Superconducting high-power cables and lines – Development status and technology roadmap

Abstract

More than 35 years after the discovery of high-temperature superconductivity and more than 20 years after the first field-test installation of a high-temperature superconducting cable, superconducting cables and lines were developed successfully up to high voltage levels and several long-term field tests demonstrated a reliable operation. There are many different applications where superconducting cables and lines were developed in the past. The technology readiness level is very different among the applications. Whereas medium voltage cables for urban areas with a length of a km have been field tested for long times in several locations, high voltage long distance cables are still in the technology concept status. This contribution is structured in four main parts. A proper description of superconducting cables cannot be made without an overview on the present material R&D and the lessons learned from the many successful projects in the past. Presently, there are substantial activities to further develop superconducting cables for AC and high-current DC applications and they are summarized in the second part. Recently, two start-up companies were founded and their R&D is also included. The third part of this paper covers the experience with a reliable operation and the cooling aspects. These contributions focus on the experience from field test applications and on future developments in this area. Hydrogen as an energy carrier is getting more and more attractive and due to the high energy density liquid hydrogen is expected to be widely used at least in some applications. This would favour the combination with superconductors very much because of its temperature of 20 K at pool boiling conditions. The last part of this contribution summarizes present R&D activities for hybrid energy lines with chemical and electricity transport in one line.