(587f) More Than Ethanol: A Techno-Economic Analysis of Corn Stover-Ethanol Biorefinery Integrated with Hydrothermal Liquefaction Process to Convert Lignin into Biochemicals

Energy being an “ingredient” for every economic activity presents challenges of providing qualitative and quantitative energy to the increasing global population. Biorenewable approach of producing energy in form of biofuels and biochemicals is the way to go. Hydrothermal liquefaction (HTL) process is an alternative to fast pyrolysis (FP) that can be used to thermal chemically convert feedstock into hydro-oil, gases, and solids. HTL compared with FP, has advantages such as low bio-oil oxygen content of 10 to 20 wt% compared to 40%, higher oil heating value of 35 MJ/kg compared to 16 -19 range MJ/kg of FP. HTL processes wet biomass whereas FP requires dry biomass thus saving on energy that would have been required for drying feedstock. Research is underway to improve biorefinery revenues by producing biochemicals and biofuels from lignin which accounts for 40% biomass energy, and 10 to 35% by weight. Besides lignin from paper and pulp industry, also ethanol plants produce lignin as a waste, thus, the objective of this work is to evaluate the techno-economics of integrating ethanol biorefineries with hydrothermal liquefaction of lignin to produce biochemicals. A 2000 metric ton per day (MTPD) corn Stover biorefinery produced 61 MMgal/yr. of ethanol and different yields of chemicals. The minimum ethanol selling price (MESP) accompanied with respective chemical were $2.70/gal (catechol), $3.17 (phenol), $3.27/gal (m-cresol), $2.80/gal (p-cresol), $3.22/gal (o-cresol), $2.91/gal (acetic acid), $2.91/gal (formic acid), $3.32/gal (furfural), and $3.36/gal (acetaldehyde). Total capital investment is M$ 479.6. The most influential factor on the minimum ethanol selling price is ethanol yield. Other critical factors are fixed capital investment, feedstock flowrate, and ethyl acetate price. Lignin derived chemicals using HTL and separation of the produced biochemicals is in the early stages of development thus more investment in terms of fixed and operating cost might be required for future commercial biorefinery plants than those obtained in this analysis.