Power applications of high-temperature superconductors: status and perspectives

The potential of superconductors to have a revolutionary impact on how electric power is generated, delivered and used has long been recognized. The first superconducting power-grid application to achieve full commercial status is superconducting magnetic energy storage (SMES); the magnets of these systems have so far been fabricated primarily with metallic low-temperature superconductors (LTS). Although LTS prototypes have been demonstrated for motors, generators, power cables, transformers and current limiters, high-temperature superconducting (HTS) systems offer striking economic and system reliability advantages and are now seen as the central vehicle for broad commercialization of superconductivity in the power grid. Operating at temperatures from 30 to 80 K, they open the door to highly simplified cryogenics and increased stability, which result in economic systems not feasible with LTS. HTS prototypes at commercial power levels have already been demonstrated, particularly power transmission cables and motors. Key merits as well as remaining open technical challenges for such HTS applications are reviewed in this paper.