An energy-storing flywheel assembly, comprising: a flywheel having a vertically-oriented axis of rotation, the flywheel being continuously solid at every point along its radius; a shaft assembly connected to the flywheel and having an axis of rotation that is collinear with the axis of rotation of the flywheel, characterized by a cageless ball thrust bearing that bears the entire weight of the flywheel and shaft assembly and rotatably supports a lower end of the shaft, the bearing including: a stator having a cylindrical recess, and a set of three free-floating bearing balls (58a, 58b, 58c) contained within the stator recess; a rotor rotatably mounted over the stator, the rotor having a cylindrical recess that is coaxial with the stator cylindrical recess and which likewise contains a set of three free-floating bearing balls (64a, 64b, 64c), and a single, middle bearing ball centrally disposed between and in mutual engagement with the three bearing balls (58a,58b,58c) of the stator and the three bearing balls (64a,64b,64c) of the rotor, wherein the diameter of the bearing balls is sufficiently smaller than the diameter of the cylindrical stator and rotor recesses (52, 62) that contain them such that the three bearing balls contained in both the stator and rotor cylindrical recesses do not contact one another when uniformly spaced 120° around their respective recesses, and a supply of lubricant in communication with the stator. a flywheel having a vertically-oriented axis of rotation, the flywheel being continuously solid at every point along its radius; a shaft assembly connected to the flywheel and having an axis of rotation that is collinear with the axis of rotation of the flywheel, characterized by a cageless ball thrust bearing that bears the entire weight of the flywheel and shaft assembly and rotatably supports a lower end of the shaft, the bearing including: a stator having a cylindrical recess, and a set of three free-floating bearing balls (58a, 58b, 58c) contained within the stator recess; a rotor rotatably mounted over the stator, the rotor having a cylindrical recess that is coaxial with the stator cylindrical recess and which likewise contains a set of three free-floating bearing balls (64a, 64b, 64c), and a single, middle bearing ball centrally disposed between and in mutual engagement with the three bearing balls (58a,58b,58c) of the stator and the three bearing balls (64a,64b,64c) of the rotor, wherein the diameter of the bearing balls is sufficiently smaller than the diameter of the cylindrical stator and rotor recesses (52, 62) that contain them such that the three bearing balls contained in both the stator and rotor cylindrical recesses do not contact one another when uniformly spaced 120° around their respective recesses, and a supply of lubricant in communication with the stator. a stator having a cylindrical recess, and a set of three free-floating bearing balls (58a, 58b, 58c) contained within the stator recess; a rotor rotatably mounted over the stator, the rotor having a cylindrical recess that is coaxial with the stator cylindrical recess and which likewise contains a set of three free-floating bearing balls (64a, 64b, 64c), and a single, middle bearing ball centrally disposed between and in mutual engagement with the three bearing balls (58a,58b,58c) of the stator and the three bearing balls (64a,64b,64c) of the rotor, wherein the diameter of the bearing balls is sufficiently smaller than the diameter of the cylindrical stator and rotor recesses (52, 62) that contain them such that the three bearing balls contained in both the stator and rotor cylindrical recesses do not contact one another when uniformly spaced 120° around their respective recesses, and a supply of lubricant in communication with the stator.