Nuclear energy originates from the splitting of uranium atoms in a process called fission. At the power plant, the fission process is used to generate heat for producing steam, which is used by a turbine to generate electricity.

Nuclear power plants aid compliance with the Clean Air Act of 1970, which set standards to improve the nation's air quality. Because they generate heat from fission rather than burning fuel, they produce no greenhouse gases or emissions associated with acid rain or urban smog. Using more nuclear energy gives states additional flexibility in complying with clean-air requirements.

No Criteria Pollutants

 The Clean Air Act of 1970 established limits on the emission of nitrogen oxides, a precursor of ground-level ozone and smog; sulfur dioxide, which produces acid rain; particulate matter, such as smoke and dust; and mercury. The U.S. Environmental Protection Agency developed extensive regulations to reduce nitrogen oxides through creation of the Ozone Transport Commission and the Budget Program—both initiatives created under the Clean Air Act amendments of 1990 to help reduce ground-level ozone in the Northeast and Mid-Atlantic states. Nuclear power plants do not produce these criteria pollutants.

No Greenhouse Gases

Carbon dioxide—the principal greenhouse gas—is a major focus of policy discussions to reduce emissions. Nuclear power plants, which do not emit carbon dioxide, account for the majority of voluntary reductions in greenhouse gas emissions in the electric power sector, according to a 2007 report from Power Partners, a partnership between the electric power industry and the U.S. Department of Energy.

Nuclear power plants generate about 20 percent of U.S. electricity. They do not burn anything when producing electricity, so they do not produce any greenhouse gases or combustion byproducts. By substituting for other fuels in the electricity sector, nuclear energy has significantly reduced U.S. emissions of air pollutants and greenhouse gases. About one-quarter of America’s electricity comes from clean-air sources, including nuclear power plants, hydroelectric plants, and wind and solar energy facilities. Nuclear energy is the only large-scale, clean-air electricity source that can be expanded widely to produce large amounts of energy. Nuclear energy makes up nearly 74 percent of all the nation’s clean-air electricity generation. In 2007, U.S. nuclear power plants prevented the emission of nitrogen oxides and sulfur dioxide—pollutants controlled under the Clean Air Act—by 1 million short tons and 3 million short tons, respectively. The amount of nitrogen oxide emissions that nuclear plants prevent annually is the equivalent of taking more than 51 million passenger cars off the road. Also in 2007, U.S. nuclear plants prevented the emissions of almost 693 million metric tons of carbon dioxide. This is nearly as much carbon dioxide as is released from all U.S. passenger cars. Environmental responsibility is an important part of nuclear power plant management. The companies that operate nuclear power plants voluntarily work to protect nearby wildlife and their habitats.