Dynamic analysis of a low-temperature Adiabatic Compressed Air Energy Storage system

Adiabatic Compressed Air Energy Storage (A-CAES) systems have received wide attention in the last decade. The variations of the air pressure and temperature in the storage cavern substantially affect the expander power output and overall system efficiency. In this paper, the dynamic performance of a low-temperature A-CAES system is studied under real-time operation. A comprehensive dynamic model is developed and validated using experimental data. The dynamic analysis shows that the predicted system efficiency agrees well with the experimental data and is about 10% lower than that obtained from the steady-state analysis. The effect of operating parameters (e.g. compression/expansion flow rate, cavern initial and storage pressure, and number of compression/expansion stages) on the A-CAES system performance is further investigated. High compressor flow rate leads to a cavern air temperature above 521 K and reduces the system efficiency relatively by 9.1%. This indicates that the compressor flow rate must be carefully selected to ensure the cavern safety and reliability and overall system performance. It is also found that increasing the expander flow rate reduces the system and heat recovery efficiencies by up to 8.8% and 40.3%, respectively under the studied flow rates. The results also show that the cavern storage and initial pressure have a large effect on the overall system efficiency. The practical cavern storage and initial pressure were around 66 and 25 bars, respectively, to achieve a good system performance.