From CO2 to CO: Techno-Economic Analysis of Integrated Capture and Conversion in Non-Aqueous Media

Abstract

This thesis investigates the techno-economic feasibility of an integrated process that captures post-combustion CO₂ and converts it into carbon monoxide (CO) via electrochemical reduction powered by renewable electricity. The approach is intended to reduce the high regeneration energy of conventional amine-based capture while producing a valuable chemical feedstock. A hybrid solvent of 0.5 M MEA in a choline chloride–ethylene glycol deep eutectic mixture was evaluated, showing comparable capture performance to aqueous MEA and a lower heat of absorption (–59.8 kJ/mol), indicating potential energy savings.

Electrolysis was assessed under worst, baseline, and best-case scenarios with current densities between 100 and 300 mA/cm², voltages of 2.5–4 V, and CO faradaic efficiencies of 20–60%. Projected annual CO production ranged from 69.8 to 174.4 kt, with energy efficiencies of 10–48%. A semi-empirical vapor–liquid equilibrium model was applied, achieving high accuracy (R² > 99%, AARD < 3%).

Economic analysis shows that none of the scenarios achieve positive net present value at current market prices (CO: €0.64/kg, H₂: €4/kg). Electricity accounts for about 98% of operating costs, making the system highly sensitive to power price and product value. The best case becomes feasible at €0.06/kWh electricity or €0.96/kg CO, while the baseline requires €1.43/kg CO. The worst case remains unviable under all tested conditions.

In conclusion, the system demonstrates strong technical potential but limited economic feasibility under present conditions. Viability depends on access to low-cost renewable electricity, improved electrolyzer efficiency, and supportive policy or market frameworks. Further research on solvent properties, process integration, and pilot-scale demonstrations is recommended to advance this concept toward industrial application.