The U.S. power sector must cut carbon dioxide emissions 30 percent by 2030 from 2005 levels, according to federal regulations unveiled on Monday that form the centerpiece of the Obama administration's climate change strategy.
The Environmental Protection Agency's proposal is one of the most significant environmental rules proposed by the United States, and could transform the power sector, which relies on coal for nearly 38 percent of electricity.
Read MoreA future with high-tech roads that generate power
Gina McCarthy, administrator of the Environmental Protection Agency, said on Monday that between 2020 and 2030, the U.S. amount of carbon dioxide the proposal would reduce under the plan would be more than double the carbon pollution from the entire power sector in 2012.
States will have flexible means to achieve ambitious but attainable targets, regardless of their current energy mixes. States which rely heavily on coal-fired power plants are thought to have the toughest tasks ahead.