April 25, 2005 3:35 PM PDT
Fuel cell pulls hydrogen out of bacteria
Researchers at Penn State University and Ion Power have developed a process for fuel cells that can harvest the hydrogen produced when bacteria consume organic matter. The process can yield four times more hydrogen than the ordinary fermentation process.
The process also doesn't require external oxygen and can use a wider variety of organic material, or biomass, than can be used in the fermentation process.
"We can theoretically use our MFC (microbial fuel cell) to obtain high yields of hydrogen from any biodegradable, dissolved, organic matter--human, agricultural or industrial wastewater," Bruce Logan, the Kappe professor of environmental engineering at Penn State, said in a 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."
The MFC can produce more hydrogen than normal because byproducts of the fermentation reaction can yield additional hydrogen. Typically in fermentation, bacteria consume carbohydrates and release hydrogen and "dead end" fermentation products like acetic acid that the bacteria can't break down.
By applying about 0.25 volts of electricity, the bacteria can leap over the so-called fermentation barrier and break the acetic acid into hydrogen and carbon dioxide.
In turn, a fuel cell produces power by stripping the electron from hydrogen atoms and then letting the remaining proton combine with other molecules.
Biomass, along with solar and wave power, is one of a number of alternative energy technologies that have begun to garner more interest from scientists and investors in the past two years.
The new approach is described in a paper by Logan and other researchers titled "Electrochemically Assisted Microbial Production of Hydrogen from Acetate" published by Environmental Science and Technology.