The continuous growth of renewable energy sources has drastically changed the paradigm of electric energy generation and distribution. Flywheel energy storage systems are a clean and efficient method to level supply and demand in energy grids, including those incorporating renewable energy generation. Environmental safety, resilience, high power capacity and quality make flywheel energy storage very promising. This paper contains a review of flywheel energy storage systems, already being in operation, and applications of flywheel energy storage in general.
