Journal of CO2 Utilization

CO2 utilization via methanol synthesis can be an effective approach to mitigate the issue of global warming. This study developed an innovative process to produce methanol by combining water electrolysis with tri-reforming of methane (TRM). The proposed design utilized carbon-free electricity to split water into O2 and H2; O2 is collected for partial oxidation reaction in the TRM and H2 is collected for stoichiometric number (SN) optimization. This process configuration eliminates the typical problems of H2 surplus or deficit associated with methanol synthesis and allows a substantial amount of CO2 to be converted. The main process flowsheet was developed with Aspen HYSYS process simulator and then the feasibility of this project was evaluated based on its technical, environmental, and economic performances. The estimated capital expenditure (CAPEX), operating expenditure (OPEX) and GHG emissions of the baseline plant are US$774 million, US$263 million/yr. and −0.14 kgCO2eq/kgMeOH, respectively. In particular, water electrolysis process accounted for 34 % of CAPEX and 51 % of OPEX. A discounted cash flow (DCF) model combined with sensitivity analyses showed that a breakeven point could be reached with a methanol price of US$491/ton. The results demonstrated that combining water electrolysis with TRM could achieve a sustainable carbon-sink process for methanol production.

Methanol production from water electrolysis and tri-reforming: Process design and technical-economic analysis