A Georgia court this week halted construction of a new 1,200-megawatt coal-fired power plant on the Chattahoochee River, dubbed Longleaf, because backers failed to provide a plan to limit climate change–causing carbon dioxide emissions from it.

"The plant as permitted [by the Georgia Department of Natural Resources] would annually emit large amounts of air pollutants, including eight [million] to nine million tons of carbon dioxide," Fulton County Superior Court Judge Thelma Wyatt Cummings Moore wrote in her decision. "There was no effort to identify, evaluate or apply available technologies that would control CO2 emissions and the permit contains no CO2 emission limits…. Since CO2 is 'otherwise subject to regulation under the [Clean Air] Act,' a PSD [prevention of significant deterioration] permit cannot issue for Longleaf without CO2 emission limitations."

The decision marks the first time that potential greenhouse gas pollution has been cited as a factor in denying permission to build a new coal-fired power plant; it is also the first that hinges on a Supreme Court ruling issued last year that found the Clean Air Act gives the U.S. Environmental Protection Agency (EPA) the power to regulate carbon dioxide and other greenhouse gas emissions.

Environmentalists applauded the decision, noting that it is another in a recent string of victories in efforts to prevent and even reverse global warming. In the past such plans have been challenged for their emissions of other pollutants, such as acid rain–causing sulfur dioxide or smog-forming nitrogen oxides. But this time, the judge also considered the impact on climate change, says Bruce Nilles of the Sierra Club, which was among green groups that sued to stop construction of the Longleaf coal plant.

"She looked at the argument that we don't have to consider CO2 and called it 'untenable,'" Nilles says. "There are a whole range of other places where industry is trying to rush to build coal plants," including Indiana, Nevada, South Dakota and Wisconsin, among others.

Dan Riedinger, a spokesman for industry group Edison Electric Institute, says he expects Dynegy—the power company that proposed Longleaf—to appeal the decision. He notes that the industry does not disagree that greenhouse gas emissions should be regulated but believes this court decision was premature, because there currently are no such regulations on the books.

According to Riedinger, the U.S. needs coal-fired generation because alternatives cannot meet the country's energy demands. "Wind is growing phenomenally but still it's 1 percent of the pie and it's an intermittent source.... New nuclear will not be online for a decade at least and that leaves us with coal and natural gas," he says." [Natural gas] pipeline capacity is already being pushed and it's not like new wells are going to come online tomorrow with the concerns about drilling. There just aren't that many options, so coal has to be a big piece of [electricity generation]."

Coal currently provides roughly 50 percent of U.S. electricity, but the ruling is part of a larger trend toward rejecting any new coal-fired generators in the U.S., such as similar plants proposed in Kansas and Texas. Environmentalists have successfully argued that coal-fired power plants should not be constructed without greenhouse gas emission safeguards and that the EPA must regulate such emissions.

"It's part of an ongoing series of cases and challenges that are trying to get at whether the EPA not only has authority to regulate greenhouse gas emissions but whether" it is obligated to use that authority, says attorney Kyle Danish, director of the climate change practice at the Washington, D.C., law firm Van Ness Feldman. Environmentalists believe that the agency is obligated to use it, but the Bush administration, which has repeatedly clashed with them, disagrees.

"There is a stark contrast between Superior Court in Georgia versus the backflips EPA has done to avoid doing their job," Nilles says. "Today, wind is cheaper than coal and solar is getting closer. You don't need to build any coal right now."