A feasibility study of an 8‐MWh flywheel‐type power storage system using oxide superconductors

Abstract

When combined with a magnet having a magnetic field gradient (for example, a permanent magnet), a Y‐based oxide superconductor is capable of forming a noncontact bearing with a strong levitational force. Since this bearing exhibits low rotational loss, it is very likely to form a highly efficient power storage system in combination with a flywheel. In this paper, an 8‐MWh power storage system utilizing a flywheel was designed conceptually to examine its applicability and the possible effects of its introduction. It was found that this system was an effective power storage.

On the detectability of the Lense–Thirring field from rotating laboratory masses using ring laser gyroscope interferometers

“…Another big ring built by Michelson had dimensions (table 1) One possibility, in principle, for detecting the Lense-Thirring effect is that of using artificial rotating masses rather than the earth. We are severely limited to whatever moment of inertia is practically achievable with a flywheel [21,29]. Against that we have the great advantages of controllability and discrimination.…”

“…If we assume a frequency of rotation f = 10 Hz, a radius of 10 m and a density of ρ = 7900 kg m −3 (steel), we obtain β = 3.40 × 10 −15 . There are formidable engineering problems posed in this example; the extrapolation from presently proposed flywheels (which are typically in the few-MWh regime [21,29]), the wrapping of the ring this close to such a flywheel, and particularly the stored energy of 720 MWh, one quarter of the annual electricity consumption of New Zealand. Even so, the resulting Lense-Thirring effect would require a ring laser relative Allan deviation β approximately a factor 200 smaller than the capabilities of a quantum-noise-limited Michelson Centenary Ring (with the conservative beam power and finesse estimated in table 1).…”

High temperature superconducting levitation flywheel system and its control

“…A number of applications have been discussed. The important application is on the non-contact magnetic bearings and energy storage flywheel systems [7][8][9][10][11][12][13]. As for an energy storage flywheel, it has a shaft, so that two types of vibrations occur, one is a transnational vibration and the other is pitching vibration.…”

“…For the system, the shaft is also supported by electromagnetic bearings at both ends. A stable levitation is obtained by use of active control of the magnetic bearings [9]. The previous systems usually use induction motor-generator.…”