Some environmental groups support a planned $1.8 billion Illinois coal plant that advocates say can be nearly pollution-free.

Others just plain don't believe the claims.

“There is going to be a waste stream coming out of this plant. It’s just not going to be a smokestack as we know it,’ said Tim Montague of Climate Justice Chicago, a coalition of eight environmental organizations.

Construction is expected to start early next year on FutureGen, an experimental clean-coal plant in the central Illinois city of Mattoon, though the U. S. Department of Energy has not yet signed off on it since the price went up.

Coal provides about half of the nation’s and the state's electricity, but it’s a smelly, nasty process that releases mercury, sulfur dioxide, particulates and the greenhouse gas carbon dioxide into the environment. This plant is a federal demonstration project to test the viability of carbon capture and storage as a means of "cleaning up" coal.

Instead of burning the coal, FutureGen would break it down into gas, using heat, pressure and steam. Many of the byproducts created by this process would be captured and re-used -- the hydrogen, for example, to power hydrogen fuel cells.

FutureGen would still create carbon dioxide, but would pump it deep into the earth rather than blow it out a smokestack.

“Instead of burning the coal and generating those emissions, we are looking at cleaner ways of capturing those emissions and storing them underground,” said Mary O’Connell of the Chicago-based nonprofit Joyce Foundation, which has helped fund research into this and similar technologies.

Josh Mogerman of the National Resource Defense Council’s Chicago office said opposing the technologies behind FutureGen is idealistic, but not realistic in a nation looking at coal as an alternative to foreign oil.

“Like it or not, it’s just politically implausible that there’s not going to be an energy economy that doesn’t include coal in the near future,” he said.

The "clean coal" theory depends on the carbon dioxide all staying underground forever.

“There is a whole protocol of measuring and verification to make sure the process is successful,” FutureGen Alliance spokesman Lawrence Pacheco said.

But forever is a claim Montague thinks FutureGen cannot make. He is concerned that even small leaks could break out over the decades or centuries. Instead of preventing global warming, the process could just push it to future generations, he said.

“We’re turning the geological part of the earth into a waste dump,” Montague said.

Under the current timeline, construction is set to start in early 2009, lasting until the end of 2012.

The main environmental concern Mattoon City Administrator Alan Gilmore has heard from residents is not about the plant, but about increased train traffic carrying coal to the plant. Gilmore said the two extra trains a week with 50 to 75 cars per train is not significant.

Gilmore hopes FutureGen could brighten the future for Mattoon, a 17,000-population city that lost almost 1,000 residents between 2000 and 2006, the Census Bureau estimates.

A University of Illinois-Carbondale study showed FutureGen could bring 1,300 temporary construction jobs, 150 permanent jobs and 1,225 “spin-off” jobs to the area.

“We have been real stagnant as far as growth goes and we are looking to grow as a community. We’re hoping FutureGen brings the growth we are looking for,” Gilmore said.