| Re: Coping With The New CAFÉ Standards OR Defying the Laws of Physics [message #793293] |
Wed, 06 February 2008 09:43 |
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"Nate Nagel" <njnagel [at] roosters.net> wrote
> Never say never, it's hypothetically possible that someone could
> genetically engineer some microbe that would fart pure hydrogen instead of
> methane or whatever.
Scientists push bacteria to quadruple hydrogen production
Researchers at Penn State university have discovered a new way of
stimulating bacteria to extract hydrogen from bio-matter. The technique can
yield four times as much hydrogen as fermentation alone, and unlike
traditional fermentation, is not limited to carbohydrate based biomass.
Dr. Bruce Logan, professor of environmental engineering at Penn State, said
that the The microbial fuel cell (MFC) can theoretically be used to get high
yields of hydrogen from any biodegradable, dissolved, organic matter -
human, agricultural or industrial wastewater. At the same time, the process
would clean the waste water.
Many researchers are working on new ways of generating hydrogen, in
anticipation of it becoming a much more important fuel source in the future.
Logan commented: "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."
In a paper entitled Electrochemically Assisted Microbial Production of
Hydrogen from Acetate, the researchers explain that the amount of hydrogen
produced by bacteria is limited by the so-called fermentation barrier.
Without extra power, bacteria will produce hydrogen and other dead-end
products such as acetic and butyric acids.
With a small power injection, around 0.25 volts or about one tenth of that
required for electrolysis, the bacteria will break acetic acid down further,
releasing more hydrogen and some carbon dioxide.
Logan explains that the research team has used a microbial fuel cell that
was developed to clean waste water, and produce electricity. By preventing
oxygen from getting in, and adding a small amount of electricity, they found
it would generate hydrogen instead.
When the bacteria eat biomass, they transfer electrons to the anode. The
bacteria also release protons or hydrogen ions, which go into solution. The
electrons on the anode migrate via a wire to the cathode, where they are
electrochemically assisted to combine with the protons and produce hydrogen
gas.
The research is published online now, and is scheduled for publication in a
future issue of Environmental Science and Technology. ®
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