Feasibility assessment of small-scale methanol production via power-to-X

Decentralized methanol production in the context of energy storage (also called power-to-methanol or PtMeOH) requires the development of new process configurations. This is due to the need to avoid energy-intensive compression stages and to adapt to intermittent H2 availability. This study aimed at the determination of the techno-economic feasibility of new small-scale PtMeOH process configurations. It was proposed that, in small scale, the pressure should be limited to 30 bar, the standard H2 delivery pressure of an electrolyzer. This is due to the cost and complexity of a H2 compressor, unsuitable for small-scale systems. As CO2 conversion is limited under these conditions, several configurations differing in the valorization strategy of the unreacted stream were assessed. Additionally, the possible coupling with other processes (e.g., biogas upgrading) was considered. It was found that it was not possible to obtain a profit in the production of methanol from renewable H2 in any configuration at high electricity prices due to the important impact of H2 cost. The highest electricity price allowing profitable operation was 0.07 USD/kWh for the recycling process. If PtMeOH is coupled with biogas upgrading, the process can also be operated in the cascade configuration with a similar economic performance. Hence, the small-scale PtMeOH process is feasible only under very specific conditions: constant low electricity price or coupled with waste-handling facilities. This study determined the set of parameters with which the PtMeOH process can be economically profitable, highlighting under which conditions cleaner methanol production can be envisaged in the near future.