Nuclear energy is by far the largest source of electric power that does not emit any air pollution — and the only one that can produce large amounts of electricity 24/7. Nuclear plants have a major role in making electricity available in the United States and in protecting America’s air quality.

When Congress passed the Clean Air Act in 1970, nuclear energy supplied less than 1.5 percent of America’s electricity. Today, 99 reactors in 30 states provide nearly 20 percent of America’s electrical power, replacing fossil-fueled plants that would have been built otherwise. Those fossil-fuel-based plants would have emitted massive amounts of carbon dioxide. In 2014 alone, nuclear energy facilities prevented 595 million metric tons of carbon dioxide emissions, equal to the amount of carbon dioxide emissions from 135 million cars.

In the years since the Clean Air Act was passed, there has been growing recognition of the need to cut carbon pollution. In 2015, the U.S. E