Performance Study On Novel Compressed Air Energy Storage Systems

The sustainable development of energy and environment is the basis of the development of national economy. Meanwhile, solving the energy and environment problem of eletrical industry is an important part to keep economy developing sustainablly of China. Electrical energy storage is one of the key technologies of adjusting energy structure, developing extensively renewable energy, improving energy security of China. Hence, the study of large scale energy storage technology has important theoretical and practical value. This research is supported by the National Natural Science Foundation, Significant Direction Project Foundation of Chinese Academy of Sciences, etc.. This thesis aims to find the large scale energy storage technology which can meet the needs of high efficiency, high energy density and environmentally friendly through the intensive study on novel supercritical compressed air energy storage system, Advanced Adiabatic Compressed Air Energy Storage (AA-CAES) system by means of system integration, thermodynamic performance analysis, comparison of varous systems.Due to the drawbacks of the conventional Compressed Air Energy Storage (CAES) relying on the fossil fuel and having large pressure losses during charging and discharging processes, an AA-CAES system with constant storage air pressure is studied. The thermodynamic model of AA-CAES with fixed pressure operation mode is established. The association relationship between system efficiency and effectiveness of heat exchanger, overall pressure ratio of compressor, stage number, pressure ratio distribution is analysed. The simulation work is carried out by the use of MATLAB software. The system efficiencies varing with effectiveness of heat exchanger, overall pressure ratio of compressor, stage number are obtained. The pressure ratio distribution is optimized too.Aiming at the restrictions of the conventional CAES relying on the large storage cavern and fossil fuel, a supercritical CAES system is studied. The system model is built and analysed through Aspen Plus software. The simulation results reveal the change law of the systematical performance along with the storage pressure, discharge pressure, efficiencies of key components, temperature difference of heat exchanger, pressure losses, etc.. The critical components and parameters are derived.In order to improve the thermodynamic performance of the supercritical compressed air energy storage system, the original liquification device-throttle valve is updated. It is replaced by expanders or a throttle combined with expanders. The systematical efficiencies of the modified systems increase in a large scale. The thermodynamic models of the modified supercritical compressed air energy storage systems is built in Aspen Plus software. The simulation results reveal the change law of the systematical performance along with some key parameters.In order to better understand the characteristics of various-types compressed air energy storage systems, a comparison study is carried out among original supercritical compressed air energy storage system, modified supercritical compressed air energy storage system, AA-CAES system and conventional CAES system. The system efficiency, stored energy density, system configuration of flow and so on are compared generally. Both positive and negative features of all these systems are concluded.