Biomass residues as raw material for dark hydrogen fermentation – A review

•H2 production from lignocellulosic biomass residues and waste is discussed.•Agricultural waste and agro-industrial residues are the main feedstocks.•The suitability of feedstocks for industrial-scale H2 production is differentiated.•A wide range of approaches to feedstock pretreatment and fermentation are in use.•Challenges for future research are reviewed.

It is now widely recognized that considerable amounts of hydrogen can be produced from renewable resources without using energy from fossil fuels. Biological processes and mainly bacterial hydrogen fermentation are considered as the most environmentally friendly alternatives for satisfying future hydrogen demand.In particular, biohydrogen production from agricultural and agro-industrial solid waste and wastewater is considered as highly advantageous as materials of this kind are abundant, cheap and biodegradable. Apart from economic considerations, the conversion of such materials into hydrogen is in many cases stimulated by the need to solve environmental problems. However, the suitability of various kinds of biomass-derived feedstock for industrial-scale hydrogen production is widely differentiated.In this paper, on the basis of numerous research contributions published mainly in the period 2008–2013, recent findings on the use of biomass residues and waste for biohydrogen production by bacterial fermentation are reviewed. The focus is on second generation (lignocellulosic) biomass substrates that are most widely available but can be fermented only after appropriate pretreatment which is rather costly at present and therefore requires further development. Research results pertaining to the use of selected sugar-containing and starchy residues are also mentioned as the conversion of these materials into biohydrogen is not in competition with food production, and their pretreatment is cheaper than that of lignocellulosic biomass.In addition to an extensive literature review, the state of the art in the area of pretreatment of biomass residues for hydrogen fermentation is evaluated, and the authors' view of challenges for future research is presented.