For $80 million, the Appalachian Power Company, an operating subsidiary of American Electric Power Corporation, last year added electrostatic precipitators to its Philip Sporn power plant in West Virginia. The original cost of the coal-burning plant, in 1960, was $126 million. During the past five years about 14 percent of the system's construction expenditures has gone into a massive program of retrofitting high-efficiency electrostatic precipitators on its plants. With completion of the final two units, the system will have spent $600 million. American Electric Power is the largest privately owned utility in the country, serving a seven-state region in the industrial Midwest, and leads the nation in coal consumption. More than 38 million tons of coal (the equivalent of 150 million barrels of oil) were burned in its 13 coal-fired power plants last year. Precipitators, when designed as original equipment for new plants, run an average of 10 to 11 percent of the total cost of the structure. The equipment is designed to eliminate more than 99 percent of the fly ash emitted from the plant stacks. The utility points out that these programs to improve the environment "do not produce a single kilowatt-hour of electricity or a penny of revenue." The air-pollution-control equipment itself uses large amounts of electric energy, thereby reducing the electric capacity available for sales and revenues. The company decided to remain with coal in the early 1970s when many utilities were basing their systems on nuclear power or switching to then-cheaper oil and gas to meet environmental requirements.