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

Yuanjing Zhao;Shiyu Wang;Grazia Leonzio;Qian Fu;Yang Wang;Jin Xuan;Lei Xing

2026-01-01

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Abstract

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 CO2 to methanol, 2). two-step schemes in which CO2 is hydrogenated using electrolytic hydrogen, and 3). three-step syngas-based system design in which CO2 is first converted to CO with co-produced H2, then supplemented with electrolytic H2 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 >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 CO2 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.