Natural gas combined cycle (NGCC) power plants are expected to remain a critical component of global electricity generation due to their high efficiency, operational flexibility, and comparatively lower specific carbon dioxide (CO₂) emissions than coal-fired power plants. However, achieving long-term climate targets requires deep decarbonization of gas-fired generation through the integration of carbon capture, storage, and utilization (CCSU) technologies. Post-combustion amine absorption is currently the most mature capture technology, while membrane separation represents a promising emerging alternative with potential advantages in modularity and operational simplicity. In parallel, process intensification strategies such as exhaust gas recirculation (EGR) have recently attracted growing attention due to their ability to increase CO₂ concentration in flue gas and reduce the energy penalty associated with capture processes. Despite significant progress, comprehensive techno-economic comparisons of absorption, membrane, and hybrid capture systems under EGR-integrated NGCC configurations remain limited.
This study presents an integrated techno-economic assessment of multiple CO₂ capture configurations applied to a 450 MW NGCC power plant. Detailed process simulations were developed using Aspen Plus and Aspen Custom Modeler to evaluate absorption-based, membrane-based, and hybrid capture systems combined with selective and non-selective EGR strategies. The modelling framework includes full process integration with the steam cycle, enabling consistent evaluation of energy consumption, efficiency penalties, and key economic indicators. The assessment focuses on net plant efficiency, energy penalty, levelized cost of electricity (LCOE), and CO₂ avoidance cost, providing a consistent basis for comparing capture options.
Results indicate that integrating EGR substantially enhances the performance of carbon capture in NGCC systems. In particular, selective EGR combined with amine absorption demonstrates the most favourable performance, reducing the energy penalty by more than 30% compared with standalone absorption and by over 70% relative to membrane separation. The selective EGR–absorption configuration achieves an estimated LCOE of approximately 72 USD/MWh and a CO₂ avoidance cost of about 39 USD/tCO₂, outperforming the selective EGR–membrane configuration, which yields approximately 77 USD/MWh and 51 USD/tCO₂. These results highlight the strong influence of flue gas composition and process integration on the overall economic viability of carbon capture.
The findings demonstrate that combining process intensification with established capture technologies can significantly improve the feasibility of CCSU deployment in NGCC power plants. This work provides insights into cost-effective decarbonization pathways for gas-fired power generation and supports ongoing efforts toward large-scale implementation of carbon capture technologies in the transition to low-carbon energy systems.
