Hydrothermal Gasification of Biomass for Hydrogen Production

Over 90 % of the world’s current hydrogen production capacity comes from the use of fossil fuels including coal, oil, and natural gas. In recent years, natural gas has become the major source of hydrogen. However, these fossil fuels are finite resources, produce greenhouse gases, and will eventually run out. Biomass presents a proven store of chemical energy, which can be converted into hydrogen by various processes. Hydrogen from biomass will be the world’s cleanest fuel, being produced from a renewable carbon-neutral source and its combustion produces no carbon emissions. Hydrothermal gasification has the potential to produce high quality and high yield of hydrogen from, especially, very wet biomass feedstocks and particularly the carbohydrate-rich types. Water is an important reactant for hydrogen production in biomass HTG, thereby avoiding dewatering of wet feedstocks. The chemistry of hydrogen production from biomass HTG largely depends on the reforming of biomass into simple organic molecules that are capable of being gasified into carbon monoxide. Hydrogen is then produced via water-gas shift reaction. The developments of various reactor designs and catalysts for high hydrogen selectivities are ongoing at various research centers around the world. A great deal of knowledge about this process is available, however, there are still challenges regarding the stability and recovery of catalysts, preprocessing of biomass for continuous operations and other process optimization and intensification issues.