Superconductors transport electrical current at low temperatures with virtually no losses - which makes them attractive for numerous energy-saving technologies. However, superconductivity usually requires cooling with liquid helium to a temperature close to minus 269°C. In contrast, a cable developed at the Karlsruhe Institute of Technology (KIT) is reaches the superconductivity state already at minus 196°C. The reason for this is the special material of which the high-temperature superconductor Cross Conductor (HTS CroCo) is made: The material used is Rare-Earth Barium Copper Oxides (REBCO), whose superconducting properties have been known since 1987. However, this superconductor could only be produced in long lengths in the form of thin strips. The KIT scientists have now developed a method in which several REBCO bands are arranged crosswise. The result is a cable with a very high current carrying capacity.
The HTS CroCos thus saves space and weight compared to conventional cables made of copper or aluminium. The production of the cable is particularly efficient: several manufacturing steps are combined in an innovative process developed at KIT. At present, a production speed of one meter per minute is achieved in a demonstrator. In an appropriately scaled industrial production plant, cable lengths of several 100 meters and more would be conceivable, which would save costs. Since the superconducting layer, which carries the high current in the finished cables, is only a few thousandths of a millimeter thick, material costs are also kept within limits. Dr. Michael Wolf from the Institute of Technical Physics at KIT explains that mass production has so far been hampered by high costs for the complex manufacturing process of REBCO tapes. According to Wolf, however, industry is currently developing new processes to make them cheaper.