VOLKER STEGER / SCIENCE PHOTO LIBRARY VOLKER STEGER / SCIENCE PHOTO LIBRARY
Microbial fuel cell research. Researcher holding a two-chambered microbial fuel cell filled with a solution of organic acids. The left chamber contains Geobacter sp. bacteria that colonise an anode electrode. This is connected by a wire to a resistor, which in turn is connected to a cathode in the second chamber. The chambers are separated by a semi-permeable membrane. Geobacter oxidises the organic acids to produce carbon dioxide with surplus electrons transferred directly to the anode. These flow from the anode to the cathode and generate electricity. The membrane allows protons to migrate to the cathode chamber to combine with oxygen to form water. Microbial fuel cells may one day offer a cheap and renewable source of energy. Photographed in 2007 at the University of Massachusetts, USA.
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