Energy and Economic Viability of Hybrid Biorefineries: A Comparative Study between Hydrogen–Sustainable Aviation Fuel and Hydrogen–Ethanol Pathways

In the pursuit of a sustainable and circular bioeconomy, the integration of hydrogen production into lignocellulosic biorefineries offers a promising strategy for decarbonizing energy systems and diversifying value-added products. This study proposes and evaluates a flexible, dual-output biorefinery capable of producing either sustainable aviation fuel (SAF) and hydrogen or ethanol and hydrogen, using bagasse and corn stover as feedstocks. A comprehensive process simulation was conducted in Aspen Plus, including steam explosion and acid pretreatment, enzymatic hydrolysis, fermentation, extractive distillation, steam reforming, and the Alcohol-to-Jet (ATJ) pathway. Techno-economic and environmental performance were assessed using Return on Investment (ROI) and CO2 emissions as key metrics. Results show that the ethanol–hydrogen configuration presents at least one economically viable scenario under current market conditions without requiring electrification of heat-demanding operations. Conversely, the SAF–hydrogen route is not economically feasible under base conditions, although its performance improves significantly when the thermal energy demand is eliminated through electrification. Sensitivity analyses of product selling prices demonstrate that modest increases in the SAF, hydrogen, or ethanol prices could make the proposed system viable. The study highlights the potential of adaptive biorefinery architectures to respond to shifting geopolitical and market conditions, supporting resilient and sustainable fuel production strategies.