From The New York Times:

Coal and electric utilities, long allied, are beginning to split. More than 100 of the 500 or so coal-burning power plants in the United States are expected to be shut down in the next few years. While coal still provides about a third of the nation’s power, just four years ago it was providing nearly half.

The decline is largely because new pollution rules have made coal plants more costly, while a surge in production of natural gas through the process of hydraulic fracturing, known as fracking, has sent gas prices plummeting. Together, the economics of coal have been transformed after a century of dominance in Washington, state capitals and the board rooms of electric utilities.

“The math screams at you to do gas,” said Mr. Morris, whose company is the nation’s largest consumer of coal.

Environmental groups, after years of targeting coal plants as leading sources of air pollution, have moved in for the kill. “We never thought we would get to a place where coal plants are falling so fast,” said Bruce Nilles, the director of the $50 million from Mr. Bloomberg, who views the campaign as part of a public health effort, and $26 million from an odd bedfellow: the top official of a natural gas company.

The environmentalists figure that if they can shut down a third of the nation’s coal burning plants by 2020, emissions of greenhouse gases in the United States could be cut at least as much as they would have under a landmark 2009 climate bill that died in Congress.

I really don’t know how I feel about this.