For most of the history of power generation in the United States, coal has been the dominant fuel used to produce electricity. In 2012, coal was used to fuel approximately 38% of power generation in the United States, as shown in Figure 1. Coal has been the fuel of choice for many decades because of its wide availability, and the relatively low cost of producing electricity in large, coal-burning power plants. Coal’s low-priced, high energy content enabled the building of power plants able to take advantage of economies of scale in steam-electric production