# Flywheels and small mechanical stores: What to track

Chinese scale-up and falling costs against batteries

Source page: https://www.materialinsights.org/energy/e_flywheels/tracking/

What this tab covers The attributes worth tracking regularly, with the latest value, the direction of travel and why each matters.

Watch Chinese deployment scale, regulation market prices, and whether costs per kW keep falling against batteries.

| Category | Attribute | Latest | Trend | Why it matters |
|---|---|---|---|---|
| Techno-economic | **Cost trajectory (cost per kW and kWh, in place of LCOS)** | About USD 1,600/kW (Dinglun 2024, calculated) vs USD 3,450/kW (Stephentown 2011, calculated)^[1](https://energy-storage.news/worlds-largest-30mw-flywheel-energy-storage-project-connects-to-grid-in-China)^[2](https://www.powermag.com/milestones-for-flywheel-lithium-battery-grid-scale-projects/) | ↗ improving | Per-MW cost matters most for regulation assets. |
| Technical | **Standing losses and bearing wear (in place of state of health)** | Self-discharge up to 15% per hour (IRENA 2017); steady-state loss below 1% of rated power claimed by Helix Power (developer claim)^[3](https://doi.org/10.1016/j.est.2021.103576)^[4](https://www.irena.org/-/media/Files/IRENA/Agency/Publication/2017/Oct/IRENA_Electricity_Storage_Costs_2017.pdf) | ↗ improving | Lower losses widen the range of useful services. |
| Supply chain | **Critical mineral cost and geopolitical concentration** | Steel or carbon fibre; rare-earth magnets possible in motors and bearings; supply led by China^[1](https://energy-storage.news/worlds-largest-30mw-flywheel-energy-storage-project-connects-to-grid-in-China) | → stable | Low mineral risk, but supplier base is narrow. |
| Market | **Ancillary service market saturation** | Revenue depends on regulation markets^[1](https://energy-storage.news/worlds-largest-30mw-flywheel-energy-storage-project-connects-to-grid-in-China)^[3](https://doi.org/10.1016/j.est.2021.103576) | ↘ worsening | Fast batteries compete in the same small markets, which saturate as storage grows. |
| ESG compliance | **Safety and environmental compliance** | Rotor burst containment and backup bearings^[3](https://doi.org/10.1016/j.est.2021.103576) | → stable | No fire or toxic gas; containment design is the key check. |
| Climate | **Lifecycle carbon payback period** | No verified figure found^[3](https://doi.org/10.1016/j.est.2021.103576) | → stable | Carbon-fibre production is energy-intensive; ask suppliers for lifecycle data. |
| Deployment | **Largest grid flywheel plant** | 30 MW (China, 2024)^[1](https://energy-storage.news/worlds-largest-30mw-flywheel-energy-storage-project-connects-to-grid-in-China) | ↗ improving | Scale-up shows whether flywheels can win share in regulation markets. |
| Deployment | **Behind-the-meter hybrid manufacturing** | Torus targets over 1 GW per quarter within three years (developer claim)^[6](https://www.torus.co/news/torus-raises-200-million-from-magnetar-deployment-of-modular-power-plants) | ↗ improving | Tests whether flywheel-battery hybrids find a volume market outside grid regulation. |

#### Sources

1. ['World's largest' 30MW flywheel energy storage project connects to grid in China](https://energy-storage.news/worlds-largest-30mw-flywheel-energy-storage-project-connects-to-grid-in-China) Energy-Storage.news, 2024
2. [Milestones for flywheel, lithium battery grid-scale projects](https://www.powermag.com/milestones-for-flywheel-lithium-battery-grid-scale-projects/) POWER Magazine, 2011
3. [A review of flywheel energy storage systems: state of the art and opportunities (Li and Palazzolo, Journal of Energy Storage 46, 103576)](https://doi.org/10.1016/j.est.2021.103576) Elsevier (Journal of Energy Storage), 2022
4. [Electricity Storage and Renewables: Costs and Markets to 2030](https://www.irena.org/-/media/Files/IRENA/Agency/Publication/2017/Oct/IRENA_Electricity_Storage_Costs_2017.pdf) IRENA, 2017
5. [Torus raises 200 million from Magnetar for deployment of modular power plants](https://www.torus.co/news/torus-raises-200-million-from-magnetar-deployment-of-modular-power-plants) Torus (company release), 2025

## Other sections

- [Summary](https://www.materialinsights.org/energy/e_flywheels/index.md)
- [Overview](https://www.materialinsights.org/energy/e_flywheels/overview/index.md)
- [Correlation](https://www.materialinsights.org/energy/e_flywheels/correlation/index.md)
- [Science and technology](https://www.materialinsights.org/energy/e_flywheels/sg-sci/index.md)
- [Engineering and performance](https://www.materialinsights.org/energy/e_flywheels/sg-eng/index.md)
- [Economics](https://www.materialinsights.org/energy/e_flywheels/sg-econ/index.md)
- [Impact and additionality](https://www.materialinsights.org/energy/e_flywheels/sg-impact/index.md)
- [Relationships](https://www.materialinsights.org/energy/e_flywheels/links/index.md)