• • • Flywheel energy storage is a promising technology that offers several advantages, including high power density, rapid charging and discharging, and long lifespan. While it faces challenges related to cost, safety, and energy efficiency, ongoing research and development are addressing these issues.
[pdf] 
First-generation flywheel energy-storage systems use a large steel flywheel rotating on mechanical bearings. Newer systems use carbon-fiber composite rotors that have a higher tensile strength than steel and can store much more energy for the same mass. .
Flywheel energy storage (FES) works by accelerating a rotor () to a very high speed and maintaining the energy in the system as . When energy is extracted from the system, the flywheel's rotational. .
A typical system consists of a flywheel supported by connected to a . The flywheel and. .
TransportationAutomotiveIn the 1950s, flywheel-powered buses, known as .
• • • – Form of power supply• – High-capacity electrochemical capacitor .
GeneralCompared with other ways to store electricity, FES systems have long lifetimes (lasting. .
Flywheels are not as adversely affected by temperature changes, can operate at a much wider temperature range, and are not subject to many of the common failures of chemical . They are also less potentially damaging to the environment,. .
• Beacon Power Applies for DOE Grants to Fund up to 50% of Two 20 MW Energy Storage Plants, Sep. 1, 2009• Sheahen,.
[pdf] Compared with other ways to store electricity, FES systems have long lifetimes (lasting decades with little or no maintenance; full-cycle lifetimes quoted for flywheels range from in excess of 10 , up to 10 , cycles of use), high (100–130 W·h/kg, or 360–500 kJ/kg), and large maximum power output. The (ratio of energy out per energy in) of flywheels, also known as round-trip efficiency, can be as high as 90%. Typical capacities range from 3 to 1.
[pdf] 
