The underground option for CO2

There's growing momentum behind the idea of turning the carbon dioxide spewed from coal into a liquid or a solid and storing it in caves.

INDIAN SPRINGS, Calif.--There may be a solution to the energy problem under our feet. Unfortunately, the answer is coal.

America is the Saudi Arabia of coal, said Ira Ehrenpreis, a partner at venture capital firm Technology Partners. Besides being abundant, the coal in the United States also has less sulfur than geologists find in places like India, but it still produces tons of carbon emissions when it burns.

The solution may be to turn the carbon dioxide that's emitted as a waste product into a liquid or a solid and then store it underground, said panelists at the Clean Tech Investor Summit taking place here this week.

"Carbon capture is easy," said Dan Arvizu, director of the National Renewable Energy Laboratory. Capturing the carbon from the smokestacks of coal-burning electrical plants would add about 20 percent to a consumer's electrical bill.

What happens to that captured carbon dioxide? Fuel giant British Petroleum and others have discussed storing the gas in depleted oil wells and caves. But those underground storage options aren't airtight.

"If only 1 percent leaks out a year, that means that in a century it's all out," Arvizu said.

To that end, the NREL has begun research into projects to turn the gas into a liquid or solid. "The research is just starting out," Arvizu said, but the idea is intriguing.

Ray Lane, a partner at venture firm Kleiner, Perkins, Caufield and Byers, said at the conference that he too liked the idea.

"It's how it was sitting in the ground (as a liquid or solid) for millions of years," he said. "I like coal."

Lane also regaled the audience with stories of hunting birds in South Dakota with friends who drive SUVs that can run on E85, a blend of gas that is mostly ethanol. A self-described Republican environmentalist, Lane said that this group was ahead of the curve.

But consumer surveys tend to show that most owners of E85-capable vehicles just fill their cars up with regular gas because . Only about 1 percent of U.S. gas stations have it.

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