Recent proposed coal plants include TXU Corp.'s plan to build 11 in Texas and NRG Energy Inc.'s plans to build in Delaware and either New York or Connecticut.

The rush to build coal plants is also boosted by the lack of US regulations on carbon dioxide, according to a report by the US Public Interest Research Group, a network of state-based advocacy groups.

But there is little chance that all 153 proposed plants, which are tracked by the Department of Energy's National Energy Technology Laboratory, will get built, an industry group spokesman said.

"They're clearly overstating the impact," said Frank Maisano, spokesman for the Electric Reliability Coordinating Council. He said that some of the plants, if built, would cancel other ones out.

But even if some of the plants don't get built, global warming emissions will worsen, PIRG said.

"This list is illustrative of a phenomenon -- which is after years of no coal plants being built, all of a sudden there's a flurry of plans for them," said Rob Sargent, an energy analyst at PIRG. He said that by the 2020s, coal-fired capacity could reach the highest levels in 40 years.

PIRG said in the report that only 16 percent of the proposed plants would use high-tech coal gasification which burns the fuel more efficiently than traditional plants. It also said none of the plants would use carbon dioxide capturing equipment. The new technique collects the heat-trapping gas from coal to keep it from reaching the atmosphere by possibly burying it underground.

PIRG said that the planned plants would require US$137 billion in investments which would be better spent in energy efficiency technology and alternative energy such as wind power.