The projects would help the power industry begin to understand which geologic formations are best for burying the gas, said the study titled "The Future of Coal." It said the sequestration projects would cost less than US$1 billion total.

"If we don't have carbon capture and sequestration coal has a very bleak future," John Deutch, a former director of the Central Intelligence Agency under Bill Clinton, MIT professor, and co-author of the study, said in an interview. There are about 150 coal plants planned in the United States but not one of them would be able to capture and bury CO2.

The United States, which has enormous reserves of cheap coal and gets 50 percent of its power from the fuel, has not agreed to regulate emissions of heat-trapping gases -- unlike all other developed countries save Australia. But the formation of a national plan in the world's top greenhouse gas emitter looks more likely as US 2008 presidential contenders in both parties favor mandatory regulations, and states on both the East and West coasts form plans to cut output of the gases.

Energy companies in Texas already inject CO2 from natural formations into oil and gas fields to boost energy production. But the study said those reservoirs do not have the capacity to store the volume of the gas from power plants that would lower overall US emissions and begin to tackle climate change. It said saline formations about 1 kilometer underground, which are widespread throughout the country, have the most potential to store the gas.

Deutch said that if coal-burning power plants don't get a head start on burying emissions it could plague them in the future. It could be much more troubling than the nuclear industry's lack of foresight on radioactive waste disposal, one of the problems that has slowed further US development in that industry, he said.

"If you don't pay attention to it at the beginning ... later on it ends up to be a more unpleasant surprise than it has to be," said Deutch.

The technology to capture emissions at power plants is more expensive than burying the gases. The report confirmed a 2005 study by scientists who advise the UN that carbon capture at power plants and sequestration could boost power bills by 20 to 25 percent.

"We're not happy about that, but the alternatives are more expensive," said Deutch. Nuclear power plants cost billions of dollars. Wind and solar will play a bigger role in coming years, but are not cheap enough yet to meet growing demand, he said.

The report recommended that China, which is building about two 500-megawatt coal plants a week, build at least two demonstration sequestration projects.

Deutch said China also has widespread underground saline formations, but that another growing coal burner, India, does not. "India has a more serious problem and lower quality coal, both issues make sequestration more difficult," he said. But the effort will have to be global.

"If we go ahead and do this diligently and the Chinese and Indians do not, global warming danger has not been averted," he said.