Exploring circularity in sorption-enhanced methanol synthesis: a comparative life cycle assessment

Abstract

The transition to renewable energy is driving sustainable chemical production methods, with power-to-X (P2X) technologies offering promising solutions. This study presents a comparative life cycle assessment (LCA) of adiabatic and isothermal sorption-enhanced methanol synthesis (SEMS) processes, across eight scenarios, varying in reactor configurations, electrolysis power sources, and methanol synthesis electricity use. Seven impact categories are evaluated, with results showing that all SEMS scenarios achieve significantly lower global warming potential (GWP) than the reference case of methanol production via steam reforming of natural gas. Adiabatic SEMS scenarios range from 71.7 to 519.7 kg CO₂ eq. per t MeOH, while isothermal SEMS scenarios range from 72 to 529 kg CO₂ eq. per t MeOH, significantly outperforming the conventional methanol production process (980 kg CO₂ eq. per t MeOH). These results indicate that SEMS-based methanol achieves 71.6–96.1% GHG savings, meeting the Renewable Energy Directive (RED II) 70% threshold for sustainability. The impacts of both corresponding adiabatic and isothermal SEMS scenarios are similar, with only slight variations. Furthermore, 61% of the impact categories analyzed across all SEMS scenarios exhibit lower impacts than the reference case. Uncertainty and sensitivity analyses revealed that electricity demand associated with water electrolysis was the dominant factor affecting system-level environmental performance of the SEM process. These findings highlight SEMS, when powered by renewable energy, as one possible solution within the P2X framework for sustainable methanol production. This study also emphasizes the critical role of integrating renewable energy into chemical processes to support industrial decarbonization and to accelerate the energy transition.