Objective The transition to a decarbonized energy structure and the integration of high proportions of renewable energy have amplified the peak-valley differences in power systems, increasing the demand for flexible regulation. Meanwhile, significant pressure energy is lost through throttling during pressure regulation at urban natural gas gate stations. In addition, the power and natural gas systems have traditionally operated independently, lacking effective technologies to integrate their flexible resources for coordinated peak shaving.

Methods To address the aforementioned issues, a novel liquefied natural gas (LNG) energy storage system was proposed, integrating compression driven by off-peak electricity with direct expansion refrigeration of high-pressure pipeline gas. The system was innovatively designed to achieve the spatio-temporal coupling and conversion of surplus electricity from the power grid and excess pressure energy from the gas pipeline network. In the energy storage stage, off-peak electricity was used to drive compressors to pressurize and precool natural gas from the pipeline network. The high-pressure natural gas was then adiabatically expanded in a turbine expander to generate cryogenic cooling, enabling the cooperative conversion of electrical energy and pressure energy into LNG for storage. In the energy release stage, the stored LNG was rapidly gasified to supply the gas pipeline network or expanded through turbines coupled with generators to produce electricity. Thermodynamic and exergy analysis models of the system were established. Based on a typical daily peak-shaving scenario of “8-hour energy storage – 8-hour energy release”, multi-objective optimization was conducted for key operating parameters, with system round-trip efficiency and liquefaction rate as the optimization objectives. Thermodynamic performance analysis and techno-economic evaluation were subsequently carried out for the optimized system.

Results Under optimal conditions, the system achieved a liquefaction rate of 78.49％, a round-trip efficiency of 322.8％, and an energy storage density of 10.08 kW·h/m³—significantly surpassing conventional compressed air and battery energy storage systems. Economic analysis indicated that for a plant with a daily peak-shaving gas capacity of 17.9×10⁴ m³, the equivalent charging and discharging powers were 412 kW and 1 329 kW, respectively, with a levelized cost of storage (LCOS) as low as USD 0.024 4/(kW·h).

Conclusion The system enables coordinated power-gas peak shaving through multi-energy flow coupling, significantly enhancing the integrated energy system’s flexibility and facilitating renewable energy consumption. However, its operation depends on synchronized peak-shaving cycles between the power and gas grids. Future improvements in adaptability and robustness could be achieved by incorporating buffer energy storage or external regulation mechanisms.