From thermal to electrochemical CO2-to-methanol conversion: A comprehensive review of process technologies, techno-economics, and life-cycle performance

• Developed a multi-scale modelling framework for e-methanol production. • Analysed one-, two-, and three-step hybrid CO2 electrolysis routes. • Harmonised TEA and LCA to compare economic viability and sustainability. • Linked electrolyser efficiency, durability and scale-up to system outcomes. • Identified bottlenecks and priorities for industrial e-methanol deployment. Methanol is central to the decarbonisation of chemicals and fuels, yet current production is almost entirely reliant on fossil syngas. This review contrasts mature thermocatalytic routes with three emerging green pathways that incorporate electrolysers: 1). one-step direct electrochemical reduction of CO 2 to methanol, 2). two-step schemes in which CO 2 is hydrogenated using electrolytic hydrogen, and 3). three-step syngas-based system design in which CO 2 is first converted to CO with co-produced H 2 , then supplemented with electrolytic H 2 for conventional methanol synthesis. Published data are reconciled consistently across technology readiness, energy and carbon efficiency, levelised methanol cost, and life cycle impacts to identify robust trends rather than case-specific results. The analysis shows that conventional steam reforming remains the lowest-cost option at present, while green electrochemical routes can reduce cradle-to-gate greenhouse gas emissions by more than 80% at the expense of significantly higher production costs, dominated by electricity prices, electrolyser performance, and capacity factors. Direct electrochemical pathways are at a low level of technological readiness but offer the prospect of compact, modular plants that avoid intermediate hydrogen handling. In contrast, the two- and three-step concepts are closer to deployment but incur the energy penalties associated with separate hydrogen generation and CO 2 capture. By integrating techno-economic, life-cycle, and scale-up considerations, the review delineates the operating windows, renewable energy prices, and methanol premiums required for economic competitiveness. It highlights research priorities in catalyst durability, large-area stack design, system integration, and policy support that are most likely to close the remaining performance and cost gaps.