Flywheel Energy Storage Systems (FESS) rely on a mechanical working principle: An electric motor is used to spin a rotor of high inertia up to 20,000-50,000 rpm. Electrical energy is thus converted to kinetic energy for storage. For discharging, the motor acts as a generator, braking the rotor to. . Flywheel energy storage (FES) works by spinning a rotor (flywheel) and maintaining the energy in the system as rotational energy. When energy is extracted from the system, the flywheel's rotational speed is reduced as a consequence of the principle of conservation of energy; adding energy to the. . From their ability to integrate seamlessly with renewable energy sources to their impressive longevity and efficiency, flywheels offer a unique and versatile solution to the energy storage conundrum. In this comprehensive exploration, we will delve into the physics behind how flywheels store. . High-speed flywheels- made from composite materials like carbon fiber and fiberglas, typically operate at speeds between 20,000 and 60,000 revolutions per minute (RPM) and can store energy for a few seconds to a few minutes. Kinetic energy can be described as “energy of motion,” in this case the motion of a spinning mass, called a rotor. The rotor spins in a nearly frictionless enclosure. By employing a rotating mass, flywheel systems store energy mechanically, allowing for quick discharge and recharge cycles. This. .