Thermodynamic and economic analyses of liquid air energy storage systems using packed bed cold thermal energy storage with different storing materials

• Thermodynamic optimization of the liquid air energy storage system. • Optimum charging and discharging pressures of 18.5 MPa and 10 MPa, respectively. • Economic viability of different storing materials. • Quartz achieved the best techno-economic performance. Liquid air energy storage is a novel technology for storing energy that is receiving increasing interest. Thermal energy storage systems are used to improve the performance of liquid air energy storage systems. The poor performance of the cold thermal energy storage is a bottleneck to achieve cost-effectiveness of the system. The objective of this paper is to identify the most appropriate storing material to be used in cold packed bed energy storage. Four types of storing materials, three sensible heat materials and a latent heat material with cryogenic phase change materials, were evaluated. Thermodynamic models for the components of the system integrated with a 1-dimensional transient numerical model, the concentric dispersion model, of the packed bed system were developed. The total number of required packed bed tanks and the cost of the cold thermal energy storage were estimated for each material. The results suggest an optimum charging pressure of 18.5 MPa, and a discharging pressure of 10 MPa for the liquid air energy storge system with a capacity of 100 MW as input power and a constant capacity of cold thermal energy storage. The maximum round-trip efficiency and the liquid air yield of the system are 50.2 % and 69.3 %, respectively. Moreover, the results indicate that the minimum cost of cold thermal energy storage is 7.4 M€ for the system with quartz as storing material with 24 packed bed tanks. These findings provide a solid basis for further development of cold storage for liquid air energy storage systems.