Hydrogen production by Chlamydomonas reinhardtii under light-driven and sulfur-deprived conditions: Using biomass grown in outdoor photobioreactors at the Yucatan Peninsula

Photosynthesis is the ultimate natural process that supports all the biofuels generation. Photosyntetic production of hydrogen by microalgae is very attractive from the renewability point of view. Moreover, it faces several challenges: since the process itself has a low yield, a large number of considerations should be studied to optimize the hydrogen production at the lowest cost. In this work, wild-type Chlamydomonas reinhartii was grown outdoors in the Yucatán peninsula. Three different diameters of tubular photobioreactors (PBRs), two autotrophic culture media, as well as two seasons of the year were analyzed. From these variables, it was determined that the best biomass yield was during the winter season and with the Sueoka culture medium. Statistical significance differences were not found for the diameters of the PBRs. During growth, the biomass was exposed to natural light-dark cycles and at the end of the exponential phase of growth it was harvested with superabsorbent polymers. This biomass was able to produce hydrogen under anaerobic conditions in Tris-Acetate-Phosphate culture medium in indoor PBRs exposed to continuous artificial illumination. Experiments with different initial biomass concentrations in the anaerobic PBRs showed direct relationship with the hydrogen production profile.