Critical factors and coupling mechanism of a Toroidal Rail Gravity Energy Storage system integrated with hybrid wind-PV power plants

Under the “Dual-Carbon” strategy, integrating highly volatile renewable energy into the grid remains challenging. This study proposes a Toroidal Rail Gravity Energy Storage (TRGES) system, whose key engineering contribution lies in its closed-loop track architecture that enables symmetric operation of freight and empty locomotives. We developed a dynamic model of the TRGES system and conducted multi-objective optimization using the NSGA-II algorithm to maximize system efficiency and minimize response time, under constraints including ≤5% daily power fluctuation and ≥ 95% renewable energy utilization. Key quantitative results demonstrate that charging/discharging power is highly sensitive to load mass and speed, increasing from 0 MW to 51.39 MW and 30.93 MW for a 2375 t load as speed scales from 0 to 50 km/h. Conversely, system efficiency remains stable with load mass but decreases with speed, with the overall system efficiency declining by only 0.04% over the same speed range. When coupled with a hybrid wind-PV plant, the TRGES system achieved a renewable energy utilization rate of 96.3% and reduced the daily fluctuation coefficient to 0.42 on a typical winter day. This study provides a theoretical and practical foundation for deploying gravity energy storage as a viable, geographically flexible solution for large-scale renewable integration and grid peak shaving, indicating its applicability for large-scale renewable integration and grid peak shaving. • The circular orbital gravity energy storage system is proposed innovatively. • A complete dynamic model is established. • The influence of key operation parameters on system performance is revealed. • A multi-objective group model for wind-solar-storage coupling system is constructed. • The fluctuation of wind power output is effectively suppressed.