Session: 09-18-01: Innovations in Storage, Recovery and Upgrade of Thermal Energy

Paper Number: 165862

Influences of Thermal Energy Storage Systems on the Performances of an Adiabatic Compressed Air Energy Storage System Under Off-Design Working Conditions 

With the rapid increase in energy consumption driven by the Fourth Industrial Revolution, the global energy production and consumption patterns have undergone profound changes, with renewable energy emerging as the cornerstone of the global energy transition. Compressed air energy storage (CAES) technology, a physical energy storage solution suitable for large-scale energy storage, effectively mitigates peak and valley load fluctuations in the power grid, making it an important technology for accommodating renewable energy. This paper focuses on a 300 MW non-combustion compressed air energy storage system with air injection. The system uses humid air with a relative humidity of 80% as the compression medium and a steady-state model is developed. The system employs staged compression and cooling methods to compress air to 17 MPa within 8 hours, storing it in underground artificial caverns. During the energy discharge process, the cavern pressure decreases from 17 MPa to 11 MPa within 6 hours. When the pressure inside the cavern is higher than 14.18 MPa, the system maintains the rated flow and rated power. When the pressure drops below 14.18 MPa, the flow of the expansion machine is increased by supplemental air to maintain the system's rated output power. The discharge process ends when the cavern pressure reaches 11 MPa. This study investigates the impact of high-temperature thermal energy storage (HT-TES)—which integrates molten salt storage with pressurized hot water—and medium-temperature thermal energy storage (MT-TES)—which utilizes only pressurized hot water—on the thermodynamic performance of compression, storage, and discharge across the system’s full operational range.The results indicate that, during the compression process, staged dewatering reduces the water content of the air at the final-stage compressor outlet by approximately 97.49%, compared to the humid air at the first-stage compressor inlet. The air temperature within the storage cavern increases by approximately 52% over the entire compression cycle, followed by a gradual decrease once the storage phase is complete.During the discharge process, both temperature and pressure within the cavern drop significantly until the process concludes. Compared to MT-TES, the total gas consumption under rated conditions is 17.12% lower when using HT-TES. Under variable operating conditions—after the air supplementation valve opens—the average gas consumption increases for both thermal storage methods. However, the total air supplementation required for HT-TES is only 84.71% of that required for MT-TES. Over a complete compression-storage-discharge cycle, the roundtrip efficiency of the CAES system employing HT-TES is also higher than that of the MT-TES system.

Presenting Author: Chaocheng Zhao Xi'an Jiaotong University

Presenting Author Biography: Chaocheng Zhao, Ph.D.Candidate, Xi'an Jiaotong University, Research field：Compressed air energy storage (CAES) technology

Authors:

Chaocheng Zhao Xi'an Jiaotong University
Ming Liu Xi'an Jiaotong University
Guangtao Ni Xi'an Jiaotong University
Wei Han Xi’an Thermal Power Research Institute Co.,Ltd
Junjie Yan Xi'an Jiaotong University