Use smoke, mirrors to combat global warming?

Scientifically, it’s known as “air capture.” But the instruments being used have been dubbed “artificial trees” — even though these devices are about as treelike as a radiator on a stick. They are designed to mimic the role of trees in using carbon dioxide, but early renderings show them looking more like the creation of a tinkering engineer with lots of steel.

Nearly a decade ago, Columbia University professor Klaus Lackner, hit on an idea for his then-middle school daughter’s science fair project: Create air filters that grab carbon dioxide from the air using chemical absorbers and then compress the carbon dioxide into a liquid or compressed gas that can be shipped elsewhere. When his daughter was able to do it on a tiny scale, Lackner decided to look at doing it globally.

Newly inspired by the $25 million prize offered by Richard Branson, Lackner has fine-tuned the idea. He wants to develop a large filter that would absorb carbon dioxide from the air. Another chemical reaction would take the carbon from the absorbent material, and then a third process would change that greenhouse gas into a form that could be disposed of.

It would take wind and a lot of energy to power the air capture devices. They would stand tall like cell phone towers on steroids, reaching about 200 feet high with various-sized square filters at the top. Lackner envisions perhaps placing 100,000 of them near wind energy turbines.

Federico Barrai / Columbia University via AP This prototype of an air capture device was built by Columbia University researchers Klaus Lackner and Frank Zeman. Carbon dioxide would flow into the bowl at lower left, be separated with absorbent chemicals, then liquid carbon dioxide mix would flow into the bucket in the picture, bottom center, and air without carbon dioxide would flow out the top right corner container.

Even if each filter was only the size of a television, it could remove about 25 tons of carbon dioxide a year, which is about how much one American produces annually, Lackner said. The captured carbon dioxide would be changed into a liquid or gas that can be piped away from the air capture devices.

Disposal might be the biggest cost, Lackner said.

Disposal of carbon dioxide, including that from fossil fuel plant emissions, is a major issue of scientific and technological research called sequestration. The idea is to bury it underground, often in old oil wells or deep below the sea floor. The Bush Administration, which doesn’t like many geoengineering ideas is spending hundreds of millions of dollars on carbon sequestration, but mostly for power plant emissions.

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