Hydrothermal liquefaction − A sustainable technique for present biofuel generation: Opportunities, challenges and future prospects

• Published in: Fuel (Guildford) 2025-04, Vol.385, p.134141, Article 134141
• Main Authors: Mozas Santhose Kumar, J, Prakash, R, Panneerselvam, Padmanathan
• Format: Article
• Language: English
• Subjects: Algae; Biocrude; Biomass; Hydrothermal liquefaction; Lignocellulosic biomass; Renewable energy sources
• ISSN: 0016-2361
• DOI: 10.1016/j.fuel.2024.134141

[Display omitted] •An overview for biofuel production through Hydrothermal Liquefaction (HTL) process.•HTL process mechanisms and impact of process parameters are systematically investigated.•Recent developments in the production of biocrude through HTL process are analysed.•Opportunities and challenges in the HTL process for sustainable biofuels production.•Upgrading of biocrude into bio-refinery and other value-added products. Urbanization and energy demand are rapidly increasing, primarily due to a heavy reliance on fossil fuels. This has led to several environmental issues, including air pollution, climate change, water pollution, thermal pollution, and solid waste disposal. Biomass-derived fuels have emerged as a promising path towards a sustainable future, especially to meet the demand for global transportation fuels. Hydrothermal liquefaction (HTL) is the most promising technology for converting wet biomass into biocrude and other valuable chemicals. The conversion of biomass to biocrude is achieved by applying high-pressure, high-temperature water or water mixed with organic solvents and catalysts. The slurry obtained from the liquefaction process is a mixture of biocrude, aqueous phase products, and solid residue, which is refined into chemicals, bio-oil, biochar, and biogas. This review provides a comprehensive overview of biomass selection challenges for biofuel production, including details of biomass characterization. The various prospects of the HTL process, such as batch mode, continuous mode, Fast-HTL, Co-solvent-HTL, Catalytic-HTL, and Co-HTL, have been systematically investigated and evaluated through critical research to assess the impact of process parameters on HTL bio-product production. The review concludes with a discussion of the opportunities and limitations of the HTL process as a sustainable and renewable technology for producing bio-oil, which can be further upgraded and used for transportation and chemicals from biomass.