Hydrothermal Liquefaction of Lignocellulosic Biomass to Liquid Biofuels: A Review

The realization that fossil fuels are fast depleting has accelerated the search for an alternative energy source that is renewable, economical, and environmentally friendly. The situation has been exacerbated by global warming which has brought it home to all that there is a need to conserve energy and reduce collectively man’s global carbon footprint. The instability in the regions from which the fossil fuels are sourced is another caused for concern, also higher oil price threatens the independence and security of nation states all this are unacceptable, hence there is need to search for more stable alternative sources of energy which is CO2 neutral fuels from biomass, Biomass is a renewable; CO2- neutral source of energy. Lignocellulosic biomass a biomass from grass, wood, and other non-food components is being considered by biofuel industries as a good agent for biofuel production, several methods are being used for this conversion, Hydrothermal liquefaction found to be the most suitable for this process, this is because the products from the hydrothermal liquefaction are insoluble in water, more deoxygenated, and have higher energy densities which are beneficial to their uses as the liquid fuels. The bio-crude produced by the hydrothermal liquefaction has also shown high stability in accelerated aging tests. This article reviews on the liquid biofuel produce from the hydrothermal liquefaction process of lignocellulosic material, including the material sources and composition and the mechanism of the process.