Superconducting magnetic energy storage device operating at liquid nitrogen temperatures

A laboratory-scale superconducting energy storage (SMES) device based on a high-temperature superconducting coil was developed. This SMES has three ma jor distinctive features: (a) it operates between 64 and 77K, using liquid nitrogen (LN2) for cooling; (b) it uses a ferromagnetic core with a variabl e gap to increase the stored energy while retaining the critical current va lue; (c) it has the option for simultaneous energy charge and discharge whi ch increases the power available at the SMES output by a factor of less tha n or equal to 2 when operating as a converter. The present prototype of liq uid nitrogen operating SMES stores 130 J at 64K and 60 J at 77K. (C) 1999 E lsevier Science Ltd. All rights reserved.