http://technology.newscientist.com/article/dn12731-grassmunching-bugs-could-charge-rural-phones.htmlGrass-munching bugs could charge rural phones
17:56 03 October 2007
NewScientist.com news service
Mason Inman
A bacteria-powered cellphone charger could keep people in developing countries talking, even when they live far from the grid.
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To tackle the problem, a team of students from Massachusetts Institute of Technology, Boston, US, has designed a microbial fuel cell (MFC) that runs on plant waste. Their prototype won the $5,000 first prize in a contest called MADMEC, which was sponsored by Dow Chemical to encourage new uses of materials that allow alternative or non-traditional sources of energy.
Cellulose power
MFCs use electrons released by feeding bacteria on sugars, starches, and other organic material, to produce electricity.
They have potential in many areas, from sewage plants that are powered by the sludge they are processing, to powering an MP3 player, like Sony's prototype unveiled in August 2007, or even aquatic robots.
The team's BioVolt prototypes run on less-refined fuel than Sony's glucose-gobbling battery, the bacteria instead digest the cellulose in plant waste. "There's a lot of cellulosic feedstock in rural areas," team member Gerardo la O' says.Novel catalyst
But for MFCs to be competitive in developing countries, they need to be cheaper. "We're using a non-platinum catalyst, so that allows us to lower the cost," la O' says. Most MFCs use platinum as a catalyst to combine oxygen with electrons and hydrogen ions into water, as part of the electrochemical reaction that produces power.
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Although far from ready to be shipped to rural Africa, "as a proof of concept, BioVolt is pretty extraordinary," says Michael Tarkanian, a materials scientist at MIT who organised the MADMEC contest. "They used a lot of materials science to drive the price down."
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