Green Hydrogen: Algal Biohydrogen Production

This chapter focuses on eukaryotic algal biohydrogen production. Green unicellular algae have a rare capability among organisms in that some have an ability to switch to a hydrogen-producing metabolism when environmental conditions become anaerobic. The process of hydrogen production is greatly accentuated in the light due to the role of the photosynthetic apparatus directing electron flow to hydrogenase enzymes located in the chloroplast. As hydrogen production through biological systems needs improvements to reach commercial targets, recent advancing technologies are included that cover bioreactor design, immobilized cultures, integrated systems, and metabolic pathways of hydrogen generation. Chlamydomonas reinhardtii has proved to be capable of sustaining the highest rates of hydrogen production among all tested algae. Currently, the process of hydrogen production involves growth of algae in an aerobic environment followed by the imposition of anaerobic conditions in the light.