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.

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a b s t r a c tThe potential of "small hydro" power generation in Europe is still largely unexploited because of strict environmental requirements and legal rights for water use. Among the EU-27 member states, Italy is recognised as one of the most promising countries for the further exploitation of small hydro power.This paper presents a methodology for assessing the technical and economic potential of small hydro on a regional scale. The methodology is applied to the Abruzzo region in Italy. The investigation covers approximately 90 river branches belonging to the major regional basins. The methodology characterises the flow duration curves of suitable stretches of river using a regional analysis based on a graphical approach.An energy model evaluates the rated power and the annual electricity production of installable smallhydro power plants based on the flow duration curve and the type of hydraulic turbine. The economic analysis estimates the unit cost of electricity produced and the profitability of the initial investment assuming two scenarios based on different fixed-and variable-cost models. The net potential obtained from the energy analysis is adjusted to give the economically feasible potential at different levels of economic competitiveness for the regional basins investigated.

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