An efficient carbon-neutral power and methanol polygeneration system based on biomass decarbonization and CO2 hydrogenation: Thermodynamic and economic analysis

This study presents a novel approach to enhance methanol synthesis (MS) efficiency through integration with an MEA-based decarbonized biomass direct-fired power plant (BFPP-CCS). The integration optimizes the utilization of chemical energy from feedstocks by combining exothermic MS reactions with diverse thermal energies, which effectively captures chemical energy through synergistic utilization from MS and various thermal inputs. Gradual methanol conversion maximizes both its chemical and fuel properties. Through such integration, the enhancement of waste heat and purge gas utilization in MS and BFPP carbon capture processes results in a 3.42 MW improvement in power generation and a 26.0 % reduction in associated energy penalties from CCS. Analysis of a 150 kton/yr MS facility and a 35 MW BFPP-CCS demonstrates 2.87 % increase in overall efficiency and reduction in CCS heat consumption by 1.03 GJ/tCO2. Moreover, this integrated approach yields a 33.1 M$ NPV increase and 3.4 years DPP decrease, achieving carbon-neutral power and liquid fuels production. Sensitivity analysis indicates the polygeneration system performs optimally around 250 °C and 60 bar, with a preference for 0.90 MS recycle ratio. Additionally, factors such as carbon recovery rate, electrolysis efficiency, and fixed carbon content in biomass are quantitatively revealed as crucial for maximizing carbon mitigation potential. •An efficient carbon-neutral power and methanol cogeneration is proposed.•Purge gas and waste heat in MS and CCS are recovered more effectively.•Mechanism of irreversible exergy losses in cogeneration system is revealed.•Carbon emissions characteristics of cogeneration is quantitatively demonstrated.•Higher primary energy utilization efficiency and better profitability are attainable.