Biogas-to-methanol: A new green methanol production process based on anaerobic digestion of biomass

•A novel bio-methanol production system is proposed.•Simulate and analyse the proposed system in Aspen plus.•The integrated energy utilization efficiency of the proposed system is 44.87%.•81.02% reduction in CO2 emissions when using photovoltaic power generation.•The initial levelised cost of methanol is 1294.89 $/t. In this study, a green methanol production system based on renewable solar energy and biomass is proposed, which includes a solar photovoltaic system, biomass anaerobic digestion system, biomass oxygen-enriched combustion system, and a methanol synthesis system. The full process simulation is conducted in Aspen plus, and thermo-economic and environmental analyses are performed. The results show that the proposed system may achieve an integrated energy utilization efficiency of 44.87 %, a total specific energy consumption of 38.22 kW/kg for methanol production and an electricity consumption rate of 21.97 kW/kg for methanol production. The initial levelized average cost of methanol is 1294.89 $/t. The economic assessment shows that the proposed system can pay back the initial cost in 9.58 years when all the electrical energy is sourced from the grid. When the total electricity consumption is from the PV system, in order to recover the initial cost within 10 years, the initial investment cost of the PV system should be kept below 150 $/KW. The results of the environmental assessment show that as the PV system scales up, the annual CO2 emissions continue to decrease, and when the entire electrical energy supply comes from the PV system, the CO2 emissions decrease by 81.02 %.