Microalgae for the Sustainable Production of Biohydrogen

Due to its advantageous qualities, such as high gravimetric energy density and clean combustion, biohydrogen has emerged as a notable renewable energy fuel. As one of the most potential fuels of the future, it requires a scientific, ecological, and environmental research before it can be used on a large-scale. The technologies for H2 gas production can rely on the use of certain renewable resources, but at present, large-scale methods rely primarily on the conversion of natural gas, heavy oils, naphtha, and coal, and only a small amount of H2 is produced through alternative methods such as electrolysis and biomass processing. Hydrogen may be produced in a completely environmentally friendly manner using technologies based on some living organisms, such as microalgae and bacteria. Hydrogen can be produced from microalgae by photosynthesis, photorespiration, fermentation, and thermochemical processes for biomass conversion. Both marine and terrestrial ecosystems are home to microalgae, which can be either prokaryotic or eukaryotic. Green algae (Chlorophyta) and diatoms (Bacillariophyta) are two examples of eukaryotic microalgae, while cyanobacteria (Cyanophyceae) are examples of prokaryotic microbes. Present chapter focuses on the mechanisms of production of Biohydrogen by microalgae, microalgal cultivation methods, types of reactors used for cultivation of microalgae, parameters influencing the production of Biohydrogen by microalgae, metabolic limitation and bottlenecks and economic evaluation for the Biohydrogen produced by Microalgae.