Electrochemical CO₂ capture from engine exhaust using NaCl electrolyte: System modeling, optimization, and economic...

Rising atmospheric CO[Formula: see text] levels and increasing emissions from internal combustion (IC) engines highlight the need for compact carbon-capture technologies suitable for distributed emission sources. This study presents a simulation-based analysis of an electrochemical CO[Formula: see text] absorption system for engine exhaust using an aqueous NaCl electrolyte. A dynamic MATLAB/Simulink model is developed by coupling gas-liquid mass transfer, Henry's-law solubility, simplified electrochemical kinetics, Faraday-based hydroxide generation, and pH-dependent carbonate/bicarbonate speciation. Under the corrected baseline conditions of [Formula: see text] exhaust flow containing [Formula: see text] CO[Formula: see text], the system captures [Formula: see text] CO[Formula: see text] over a [Formula: see text] operating period, corresponding to a cycle-integrated capture efficiency of [Formula: see text]. At the simulated bulk pH of approximately [Formula: see text], bicarbonate formation is dominant; therefore, the effective electron requirement is treated as [Formula: see text] rather than assuming complete carbonate formation. Using a representative Faradaic efficiency of [Formula: see text], the current required to support the corrected capture rate is [Formula: see text], giving a corrected cell-level specific energy consumption of [Formula: see text]. When first-order auxiliary loads for gas handling, cooling, electrolyte circulation, and control electronics are included, the estimated system-level energy requirement increases to approximately [Formula: see text]. Sensitivity and optimization analyses indicate that mass-transfer performance, electrode area, electrolyte concentration, Faradaic efficiency, and auxiliary power demand strongly influence overall system performance. Because the model is not experimentally validated, the results should be interpreted as a preliminary feasibility and sensitivity assessment rather than a definitive prediction of reactor performance. The Bangladesh case study is used only to illustrate potential deployment relevance for distributed exhaust sources, while experimental validation, improved electrode kinetics, chloride-management strategies, and detailed techno-economic assessment are identified as essential future work.