China Achieves “Tongliao Speed”: Inner Mongolia Launches 2,000 MWh Megabattery in Record Time
China’s push for large-scale energy storage just hit a new benchmark. A massive 500 MW / 2,000 MWh standalone Battery Energy Storage System (BESS) in Tongliao, Inner Mongolia, has officially begun commercial operation. The project was completed in a stunning five-month construction period, reflecting China’s accelerating commitment to integrating high penetrations of wind and solar generation into its grid.
Project Scale and Development
Located in Naiman Banner, Tongliao, this facility is Inner Mongolia’s largest single-site new-type storage facility.
Developer: The project was developed and financed by Tongliao Conch New Energy Co., Ltd., a subsidiary of China’s largest cement manufacturer, the Conch Cement Group.
Timeline: Construction began on June 28, 2025, and achieved grid connection a month ahead of schedule on November 28, 2025—a feat local authorities are calling the “Tongliao speed.”
Investment: The total investment reached approximately CNY 1.5 billion.
Impact: The system is expected to provide annual peak–valley shifting of about 600 GWh, with an annual throughput of up to 1.5 TWh.
Cutting-Edge Technology Under Extreme Conditions
The facility relies on robust Lithium Iron Phosphate (LFP) battery technology and connects directly to the regional high-voltage network via a 220kV booster substation.
| Component | Supplier | Key Specification |
| DC Side (Batteries) | CATL | 5MWh containerized systems based on 314Ah cells. Expected to increase discharged energy by 3–5% over the lifecycle and achieve parts-per-billion (PPB) safety-failure rates. |
| AC Side (PCS) | Kehua | 5MW centralized PCS–step-up integrated units. Designed with an IP65 rating for extreme Inner Mongolia conditions ($\text{operating in } -35^\circ \text{C}, \text{ high-wind, high-sand}$). Features peak conversion efficiency above 99%. |
Core Function: A Cornerstone for Grid Stability
The Tongliao BESS operates as an independent storage asset in North China’s Mengdong power market. Its core mission is to solve the grid-balancing challenges created by the region’s high renewable energy output.
The plant delivers crucial services, including:
Peak Shaving and Valley Filling
Frequency and Voltage Support
Ramp-Rate Smoothing and Power Quality Improvement
By charging when wind and solar output is high and discharging during demand peaks, the facility directly tackles the issue of renewable curtailment. This project is framed as a key “Tongliao solution” and a template for integrating large-scale standalone storage into future power systems across China.