Flywheels are best suited to produce high power outputs of 100 kW to 2 mW over a short period of 12-60 seconds. The peak output, at 125 kW for 16 seconds, is sufficient to provide 2 mW for one second.
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.
How much energy is stored in a flywheel?
The amount of stored energy is proportional to the flywheel's rotational speed square. The traditional flywheels are generally limited to a rotational speed of a few thousand revolutions per minute (RPM) due to bearings and materials. It can distinguish between high-speed and low-speed flywheels according to the number of revolutions per minute.
What is a flywheel energy storage system (fess)?
Think of it as a mechanical storage tool that converts electrical energy into mechanical energy for storage. This energy is stored in the form of rotational kinetic energy. Typically, the energy input to a Flywheel Energy Storage System (FESS) comes from an electrical source like the grid or any other electrical source.
How do flywheels work?
Flywheels are kinetic energy storage devices that store energy in a rotating mass. Their structure consists of rotating cylinders connected to a motor that stores kinetic energy. The conversion of electric to kinetic energy is achieved through the use of a variable-frequency motor or drive.
The flywheels can be charged and discharged rapidly, transferring a large amount of power in seconds with high efficiency. The largest commercially used flywheel provides around 1.6MW for 10s.
A 30 MW flywheel grid system started operating in China in 2024. Flywheels may be used to store energy generated by wind turbines during off-peak periods or during high wind speeds. In 2010, Beacon Power began testing of their Smart Energy 25 (Gen 4) flywheel energy storage system at a wind farm in Tehachapi, California.