Techno-economic and life cycle assessment of wet waste hydrothermal liquefaction with different biocrude upgrading strategies

Abstract

Hydrothermal liquefaction (HTL) emerges as a promising technology for producing renewable, low-carbon biofuels from wet wastes, offering a sustainable alternative to fossil fuels. This process is particularly advantageous because it minimizes the need for feedstock drying and allows for the implementation of customized upgrading strategies to meet diverse fuel specifications. A comprehensive study was conducted to evaluate the economic and environmental impacts of using HTL to convert various wet wastes into biofuels. The research involved techno-economic analyses and life cycle assessments of the HTL process integrated with different and biocrude upgrading strategies. Aspen Plus models and experimental data from lab-scale systems were used, with a focus on three feedstock types (sewage sludge, manure, and food waste) and three upgrading strategies for marine fuel, sustainable aviation fuel, and renewable diesel production. For marine fuel, biocrude underwent mild hydrotreating, whereas for sustainable aviation fuel and renewable diesel production, the biocrude was necessarily subjected to full hydrotreating and fractionation. The results revealed that feedstock type and process choice significantly influence economic and environmental outcomes. This research highlights HTL's potential for advancing renewable fuel production, contributing to national energy security, diversification, and emission reduction.