Thermodynamic and economic analysis of an advanced liquid air energy storage system coupled with LNG cold energy, waste heat and solar energy

LAES systems integrated with external energy sources continue to face persistent challenges, including low round-trip efficiency, constrained flexibility, suboptimal energy utilization, and poor economic viability. In this paper, an advanced LAES system coupled with LNG regasification, flue gas waste heat recovery, and solar energy utilization was proposed. Flue gas waste heat was introduced as a heat source for the cascaded utilization of LNG cold energy, effectively achieving its graded recovery. Thermodynamic analysis, exergy analysis, and economic analysis were conducted to evaluate system performance. The parameter analysis was conducted to evaluate the effects of key operational parameters, including compressor inlet temperature, compressor efficiency, air liquefaction rate, and cold storage capacity, on overall system performance. The economic indicators of the system under different operating modes were analyzed based on electricity pricing policies in four representative regions of China. Results indicate that the proposed system achieves a round-trip efficiency of 243.30 % and an exergy efficiency of 78.85 %. It is worth noting that the proposed system has a higher energy capacity compared to the existing LAES systems, yielding 0.132 kW/kgLNG. In Mode 1, the system operates in Qinghai with an expected investment payback period of 2.09 years and an NPV of 3.01 million US dollars. And it can achieve an LCOE of 0.063 USD/kWh, which is better than the previously reported LAES system. This research provides an important theoretical foundation and technical support for the application and promotion of liquid air energy storage systems.