Thermodynamic and economic analysis of a novel biomass-derived methanol production assisted by electrolytic H2 adjustment and O2 recirculation

To address global imperatives for energy transition and renewable energy utilization, a novel biomass gasification-green hydrogen-to-methanol system (BG-H2-MeOH) is proposed. The core contributions comprise: (1) By systematically replacing energy-intensive units such as ASU and WGSR with green hydrogen and its derived components, we achieve efficient elemental-level conversion of carbon, hydrogen, and oxygen. This approach significantly enhances system carbon conversion efficiency, energy efficiency, and renewables integration capacity; (2) A graded energy cascade integration mechanism minimizing process exergy destruction through grade-matched recovery of waste heat/chemical potential and optimized exergy transfer, amplifying synergistic effects across energy flows. Under constant total energy input, biomass contribution decreases from 100.00 % to 51.25 % while carbon conversion reaches 94.60 %. Efficient waste heat/purge gas utilization and elimination of high-energy devices elevate net power generation to 11.65 MW, reducing exergy destruction by 47.05 MW. Consequently, system energy and exergy efficiencies rise by 10.36 % and 13.52 %, respectively. Economic benefits include a 58.1 M$ increase in net present value and 3.1-year decrease in discounted payback period, enabling carbon-neutral power-liquid fuel co-production. Sensitivity analysis confirms optimal performance at 1300 °C gasification temperature, 250 °C/50 bar methanol synthesis conditions, and 2.05 (H2-CO2)/(CO + CO2) syngas mole ratio. Furthermore, the system performs optimally economically when hydrogen prices are low and methanol prices are high.