Flywheel energy storage is a mechanical energy storage technology with high power, fast response, high frequency and long life, which is suitable for transportation (rail transit [5–7], ship [8,9], automobile [10–13], aviation [14,15]), power grid quality management. Flywheel energy storage is a mechanical energy storage technology with high power, fast response, high frequency and long life, which is suitable for transportation (rail transit [5–7], ship [8,9], automobile [10–13], aviation [14,15]), power grid quality management. Flywheel energy storage (FES) works by spinning a rotor (flywheel) and maintaining the energy in the system as rotational energy. When energy is extracted from the system, the flywheel's rotational speed is reduced as a consequence of the principle of conservation of energy; adding energy to the. Flywheel Energy Storage Systems (FESS) rely on a mechanical working principle: An electric motor is used to spin a rotor of high inertia up to 20,000-50,000 rpm. Electrical energy is thus converted to kinetic energy for storage. It typically is used to stabilize to some degree power grids, to help them stay on the grid frequency, and to. There is noticeable progress in FESS, especially in utility, large-scale deployment for the electrical grid, and renewable energy applications. This paper gives a review of the recent developments in FESS technologies. Due to the highly interdisciplinary nature of FESSs, we survey different design. Abstract: The flywheel energy storage system is a way to meet the high-power energy storage and energy/power conversion needs.