Penn State researchers have demonstrated that hydrogen can be recovered from wastewater. An article on the Renewable Energy Access Website tells about the process which can produce four times the hydrogen than can be produced directly by fermentation. They use the same microbial fuel cell (MFC) that they have developed to clean wastewater and produce electricity. To produce hydrogen they keep the oxygen out of the MFC and add a small amount of power to the system. They call their hydrogen producing MFC a BioElectricrochemically Assisted Microbial Reactor or BEMAR.
Only a tiny amount of electricity, about 0.25 volts is applied across an annode and a cathode inserted in the BEMAR. In a university press release the process is described in more detail. When bacterial eat the biomass contained in wastewater, they transfer electrons to the anode. The bacteria also release protons which go into the solution. The electrons migrate via a wire to the cathode where they are eltrochemically assisted to combine with the protons to form hydrogen gas.
A paper titled "Electrochemical Assisted Microbial Production of Hydrogen from Acetate" fully describes the approach. The paper was authored by Hong Liu, a post graduate researcher; Stephen Grot, president and founder of Ion Power, Inc.; and Dr Bruce Logan, professor of environmental engineering and inventor of the MFC. Grot is a former Penn State student who suggested the idea of modifying the MFC to generate hydrogen.
Links at Logan's website reveal the following: The process releases about 50% of the hydrogen locked up in the biomass. At this efficiency, if all the domestic wasetewater was treated by this process, about 4000 MW of electricity could be produced. While this process will not sustain a hydrogen economy, it could offset the substantial costs of wastewater treatment.
This sounds like a very useful and environmentally friendly use of hydrogen if it all works out. How about a fuel tank full of wastewater providing power for your car?
What about using septic tanks that naturally exclude oxygen for power suplementation and hydrogen production for heating?
Posted by: Tim Callahan | October 07, 2005 at 03:06 PM