In 2003, U.S. nuclear power plants avoided the emission of 679 million metric tons of carbon dioxide, from the fossil fuels that would have been burned to generate power in the absence of nuclear energy. Annual carbon dioxide emissions from the U.S. electric sector are approximately 2,215 million metric tons. Without nuclear energy, U.S. electric sector carbon emissions would have been approximately 30 percent higher.
Source: Environmental Protection Agency and DOE’s Energy Information Administration