The policy problem of greatest significance to the near future of coal consumption is undoubtedly the question of air pollution and its control. Under the authority of the Clean Air Act of 1970 and its 1977 amendments, the federal government directly and indirectly regulates the siting of fossil-fueled utility and industrial boilers, as well as their permissible emissions of particulates, sulfur oxides, and nitrogen oxides. Other considerations may arise under the Clean Water Act, the National Environmental Policy Act, the National Historic Preservation Act, the Endangered Species Act, and other regulations, but it is the provisions of the Clean Air Act that apply most consistently and with most force.
The Clean Air Act sets national ambient air quality standards (NAAQS) for atmospheric concentrations of sulfur dioxide, nitrogen dioxide, and particulate matter. These are enforced in a variety of ways to control emissions from different stationary and mobile pollution sources. The requirements are different not only for different types of sources, but also for different regions. The act divides the nation into 247 air quality control regions, and charges the states with developing strategies for meeting the applicable ambient pollutant standards. In regions that are already in violation of the ambient standards, any new pollution source must meet the lowest attainable emission rate and at the same time secure from other sources in the region reductions in emissions that more than offset its own. In areas where the air is cleaner than required by the NAAQS (so-called “prevention of significant deterioration” areas), emissions are regulated to prevent significant increases in ambient concentrations of particulate matter and sulfur dioxide. Regulations covering certain other pollutants (including nitrogen dioxide and hydrocarbons) will be promulgated in late 1979.
In addition to the standards regulating ambient air quality, and thus the siting of plants, the Environmental Protection Agency promulgates and enforces regulations limiting the emissions of individual plants. Under the authority of the 1977 amendments to the Clean Air Act, EPA proposed new, tighter standards governing the sulfur dioxide, nitrogen dioxide, and particulate emissions of all new or substantially modified fossil-fueled steam power generating units that consume more than 250 million Btu of fuel energy per hour.16 This is equivalent to about 10 tons of coal per hour—enough to fuel a 10-MWe unit. The standards apply, regardless of the ambient air quality, to plants whose construction or alteration begins after September 18, 1978.
The standards, made final in May 1979, set ceilings on the emissions of the three above-mentioned pollutants, and in the case of sulfur dioxide impose the further requirement that “potential” emissions (those that