(476i) Comparable Techno-Economic Analysis of Wet Waste Hydrothermal Liquefaction with Different Biocrude Upgrading Strategies

Renewable, low carbon, “drop-in” biofuels offer greater potential to decarbonize aviation, marine, and heavy-duty transportation sectors and play a significant role to meet the zero-greenhouse gas (GHG) emission goal by 2050. Hydrothermal liquefaction (HTL) is one of many promising biofuel technologies, that can convert any wet waste (i.e., sewage sludge, manures, and food waste) to biocrude at high pressure (~20 MPa) and medium temperature (~360°C). It eliminates the need for feedstock drying and produces a high quality biocrude, of which the upgrading/fuel finishing strategies can be optimized and tuned to meet specific needs of the end users for different applications (i.e., marine, aviation and heavy-duty). For marine biofuel production, the upgrading strategy includes mild hydrotreating to remove the heteroatoms, lower total acid number (TAN) for meet fuel standard, as well as using the whole distillates without fractionation as marine fuel. For SAF and renewable diesel production, the HTL biocrude is fully hydrotreated for heteroatoms removal, followed by fractionation into naphtha, jet, heavy diesel/ residue, and hydrocracking of residue and/or heavy diesel. Finally the combined jet fraction from both hydrotreating and hydrocracking went through a deep dehydronitrogenation process to remove the nitrogen below 2 PPM for the SAF requirement. Tuning the distillation column and hydrocracking operating can maximize SAF or renewable diesel production. In this study, techno-economic analyses (TEA) were conducted for a small scale HTL plant (110 dry ton per day waste) with a centralized upgrading plant (about 3000-barrel biocrude per day) based on rigorous process model developed in Aspen Plus and experimental data collected from lab-scale continues flow system. A variety of biocrude upgrading configurations were explored for maximizing marine, SAF and renewable diesel production, respectively.