Current status, barriers and developments in biohydrogen production by microalgae

Biohydrogen presents tremendous potential as an alternate source of energy. Microalgae are cheaper and sustainable source of biohydrogen production. To produce hydrogen from microalgae, a two-stage method is adopted; stage-1 for carbon fixation and stage-2 for anaerobic digestion and hydrogen production. In-efficient anaerobic digestion, low hydrogen yield, and high cost are the fundamental issues of two-stage process. All these issues are attributed to the lack of understanding in key processes of hydrogen production, such as cultivation, immobilization, sulfur deprivation, and anaerobic digestion. This review gives an insight into the improvement of hydrogen yield by discussing the whole process of hydrogen production. This work also delineates the developments, barriers, and recent trends of biohydrogen production.