Flywheel energy storage advances using HTS bearings

High-temperature-superconducting (HTS) bearings have the potential to reduc e rotor idling losses and make flywheel energy storage economical. Demonstr ation of large, high-speed flywheels is key to market penetration. Toward t his goal, we have developed and tested a flywheel system with 5- to 15-kg d isk-shaped rotors. Rim speeds exceeded 400 m/s, and stored energies were >8 0 Wh. Test implementation required technological advances in nearly all asp ects of the flywheel system. Features and limitations of the design and tes ts are discussed, especially those related to achieving greater energy stor age levels.