Techno-economic assessment of the by-products contribution from non-catalytic hydrothermal liquefaction of lignocellulose residues

Hydrothermal liquefaction of biomass continues to show promise in experimental and pilot scale tests for carbon partitioning toward desirable multi-phase organic products. Results from a techno-economic investigation are presented for a commercial scale stand-alone plant with primary production of renewable liquid fuels compatible with current transportation infrastructure. The plant feedstock was forest residues and the non-catalytic hydrothermal conditions were set to 330 °C and 210 bar. A sequential flowsheet was developed and simulated on Aspen Plus® that includes pre-treatment, hydrothermal liquefaction, fuel upgrading and residue recovery functional blocks. Different scenarios for the valorization of the liquefaction residue streams are examined to maximize organic recovery and eliminate process waste streams. The highest plant thermal efficiency on lower heating value basis was recorded for the polygeneration of renewable liquid fuels, Bio-char and hydrogen gas at 85.2%. The plant recorded a minimum selling price of 66 € per MWh of co-products. The break-even prices of the co-products under existing market conditions was found to be 1.03 € per kg of gasoline or 2.46 € per kg of hydrogen gas or 51.4 € per MWh of Bio-char.