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] The earliest form of a device that used gravity to power mechanical movement was the , invented in 1656 by . The clock was powered by the force of gravity using an mechanism, that made a pendulum move back and forth. Since then, gravity batteries have advanced into systems that can utilize the force due to gravity, and turn it into electricity for large scale energy storage.
[pdf] Gravitricity, based in the UK, employs weights suspended in deep mine shafts to store energy, while Energy Vault, a Swiss company, uses massive cranes to stack and unstack concrete blocks around a central tower.
[pdf] 
