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.