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

Area of Science:

• Environmental Engineering
• Electrochemistry
• Chemical Engineering

Background:

• Rising atmospheric carbon dioxide (CO2) levels necessitate compact carbon capture technologies for distributed sources like internal combustion (IC) engines.
• Existing carbon capture methods are often not suitable for the scale and nature of IC engine exhaust.

Purpose of the Study:

• To analyze the feasibility of an electrochemical CO2 absorption system for IC engine exhaust.
• To develop and utilize a dynamic simulation model for assessing system performance.

Main Methods:

• Developed a MATLAB/Simulink dynamic model integrating gas-liquid mass transfer, solubility, electrochemical kinetics, and speciation.
• Simulated system performance under specific exhaust conditions, considering bicarbonate dominance in the electrolyte.
• Included auxiliary loads for gas handling, cooling, and circulation in the energy consumption estimates.

Main Results:

• The model predicted CO2 capture from simulated engine exhaust with a cycle-integrated efficiency of 76.5%.
• The system's specific energy consumption was estimated at 1.17 MJ/mol CO2 at the cell level.
• System-level energy consumption, including auxiliary loads, was approximately 2.2 MJ/mol CO2.

Conclusions:

• Electrochemical CO2 capture is a potentially viable technology for IC engine exhaust, but requires experimental validation.
• Key factors influencing performance include mass transfer, electrode area, electrolyte concentration, and auxiliary power.
• Future work should focus on experimental validation, improved kinetics, chloride management, and techno-economic assessment.