Abstract
Liquid air energy storage (LAES) is one of the most promising large-scale energy storage technologies for the decarburization of networks. When electricity is needed, the liquid air is utilized to generate electricity through expansion, while the cold energy from liquid air evaporation is stored and recovered in the air liquefaction process. The packed bed filled with rocks/pebbles for cold storage is more suitable for real-world application in the near future compared to the fluids for cold storage. A standalone LAES system with packed bed energy storage is proposed in our previous work. However, the utilization of pressurized air for heat transfer fluid in the cold storage packed bed (CSPB) is confusing, and the effect of the CSPB on the system level should be further discussed. To address these issues, the dynamic performance of the CSPB is analyzed with the physical properties of the selected cold storage materials characterized. The system simulation is conducted in an experiment scale with and without considering the exergy loss of the CSPB for comparison. The simulation results show that the proposed LAES system has an ideal round trip efficiency (RTE) of 39.38–52.91%. With the consideration of exergy destruction of the CSPB, the RTE decreases by 19.91%. Furthermore, increasing the cold storage pressure reasonably is beneficial to the exergy efficiency of the CSPB, whether it is non-supercritical (0.1 MPa–3 MPa) or supercritical (4 MPa–9 MPa) air. These findings will give guidance and prediction to the experiments of the LAES and finally promote the development of the industrial application.
Highlights
To combat climate change, the demand for renewable energy sources still increased in 2020 under the effect of COVID-19, while the consumption of fossil energy sources declined.Between 2021 and 2022, renewable energy expansion accounted for 90 percent of global electricity expansion [1,2]
The main objective of this study is to investigate the effect of the dynamic cold storage packed bed (CSPB) on the Liquid air energy storage (LAES) system
When the electricity is excess, the charging process operates to produce liquid air: the ambient air mixed with reflux air is compressed and cooled by a three-stage air compressor with inter-coolers, the compression heat is harvested and stored in the heat storage packed bed (HSPB) by thermal oil; the air after compression is deeply cooled down in the cold box by the reflux air and the pressurized air from the CSPB; the liquid air is generated through expansion, stored in the tank
Summary
The demand for renewable energy sources still increased in 2020 under the effect of COVID-19, while the consumption of fossil energy sources declined.Between 2021 and 2022, renewable energy expansion accounted for 90 percent of global electricity expansion [1,2]. Thermal energy storage is greatly used in people’s lives, and phase change materials are popular in recent years, employed in many commercial applications where stable temperatures are required [5,6]. Among large-scale electricity storage, pumped hydro energy storage is the most developed technology with a high efficiency of 65–80%. Pumped hydro energy storage, along with compressed air energy storage, has geographical constraints and is unfriendly to the environment. Liquid air energy storage (LAES) is another large-scale mechanical energy storage technology, which belongs to thermal energy storage. It has attracted extensive attention over the years due to several significant advantages such as no geographical constraints, friendly energy storage materials, high energy storage density, etc. It has attracted extensive attention over the years due to several significant advantages such as no geographical constraints, friendly energy storage materials, high energy storage density, etc. [10]
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