Process evaluation of simulated novel cellulosic ethanol biorefineries coupled with lignin thermochemical conversion

The conversion of lignocellulose into valuable products is an area of interest to achieve sustainable development. Nowadays, the corn stover-ethanol biorefinery just produces lignin as a waste. However, lignin valorization can enhance profitability, improve resource utilization efficiency, and reduce carbon emissions. Thus, the objective of this work is to comprehensively evaluate the benefits of integrating lignin thermochemical conversion to generate bioproducts within ethanol biorefineries. Herein, 2000 metric tonne per day corn-stover biorefineries with various lignin utilization processes (combustion for power, pyrolysis to produce arenes, and gasification-syngas fermentation to produce ethanol) were modeled. Then, a comparative analysis was conducted across various dimensions of energy, environment, and economy (3E). The results suggest that integrating lignin valorization instead of combustion enhances carbon and energy recovery, as well as environmental and economic benefits. The minimum ethanol selling price has been estimated to be 834–873 $/t for various lignin utilization processes. Notably, lignin gasification-syngas fermentation demonstrates the best performance in all 3E metrics. However, related lignin thermochemical conversion processes still face high levels of uncertainty, necessitating further laboratory and pilot-scale research to improve technology readiness levels. This work is valuable for future advancements in the full conversion of lignocellulose into biofuels and chemicals.