Millisecond response. China is building a hybrid energy storage facility with a kinetic flywheel

China Green Development Investment Group, a Chinese state-owned company, has begun construction of an innovative 20 MW flywheel energy storage system in Qinghai province. The project is designed to provide so-called synthetic inertia to the power grid, helping stabilize a system increasingly dominated by large-scale wind and solar farms.

Construction officially began on August 1 in the city of Golmud. A consortium of ten institutions is involved in the project, including the China Electric Power Research Institute and the prestigious Tsinghua University. The investment is part of a national key research and development program approved by China’s Ministry of Industry and Information Technology.

A unique combination of three technologies – batteries, flywheels and supercapacitors

The 20 MW kinetic storage system is part of a much larger hybrid complex – the Golmud Dongyue energy storage station. Construction of the entire facility began in April 2026, with full commissioning scheduled for 2027.

The Dongyue station combines three complementary technologies at a single site:

• Lithium iron phosphate batteries – a 150 MW/600 MWh installation with grid-forming capability is responsible for long-duration balancing and energy shifting over a four-hour window.
• Kinetic energy storage (flywheel) – a 20 MW rotor system with millisecond-scale response provides the rotational inertia needed during sudden frequency drops.
• Carbon supercapacitor – a 5 MW system described as the world’s first unit of its kind in this power class, designed to respond to ultra-short power fluctuations.

Protecting batteries and stabilizing a renewables-based grid

Qinghai province is rapidly expanding its wind and solar power capacity. However, replacing conventional steam and coal-fired turbines with inverter-based renewable energy sources leads to a loss of the grid’s natural inertia.

The hybrid model developed by CGDG is intended to test close coordination between three different technologies. By allowing flywheels and supercapacitors to absorb the fastest and most aggressive power fluctuations, the system will reduce the load on LFP lithium batteries. This will help prevent rapid wear and degradation caused by micro-cycling, significantly extending the service life of the entire complex.