Photosynthesis | Algal Hydrogen Production

Abstract

Hydrogen (H2) is an attractive renewable source of energy since it is the only gas that is carbon neutral. Indeed, when oxidized, H2 generates water and does not release CO2 in the atmosphere. Thus, it is the only source of energy that is 100% clean, nonpolluting and also it has better energy properties compared with other biofuels. There are many ways to produce H2 but most of the processes like biomass gasification/pyrolysis, electrolysis/thermochemical treatment of water or producing H2 from fossil fuels, are either energy intensive or produce pollutants like CO/CO2 (Khetkorn et al., 2017). Instead, biological hydrogen production is a promising approach to produce H2 since microbes produce H2 at ambient temperatures and atmospheric pressures, which does not require excessive energy (Das and Veziroǧlu, 2001). Green algae produce H2 by requiring sunlight, water and CO2, which makes this approach a very simple and ecologic way of H2 production (Ghirardi et al., 2000). Thus, in theory, photobiological H2 evolution is a promising sustainable technology that may satisfy some of the world´s energy requirement in the future (Chandrasekhar et al., 2015). Researchers are therefore very interested in understanding how hydrogen metabolism functions in algae and how H2 production can be optimized.