Abstract: A rotating mass energy store includes a rotor that contains conductors and a magnet arrangement. The rotating mass is symmetrical about axis of rotation and is hollow with a cavity, wherein an electrical stator is located in the cavity. All components of the energy store are enclosed in a housing that has a fitting/connection for a vacuum pump and or seal, and wire connection seals for conductive wire to pass through. The rotor is permanently magnetically levitated axially and radially. Electrical energy is exchanged and stored as kinetic energy in a rotating mass, otherwise known as a rotor.