Comparison and Limitations of Biohydrogen Production Processes

Hydrogen gas can be produced by conventional methods such as thermo-chemical gasification, pyrolysis, solar gasification and supercritical conversion. For sustainable energy, it is mandatory to go for hydrogen production towards biological processes. In this review, the major biological processes discussed for hydrogen production are bio-photolysis of water by algae, dark fermentation, photo-fermentation of organic materials and the sequential dark and photo-fermentation processes. Major constraints in dark and photo-fermentative hydrogen production include the raw material cost, lower hydrogen yields and rates of hydrogen production. To overcome those constraints intensive research work was strongly recommended to be carried out on the advancement of these processes. It is revealed that the hydrogen yield could be even achieved greater with the effective pretreatment methods of inoculum and substrates. Hydrogen production can be improved particularly with pretreatment methods.