Exergoeconomic analysis and optimization of a novel isobaric adiabatic compressed air energy storage system
Résumé
The contribution of the renewable energy sources in the electricity generation mix is greatly increasing. Nonetheless, the intermittence of these sources breaks the balance between supply and demand for electricity. Thus, the integration of the energy storage technologies with the electrical grid is becoming crucial. They allow restoring the balance and reducing the drawbacks of the renewable energy sources. Hence, this paper discusses the modeling, the exergy and the exergoeconomic analyses of a novel isobaric adiabatic compressed air energy storage (IA-CAES) system. This system is characterized by the recovery of the compression heat in order to reuse it during production phase and the storage of the compressed air under fixed pressure in hydro-pneumatic tanks. This allows the improvement of the efficiency of the storage system. A steady state model is then developed to perform energy and exergy analyses of the IA-CAES system and to compute the thermodynamic characteristics of the latter. An exergoeconomic model is also carried out in order to optimize the cost-effectiveness of the storage system by using a genetic algorithm. So, an objective function, which includes the investment cost and the fuel cost, is defined to be minimized. The system efficiency is 55.1% in the base case, it is improved to 56.6% after optimization with a decrease in the capital investment by 5.6%. The average cost rate of the turbines product is also decreased by 5.5%. Global sensitivity analyses are finally carried out to estimate the effects of some key parameters on the system efficiency and the objective function, such as the efficiencies of the rotating machinery and the pinch of the heat exchangers. They show that the system's cost-effectiveness is mostly influenced by the isentropic efficiency of the gas turbines.