Carbohydrate-to-hydrogen production technologies: A mini-review

Hydrogen is a promising future with high-energy utilization efficiency and a clean energy carrier featuring lower emissions of pollutants as compared to the liquid fuels used in internal combustion engines. Hydrogen fuel production from renewable biomass carbohydrates has a better future perspective as it achieves zero CO2 emissions lifecycle and hence will reduce global warming, acid rain and improve rural economy. Herein, we present H2 production from biomass carbohydrates by using different types of catalysis such chemical catalysis, biocatalysis, and their combinations. The chemical catalysis includes aqueous phase reforming, pyrolysis, gasification, and gasification in supercritical water. The biocatalysis includes electrohydrogenesis, anaerobic fermentation, photo-fermentation, cell-free synthetic pathway biotransformation (cell-free SyPaB). Since, energy efficiency or hydrogen yield is the most critical economic factor for H2 production, cell-free SyPaB which can produce 12H2 / glucose equivalent appears to be a potential solution for H2 production. In addition, the pathway design of cell-free SyPaB has several advantages such as use of availability of stable enzymes and coenzymes building blocks, less expensive bioreactors, modest reaction conditions, acceptable reaction rates, metabolic load balancing, in-situ monitoring, absence of cell membrane, real-time control, and reduced toxicity effects. Along with all these advantages, cell-free SyPaB addresses few more challenges associated with costly infrastructure, distribution, storage and safety.