Efficiency and Sensitivity Analysis of Cavern-Based CAES Systems During off-Design Operating Conditions

摘要

This work deals with the efficiency of cavern-based compressed air energy storage(CAES)facilities.Due to the complex interactions of the components of cavern-based CAES plants,a small deviation from designed for operating conditions can significantly alter the efficiency of the system.In this work,the sensitivity of individual system components to off-design working conditions are investigated,and components with the highest effect on both the exergy efficiency and the system efficiency are identified.The interaction between system components is also studied to identify the weak points of the system.The results show that the overall system efficiency is most sensitive to deviations in approach temperature in heat exchangers,energy leakage(as heat or compressed air)while the system is in a standby state,and leakage from compressors.For instance,a change of 10 °C in the approach temperature in the heat exchangers can lower system efficiency by 3.5%.System standby for 18 h with an air leakage rate of 4% per day from the cavern drops system efficiency by 2.1 %.Additionally,a leakage rate of only 0.06% in the compressors can lower the system efficiency by 1.7%.This work also reveals that the combined effect of having multiple system components working at off-design conditions is more than the linear sum of their individual effects because of the exogenous influence these components have on peripheral components.The results from this study can help to improve the efficiency of CAES facilities.