The Environmental Protection Agency issued the first limits on greenhouse-gas emissions from U.S. power plants, the largest source of carbon dioxide linked to climate change.
The rules will permit emissions from new power plants at about the level established for a natural-gas plant, the EPA said today in an e-mailed statement, which would effectively preclude construction of new coal-fired plants.
The rule would only apply to the construction of new plants, and the administration said it would exempt plants that are proposed to be built within the next year.
The initial impact would be minimal as utilities are closing, not building, coal plants because natural gas prices are at 10-year lows. The share of coal in electricity generation dropped below 40 percent by the end of 2011, the first time it had been that low since 1978, according to the U.S. Energy Information Agency in Washington.
The average U.S. coal plant emits 2,249 pounds of carbon dioxide for each megawatt hour of power produced, compared with 1,135 pounds for a natural gas plant, according to the EPA. Newer combined-cycle natural gas plants, in which the heat exhaust of a first gas-fueled turbine drives a second generator, are more efficient.