A sustainable production and extraction of bio-fuels using hydrous liquefaction of agricultural waste

The depletion of fossil fuels and the increasing environmental pollution resulting from their widespread use have raised significant concerns. Consequently, renewable energy sources, such as biomass, are being actively investigated as alternatives. Biomass offers the advantage of being readily available and provides economic benefits to manufacturers while simultaneously reducing landfill waste. However, biomass has a lower energy density compared to fossil fuels. Among various biomass conversion methods, hydrothermal liquefaction (HTL), which is suitable for both wet and dry biomass, is identified as one of the most efficient processes for fuel production. This study explores the catalytic HTL of sugarcane bagasse using green solvents-specifically, Deep Eutectic Solvents (DESs) as both catalysts and co-solvents for sustainable bio-oil production. The biomass feedstock is thoroughly characterized based on its cellulose, hemicellulose, and lignin content, while the resulting bio-oil is assessed for its physical, elemental, and chemical composition, along with essential fuel properties. A remarkable bio-oil yield of 52.8% is achieved using a ChCl-oxalic acid DES catalyst, significantly surpassing the 24.2% yield obtained with a conventional KOH catalyst. Additionally, the DES-derived bio-oils demonstrated superior higher heating values (39–43 MJ/kg), compared to those from KOH (33–39 MJ/kg). The study also provides a detailed overview of the HTL process, outlining the elemental composition of the bio-crude, underlying reaction mechanisms, and a schematic flow diagram. Furthermore, a life cycle assessment (LCA) is performed to evaluate the environmental implications of both catalytic systems. A techno-economic analysis (TEA) further validated the scalability and commercial viability of the HTL process for bio-oil production. • Green DES ChCl-Oxalic acid performs better compared to KOH: 52.8% vs 24.2% bio-oil yield at mild condition/ • Enhanced deoxygenation: DES bio-oils reach 43 MJ/kg HHV with lower oxygen content/ • Environmental assessment reveals 8% lower GWP and 14% reduced human toxicity/ • Economics analysis indicates commercial viability with 3.4 yr payback/