Flywheel system with stationary shaft

A method for operating a flywheel system, comprising:

• a rotor forming an aperture extending through a rotation axis of the rotor;
• a fixture including a shaft assembly for passing through the aperture of the rotor, wherein the rotor rotates about the shaft assembly, the shaft assembly further comprising:
• a bottom support;
• a top support;
• a central rod connecting the bottom support to the top support;
• a plurality of stacked modules, each module forming an aperture for receiving the central rod;
• a top pre-tensioning nut affixed to a top end of the central rod;
• and
• a bottom pre-tensioning nut affixed to a bottom end of the central rod wherein the top pre-tensioning nut and the bottom pre-tensioning nut clamp the plurality of stacked modules between the bottom support and the top support;
• wherein at least one module of the plurality of stacked modules is a generator module, and the method for operating the flywheel system comprises:
• operating the generator module in:
• a generator mode, by magnetically converting rotational energy of the rotor to electrical energy;
• or
• a motor mode, by magnetically converting electrical energy to rotational energy of rotor.