Giant carbon vacuums could cool Earth

from the April 19, 2007 edition

Clean Air: In order to capture all of humanity’s yearly carbon emissions, an area the size of Arizona would have to be planted with 250,000 300-foot high carbon-capturing devices. Courtesy of Stonehave Productions

Giant carbon vacuums could cool Earth

Tall metal structures would scrub the greenhouse gas from the air.

By Moises Velasquez-Manoff | Correspondent of The Christian Science Monitor

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For a decade, Columbia University physicist Klaus Lackner has written about a way to stave off – and even reverse – climate change from human-emitted carbon dioxide: Scrub it directly from the atmosphere. And now, after three years of R&D, a Tucson, Ariz., company has unveiled a working model of a device based on Professor Lackner's idea.

Nine-feet tall and able to remove 50 grams of CO2 from the atmosphere daily, the device is a far cry from Lackner's vision of a 300-foot-tall structure sucking 15,000 cars' worth of emissions from the atmosphere yearly. But it fulfills the basic criterion of removing more carbon than it emits.

"We've got the way," says Allen Wright, president of Global Research Technologies, LLC, the company that developed the contraption. "Now we have to get the will."

Important details such as where to store the captured CO2 have yet to be resolved. And the carbon-capping regulation that would make such a device profitable has yet to be implemented. But with predictions of a 5.7 degrees F. increase and changes in rainfall patterns by century's end, the potential benefits of a direct control over atmospheric CO2 are evident to all. Although far from cost-effective, the technology exists to capture CO2 at coal-fired electric plants. But nothing yet exists for mobile sources such as cars and planes that account for about one-third of emissions. Capturing carbon directly from the atmosphere, says Lackner, precludes the need for cumbersome – and impractical – storage devices on vehicles. In theory, this technology could both offset emissions from human activity and remove greenhouse gases accumulated since the industrial revolution.

And it could allow civilization to burn through the estimated 100 to 200 years' worth of coal reserves without disastrously changing the climate.

"Fossil fuels will run out not because of limited resources but because of the environmental impact," says Lackner. "If I can solve that impact, I have basically increased the resource base by a vast amount."

But Lackner's approach is not without its critics. Some surmise that the chemical processes involved in capturing CO2 directly from the air demand too much energy. Others think that, because it's likely decades away from functional deployment, the mere suggestion of such technology at this point is a distraction, and could divert resources away from more concrete steps. One scientist says that more can be done to harness photosynthesis, Mother Nature's carbon-capturing process, instead.

Although CO2 is relatively scarce in the atmosphere, only 380 molecules for every million, Lackner figures there's enough to make going after it feasible. He imagines it this way: Assuming a brisk breeze, one American's yearly share of emissions – 22 tons – would pass through a medium-size window. By extrapolating, he calculates that, in order to capture all of humanity's emissions, an area the size of Arizona would have to be planted with some 250,000 of his proposed devices. Each would capture 90,000 tons of CO2 yearly.

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