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Although some fear that the hydrogen economy, should it come, will be built atop of nuclear power plants, and others hope that solar and wind will provide enough juice to crack hydrogen from water, it may well turn out that the ideal source of hydrogen for fuel cells is the lowly bacteria.

We've mentioned microbial fuel cells before, tiny powerhouses that generate electricity while cleaning wastewater. But researchers at Penn State have taken the microbial fuel cell off in a new direction, pulling hydrogen out of wastewater at a rate four times greater than the standard fermentation process, and ten times greater than straight electolysis.

In their paper, the researchers explain that hydrogen production by bacterial fermentation is currently limited by the "fermentation barrier" -- the fact that bacteria, without a power boost, can only convert carbohydrates to a limited amount of hydrogen and a mixture of "dead end" fermentation end products such as acetic and butyric acids.

However, giving the bacteria a small assist with a tiny amount of electricity -- about 0.25 volts or a small fraction of the voltage needed to run a typical 6 volt cell phone -- they can leap over the fermentation barrier and convert a "dead end" fermentation product, acetic acid, into carbon dioxide and hydrogen.

Logan notes, "Basically, we use the same microbial fuel cell we developed to clean wastewater and produce electricity. However, to produce hydrogen, we keep oxygen out of the MFC and add a small amount of power into the system."

[...] The researchers call their hydrogen-producing MFC a BioElectrochemically-Assisted Microbial Reactor or BEAMR. The BEAMR not only produces hydrogen but simultaneously cleans the wastewater used as its feedstock. It uses about one-tenth of the voltage needed for electrolysis, the process that uses electricity to break water down into hydrogen and oxygen.

The process does produce CO₂, but as it's derived from biomass, the setup is closer to carbon neutral than other carbon dioxide generating methods of distilling hydrogen.

The big potential here is suggested in the final line of the excerpt: this process is significantly more efficient than straight electrolysis as a means of separating out hydrogen from water. One of the strongest arguments made in support of the use of nuclear plants for hydrogen generation is that the electricity generated by solar and wind will be insufficient to generate enough hydrogen. If this process does in fact work as described, it could be the breakthrough making solar & wind a competitive path to hydrogen generation.