A detailed electrochemical performance and sustainability assessment of a high-temperature CO2 electrolyser system for green and efficient methanol production

Electrochemical conversion of CO 2 into value-added fuels offers a promising pathway for sustainable carbon utilisation and energy storage. In this study, an electrochemical and sustainability assessment model is developed to investigate the performance of a high-temperature electrolyser for methanol production from CO 2 in a eutectic molten salt system. The electrochemical model incorporates activation, ohmic, and diffusion overpotentials, along with thermodynamic and mass-transport effects, to predict overall cell behaviour. The governing equations are solved using MATLAB, and the model is validated using experimental electrochemical data. In addition, a cradle to gate life-cycle assessment (LCA) is performed in SimaPro to evaluate the environmental impacts associated with different energy supply scenarios. The results indicate that the overall cell potential increases with increasing current density due to higher polarisation losses, whereas increasing operating temperature improves electrochemical performance by reducing ohmic and mass-transport resistances. The analysis further shows that cathodic activation losses dominate the overall polarisation behaviour. Energy and exergy analyses reveal that both efficiencies decrease with increasing current density and methanol production rate, whereas higher operating temperatures improve the thermodynamic performance of the system. Model validation shows good agreement with experimental observations, with a predicted cell voltage of 1.605 V compared to an experimental value of approximately 1.55 V at 623 K and 100 mA/cm². The LCA results demonstrate that the proposed electrochemical methanol production pathway significantly reduces global warming potential compared to conventional fossil-based methanol synthesis routes. Renewable-energy-assisted operation further minimises the impacts of terrestrial acidification, toxicity, and fossil resource depletion relative to grid-based electricity scenarios. The combined electrochemical, thermodynamic, and sustainability analyses confirm that high-temperature molten-salt electrolysis offers a promising pathway for green and energy-efficient methanol production from CO 2 . The developed framework provides valuable insights for optimising operating conditions and energy integration strategies to enhance both process efficiency and environmental sustainability.