Current trends on the advancement and limitation of biohydrogen research: An exclusive overview

Hydrogen is believed to be the most potential energy-resources in the coming time due to its high energy density and zero greenhouse gas footprint. Among all types of hydrogen production processes, bio-based hydrogen (biohydrogen) generation processes are found to be relatively cleaner than the other processes. In this review article current biohydrogen generation processes are critically reviewed to understand the critical factors associated with the hydrogen generation along with the challenges to be eliminated. In this review the factor like types of substrates, their pretreatment, bioreactor design, and other parametric influences on the overall biohydrogen production is discussed. Also, impact of different catalyst in hydrogen production has been discussed in this topic. The review indicated that most of the current hydrogen-research are focused on the development of processes with high yield. However, one of the major drawbacks of biohydrogen process is purification of H₂ from the gaseous mixture produced by microbial strains. To establish the biohydrogen production processes as promising as it considered to be there needs to have a robust purification system. Also, this review highlights that more rigorous research on the biohydrogen storage and its hazard analysis is necessary to meet the future expectation of hydrogen use in mass-scale.