Research On Cycle Design And Efficiency Optimization Of Compressed Air Energy Storage In Aquifers

In recent years,with the rapid development of clean and renewable energy,the installed capacity of renewable energies increases gradually.However,this kind of energy has the characteristics of intermittent,unstable and uncontrollable,which puts forward higher demand for large-scale energy storage.Compressed air energy storage is a large-scale energy storage technology in addition to pumped hydro storage.Compressed air energy storage in aquifers(CAESA)has become a promising energy storage technology due to the wide distribution of underground aquifers.The use of CAESA technology can reduce the wind and solar curtain of clean energy and greatly improve the utilization rate of clean energy.The research results have important theoretical and practical significance for the practical engineering application of compressed air energy storage technology.A numerical model is established based on the field data of the compressed air energy storage in the Pittsfield aquifer conducted by the Department of energy of US.Through the actual geological data and monitoring data,the historical fitting of the numerical simulation results is carried out,which demonstrated the feasibility of numerical model.The numerical simulation results show that the formation of the initial bubble has a great impact on the CAESA system.The sufficient pressure can prevent the energy dissipation in the air bubble from being too large,so as to ensure the operation of the subsequent cycle.Under suitable formation and aquifer conditions,different cycle modes of CAESA system can be realized,including daily cycle,weekly cycle,monthly cycle and even seasonal cycle.Simulation results show that the daily cycle,weekly cycle and monthly cycle can achieve higher energy recovery efficiency for engineering application.With the same amount of injected compressed air,the energy storage efficiency of the daily cycle is slightly higher than the other two cycles,which means that under the same energy storage scale,the daily cycle has advantages of efficiency.Under certain conditions,seasonal circulation can be realized,but due to the large energy loss in the air bubble,the cycle cannot last for a long time,so it needs to be replenished during the circulation process.The injection of high temperature gas into the CAESA system can greatly improve the total energy output.When multiple wells circulate the system at the same time,the positive and negative superposition effect of energy appears in the system,which makes the well injected with more energy;however,in the stage of gas extraction,more energy will be consumed,and the gas in the air bag will be consumed faster,so as to reduce the number of system cycles.When multiple wells circulate,it has a great contribution to improve the energy storage scale of the system.There is an optimal I/W well distance in the system,and the circulation efficiency of the system is the best.