A fuel cell produces hydrogen from dissolved organic matter
us scientists who developed a microbial fuel cell (mfc) to simultaneously clean wastewater and produce electricity, have now altered the cell to produce almost four times as much hydrogen directly out of biomass than can be generated typically by fermentation alone. Hydrogen can be used as a clean fuel.
In the new mfc, when the bacteria eat dissolved biomass (such as wastewater), they transfer electrons to an anode -- the positive terminal of a cell. The bacteria also release protons -- hydrogen atoms stripped of their electrons -- into the solution. The electrons on the anode migrate via a wire to the cathode, the other electrode in the fuel cell, where they are electrochemically assisted to combine with the protons and produce hydrogen gas. This requires connecting the positive terminal of a power supply that provides at least 0.25 volts to the anode and the negative pole to the cathode.
Hydrogen production by bacterial fermentation is currently limited by the "fermentation barrier" -- the fact that bacteria, without a power boost, can only convert carbohydrates to a limited amount of hydrogen and "dead end" products such as acetic acid.
The new approach appears in a paper by Bruce Logan and other researchers at the Pennsylvania State University in the us, released online currently and scheduled for a future issue of Environmental Science and Technology.
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