Flywheel energy storage stores kinetic energy by spinning a rotor at high speeds, offering rapid energy release, enhancing grid stability, supporting renewables, and reducing energy costs.
Flywheel energy storage (FES) works by accelerating a rotor (flywheel) to a very high speed and maintaining the energy in the system as rotational energy.
To create kinetic energy, the motor derives energy from the electric grid to power the cylinder or disk to spin at a rate of up to 60,000 RPM. Because a flywheel must be accelerated by an external force before it will store energy, it is considered a “dynamic” storage system.
As the flywheel spins faster, it experiences greater force and thus stores more energy. Flywheels are thus showing immense promise in the field of energy storage systems designed to replace the typical lead-acid batteries. For a flywheel, kinetic energy is calculated as for a spinning object, as
Electrical inputs spin the flywheel rotor and keep it spinning until called upon to release the stored energy. The amount of energy available and its duration is controlled by the mass and speed of the flywheel. In a rotating flywheel, kinetic energy is a function of the flywheel's rotational speed and the mass momentum of inertia.
How can flywheel energy storage improve battery life & system availability?
To improve battery life and system availability, flywheels can be combined with batteries to extend battery run time and reduce the number of yearly battery discharges that reduce battery life (Figure 2). Many types of medical imaging equipment, such as CT or MRI machines can also benefit from flywheel energy storage systems.
What is the difference between a flywheel and a battery?
The physical arrangement of batteries can be designed to match a wide variety of configurations, whereas a flywheel at a minimum must occupy a certain area and volume, because the energy it stores is proportional to its rotational inertia and to the square of its rotational speed.