science environment

Cryogenics Could Capture and Freeze Carbon Dioxide

By Bonnie Stewart (OPB)
Aug. 28, 2012 5 a.m.
A coal-fired power plant in Shuozhou, Shanxi, China.

A coal-fired power plant in Shuozhou, Shanxi, China.

Kleineolive/Wikimedia Commons

University of Oregon researchers say they have found a way to reduce carbon dioxide emissions from coal-burning plants by more than 90 percent. Their biggest problem may be convincing the power industry to use it.

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The researchers have developed a formula that uses cryogenics to capture and control the dangerous chemicals pumped out of smoke stacks.

"What the system I’m proposing does is freeze the carbon dioxide; it goes directly from a gas to a solid," said University of Oregon physicist Russell Donnelly.

The frozen carbon dioxide would then be warmed and compressed into a gas that could be piped away and stored, he said. The process also will work to eliminate mercury from the waste stream and as much as 98 percent of the sulfur dioxide.

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Coal-powered plants generate roughly one-third of all U.S. emissions of carbon dioxide, according to a June 2012 report by the Congressional Budget Office. Carbon dioxide also is a major greenhouse gas that scientist have found contributes to global warming.

The U.S. Department of Energy funded Donnelly's research team, which included Charles E. Swanson, John W. Elzey and Robert E. Hershberger. Their findings were published recently in Physical Review E, a journal of the American Physical Society.

Even though cutting carbon dioxide would have major health and environmental benefits, Donnelly suspects power-plant owners won't be enthusiastic about adopting his method. He estimates installing the huge refrigeration systems could raise the cost of electricity by about 25 percent. For a large power plant, the cryogenic units also could be the size of football stadiums, he said.

China likely will be the first country to try freezing smokestack emissions, Donnelly said. One of his colleagues already has introduced the idea there.

In Australia and Canada the natural gas industry is already using cryogenics to remove carbon dioxide from small-scale wells, Donnelly said.

In 2011, coal was used to generate 42 percent of the 4 trillion kilowatt hours of electricity produced in the United States, according to the Energy Information Administration. Natural gas accounted for 25 percent, nuclear 19 percent and renewable 13 percent.

The University of Oregon study is just one of dozens of federally funded projects trying to find solutions to the negative impacts of burning coal.

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