That essentially means that for every five coal plants using the technology, a sixth would be required just to power the capture and burial of carbon dioxide produced, said Hill & Associates analysts speaking on the sidelines of the McCloskey 2008 Coal USA conference.

Hill, a unit of Wood Mackenzie, is a leading coal industry consulting firm.

The challenge may not be widely understood by the public, analysts said.

"We're very aware of it," Connie Trecazzi, Hill's lead analyst for US coal research, said of the coal and power industry. "It's going to be very expensive."

Efforts continue to find a way to do carbon capture and storage, or CCS, as cheaply as possible.

There are four wells being drilled in the Southeastern United States to test and develop the technology, said Kenneth Nemeth, executive director of the Southern States Energy Board, a coalition of 16 US states and two territories that is promoting the project.

Industry cannot solve the problem alone, conference attendees said.

"Government will have to be involved. We've got to close this environmental loop somehow," said Colin Gubbin, chief consultant for The McCloskey Group, the firm for which the conference is named.

"We certainly do care," Gubbin said, rejecting criticism of the industry by Greenpeace and other environmental groups that profits outweigh humanitarian considerations.

Gubbin predicted continued effort to find ways to meet energy needs with minimal environmental cost. "Our effort will be to produce coal-fired power stations which satisfy Greenpeace," he said. (Reporting by Bruce Nichols, editing by Matthew Lewis)