Industrial ultra-low-carbon methanol synthesis routes: techno-economic analysis, life cycle environment assessment and multi-dimensional sustainability evaluation†

Abstract

This study establishes the industrial green hydrogen-coupled coal-to-methanol (GH₂-CTM) process and the biomass-to-methanol (BTM) process from the perspectives of process coupling and raw material greening. A comprehensive comparison of the two low-carbon methanol synthesis routes was conducted, aiming to promote environmentally friendly and efficient methanol production, based on detailed process modeling and simulation results. Techno-economic and life cycle assessments were performed on these low-carbon methanol processes as well as the conventional coal-to-methanol (CTM) process, and a multi-dimensional feasibility analysis was performed on key parameters (such as green hydrogen coupling amount, green hydrogen price, carbon tax, and biomass policy subsidies). The findings revealed that the industrialized GH₂-CTM process exhibited a 16.2% increase in methanol production and a 16.5% reduction in energy consumption. As the cost of green hydrogen decreases to 10.52 CNY kg⁻¹, renewable energy electrolysis hydrogen production could potentially replace the water-gas shift unit, leading to a 46.4% increase in methanol production and approximately 62.5% and 55.0% reductions in GHG emission and NED consumption compared to the CTM process. Government subsidies for straw-based energy production resulted in comparable economic performance between the BTM process and the CTM process. The BTM process demonstrated significant reductions in GHG emission and NED consumption of approximately 62.1% and 41.2%, respectively. These findings can ensure the realization of genuine ultra-low-carbon methanol production under the premise of determining the industrial scale and provide guidance for the more sustainable and environmentally friendly transformation of large coal-based methanol plants in China.