Scientists at Pennsylvania State University (University Park) have developed a microbial fuel cell (MFC) that they say can obtain significant amounts of hydrogen gas from municipal, industrial, or agricultural wastewater while simultaneously cleaning the wastewater, according to a university press statement.
"While there is likely insufficient waste biomass to sustain a global hydrogen economy, this form of renewable energy production may help offset the substantial costs of wastewater treatment as well as provide a contribution to nations able to harness hydrogen as an energy source," said Bruce Logan, Kappe professor of environmental engineering at the university and one of the MFC's developers, according to the statement.
By themselves, bacteria are capable of generating only limited quantities of hydrogen, along with various "dead-end" byproducts of fermentation, through the conversion of carbohydrates, the press statement said. However, Logan and his research team discovered that assisting the bacteria with a small amount of electricity, about 0.25 volts, in an oxygen-free environment enabled them to convert such dead-end fermentation byproducts as acetic acid into carbon dioxide and larger quantities of hydrogen, the statement says. The MFC used in the research is based in part on one developed by Logan and his colleagues last year that demonstrated an ability to clean wastewater and also generate small amounts of electricity, the statement noted.
Using the new, electronically assisted MFC, "when the bacteria eat biomass, they transfer electrons to an anode," the press statement explained. "The bacteria also release protons, hydrogen atoms stripped of their electrons, which go into 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."
The research is described in a paper scheduled for publication in a forthcoming issue of the journal Environmental Science and Technology. For more information, send e-mail to Logan at [email protected]