Globally, research and development of electrical energy storage is rapidly gaining popularity amongst scholars. These can be attributed to the fact that it plays a crucial role in the areas of: renewable energy power generation, smart grid, off-peak electricity utilization, distributed energy system, micro-grid and energy internet. At present, several power storage techniques exist. Amongst these techniques, compressed air energy storage system is the most promising technique given its highly desired advantages that include: low initial, operational and maintenance costs, environmental friendliness, deployable at large scale, high efficiency and long lifetime. Conversely, conventional compressed air energy storage systems are subject to limitations such as: dependency on fossil fuels and large chambers, reduced efficiency and minimal energy density, thereby, their development and large scale application is limited. To counteract these issues, researchers have sought to introduce the supercritical compressed air energy storage system.
In a recent paper published in the journal, Applied Energy, Haisheng Chen and colleagues from Institute of Engineering Thermophysics at Chinese Academy of Sciences set out to present an analytical solution for a novel compressed air energy storage system – supercritical compressed air energy storage system. Their goal was to explore the influence of key parameters on system efficiency since it is known that the coupling relationships of system processes and parameters cannot be explored thoroughly with numerical approaches.
The research team commenced their empirical work by obtaining and calculating the exergy destruction for each part of the model. A method of sectional treatment of the system and Taylor expansion ignoring higher order terms was also carried out so as to obtain the variation of system efficiency with key parameters through the analytical solution as well as the reasons for such variation. Eventually, a sensitivity analysis and an exergy analysis were undertaken for supercritical compressed air energy storage system.
The authors mainly observed that the system efficiency varies linearly with isentropic efficiencies of compressor and expander, temperature difference of intercooler and reheater, pressure loss of intercooler and reheater. More so, they noted that the analytical solution was universal for compressed air energy storage system systems with similar layout to the supercritical compressed air energy storage system due to the deduced method of sectional treatment.
Concise analytical model of the supercritical compressed air energy storage system has been established in their study. A comparison of the existing compressed air energy storage system with our novel supercritical compressed air energy storage system has also been presented. It has been mainly noted that our novel system possesses great development potential with important advantages such as: eliminating reliance on fossil fuel and large chambers, increased energy storage density and high system efficiency. The outcomes of this study are impressive and can be used as reference for designing and optimizing of the supercritical compressed air energy storage system and other similar compressed air energy storage systems.
Currently, the world’s first 10MW advanced CAES plant has been built in Bijie, China by the research team, and the plant is shown in Fig.1.The test data of the plant will provide support to verify the analytical solution of this work.
Huan Guo, Yujie Xu, Haisheng Chen, Cong Guo, Wei Qin. Thermodynamic analytical solution and exergy analysis for supercritical compressed air energy storage system. Applied Energy volume 199 (2017) pages 96–106.
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