The production of hydrogen gas from biomass to meet the foreseen demand arising from the expected introduction of fuel cells is envisaged. Apart from the well-known gasification method, fermentative conversion can also be applied for this purpose. Two options of the latter method, that is, thermophilic fermentation and photofermentation can be combined in a two-stage process in which about 70% of hydrogen present in biomass is converted to gaseous form. It is expected that this process can be applied in decentralized, small-scale production units.
The main stages of the fermentative hydrogen production process are the following:
– biomass pretreatment to give fermentable feedstock and non-fermentables,
– thermophilic fermentation in which fermentable feedstock is converted to hydrogen gas and organic acids,
– photofermentation in which the organic acids are converted to hydrogen gas,
– upgrading of hydrogen gas to meet product specification,
– separation and treatment of non-fermentables.
In order to develop a sustainable hydrogen production route based on fermentation, it is necessary to improve the existing knowledge of these process stages and to carry out process optimization studies. As a major step in this direction, the European research project HYVOLUTION has been organized under the 6th Framework Programme of the EU.