Huaneng integrates dual-flywheel storage for grid regulation in China

What happened

According to pv magazine, China-based Huaneng Group synchronized a dual-flywheel frequency regulation setup to the grid at its Lanzhou combined heat and power plant. The milestone followed a commissioning process lasting approximately one year, which the company states validates the use of large-scale flywheel storage alongside coal-fired generation infrastructure.

The installation consists of two distinct flywheel devices delivering a total rating of 5.5 MW alongside 1.375 MWh. The larger primary component provides 5 MW and 1.25 MWh, spinning at speeds reaching 3,200 rpm supported by a five-axis active magnetic levitation mechanism. Huaneng reports this apparatus represents the highest-power single flywheel unit in the country. A smaller secondary asset rated at 0.5 MW and 125 kWh manages minor frequency fluctuations alongside the main device.

Technical performance

Data provided by the energy group indicates the paired architecture achieves a grid reaction speed under 100 milliseconds alongside a regulation accuracy exceeding 99.5%. The enterprise credits these outcomes to proprietary control integration linking the storage units with the facility's distributed control system. These operational metrics lack independent verification.

The deployment addresses rapid response requirements. While lithium battery setups typically react within several hundred milliseconds, the flywheel array provides sub-100-millisecond responses. This allows the thermal generator to counteract grid disturbances faster than its internal mechanical inertia permits. The primary device handles substantial frequency deviations, whereas the smaller unit addresses continuous minor corrections to reduce wear on the larger machine.

Development of the technology was spearheaded by the Xi’an Thermal Power Research Institute, serving as Huaneng’s internal research and development division. Following equipment setup and a mandatory 168-hour continuous trial run concluded in December 2025, the system underwent supervised monitoring prior to commercial grid integration.

Why it matters

Located inside Gansu province, the Lanzhou facility operates within a primary zone for northwest China's wind and solar expansion. Regional grids have encountered continuous frequency stability hurdles as variable renewable energy additions outpace conventional dispatchable power sources. Thermal generators face growing pressure to function as regulating assets rather than baseload providers, with grid operators imposing financial penalties under local ancillary services regulations when frequency responses fail to meet established benchmarks.

For energy investors and policymakers observing grid modernization efforts, the deployment highlights the intersection of thermal infrastructure and advanced storage for ancillary services revenue. While flywheel systems offer structural benefits including immunity to chemical degradation, extensive cycle life, and minimal fire risks, they remain more capital-intensive per megawatt than lithium-ion alternatives. The economic viability of replicating this dual-flywheel model across other thermal facilities will depend heavily on how ancillary services markets value millisecond-level response capabilities.