Abstract: A flywheel energy storage system includes a rotating assembly having a plurality of magnets and a longitudinal axis about which the rotating assembly rotates and static assembly having a stator configured to magnetically interact with the plurality of magnets of the rotating assembly. The rotating assembly includes a rotor back iron supporting the plurality of magnets and disposed further from the longitudinal axis in a radial direction than the plurality of magnets. The back iron being formed of a material having a first stiffness, relative permeability of at least 10, and an electrical conductivity 10% or less than the electrical conductivity of magnetic steel. There is composite structure supporting the rotor back iron and disposed further from the longitudinal axis in a radial direction than the rotor back iron. The composite structure comprises a composite material having a second stiffness, which is greater than the first stiffness.

Abstract: A flywheel energy storage system includes a rotating assembly having a plurality of magnets and a longitudinal axis about which the rotating assembly rotates and static assembly having a stator configured to magnetically interact with the plurality of magnets of the rotating assembly. The rotating assembly includes a rotor back iron supporting the plurality of magnets and disposed further from the longitudinal axis in a radial direction than the plurality of magnets. The back iron being formed of a material having a first stiffness, relative permeability of at least 10, and an electrical conductivity 10% or less than the electrical conductivity of magnetic steel. There is composite structure supporting the rotor back iron and disposed further from the longitudinal axis in a radial direction than the rotor back iron. The composite structure comprises a composite material having a second stiffness, which is greater than the first stiffness.

Abstract: A crash management system for implementation in a flywheel energy storage system (FESS) is provided. Implementation of such a system entails designing an FESS rim that is highly failure resistant, and designing the FESS such that if one, some, or even all of its components fail, they are physically prevented from accumulating and releasing enough energy to cause rim burst, thus leaving the rim intact and capable of safely remaining spinning even after one or more FESS component failures have occurred.

Abstract: Featured are methods for regulating the AC frequency of the electrical power be supplied on an electrical distribution system or grid. Such a method includes electrically coupling an energy storage sub-system to the electrical distribution network, where the energy storage sub-system includes one or more flywheel energy storage systems. Also featured as devices, systems and apparatuses embodying such methodologies or for use in implementing such methodologies of the present invention.