Insights into Energetic\nPenalties in Electrochemical\nCO<sub>2</sub> Separation Systems

While innovative electrochemical approaches continue\nto emerge\nfor carbon capture, open questions remain regarding the performance\ncharacteristics of these nascent concepts. A wide range of energy\nrequirements have been reported; the different sources of performance\nloss and their relative magnitudes are not yet fully understood, challenging\nboth quantitative comparisons between devices and identification of\nperformance improvement pathways. Herein, we develop a mathematical\nframework to evaluate the energetics of four-stage electrochemical\nseparation systems in which soluble capture chemistries are activated\nand deactivated in an electrochemical reactor, and the liquid capture\nmedium absorbs and desorbs carbon dioxide (CO<sub>2</sub>) in separate\nunits. Specifically, we construct a dimensionless electrochemical\nreactor model, derive key groups associated with thermodynamics, kinetics,\nohmic resistance, and mass transport, and, subsequently, evaluate\ntheir impact on energetic penalties. We also discuss the use of this\nmodel for exploring different performance improvement pathways. Ultimately,\nthis work seeks to facilitate understanding of the interplay between\nmaterial properties, operating conditions, and energy requirements.