N2 selective membrane based hybrid cryogenic carbon capture process for coal-fired power plants: A techno-economic case study

Abstract

Recent advances in N2-selective membranes have led to significant breakthroughs, enabling them to outperform the previous generations by a substantial margin. A hybrid membrane cryogenic (HMC) process may represent a promising synergy between membrane separation and cryogenic technology, providing an efficient solution for CO2 capture by minimizing costs and energy consumption. This study presents a newly designed N2 selective HMC process for post-combustion carbon capture and compares its performance to a multi-stage CO2-selective HMC process and a low-temperature membrane cryogenic (LTMC) process. The HMC processes involve energy recovery systems (ERS), exhaust gas recirculation (EGR), and multi-stream cryogenic heat exchangers. Results demonstrate that the N2-selective HMC process achieves a 90 % CO2 recovery rate and 95 % CO2 purity, with significantly lower membrane area requirements and capture costs compared to the other two processes. Remarkably, the capture cost and energy consumption for the N2-selective HMC process are $23.36/tCO2 and 1.342 GJ/tCO2, respectively, highlighting the economic and environmental benefits of this approach. This research also underscores the importance of developing membranes with high N2/CO2 selectivity, rather than focusing solely on high N2 permeance, critical for optimizing HMC processes for CO2 capture.