Flywheel Energy Storage: An Overview

摘要

Flywheel energy storage (FES) works by rapidly spinning a rotor (flywheel) and storing the energy as rotational energy in the system. As a result of the concept of conservation of energy, when energy is withdrawn from the system, the flywheel's rotating speed is lowered; when energy is added to the system, the flywheel's rotational speed is increased. The majority of FES systems use electricity to accelerate and decelerate the flywheel; however mechanical energy-based devices are being developed. Rotors composed of high-strength carbon-fiber composites are hung by magnetic bearings and spin at speeds ranging from 20,000 to over 50,000 rpm in a vacuum enclosure in advanced FES systems. Flywheels can get up to speed in minutes, allowing them to reach their energy capacity far faster than other types of storage. A flywheel supported by rolling-element bearings is coupled to a motor–generator in a typical setup. To reduce friction and energy waste, the flywheel and sometimes the motor–generator are encased in a vacuum chamber. A massive steel flywheel rotates on mechanical bearings in first-generation flywheel energy storage systems. Carbon-fiber composite rotors, which have a higher tensile strength than steel and can store significantly more energy for the same mass, are used in newer systems. Magnetic bearings are occasionally used instead of mechanical bearings to reduce friction.