Bird Lungs Inspire CO2-Scrubbing Filter

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Power plants and cars generate huge amounts of carbon dioxide, the greenhouse gas implicated in raising global temperatures. Since both industries are here to stay, scientists and engineers have been looking for ways to keep the CO2 out of the air.

Tasty Tech Eye Candy of the WeekAt the University of California, Irvine chemist Aaron Esser-Kahn thinks he has found a way to that and his innovation is inspired by bird lungs.

In birds lungs, inhaled air enters thousands of tiny tubes, called parabronchii, that transfer the oxygen to the blood. When birds exhale, the blood releases CO2 and it passes from the blood vessels to the air, while at the same time picking up any leftover oxygen. It’s a pretty efficient method of gas exchange because the parabronchii have extensive surface area, so a great deal of blood is in exposed to oxygen in the air.

Esser-Kahn’s idea is to pump the CO2 emitted by a power plant through a set of tubes, which would be made of a material that only lets the gas pass in one direction. The gas-filled tubes would be placed next to a second set of smaller ones, which would be filled with a liquid that CO2 dissolves in. As the waste gas passes by the smaller tubes, the liquid would absorb the CO2. At the end of the process, any emitted gas would be CO2-free. The trick, he told DNews, is to create extensive surface area that gives the CO2 more chances to diffuse into the liquid.

Part of that has to do with how the tubes are arranged. After running several computer simulations, the UC Irvine team found that a repeating square pattern was the most efficient design. They then fabricated and tested a small version of their gas-exchange device and found that it outperformed birds’ lungs by a factor of 50 percent.

Carbon Dioxide Turned Into Electricity

Esser-Kahn noted that a key advantage of this design is that it doesn’t have to be large — it’s possible to build this kind of artificial lung in a space small enough to fit in the back of a car, which means that not only power plants, but automobiles could get the CO2 out of the exhaust.

There are many possibilities for the material that would make up the air tubes, and that’s worth studying further, he said. Esser-Kahn’s findings were presented at the American Chemical Society meeting today.

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