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Rethinking Carbon Dioxide (CO2): from a pollutant to a moneymaker

Three startup companies led by prominent scientists are working on new technologies to remove carbon dioxide (CO2) from the atmosphere. The scientific community is skeptical, but these entrepreneurs believe removing CO2 can eventually be profitable and help cool the planet.

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Global Thermostat has built a small demonstration plant at SRI International in Menlo Park, Calif., that today is sucking carbon dioxide from the air. About the size of a two-story elevator shaft, the pilot module sucks air past porous ceramic blocks known as monoliths, where amines bind with the carbon dioxide; the blocks are then lowered into a chamber where they are flooded with steam that releases the CO2, and the process then repeats itself.

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Finally, there’s Carbon Engineering, a startup run by David Keith out of Calgary, Alberta, the nerve center of Canada’s oil and gas industry. Bill Gates is an investor, as is his friend Jabe Blumenthal, a former Microsoft executive who is passionate about climate issues. So is N. Murray Edwards, an oil and gas billionaire. Keith, a physicist and climate scientist, has a joint appointment at the University of Calgary and at Harvard’s Kennedy School.

There’s no doubt that CO2 can be removed from the air using chemical processes. That’s how people can breathe on submarines or in spaceships. But the conventional wisdom among scientists is that it’s expensive and therefore impractical to do air capture on a global scale. Last year, a committee of the the American Physical Society produced a 100-page technology assessment, called "Direct Air Capture of CO2 with Chemicals," which estimated that the cost of an air capture system would be “of the order of $600 or more per metric ton of CO2.” The report concluded: “Direct air capture is not currently an economically viable approach to mitigating climate change.”

Howard Herzog, an MIT professor, argues that it makes more sense to capture CO2 from the flue gas of power plants, where concentrations are higher – about 12 percent for coal plants or 4 percent for natural gas plants. (In the air, CO2 levels remain under 400 parts per million, which means that less than 0.04 percent of the air is CO2.) Herzog says anyone who claims that they can capture CO2 from the air at a low cost is “either not being totally honest or they’re deluding themselves.” He co-authored a peer-reviewed study in the Proceedings of the National Academy of Sciences that estimated the cost of air capture at “on the order of $1,000 per ton of CO2.”

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