Burning of coal supplies more than 95% of the electricity generated in Kentucky. Coal-burning utilities have responded to evolving clean air standards in a number of ways, including adding flue-gas desulfurization (FGD) to existing plants or switching to lower sulfur coals. No power plant in Kentucky burned < 1% sulfur coal in 1978. By 1997, many utilities had switched to lower sulfur and, in some cases, lower ash coal. The means of switching varied, with many choosing Central Appalachian coals. One plant now uses low-sulfur western US bituminous coal after having used Central Appalachian coals while another plant uses subbituminous Powder River Basin coal in a blend with Illinois Basin coal. The rank range of coals purchased has widened, not only with the addition of subbituminous coals but also with the use of medium and low volatile bituminous coals. No other state matches Kentucky in FGD capability, with 48% of the state＇s generating capacity equipped with FGD as an SO2 reduction option. The expansion of FGD has maintained a market for higher sulfur coal. The newest power plants were designed in tandem with the FGD system and can handle coals with > 4% sulfur. Quality of delivered coals has changed significantly over the past 20 years, and will continue to change as coal-fired power plants continue to work to meet the challenges presented by existing and potential new clean air standards.