The proposal would help reshape where Americans get electricity, away from a coal-dependent past into a future fired by cleaner sources of energy. It's also a key step in President Barack Obama's global warming plans, because it would help end what he called "the limitless dumping of carbon pollution" from power plants.
Although the proposed rule won't immediately affect plants already operating, it eventually would force the government to limit emissions from the existing power plant fleet, which accounts for a third of all U.S. greenhouse gas emissions. Obama has given the Environmental Protection Agency until next summer to propose those regulations.
The EPA provided The Associated Press with details of the proposal prior to the official announcement.
(Watch: The war on coal)
The public will have a chance to comment on the rule before it becomes final.
Despite some tweaks, the rule packs the same punch as one announced last year, which was widely criticized by industry and Republicans as effectively banning any new coal projects in the U.S.
That's because to meet the standard, new coal-fired power plants would need to install expensive technology to capture carbon dioxide and bury it underground. No coal-fired power plant has done that yet, in large part because of the cost. And those plants that the EPA points to as potential models, such as a coal plant being built in Kemper County, Miss., by Southern Co., have received hundreds of millions of dollars in federal grants and tax credits.
Coal, which is already struggling to compete with cheap natural gas, accounts for 40 percent of U.S. electricity, a share that was already shrinking. And natural gas would need no additional pollution controls to comply.
"For power producers and coal mining companies that reject these standards, they have no reason to complain, and every excuse to innovate," said Sen. Ed Markey, D-Mass., the author of a 2009 bill to limit global warming. The legislation, backed by the White House, passed the House, but died in the Senate.
A powerful Republican opponent of the EPA plan, Senate Minority Leader Mitch McConnell of Kentucky, said in an emailed statement that "the president is leading a war on coal."
The regulations have been in the works since 2011 and stem from a 1970 law passed by Congress to control air pollution. In 2007, the Supreme Court ruled that that law, the Clean Air Act, could be applied to heat-trapping pollution. The EPA already has issued rules aimed at curbing global warming pollution from automobiles and the largest industrial sources.
An EPA official told the AP that the rule doesn't specify any particular technology. But the official acknowledged that carbon capture was the only current technology available for a company to meet the threshold of 1,100 pounds of carbon dioxide emissions per megawatt hour of electricity. To put that in perspective, a modern coal plant without carbon controls would release about 1,800 pounds per megawatt hour.
The official spoke on condition of anonymity because the announcement of the rule had not been made.
The administration went back to the drawing board after receiving more than 2 million comments on its first proposal, which was legally vulnerable because it required coal and natural gas to meet the same limit. Coal and natural gas now have separate standards, but the latest proposal will almost certainly to be litigated once it becomes final, which the law requires the EPA to do in a year.
The legal argument likely will be based around whether carbon capture and storage is a demonstrated technology.
"EPA has set a dangerous and far-reaching precedent for the broader economy by failing to base environmental standards on reliable technology," said Hall Quinn, president and CEO of the National Mining Association. The EPA regulation "effectively bans coal from America's power portfolio," he said.
The EPA will seek comments on whether to subject three coal plants in various stages of the development to the new standard, or treat them as existing sources. They are the Sunflower Electric Power Corp.'s facility near Holcomb, Kan., Power4Georgian's planned Washington County, Ga., facility, and Wolverine Power Cooperative's plans for a new power plant near Rogers City, Mich.