Governors' Wind Energy Coalition

A coal-fired power plant in Ohio. New coal plants will face hurdles under the proposed rule.

The draft rule, unveiled on Tuesday by Lisa P. Jackson, the Environmental Protection Agency administrator, would limit carbon dioxide emissions from new power plants to 1,000 pounds per megawatt-hour.

Recently built power plants fired by natural gas already easily meet the new standards, so the rule presents little obstacle for new gas plants. But coal-fired plants face a far greater challenge, since no easily accessible technology can bring their emissions under the limit. Coal-fired plants are a major source of emissions associated with global warming. The new rules do not apply to existing plants.

The coal industry is an economic mainstay of many local economies, and the rule was denounced from West Virginia to Wyoming and on the Republican presidential campaign trail on Tuesday.

“This E.P.A. is fully engaging in a war on coal, even though this country will continue to rely on coal as an affordable, stable and abundant energy source for decades to come,” said Senator Joe Manchin III, a West Virginia Democrat and former governor. “This approach relies totally on cheap natural gas, and we’ve seen that bubble burst before.”

The declining price of natural gas has made it the fuel of choice in recent years for companies planning new plants. The E.P.A.’s move follows a shift that is already unfolding in the electric power market.

The proposed rule is rooted in a 2007 directive from the Supreme Court instructing the E.P.A. to decide whether carbon dioxide was a pollutant under the Clean Air Act. In late 2009, the agency declared that it was, and so had to be regulated.

It took more than two years for the agency to work out the regulatory details.

To open an avenue to companies still planning to build coal plants, for example, the E.P.A. said it would allow new ones to begin operating with higher levels of emissions as long as the average annual emissions over a period of 30 years met the standard.

In a statement, Ms. Jackson called the proposed rules “a common-sense step to reduce pollution in the air, protect the planet for our children and move us into a new era of American energy.”

Environmental groups generally applauded the standards, although some expressed disappointment with the agency’s decision not to regulate existing power plants for the moment.

“This Environmental Protection Agency action means any new coal plants built in America must use modern, state-of-the-art carbon pollution controls,” Frances Beinecke, the president of the Natural Resources Defense Council, said in a statement. “The logical next step is to improve the aging fleet of existing coal-fired power plants, which remain the major source of industrial carbon pollution in our country.”

In a conference call with reporters, Ms. Jackson said that if such action were to be taken in the future, the agency would thoroughly consult with the industry and all others affected.

Rick Santorum, a Republican presidential contender and a coal industry supporter, derided the proposed rule.

President Obama’s environmental agenda kills American jobs, creates higher energy prices and weakens our nation’s security,” he said. “America is the Saudi Arabia of coal, and we could create our own energy if the government would let us. Instead, Barack Obama would rather pick winners and losers in the energy field.”

At Peabody Energy, the largest coal mining company in the United States, Vic Svec, a spokesman, questioned the legality of the standard, arguing that the E.P.A. was supposed to set standards based on existing technology and that technology was not ready.

A standard of 1,000 pounds per megawatt-hour for coal plants would “require something that doesn’t exist as a commercial technology,” he said.

But the lack of a commercial technology for carbon capture is one reason that the E.P.A. could not realistically impose such a requirement on existing plants and decided to push the challenge into the future.

Carbon capture has so far proved too expensive to be practical because the chemical work of separating carbon dioxide from the other components of exhaust gas requires large amounts of energy.

By some estimates, what is today a 1,000-megawatt coal plant might yield only 700 megawatts after some of its energy went into a carbon capture plant in the form of steam and electricity. And sequestering the gas underground could prove difficult.

Michael Brune, executive director of the Sierra Club, said in an interview that ending coal-fired generation as it now exists should be the whole point. “It’s a rule that follows the marketplace,” he said, adding: “Right now, next to no coal plants are being built. This basically means that new coal plants are going extinct.”

As for coal plants built in the 1970s or earlier, he said, “we can put them in our rear-view mirror.”