Techno-economic benchmarking of cryogenic carbon capture with membrane separation against conventional capture methods

This study presents a technoeconomic assessment of a cryogenic carbon capture process enhanced by membrane pre-separation, aimed at improving energy efficiency in post-combustion CO₂ removal. The system integrates a hollow fibre membrane module to remove up to 99 % of nitrogen from a flue gas stream containing 85 % N₂ and 15 % CO₂ by volume, thereby enriching the CO₂ stream before entering a multi-stage compression and cryogenic cooling sequence for liquefaction. Simulation and optimisation were conducted using DWSIM software, with results benchmarked against conventional technologies such as monoethanolamine absorption and oxy-fuel combustion on a consistent basis, evaluating all energy inputs as equivalent work losses from a host power plant. Although the capital expenditure (CAPEX) of the hybrid system is 224 % higher than a classic MEA process and 47 % higher than an Oxyfuel post combustion process, it achieved a 51 % and 17 % reduction in energy consumption respectively. The uncertainty limits were determined to be ±5 % of each calculated value and attributed to simulation and model errors. A sensitivity analysis has shown that the electricity price has the highest sensitivity at ±£ 29, £ 14, and £ 24/tCO 2 for the hybrid, traditional CCC, and MEA processes. CAPEX had the next highest for all three followed by non-energy OPEX and the discount rate had the least sensitivity. Despite its lower OPEX, the CAPEX was substantially higher than that of the two conventional systems. This trade-off underscores a critical barrier to scalability. Nevertheless, the hybrid system offers promising advantages in energy efficiency and CO₂ purity. • Hybrid cryogenic-membrane capture simulations carried out and compared to baseline technologies. • Hybrid system significantly reduces energy consumption hence low operational expenditure per ton of CO₂ captured. • High capital expenditure still a key barrier to scalability. • System sensitivity is dominated by electricity price for the new system, not steam costs. • High-purity (99.5 %) CO₂ product stream achieved for storage, transport, and utilisation.