A flywheel based energy storage apparatus includes a housing and a hub-less flywheel mounted within the housing. The hub-less flywheel has a mass which is shifted radially outwards from a central axis of the hub-less flywheel thus increasing the energy density of the apparatus. The flywheel includes an outer axially extending annular surface, an inner axially extending surface and two radially extending side surfaces. The inner axially extending surface has a plurality of magnets aligned to form a rotor. A plurality of coils is supported by the housing and is aligned with the rotor to form a motor/generator. A controller controls the motion of the hub-less flywheel to reduce vibrations and controls electrical power transfer to and from the motor/generator.