Modeling and Comparative Analysis of CO2 Absorption Columns in Electrochemical and Thermochemical Carbon Capture Systems

Deployment of post-combustion carbon dioxide (CO2) capture technologies is needed to reduce emissions from power and industrial sources. Comparisons between existing thermochemical CO2 capture methods and emerging electrochemical concepts can help contextualize the promise of these new approaches. Here, we investigate the required absorber sizes for three capture systems: amine scrubbing using monoethanolamine (MEA), direct electrochemical (redox-active sorbent), and indirect electrochemical (pH-swing). For the electrochemical systems, we study how column size varies as a function of molecular properties and operating conditions, finding that parameters most closely related to CO2 uptake rates (i.e., rate constants and pKa) have the greatest impact. Through a Monte Carlo analysis, we find that the direct process can be designed to have column sizes similar to the thermochemical process, however, the CO2 uptake rate in the indirect process is too slow to enable smaller columns. Broadly, this work connects system input parameters to absorber performance for electrochemical CO2 capture and provides a foundation for technoeconomic and engineering analyses.