Feedstocks and Cases III: Biohydrogen From Algal Biomass (Macro and Microalgae)

The rapid depletion of fossil fuels along with the negative effects of their use in industries and combustion engines has necessitated the development of more sustainable energy sources such as biofuel. Biohydrogen gas, alongside other biofuels such as biodiesel, bioethanol, and biomethane, is gaining momentum as a clean energy option, owing to its high energy density, pollutant-free combustion products, and renewable nature. Though domestic and agricultural wastes, plants, and microbes are all useful sources of renewable biomasses for biofuel production, algal biomass has emerged as a potential raw material in this area. Algal biomass, which has predominantly been investigated for biodiesel production, is an ideal substrate for biohydrogen production. Furthermore, algae-based biohydrogen production has been described as a highly appealing strategy that can provide bioenergy sustainability through the generation of safe, clean energy with net-zero carbon dioxide emissions. This chapter, therefore, investigates the different types of micro- and macroalgae and their biochemical composition for biohydrogen production. Furthermore, the mechanisms of direct and indirect bio-photolysis, photo fermentation, and dark fermentation for biohydrogen production are described. The algal cultivation and harvesting techniques, pretreatment methods, and strategies to improve biomass and biohydrogen production are also briefly discussed.