Abstract: 　　With global energy transition and the increasing penetration of intermittent renewable sources, integrated energy systems face critical challenges in enhancing flexibility and optimizing resource utilization. To address this point, this paper addresses the dual and interconnected issues of pressure energy waste during pressure regulation processes at urban natural gas city gate stations, and the insufficient operational flexibility coupled with constrained renewable energy accommodation capacity stemming from the traditionally independent peak-shaving practices in electricity and natural gas infrastructures. This system integrates off-peak electricity-driven compression with direct expansion refrigeration using high-pressure pipeline gas. It innovatively couples and converts the surplus electrical energy from the power grid with the excess pressure energy from the natural gas pipeline network across both temporal and spatial dimensions, thereby achieving bidirectional electricity-gas peak shaving.
　　During the energy storage phase, off-peak electricity drives a multi-stage compressor to pressurize and pre-cool pipeline natural gas. The high-pressure gas is then expanded in a turbo-expander. This adiabatic expansion recovers pressure energy and generates the deep cryogenic refrigeration required to liquefy another portion of the feed gas. The process converts and stores the combined electrical energy and recovered pressure exergy as LNG in insulated tanks. An integrated thermal management subsystem stores the compression heat and captured cold energy, enhancing overall cycle efficiency. During the energy release phase, the stored LNG is regasified using the stored thermal energy to meet simultaneous peaks in electricity and gas demand. The resulting high-pressure gas is deployed for dual-grid support: a significant portion is directly injected into the urban gas distribution network to address supply shortfalls, while another stream passes through expansion turbines coupled with generators to produce electricity, providing reliable power generation during critical peak periods. This dual-output capability is the cornerstone of the system's synchronous peak-shaving function. This study establishes a refined thermodynamic and exergy analysis model for the proposed system. Based on a typical daily peak-shaving scenario characterized by an "8-hour energy storage followed by 8-hour energy release" cycle, a multi-objective optimization was conducted targeting the system's round-trip efficiency and liquefaction rate. The results indicate that under optimal operating conditions, the system attains a liquefaction rate of 78.49% and a remarkably high round-trip efficiency of 322.8%. Furthermore, the system's energy storage density reaches 10.08 kWh per cubic meter. These performance metrics are significantly superior to those of conventional compressed air energy storage and battery energy storage systems. Economic analysis reveals that for an installation with a daily peak-shaving gas volume capacity of 179, 000 standard cubic meters, the equivalent electrical charge and discharge power ratings are 412 kW and 1, 329 kW, respectively. The levelized cost of storage for this system can be as low as 0.0244 US dollars per kilowatt-hour. Through the effective coupling of multiple energy streams, the system achieves substantial improvements in both energy storage efficiency and economic performance compared to traditional single-purpose energy storage devices. this work presents an efficient, compact solution for coordinated energy storage. The system mitigates energy waste, enhances multi-energy flexibility, and facilitates renewable integration through electricity-gas coupling.