Integrated CO2 Capture and Utilization for Methanol Production: Techno-Economic Trade-offs between Capture Savings and Purification Costs

Solvent regeneration and gas compression in CO2 capture and utilization (CCU) to methanol processes are energy- and cost-intensive. Integrated CO2 capture and utilization (ICCU) has been proposed to eliminate the desorption and compression steps; however, the complexity of ICCU potentially shifts energy demands elsewhere, impacting the overall economics. This work evaluates whether ICCU offers economic and environmental advantages over a conventional CCU process (CCU-MEA case). Experimental methanol activities for two ICCU solvent systems of hexanol–triethylamine (ICCU-NEt3 case) and ethylene glycol–tetramethyl-1,6-hexanediamine (ICCU-TMHDA case) were collected for process simulations. ICCU cases reduced energy requirements in CO2 capture while increasing energy use in purification steps due to higher distillation loads, revealing a trade-off between capture savings and separation costs. CO2 capture capacity strongly influenced the minimum methanol selling prices as ICCU-TMHDA and CCU-MEA cases achieved 1997 and 1959 USD/t, respectively, while the ICCU-NEt3 case reached 5687 USD/t due to limited capture performance. Increasing the solvent flowrate in the ICCU-NEt3 process reduced the minimum selling price to 1735 USD/t. The presented results emphasize that high CO2 capture capacity and methanol activity are decisive for making ICCU both economically and environmentally viable, providing guidance for designing industrial ICCU systems for methanol synthesis.