Flywheel energy storage

Flywheels are one of the earliest forms of energy storage and have found widespread applications particularly in smoothing uneven torque in engines and machinery. More recently flywheels have been developed to store electrical energy, made possible by use of directly mounted brushless electrical machines and power conversion electronics. This chapter takes the reader from the fundamentals of flywheel energy storage through to discussion of the components which make up a flywheel energy storage system. The place of flywheel energy storage in the storage landscape is explained and its attributes are compared in particular with lithium-ion batteries. It is shown that flywheels have great potential for rapid response, short duration, high cycle applications, many of which are listed and described. For flywheels to succeed beyond niche applications, cost reduction is necessary but certainly possible by use of low-cost materials and innovative design.