electric generation comes from coal. However, coal fired power plants are more complicated, largely due to the coal handling equipment and strict environmental regulations, and are generally more expensive to build than oil or natural gas fired plants.

The coal is most often delivered to the power plant using railroad cars or barges and stored on a stock pile which usually contains a 90-day supply. The coal is transported from the storage pile to the plant where it is ground into a fine powder and burned in the boiler.

Coal presents several environmental challenges in that it produces more combustion byproducts than either oil or gas. Burning coal produces four main byproducts which must be carefully controlled in compliance with strict federal and regulations. These include fly ash, bottom ash, nitrogen oxides, and sulfur oxides. Many utilities sell fly ash to concrete companies to be used as a concrete additive. Bottom ash is collected and stored until it can be ground up and used as a concrete additive and for stabilizing road beds. Scrubbers and other equipment are used to clean and limit the amount of sulfur oxides and nitrogen oxides released through the stack.

Environmental emissions are also affected by the type of coal which is burned. Three different types of coal are burned in North America -- anthracite, bituminous, and lignite -- and they are generally considered to be high-, medium- and low-quality coal, respectively. The higher the quality of coal, the higher the heating value and the lower the sulfur and ash content per pound. These characteristics help to improve fuel efficiency and reduce environmental emissions.