In a country where approximately half the electricity consumed is generated by coal, TXU's move adds fuel to the debate over whether environmental concerns about coal's contribution to global warning should trump economic necessity.

"Litigation is continuing and it's going to be tough to get new coal-fired plants out of the gate," said Richard Price, who follows the coal industry for Westminster Securities.

"Retrofits of existing plants to reduce emissions will probably get done. But new plants? I am beginning to be skeptical," said Price.

Ian Synnott, an analyst with Natexis Bleichroeder, said TXU's decision pushes back some near-term plans. "There are still a number proposed, but they would have to scale back.

"If you were a coal company looking at TXU plants coming on, with 30 million tons, you may slow down your growth, but it is not a death blow by any means."

Another analyst, who declined to be identified, said: "Environmental regulations on carbon emissions I believe will slow down the construction of new coal-fired plants."

LITIGATION "EVERY STEP OF THE WAY"

Price said Peabody Energy Corp has been unable to build two coal-fired plants for several years, as opposition by environmental groups has tied up the plans in courts.

North Carolina just approved one of two planned 800-megawatt coal-fired power units Duke Energy wants to build, but only four U.S. plants have come on line since 2000, even though 155 were built between 1980 and 1999.

"The Sierra Club and other groups are litigating every step of the way," said Price. "It's an arduous process and no matter who wins, someone will appeal."

Getting plants approved takes 12-24 months, he said, followed by 2-3 years for construction. "I don't see any favorable impact for coal in that time frame."

There are 160-170 new U.S. power plants on the drawing board. Coal-based plants account for 50 percent of U.S. electric power and are predicted to increase their share to about 57 percent by 2030, according to the Energy Information Administration. That would bring U.S. coal production to 1.78 billion tons by 2030 from 1.1 billion tons in 2004.

"Environmentalists are pushing really aggressively and I was surprised how strong it was in Texas and it caught the market by surprise," said Synnott. "It raises question marks about the long-term outlook for coal. But I don't see it changing the outlook for coal as a low-cost alternative."

The key, many analysts say, is how quickly "clean-coal", carbon-capturing technology is developed for the new generation of power plants. Also coal gasification and coal-to-liquid technology is still a few years off.

"Until new technology makes coal-burning cleaner in 3-5 years, it's gonna be real tough to get new plants built," said Price.

CALL FOR A MORATORIUM ON COAL PLANTS

NASA climate scientist James Hansen recently called for a halt to building all coal-fired power plants until technology allows for the capture of emissions from burning coal.

"There should be a moratorium," Hansen, director of NASA's Goddard Institute for Space Studies, told the National Press Club, "Until we have that clean coal power plant, we should not be building them."

The mining industry acknowledges not all plants currently planned will get built. "We encourage conservation and a diverse mix of energy sources," said Carol Raulston, spokeswoman for the National Mining Association, which represents America's mining companies.

While the industry is working to promote public policies for cleaner air, "we still believe coal will be required for at least half of our electricity needs," Raulston told Reuters.

And with electricity demand growing by about 1 percent per year, analysts believe the country will have to accept more coal-fired plants. Synnott noted that some under construction and due for completion in 2010 to 2012 will add 11,000 megawatts (MW) of capacity. Current U.S. capacity is about 1 million MW.

"There are still opportunities to build new coal-fired plants, which are less expensive than natural gas," he said. "(But) We will need to see carbon control through regulations and a significant incentive to develop carbon capturing technology.