Biohydrogen production by dark fermentation

Hydrogen has emerged as a promising alternative because it can be derived from a renewable energy sources and used in fuel cells with high efficiency and thus appears as the most promising alternative to fossil fuels. Among the various biological processes known to produce biohydrogen, dark fermentation offers an excellent potential for practical application such as treatment of organic wastes. However, commercialization of the process depends on advances in bioprocess design and optimization along with an understanding of the structure of biohydrogen producing communities and their improvement. The present paper highlights the major factors affecting biohydrogen production as well as the importance of consortium development and molecular understanding of the microorganisms involved in the process toward the realization of a stable hydrogen economy. Further, technological advancements based on improved bioreactor designs and integrated systems based on process economy have been discussed. Based on the recent research on dark fermentative hydrogen production, several new findings and achievements in the field have been highlighted.