Ring-shaped flywheel energy storage systems with superconducting levitation

This paper proposes an energy storage system that combine two new concepts: a ring-shaped flywheel and superconducting levitation. The ring-shaped flywheel differs from conventional disk-shaped flywheels in that it can be applied to large-scale electric power storage systems like pumped storage power generation systems. Superconducting levitation is automatically-stable noncontacting levitation without control and is suitable as support mechanism for the ring-shaped flywheel that has no shaft and hub. To evaluate the feasibility of this new combination, a small-scale prototype was built and tested to investigate the stiffness of superconducting levitation and the properties of the ring, such as horizontal vibration and rotational loss