Scientists push bacteria to quadruple hydrogen production

Amazing what a zap of electricty will do

By Lucy Sherriff • Get more from this author

Posted in Science, 26th April 2005 12:00 GMT

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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. ®