New technique creates cheap, abundant hydrogen

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Novel technique for cheap and abundant hydrogen



CHICAGO (AFP) - US researchers have developed a method of producing hydrogen gas from biodegradable organic material, potentially providing an abundant source of this clean-burning fuel, according to a study released Monday.

The technology offers a way to cheaply and efficiently generate hydrogen gas from readily available and renewable biomass such as cellulose or glucose, and could be used for powering vehicles, making fertilizer and treating drinking water.
Numerous public transportation systems are moving toward hydrogen-powered engines as an alternative to gasoline, but most hydrogen today is generated from nonrenewable fossil fuels such as natural gas.
The method used by engineers at Pennsylvania State University however combines electron-generating bacteria and a small electrical charge in a microbial fuel cell to produce hydrogen gas.
Microbial fuel cells work through the action of bacteria which can pass electrons to an anode. The electrons flow from the anode through a wire to the cathode producing an electric current. In the process, the bacteria consume organic matter in the biomass material.
An external jolt of electricity helps generate hydrogen gas at the cathode.
In the past, the process, which is known as electrohydrogenesis, has had poor efficiency rates and low hydrogen yields.
But the researchers at Pennsylvania State University were able to get around these problems by chemically modifying elements of the reactor.
In laboratory experiments, their reactor generated hydrogen gas at nearly 99 percent of the theoretical maximum yield using aetic acid, a common dead-end product of glucose fermentation.
"This process produces 288 percent more energy in hydrogen than the electrical energy that is added in the process," said Bruce Logan, a professor of environmental engineering at Penn State.

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Link to study, ..

Sustainable and efficient biohydrogen production via electrohydrogenesis -- Cheng and Logan, 10.1073/pnas.0706379104 -- Proceedings of the National Academy of Sciences

Abstract of the actual study, ..

SUSTAINABILITY SCIENCE
Sustainable and efficient biohydrogen production via electrohydrogenesis
Shaoan Cheng and Bruce E. Logan^*
Department of Civil and Environmental Engineering, Pennsylvania State University, University Park, PA 16802
Edited by James M. Tiedje, Michigan State University, East Lansing, MI, and approved September 17, 2007 (received for review July 9, 2007)
Abstract
Hydrogen gas has tremendous potential as an environmentally acceptable energy carrier for vehicles, but most hydrogen is generated from nonrenewable fossil fuels such as natural gas. Here, we show that efficient and sustainablehydrogen production is possible from any type of biodegradable organic matter by electrohydrogenesis. In this process, protons and electrons released by exoelectrogenic bacteria in specially designed reactors (based on modifying microbial fuel cells) are catalyzed to form hydrogen gas through the addition of a small voltage to the circuit. By improving the materials and reactor architecture, hydrogen gas was produced at yields of 2.01–3.95 mol/mol (50–99% of the theoretical maximum) at applied voltages of 0.2 to 0.8 V using acetic acid, a typical dead-end product of glucose or cellulose fermentation. At an applied voltage of 0.6 V, the overall energy efficiency of the process was 288% based solely on electricity applied, and 82% when the heat of combustion of acetic acid was included in the energy balance, at a gas production rate of 1.1 m³ of H₂ per cubic meter of reactor per day. Direct high-yield hydrogen gas production was further demonstrated by using glucose, several volatile acids (acetic, butyric, lactic, propionic, and valeric), and cellulose at maximum stoichiometric yields of 54–91% and overall energy efficiencies of 64–82%. This electrohydrogenic process thus provides a highly efficient route for producing hydrogen gas from renewable and carbon-neutral biomass resources.