Integrated biomass power with CCS and green hydrogen to methanol: A comprehensive thermodynamic, economic analysis and strategic assessment for China

An integrated system is proposed that retrofits an existing biomass-fired power plant by coupling mixed-amine (MDEA/PZ) CO2 capture with green-hydrogen-based methanol synthesis. It (1) proposes and evaluates a closed-loop “carbon hydrogen energy” pathway, where CO2 captured from biomass flue gas reacts with green hydrogen so that carbon shifts from emission to synthesis, forming a poly-generation system for power and fuel; (2) realizes system-level thermal and power integration with deep waste heat recovery, decreasing waste heat loss and power penalty, improving energy and exergy efficiencies, and revealing synergistic effects; and (3) develops a China-oriented assessment framework that quantifies carbon mitigation and fossil fuel substitution and demonstrates technical, environmental, and economic benefits. For the same methanol output and biomass consumption, the system achieves 57.69% energy efficiency and 56.92% exergy efficiency, higher than a reference coal-to-methanol system and standalone biomass power plant, while avoiding an expensive, energy-intensive gasification section. The net present value is 164.3 M$, the payback period of 6.8 years, and the levelized green methanol cost 628.0 $/t. The system achieves a life-cycle carbon emission intensity of 465.54 kg-CO2/t-MeOH which is below the green methanol limit. At the national scale in China, it produces methanol of 73.61 Mt/yr, displaces 34.07 Mt gasoline, and cuts CO2 emissions by 24.27 Mt. Sensitivity analysis shows that a green hydrogen price of 2000 $/t makes green methanol cost-competitive with gasoline, while a sufficiently high carbon tax makes it competitive with gray methanol.