Monday, April 30, 2007

Non thermal production of hydrogen from biomass

Pieternel A.M. Claassen, Truus De Vrije, and Astrid Mars. Agrotechnology and Food Sciences Group, Wageningen UR, Bornsesteeg 59, Wageningen, Netherlands

Hydrogen is generally regarded as the energy carrier of the future because i) hydrogen is non-carbonaceous so no CO2 is produced during its utilization and ii) hydrogen is required to feed the fuel cells for efficient conversion to electrical power. Because of the increasing societal interest in the use of energy obtained from renewable resources, the development of renewable hydrogen production technologies is needed as hydrogen is presently produced from fossil fuels. These new technologies are based on the use of renewable sources, such as solar, geothermal and wind energy, hydropower and biomass.

There are two distinctly different options for the production of hydrogen from biomass: thermochemical and biological conversion. The dry weight content of the raw material more or less determines which option is best. In comparison to thermo-chemical conversion, biological conversion offers the advantage of yielding very pure hydrogen from wet biomass. Furthermore, a biological process can be economically feasible at a small scale, e.g. enabling hydrogen production near the site of biomass production.
We will present results obtained in the development of a two stage bioprocess for hydrogen production from biomass. The first stage is the conversion of carbohydrates to hydrogen and acetic acid by extreme thermophilic bacteria. The second stage is a photofermentation in which acetic acid is converted to hydrogen by phototrophic bacteria. Besides, the whole chain of pretreatment of biomass to fermentation and up-grading of the produced gas will be addressed.

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