The capture and sequestration of the CO₂ emitted from fossil-fuelled power plants is gaining widespread interest for controlling anthropogenic emissions of greenhouse gases. Among technology options for CO₂ capture, membrane-based gas separation systems are noteworthy owing to their low energy requirements, promising technology evolution and effective integration with power plants. This paper presents a mathematical model for membrane-based separation systems that is able to cover the most significant membrane types and configurations. This model has been integrated in a general simulation method for analysing and optimizing advanced energy conversion systems. Performance of these simulation tools is demonstrated by evaluating the influence of different operating conditions on the behaviour of pre-and post-combustion separation units, based on metallic or polymeric membranes. Finally, the feasibility of integrating a metallic membrane system into a chemically recuperated gas turbine (CRGT) power plant is explored, obtaining encouraging results for CO₂ capture.

Carbon capture and storage is considered as one of the key strategies for reducing the emissions of carbon dioxide from power generation facilities. Although post-combustion capture via chemical absorption is now a mature technology, the separation of CO2 from flue gases shows many issues, including the solvent degradation and the high regeneration energy requirement, that in turn reduces the power plant performances.Focusing on a triple pressure and reheat combined cycle with exhaust gas recirculation, this paper aims to evaluate the potential impacts of integrating a post-combustion capture system, based on an absorption process with monoethanolamine solvent. Energy and economic performances of the integrated system are evaluated varying the exhaust gas recirculation fraction and the CO2 capture ratio. The different configurations examined are then compared in terms of efficiency and rated capacity of the integrated system, as well as considering the cost of electricity generated and the cost of CO2 avoided

In the field of fossil-fuel based technologies, natural gas combined cycle (NGCC) power plants are currently the best option for electricity generation, having an efficiency close to 60%. However, they produce significant CO2 emissions, amounting to around 0.4 tonne/MWh for new installations. Among the carbon capture and sequestration (CCS) technologies, the process based on chemical absorption is a well-established technology, but markedly reduces the NGCC performances. On the other side, the integration of molten carbonate fuel cells (MCFCs) is recognized as an attractive option to overcome the main drawbacks of traditional CCS technologies. If the cathode side is fed by NGCC exhaust gases, the MCFC operates as a CO2 concentrator, beside providing an additional generating capacity.In this paper the integration of MCFC into a two pressure levels combined cycle is investigated through an energy analysis. To improve the efficiency of MCFC and its integration within the NGCC, plant configurations based on two different gas recirculation options are analyzed. The first is a traditional recirculation of exhaust gases at the compressor inlet; the second, mainly involving the MCFC stack, is based on recirculating a fraction of anode exhaust gases at the cathode inlet. Effects of MCFC operating conditions on energy and environmental performances of the integrated system are evaluated