Process Design and Techno-Economic Assessment of biogenic CO2 Hydrogenation-to-Methanol with innovative catalyst

A small-scale 10 ton per day methanol (MeOH) synthesis plant, from CO2 and hydrogen, is designed and simulated with Aspen Plus and a techno-economic analysis is conducted. The e-fuel (MeOH) is produced in a conventional fixed bed reactor featuring an innovative Cu/Zn/Al/Zr catalyst, converting biogenic CO2 from a biogas upgrading plant with H2 produced by a grid powered PEM electrolyzer. The process is thermally autonomous as a result of heat integration and combustion of purged unconverted reactants. A sensitivity analysis is carried out in order to evaluate and compare the impact of the different technical (purge fraction, Gas Hourly Space Velocity and Pressure of the methanol synthesis) and economic parameters (Capital Charge Factor, electricity and H2 cost) on the Levelized Cost Of Methanol (LCOM). Results show that, although the energy efficiency is greater (47.4 % electricity to methanol conversion) in the scenario with “self-sufficiency” in which all the net heat required by the process is provided by off-gas streams, the case with the highest profitability is the one with maximum methanol yield and, therefore, minimum purge and non-zero thermal energy import (provided by a biogas boiler). The best case scenario features a LCOM equal to 1,361 €/tonMeOH, with a GHSV of 7,500 h−1 and synthesis reactor operating at 70 bar, 250 °C. H2 production cost is the key variable and shall be reduced from the base case value of 5.8 €/kgH2 to 1.6 €/kgH2 in order to make the CO2 to methanol plant competitive with a MeOH market price of 550 €/tonMeOH; synthesis reactor operating conditions have more limited impact from a cost perspective, except for the purge fraction that shall be optimized to maximize the amount of MeOH produced.