Exergoeconomic and exergoenvironmental analysis of an integrated solar gas turbine/combined cycle power plant

Integration of solar power to existing or foreseen Gas Turbine/Combined Cycle Power Plants (CCGT) is a solution attracting increasing interest, bridging solar thermal technology to a well-proven and developed energy conversion solution for the market. The integration is attractive for countries passing to natural gas as an energy feedstock, and it can improve the environmental performance with respect to the use of the single fossil fuel. In order to identify the performance and environmental benefits, a model of the plant was applied covering a one-year operation period and including the effects of surroundings variables (sun radiation and temperature of the surrounding). The model is able to predict the power plant performance, and calculates a complete exergy balance for all the components of the complex plant (both the original CCGT and the Integrated Solar CCGT (ISCCGT), including solar collectors performance with variable radiation and advanced control laws, maximizing the instant exergy collected). A complete exergoeconomic and exergoenvironmental model was applied at the design conditions after evaluating the cost of equipment and their environmental score using a detailed Life Cycle Assessment (LCA) modelling tool. The results, applied to a power plant in Southern Poland, show that the solution can be attractive for improving the environmental performance of a CCGT, and that the capital cost is only slightly increased so that the rate of return of the investment is only marginally affected.