Flywheel energy storage technology is an energy storage technology that accelerates a flywheel (rotor) to a very high speed and stores the energy in the system as the rotational energy (angular kinetic energy) of the rotor.
The biggest advantage of flywheel energy storage systems is their extremely fast charging speed; the rotor speed can be increased to maximum within minutes, reaching its energy storage capacity limit. Compared with other electricity storage technologies, flywheel energy storage systems have the following advantages:
1. Extremely long service life: New generation flywheel energy storage systems generally use magnetic bearings, which enables the flywheel energy storage system to work stably for decades with almost no maintenance required.
2. High number of charging cycles: While a typical lithium battery can only be charged a few thousand times, a flywheel energy storage system can be charged 100,000 to 1 million times or more.
3. High energy density: Flywheel energy storage technology has a very high energy density, approximately 100–130 W·h/kg, or 360–500 kJ/kg.
4. Very high maximum power input/output: Flywheel energy storage systems have very fast charging speeds. Currently, a typical flywheel energy storage system has a capacity range of approximately 3kWh to 133kWh, and it can be fully charged in 15 minutes. Simultaneously, it can release all this energy in a very short time.
For example, the aircraft catapults on the Ford-class aircraft carriers use a flywheel energy storage system, which can store approximately 122 MJ (34 kWh) of energy in 45 seconds and release all of that energy in 2 to 3 seconds.
5. Unaffected by temperature: As we all know, the amount of electrical energy that a lithium battery can store decreases significantly as the temperature decreases. However, this does not happen with flywheel energy storage systems, which can operate over a wider temperature range.
6. High energy efficiency: The energy efficiency (energy output/energy input ratio) of flywheel energy storage systems can reach 90%, making it a highly efficient energy storage technology.
Flywheel energy storage systems have many other advantages, such as being very easy to measure remaining energy (simply measuring the rotational speed) and requiring very little maintenance throughout their lifespan.
