Electronic Design

Microbe Turns Sugar Into Electricity

A tiny bug can be a big help in creating clean energy. Researchers at the University of Massachusetts Amherst have discovered a microorganism that can oxidize carbohydrates for stable, long-term electricity production. Rhodoferax ferrireducens transfers electrons directly onto an electrode as it metabolizes sugar into electricity. Its only byproduct is carbon dioxide. In past experiments, electricity-yielding microbes have converted 10% or less of available electrons. But the UMA team has been able to convert over 80%. Also, previous attempts with this technology have required an electron shuttle, or mediator, which is toxic. Rhodoferax ferrireducens, though, negates the need for a mediator by applying electrons directly to the electrode's surface.

"In the end, the electrons in the fuel cell are transferred to oxygen, so what we are really doing is putting a wire in between the microbe and the oxygen and harvesting this electron flow that would just go directly to oxygen," says Derek Lovley, professor and discoverer of the microbe. Also, Lovley notes that carbohydrates could become economical alternatives to fossil fuels in electricity production because sugars are a substantial component of many types of waste and carbohydrate-rich crops, such as corn, which are renewable energy sources. Theoretically using this method, a cup of sugar could power a 60-W light bulb for 17 hours, though Lovley admits that such applications are still in the future.

For details, go to www.umass.edu.

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