New federal regulations that aim to reduce carbon dioxide emissions from power plants will have a large economic upside, largely through health savings, says Gina McCarthy, administrator of the Environmental Protection Agency.

"We are talking by 2030 having $90 billion in benefits," McCarthy told NPR's Robert Siegel in an interview airing on All Things Considered.

The rules, which were published on Monday, set a countrywide target for reducing greenhouse gases by 30 percent by 2030, from where they were in 2005. Each state will have its own target, says NPR energy reporter Jeff Brady. Some will be more than 30 percent, others less.

Those in coal country won't have to cut the full 30 percent. But officials in those states aren't happy.

"These proposals appear to realize some of our worst fears," Earl Ray Tomblin, the Democratic governor of West Virginia, told reporters. "Based on our initial review of these rules, not a single West Virginia power plant would be in compliance if the rules were in effect today, despite billions of dollars companies have spent to modernize their facilities."

McCarthy, the EPA administrator, said that the economy has continued to grow throughout the agency's 40-year history of reducing air pollution. She predicted that coal will remain the source of about 30 percent of the country's electricity supply in 2030, down from its current 37 percent.

She said that decline will be due more to market forces than to her agency's new regulations.

"What you see in the future is going to be natural gas plants that are very efficient, and you're going to see some renewables," McCarthy told NPR. "But that doesn't mean that the share of electricity from coal is going to be significantly diminished."

Despite complaints from critics of executive overreach by the Obama administration in promulgating these rules, McCarthy said they are "within the four corners of the Clean Air Act, and it's legally what we're supposed to do."

But McCarthy did not play down their impact.

"I think EPA has never produced a rule that is going to be as significant," she said.

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