Thermodynamic analysis of a novel hybrid liquid air energy storage system based on the utilization of LNG cold energy

Highlights: • A novel hybrid LAES system utilizing LNG cold energy is proposed and studied. • A two-stage ORC system is introduced to generate additional electricity. • Energy and exergy analysis of the entire and each subsystem were conducted. • The electricity storage efficiency of the proposed system could reach 70%. • The system can be used in LNG terminals for its stability and easy realization. Liquid air energy storage (LAES) is a promising solution for electricity energy storage and grid load shifting. The storage and application of cold energy can significantly affect the performance of LAES systems. A stable and sufficient source of cold energy in the liquefaction process is the key factor for the stable and efficient operation of an LAES system. Hence, a novel hybrid LAES system combined with organic Rankine cycle (ORC) systems based on the utilization of liquefied natural gas (LNG) cold energy is proposed in this paper. In the charging process, the LNG helps cool the compressed air, and the cold energy of the liquid air and excess compression heat are utilized in a two-stage ORC system to generate additional electricity during the discharging process. A mathematical model comprising energy and exergy analyses was developed to analyze the performance of the proposed system and the influence of key parameters. Compared to standalone LAES systems, the cold energy storage system is extremely simplified in the proposed system, and higher electricity storage efficiency and density are obtained. Therefore, the proposed system has a promising prospect in LNG terminals owing to its stability and ease of implementation.