Refinery-based CO₂ conversion to ethanol: Techno-economic-environmental assessments into carbon-reducing blending fuel systems

This study proposes and evaluates a thermocatalytic CO₂-to-ethanol (C2E) system designed to mitigate refinery emissions while enabling on-site blending with gasoline. In this concept, CO₂ from combustion and distillation units is captured and catalytically converted to ethanol via methanol- and syngas-based pathways integrated into refinery operations. Techno-economic analysis shows that the leading configuration achieves ethanol-blended fuel price of $2.93/GGE for E10, $2.79/GGE for E20, and $1.92/GGE for E85, all comparable to or below market benchmarks, demonstrating clear cost competitiveness across blending levels. Carbon intensity assessment further indicates that the most efficient C2E pathways exhibit carbon intensities below 92–93 g CO_2-eq./MJ for E10–E20 and 115 g CO_2-eq./MJ for E85 lower not only than gasoline but also than conventional ethanol-blended fuels. Sensitivity and major parameter correlation analyses reveal that process competitiveness is primarily influenced by hydrogen feedstock costs and quantify how variations in carbon tax and gasoline price affect ethanol production cost and optimal blending ratios. System impact analysis further quantifies the potential emission reductions achievable through large-scale C2E deployment across major ethanol-consuming regions. These findings highlight the potential of C2E technology to serve as an economically viable and environmentally advantageous pathway for decarbonizing liquid fuel systems.