Biofuels & Bioenergy

Hydrogen (H2) is considered the “energy of the future” due to its high energy content (143 MJ/Kg) which is 5.3-fold and 3.3-fold higher than that of ethanol and gasoline, respectively, and non-polluting nature (water is the only product). An environmentally friendly and potentially viable alternative for sustainable H₂ production is presented through the utilization of renewable, low-cost cellulosic materials (energy crops and biomass waste) employing robust microorganisms with high substrate utilization efficiency and high H₂ yields. The H₂ production potential of the extreme thermophile Caldicellulosiruptor saccharolyticus DSM 8903 was examined on switchgrass and municipal solid waste. It was demonstrated that C. saccharolyticus can ferment switchgrass to H₂ in one step without any physicochemical or biological pretreatment, whereas H₂ production from glucose reached the theoretical maximum for dark fermentation of 4 mol H₂/mol glucose. The thermophilic consolidated bioprocessing capabilities of C. saccharolyticus offer opportunities for significant savings of capital and operational expenses in excess of 50% by consolidating four processing step into a single operation.