"Clean coal is a dirty lie," says environmentalist Robert F. Kennedy Jr., who calls President Barack Obama and other politicians who commit taxpayer money to develop it "indentured servants" of the coal industry.
Click here to read more of Brian Ross' interview with Robert F. Kennedy Jr. on the issue of clean coal.
Despite a series of expensive false starts and failures, President Obama proposed $3.4 billion in stimulus legislation to fund continued research on "clean coal" projects.
"Clean coal is like healthy cigarettes, it does not exist," says former Vice President Al Gore.
Click here to see the coal industry's commercials featuring President Obama.
"You can't tell me we can't figure out a way to burn coal that we mine right here in the United States and make it work," says Obama in the commercial, which ends with on-screen words: Yes We Can.
"It is the dirtiest of all fuels that we know of," said Bruce Nilles of the Sierra Club, which says talk of "clean coal" is designed to put off efforts to wean the country off coal.
"Today in the United States, most of the pollution is coming from coal burning power plants," said Nilles.
After 24 years and billions of dollars spent trying, there is still no operating coal power plant using "clean coal" technology.
"How many such plants are there?" asked former Vice President Gore at a the Clinton Global Initiative last year. "Zero. How many blueprints? Zero."
What was to be the premier "clean coal" project in Mattoon, Illinois, was abandoned last year by the Bush administration when the projected cost doubled to nearly $2 billion.
"It has suffered the same fate as other clean coal efforts, it simply became too expensive and doesn't work," said Tom Schatz, of the organization Citizens Against Government Waste.
A similar project in southern California, announced with great fanfare, was also abandoned after environmental concerns were raised by local residents.
A third "clean coal" project set for Indiana, was put on hold when the money ran out.
"Carbon capture, storage technologies are expensive," concedes Steve Miller of the American Coalition for Clean Coal Electricity, an industry group. "They are high risk ventures."
Half of the electricity in the United States is produced through burning coal, and given the worldwide dependence on coal, the industry says there's no choice but to keep trying to make clean coal technology work.
"It's the only way to have affordable, reliable energy and also meet our environmental ethic," said Miller of the industry group.
Despite the failures, "clean coal" got new life during last year's Presidential campaign when both major candidates endorsed the concept as they campaigned in coal-producing states.
The coal industry contributed $15.6 million to all federal campaigns in the last election cycle, according to the Center for Responsive Politics.