(502d) Techno-Economic and Life-Cycle Assessment of Electrochemical Captured CO2 Conversion Process in Monoethanolamine

Severe climate crisis caused by large amounts of CO₂ emissions has led to a global climate agreement about carbon neutrality. Accordingly, efficient carbon capture utilization and storage (CCUS) technology must be developed for the transition to a sustainable low-carbon society. Post-combustion CO₂ capture (PCC) technology based on a 30 wt% aqueous monoethanolamine (MEA) has a mature technology level used on a commercial scale [1]. However, it is an energy-intensive process that consumes more than 57% of total energy for solvent regeneration [2]. In order to overcome this problem, the direct utilization of captured CO₂, which can eliminate the CO₂ separation step, has been proposed as an alternative to the current energy demanding CO₂ separation process. The direct electrochemical conversion via the captured CO₂ reduction reaction (cCO₂RR) proceeds using a CO₂ absorption medium as the electrolyte. Although many studies have been conducted to find the conditions under which the cCO₂RR achieves maximum faradaic efficiency and conversion by changing the type of electrolyte or process operating conditions [3]-[5], there is no precedent that discusses about technological economic prospects of the direct electrochemical conversion process via the cCO₂RR compared to the conventional electrochemical conversion process via the CO₂ supply electrochemical reduction reaction (CO₂RR) process.

Here, we designed two commercial-scale CCU processes, a direct electrochemical conversion process via the cCO₂RR and the conventional electrochemical conversion process via the CO₂RR. And compared them through economic evaluation and environmental analysis. As a result, by comparing the minimum selling price (MSP) of CO product as an economics index, the value of $1.3/kg in the direct electrochemical conversion process and $1.4/kg in the conventional electrochemical conversion process were derived. In other words, our team demonstrated the economic feasibility of the direct electrochemical conversion process with MSP results as low as 7.1% than the conventional electrochemical conversion process. And by performing global sensitivity on current density, overpotential, and faradaic efficiency, it was found that the current density has the greatest influence on the economic feasibility of the entire process. In addition, it was demonstrated that the negative impact on the environment of the direct electrochemical conversion process can be reduced through the life-cycle assessment of the comparative process. The reliable technology economics and environmental analysis reported by our team will be a driving force to take one step further toward the goal of a sustainable society, and this study will be a good guideline used in the future prospect of CCUS technology development.

[1] Khalifa, Omar, et al. "Modifying absorption process configurations to improve their performance for Post-Combustion CO₂ capture–What have we learned and what is still Missing?" Chemical Engineering Journal 430 (2022): 133096.

[2] Zhao, Bin, et al. "Enhancing the energetic efficiency of MDEA/PZ-based CO₂ capture technology for a 650 MW power plant: Process improvement." Applied energy 185 (2017): 362-375.

[3] Lee, Geonhui, et al. "Electrochemical upgrade of CO₂ from amine capture solution." Nature Energy 6.1 (2021): 46-53.

[4] Pérez-Gallent, Elena, et al. "Integrating CO₂ Capture with Electrochemical Conversion Using Amine-Based Capture Solvents as Electrolytes." Industrial & Engineering Chemistry Research 60.11 (2021): 4269-4278.

[5] Kim, J. H., et al. "Insensitive cation effect on single-atom Ni catalyst allows selective electrochemical conversion of captured CO₂ in universal media." (2022).