Process Simulation of Methanol Production from Water Electrolysis and Tri-Reforming

Abstract

The alarmingly increase in anthropogenic CO2 emissions is widely considered as the root cause of global warming. To mitigate this issue, CO2 utilization via methanol production can be an effective approach. The present study develops an innovative process to produce methanol by combining water electrolysis with tri-reforming of methane (TRM). The proposed process utilizes 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 problem of H2 deficiencies associated with methanol synthesis and allows for additional CO2 to be converted. The main process flowsheet is developed with the well-known Aspen HYSYS process simulator. Then the feasibility of this project is evaluated based on its techno-economic performance as well as greenhouse gas (GHG) emissions. The estimated capital expenditure (CAPEX), operating expenditure (OPEX) and GHG emissions of the baseline plant are $774 million, $263 million/year and -0.14 kgCO2eq/kgMeOH, respectively. In particular, water electrolysis process accounts for 34% of CAPEX and 54% of OPEX. A discounted cash flow (DCF) model combined with sensitivity analyses show that a breakeven point can be reached with a methanol price of $491/ton. The results from this study demonstrate that combining water electrolysis with TRM can improve the sustainability and economic viability for methanol production. However, in order for the process to become more financially attractive, further research and development are necessary to drive down the costs of the current water electrolysis technology.