Flywheel Battery Hybrids: Pairing High-Speed Flywheels with Lithium-Iron-Phosphate Batteries for Grid Stability: A Growing Trend

       This post is a review of a guest or sponsored article in Utility Dive by Nate Walkingshaw, CEO and co-founder of Torus. It is about a new configuration for demand response and for managing distributed energy resources.

     First, he notes a K-12 school in Sandy, Utah, that has a science center with a display of their flywheel and Li-Fe-P battery combo used for power and to smooth geothermal loads. It sits outside the center and is shown below. It is a demonstration for educational purposes.

     The same configuration is deployed at a larger scale in utility demand response programs. He calls it smart storage.

     Battery degradation, he says, is a very real issue that condemns utility-scale battery systems to be retired or need replacement earlier than planned, or projects to be shelved due to cost, complexity, and supply chain issues.

“Ask any utility engineer about frequency regulation duty cycles, and you’ll hear the same story: batteries degrade quickly under constant cycling. The field is littered with early replacements, derailed economics, and procurement teams hesitant to greenlight large-scale deployments.”

     He notes that batteries are great for energy storage but not for high-frequency power management. However, “flywheels are the opposite: not ideal for long-duration storage, but unmatched for fast response and power quality.” Paired together, they can thrive.

    Voltage spikes, frequency swings, and rapid cycling can wreak havoc on batteries. The science center draws energy and heat from 45 geothermal wells. The electrical load varies as the HVAC systems cycle. The flywheel prevents that load variation from damaging the battery system. Students can watch frequency regulation and voltage control in real time, learning hands-on how power grid operation works.

     He notes that this configuration is on the road to being competitive

“For hybrid systems to scale, we need a reliable domestic supply chain. Domestic battery manufacturing is finally becoming competitive. New American-made LFP cells now deliver 3–6C performance, rivaling the world’s best. These cells are engineered for demanding grid applications, built domestically, and designed for recyclability.”

“Pair them with flywheel technology, and you get hybrid systems that can manage temperature extremes, meet uptime requirements, and support grid services like demand response, peak shaving, and ancillary reserves without compromising asset life.”

     The result, he says, is a responsive architecture that can avoid costly upgrades. For high load demand functions like EV fast charging and AI data centers, this configuration can work. The flywheel absorbs the fluctuations, and the battery provides energy for longer outages and load shifts.

     He notes that while flywheels can have high upfront costs, they can extend the lives of batteries from 8-10 years to 15-20 years. That results in overall savings over the long run.

     He notes that this hybrid technology has been proven, even in scaled-up versions, and is ready to move beyond demonstration projects and, with American manufacturing to be deployed smartly in places where it would work best.

“The grid America needs won’t run on any single technology. It will depend on systems that combine mechanical durability, chemical efficiency, and intelligent control from the edge of the grid to the core.”

     A July 2023 paper in the Journal of Energy Storage compared costs for a hydrogen fuel cell-battery hybrid storage system and a flywheel-LFP battery hybrid storage system. They found that the flywheel hybrid was a better value, especially as it extended the life of the battery system a little over the hydrogen fuel cell system. As noted below from the paper, while the levelized cost of delivery (LCOD) was the same for the two systems, the levelized cost of storage (LCOS) was much lower for the flywheel hybrid.

 

  

References:

 

The hybrid advantage: Why flywheel -battery systems are grid stability’s best-kept secret. Nate. Walkingshaw, CEO and co-founder of Torus. Utility Dive. August 11, 2025. The hybrid advantage: Why flywheel-battery systems are grid stability’s best-kept secret | Utility Dive

Battery-hydrogen vs. flywheel-battery hybrid storage systems for renewable energy integration in mini-grid: A techno-economic comparison. Dario Pelosi, Arianna Baldinelli, Giovanni Cinti, Dana-Alexandra Ciupageanu, Andrea Ottaviano, Francesca Santori, Federico Carere, and Linda Barelli. Journal of Energy Storage. Volume 63, July 2023. Battery-hydrogen vs. flywheel-battery hybrid storage systems for renewable energy integration in mini-grid: A techno-economic comparison - ScienceDirect