Superconducting high-power cables and lines—development status and technology roadmap

The energy transition requires a tremendous investment in electric grids, mainly due to electrification of heat and mobility sectors and due to the huge expansion of renewable energy. Superconductors offer an extremely high current density while having no resistance. In the past years, the cost-performance of high-temperature superconducting tapes decreased constantly, and the manufacturing capacity was expanded considerably. In parallel, many AC and DC superconducting cables for various applications from low-voltage up to high-voltage levels have been developed, successfully tested and operated in field tests. The availability of the high-temperature superconducting tapes and the increasing need for network expansion result in an increased interest on the development of superconducting cables. In this paper, the most important and most recent R&D activities on superconducting cables are summarized. The paper is structured in four main parts. Firstly, an introduction is given not only on the history of R&D but also on the high-temperature superconducting materials and conductors. The main part shows some selected R&D projects in more detail, while in the third part common issues relevant to all cables like cooling are discussed. The paper ends with contributions to hybrid superconducting cables, where electricity transport is combined with chemical energy carriers like liquid hydrogen. It can be summarized that several projects demonstrated, that superconducting cables can fulfil all technical requirements for a long-term field operation and first permanent installations are realized. Attractive applications for superconducting cables include electric grids, high-current industry bus bars, data centers and aviation.