National Geographic : 2010 Aug
• THE BIG IDEA |CARBON CAPTURE EVERY TIME YOU DRIVE TO WORK, or worse yet, fly on a plane, the vehicle emits carbon dioxide that will stay in the atmosphere, warming the planet for thousands of years. Does it have to? Trees can take CO back out again---but even covering the planet with forests wouldn't solve our problem, and there would be an awful lot of wood to preserve. (If allowed to rot or burn, trees release their carbon again.) Physicist Klaus Lackner thinks he has a better idea: Suck CO out of the air with "artificial trees" that operate a thousand times faster than real ones. They don't exist yet, and when they do, they probably won't look like real trees. But in Lack- ner's lab at Columbia University he and colleague Allen Wright are experimenting with bits of whitish-beige plastic that you might call artificial leaves. The plastic is a resin of the kind used to pull calcium out of water in a water softener. When Lackner and Wright impregnate that resin with sodium carbonate, it pulls carbon dioxide out of the air. The extra carbon converts the sodium carbonate to bicarbonate, or baking soda. CO scrubbers that rely on similarly simple chemistry already recycle human exhalations in submarines and space shuttles. Devising an economic way of scrubbing the outside air, though, is harder. Lackner's plastic offers two advantages, he says, over schemes that other labs are working on. It sponges up CO quickly--- the porous material has lots of surface area to contact the air---and holds on Pulling CO back out of the air might be easier than building jets and cars that don't emit it. the Skies Scrubbing (Continued) THE CO SITUATION Roughly a third of carbon dioxide emissions come from cars, planes, and other vehicles. Scientists are developing scrubbers to capture colorless CO from the outside air. THE SOLUTION In physicist Klaus Lackner's plan, a single scrubber, small enough to fit in a shipping container, could capture a ton of CO a day---the output of 75 average U.S. cars. CO spreads quickly, so scrubbing it out anywhere benefits everyone.