Biofuel Production Potential for Different Waste Streams as a Form of Waste to Energy Through Hydrothermal Liquefaction: Present State of the Art Review and Future

Day-to-day increases in environmental pollution caused by the wide-ranging use of fossil fuels have raised concerns about the usage of traditional fossil fuels, and thus the search for alternative renewable and environmentally friendly fuel sources have started over the past few generations. Conversion of waste to bio-fuel can be a promising approach to the waste-to-energy (WtE) technology. This article briefly enlightened the potential of different waste streams using hydrothermal liquefaction (HTL) conversion technology. A higher percentage of carbon (C) and hydrogen (H) in biomass favors higher bio-oil yield. HTL process is highly affected by physical and chemical properties which include temperature–pressure variation, retention time, and solvent addition during operation which can influence the production of yield percentage. From the analysis, Researchers observed a maximum of 76% crude yield found in corn cob in the presence of acetone solvent. Sewage sludge and cattle manure produce 55% and 49% of yield respectively through HTL. Therefore, this review summarizes the most significant advancements in lignocellulose liquefaction research, with a focus on the feedstock, liquefaction technology, target products, and degradation mechanisms of each biomass component. This review is likely a valuable resource for further research on lignocellulose solvent liquefaction.