Flywheel Energy Technology
Flywheel energy storage works by accelerating a cylindrical assembly called a rotor (flywheel) to a very high speed and maintaining the energy in the system as rotational energy. The energy is converted back by slowing down the flywheel. The flywheel system itself is a kinetic, or mechanical, battery spinning at very high speeds to store energy that is instantly available when needed.
The flywheel itself comprises a patented high-strength carbon-fibre composite rim, supported by a metal hub and shaft, with a motor/generator on the shaft. Together the rim, hub, shaft and motor/generator assembly form the rotor. To nearly eliminate friction, the rotor is sealed in a strong vacuum chamber and levitated magnetically. The rotor spins between 8,000 and 16,000 rpm. When the controller senses that the system frequency is too high, it will send a signal that requests the flywheels to absorb power from the grid; which speeds up the flywheel. Conversely when the system frequency is too low, the momentum of the spinning flywheel will drive a generator and the kinetic energy will be converted into electrical energy and injected back into the grid.
The flywheel can spin for extended periods with great efficiency because friction and drag are reduced by the use of magnetic bearings in a vacuum-sealed environment. Multiple flywheels can be connected together to provide various megawatt-level power capacities and various levels of energy storage. Other benefits of fast-response flywheel based regulation are that it produces much less CO2 emissions than fossil-based regulation, and reduces dependency on fossil fuels.