A microbial fuel cell uses harmless bacteria as a catalyst and impure, low-grade fuel to produce an electric current. The cell consists of two electrodes, known as the anode and cathode. The electrodes are separated by a Proton Exchange Membrane (PEM).
 A layer of bacteria or microbes is formed on the anode surface. The bacteria take an impure fuel supply (formaldehyde, lactic acid etc) as their food source and oxidize the fuel into carbon dioxide (CO2).
 The bacteria also produce electrons, which are transferred to the anode and conducted away from the anode through an external circuit. The flow of electrons produces an electric current or electric power. Meanwhile, protons are also produced on the anode and transported through the proton exchange membrane.
 In the cathode chamber, oxygen (O2 or air) is supplied; and the electrons, protons, and oxygen meet at the cathode surface to combine into water (H2O)
Many bacteria can function as a catalyst to turn fuel energy into electric power. In our work, we use Shewanella oneidensis MR-1, a type of bacteria isolated from sediments of Lake Oneida in New York.
The electric power produced by MFCs is currently too small to be of practical use. We envision that MFCs can have a bright future as a power source, if we can understand the science behind MFCs and engineer them to maximize their power production.
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QuickTime (324 kb)
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By Keren Albala
USC Division of Animation and Digital Arts (DADA).
Commissioned by the USC Wrigley Institute for Environmental Studies.
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