A prototype microbial fuel cell designed to generate a steady stream of electricity as it cleans wastewater now has been modified to produce hydrogen instead (Environ. Sci. Technol., published online April 22, dx.doi.org/10.1021/es050244p).
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WASTE NOT Liu (left) and Logan test their team’s new hydrogen-generating microbial fuel cell. |
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Environmental engineer Bruce E. Logan and postdoc Hong Liu at Penn State University originally designed their flow-through fuel cell to use bacteria living on the carbon anode to oxidize organic matter in wastewater. Hydrogen ions and electrons generated by the oxidation combine at the cathode with O2 from air to form water and generate electricity.
Bacteria have a “fermentation barrier” that limits their ability to completely degrade carbohydrates to CO2 and H2, but the Penn State researchers along with former Penn State student Stephen Grot of New Castle, Del.-based Ion Power Inc. determined that excluding O2 from the system and applying an additional 0.25 V to the circuit could overcome the barrier. The modified fuel cell efficiently generates H2 from acetic acid in the lab, but any type of organic matter in wastewater would work.
The researchers believe their “electrochemically assisted” fuel cell could supply enough H2 for energy production to significantly offset the cost of wastewater treatment.
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