The idea, called carbon capture and sequestration, or CCS, is at the cutting edge of attempts to dramatically reduce CO2 spewed by industrial plants into the atmosphere.

The technology exists, but is little tested and a group of energy companies, academics and state officials hope to make New York one of the field's trail blazers.

"We have the opportunity to demonstrate new technology that could be revolutionary internationally," Paul DeCotis, deputy head of energy policy for New York state, told a conference at Columbia University.

"We would love to be exporting to the rest of the world on carbon capture sequestration technology."

These are early days for the daring concept, in which CO2 gasses from coal factories and other sources of pollution are captured, rather than being allowed to pour skyward, and injected deep underground.

Despite global interest, high costs and lingering uncertainties about safety mean only a handful of projects are running. The world's first coal-fired power plant to use CCS opened last year in Germany.

New York's planned experiment at a coal-fired plant in Jamestown, in the far north of the state, has government backing. But new regulations and funding are needed before work can even start.

Experts at a conference hosted by Columbia's Earth Institute in New York city said the technology could be a planet saver when economies are turning increasingly to coal as an abundant, but dirty alternative to oil.

"Burning coal is not clean," said Jared Snyder, state assistant commissioner for air resources and climate change. "But with carbon capture and sequestration, the use of fossil fuels can at least be low carbon."

Jeffrey Sachs, director of the Earth Institute, said that CCS would be crucial for giant emerging economies like China and India.

China, said to be building one new coal-fired power plant a week, has overtaken the United States as the biggest producer of greenhouse gasses, with 80 percent of those emissions coal-related, Sachs said.

For India, the figure is 70 percent, he said.

"If it turns out that there is no such thing as clean coal ... we are in a world of massive crisis beyond where we are now, because a lot of the world depends on coal," Sachs said.

"If it turns out this technology doesn't work we're in a lot of trouble."

Some environmental activists, including Greenpeace, question the use of CCS, saying money would be better spent on moving from fossil fuels altogether to alternative sources such as wind or sun.

Even backers admit that potential risks have not yet been properly addressed.

The process involves injecting CO2 to depths of about 2,500 feet (760 meters) underground.

At that depth the pressure compresses the gas to what's known as supercritical state, a liquid-like form that is easily pumped.

The bad gas is then literally sponged up and stored, much like subterranean concentrations of natural gas and oil.

To work safely, storage areas must consist of porous rock yet lie capped under impenetrable layers of rock preventing leakage.

The US energy department estimates there is capacity in the United States to store one to four trillion tons of CO2, compared to annual emissions of about 5.5 billion tons.

But the absence of even a basic regulatory framework means they won't be used soon.

"Sequestering billions of tons of carbon dioxide and then having leakage rates that are significant would be devastating for this approach," Sachs said.

"You're going to have meet standards for non-leakage and those have never been worked out. How are we going to monitor this? Who's going to monitor this?"

Klaus Lackner, a Columbia geophysics professor and veteran specialist on CCS, said that since fossil fuels are not going away, carbon capture simply must be tried.

"Somebody has to go through and demonstrate these things are really valuable and there will be a lot of little things that have to be ironed out," he said.

"But the important (point) is: if we don't do it, we literally run into a brick wall."

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