Techno-economic analysis and life cycle assessment of a hydrothermal conversion process for renewable diesel production from animal waste oil

The conversion of renewable waste into energy is crucial for sustainable energy production and for mitigating anthropogenic CO₂ emissions. This study investigates the production of renewable diesel (RD) from animal waste oil (AWO) via a hydrothermal conversion (HTC) process, focusing on economic and environmental feasibility. The yields of the HTC reaction at 420 °C and 3.5 MPa were obtained from lab-scale experiments, resulting in 74.1 % biocrude with a diesel yield of 61.6 %. Techno-economic analysis (TEA) and life cycle assessment (LCA) were performed in an industrial-scale for the treatment of 50 t/d AWO. The minimum fuel selling price (MFSP) was estimated to be $0.76/kg. The sensitivity of the MFSP to the total capital investment, AWO price, labor cost, and heavy oil price as key economic factors was analyzed applying ±30 % variations, resulting in an MFSP range of $0.64 – $0.89/kg. The cradle-to-gate LCA revealed that the global warming potential of RD production from AWO (0.4 kg-CO₂/kg-RD) was 34 % lower than that of petroleum diesel (PD) production (0.6 kg-CO₂/kg-PD). This reduction was primarily due to the use of domestic waste, which eliminates the environmental costs associated with importing crude oil. This study demonstrates economic and environmental benefits of producing RD from AWO. Further research on biofuel production from various other raw materials via HTC is required to evaluate and compare economic and environmental feasibility of such processes.