A flywheel is a mechanical device specifically designed to efficiently store rotational energy. Flywheels resist changes in the speed of rotation due to their moment of inertia. The amount of energy stored in a flywheel is proportional to the square of its speed of rotation. The way to change an energy stored in the flywheel is to increase or decrease its speed of rotation by applying a pair aligned with its axis of symmetry,
Common uses of a flyer include:
• Smooth the power output of a power source. For example the flywheels are used in reciprocating engines because the active torque of the individual pistons is intermittent.
• Energy storage systems Steering wheel energy storage
• Provide power at speeds greater than the capacity of a power source. This is achieved by collecting energy in a flywheel over time and then releasing it rapidly at speeds that exceed the capabilities of the energy source.
• Control of the orientation of a mechanical system, gyroscope and reaction wheel
Flywheels are typically made of steel and rotate in conventional bearings; These are usually limited to a maximum revolution speed of a few thousand RPM. High energy density flywheels can be made from carbon fiber composites and use magnetic bearings, allowing them to rotate at speeds up to 60,000 RPM (1 kHz).
Coal-compound flywheels batteries have recently been manufactured and are proving to be viable in real-world tests on conventional cars. In addition, its disposal is greener.