What is a flywheel energy storage system?

Flywheel energy storage systems (FESSs) store mechanical energy in a rotating flywheel that convert into electrical energy by means of an electrical machine and vice versa the electrical machine which drives the flywheel transforms the electrical energy into mechanical energy. Fig. 1 shows a diagram for the components that form a modern FESS.

Why are composite rotor flywheel energy storage systems more expensive?

The differences in the TIC of the two systems are due to differences in rotor and bearing costs. The composite rotor flywheel energy storage system costs more than the steel rotor flywheel energy storage system because composite materials are still in the research and development stage and material and manufacturing costs are high.

What is the power rating of a flywheel energy storage system?

Utility-scale energy storage systems for stationary applications typically have power ratings of 1 MW or more . The largest flywheel energy storage is in New York, USA by Beacon Power with a power rating of 20 MW and 15 min discharge duration .

Can flywheel energy storage be commercially viable?

This project explored flywheel energy storage R&D to reach commercial viability for utility scale energy storage. This required advancing the design, manufacturing capability, system cost, storage capacity, efficiency, reliability, safety, and system level operation of flywheel energy storage technology.

How do flywheels work?

Flywheels function as energy storage devices by containing the kinetic energy in a fast moving rotary drum, which acts as the rotor of a generator. When additional energy is unconsumed, it is used to boost the rotary drum’s speed.

How much does a steel rotor flywheel cost?

The steel rotor flywheel has a lower capital cost and levelized cost of storage. The costs of composite and steel rotor flywheels are $190 and $146/MWh, respectively. Flywheel energy storage systems are increasingly being considered as a promising alternative to electro-chemical batteries for short-duration utility applications.