Concept of the thermal integration of the compressed air energy storage system with the power plant

This paper presents the concept of an innovative hybrid system that integrates a compressed air energy storage system with a conventional power plant. Using simple mathematical models, the proposed hybrid system is compared with the classic adiabatic system. It also presents the results of more detailed thermodynamic analyses for the compressed air energy storage system, which is thermally integrated with a 600 MW coal-fired power plant. The first stage of integration enables the storage system to utilize the heat of compressed air (air cooling) for condensate heating, which results in partial replacement of the low-pressure regeneration of thepower unit and subsequently in an increase in power. The second stage of integration heats the air during discharge of the energy storage system before the air expander, using the heat of superheated steam which is directed from the steam turbine bleeding to the high pressure regeneration exchanger. While integration organized in this way decreases power unit efficiency, it eliminates the need for (i) gaseous fuel in the energy storage system, as in the case of diabatic systems or (ii) heat storage, as in the case of adiabatic systems. Three variants of the hybrid system were analyzed. Evaluation of the hybrid system variants was made using energy storage efficiency as defined in the paper.