March 23, 2009 -- Powered by sunlight, titanium oxide nanotubes can turn carbon dioxide into methane, which can be harnessed as an energy source, say scientists at Pennsylvania State University. The nanotubes could dramatically reduce CO2 emissions into the atmosphere and reduce our need for fossil fuels. "Right now there is lots of talk about burying carbon dioxide, which is ridiculous," said Craig Grimes of Penn State, who, along with Oomman Varghese, Maggie Paulose and Thomas LaTempa, co-authored a paper on the nanotubes in the journal Nano Letters. "Instead we can collect the waste out of the smoke stack, put it though a converter, and presto, use sunlight to change [CO2] back into fuel." The nanotubes are arranged vertically, almost like empty honeycomb. Over the top of the nanotubes sits a thin, reddish-brown layer of copper oxide. Both the copper and titanium oxide act as catalysts, speeding up reactions that take place naturally. When sunlight hits the copper oxide, carbon dioxide is converted into carbon monoxide. When sunlight hits the titanium oxide, water molecules split apart. The hydrogen freed from the water and the carbon freed from CO2 then recombine to create burnable methane, and the spare oxygen atoms pair up to create breathable oxygen. Related Content:
The scientists have created thin membranes that cover either 3.8 or 15.5 square inches. So far, those membranes have produced an estimated 66 gallons of methane, said Grimes. Adding more light and CO2 creates more methane. Grimes estimates that focusing the light collected from 1,100 square feet onto one of the membranes would generate more than 132 gallons of methane on a sunny day. This is solar power by another name, say Grimes and other scientists. Instead of storing electrons in batteries, Grimes' idea would store energy chemically. |
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