Scientists Use Sunlight To Make Fuel From CO2

The idea of recycling carbon dioxide is not new, but has generally been considered too difficult and expensive to be worth the effort. But with oil prices exceeding $100 per barrel and concerns about global warming mounting, researchers are increasingly motivated to investigate carbon recycling. Los Alamos Renewable Energy, for example, has developed a method of using CO2 to generate electricity and fuel. S2P uses a solar reactor called the Counter-Rotating Ring Receiver Reactor Recuperator, or CR5, to divide carbon dioxide into carbon monoxide and oxygen. "It's a heat engine," Stechel said. "But instead of doing mechanical work, it does chemical work." Lab experiments have shown that the process works, Stechel said. The researchers hope to finish a prototype by April. The prototype will be about the size and shape of a beer keg. It will contain 14 cobalt ferrite rings, each about one foot in diameter and turning at one revolution per minute. An 88-square meter solar furnace will blast sunlight into the unit, heating the rings to about 2,600 degrees Fahrenheit. At that temperature, cobalt ferrite releases oxygen. When the rings cool to about 2,000 degrees, they're exposed to CO2. Since the cobalt ferrite is now missing oxygen, it snatches some from the CO2, leaving behind just carbon monoxide -- a building block for making hydrocarbons -- that can then be used to make methanol or gasoline. And with the cobalt ferrite restored to its original state, the device is ready for another cycle. Fuels like methanol and gasoline are combinations of hydrogen and carbon that are relatively easy to synthesize, Stechel said. Methanol is the easiest, and that's where they will start, but gasoline could also be made. However, creating a powerful and efficient solar power system to get the cobalt ferrite hot enough remains a major hurdle in implementing the technology on a large scale, said Aldo Steinfeld, head of the Solar Technology Laboratory at the Paul Scherrer Institut in Switzerland, in an e-mail. ... http://www.wired.com/science/discoveries/news/2008/01/S2P

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