A new type of high-temperature superconducting cable for power transmission has been developed by Tokyo Electric Power Co. (Tepco), Sumitomo Electric Industries Ltd. and Mayekawa Mfg. Co. In August, work on installing the cable commenced at a Tepco substation. When the installation is completed and testing begins, probably in November of next year, it will represent the first introduction of a superconducting cable into a commercial power grid in Japan. Sumitomo will be responsible for manufacturing the superconducting cable itself, while Mayekawa will make the cooling system.
The cable is made from an alloy of bismuth, strontium, calcium and copper that superconducts at -196°C. Sumitomo Electric Industries has already completed power transmission tests on a 30 m prototype, and a similar 30m cable will be installed in the 66kV Asahi substation in Yokohama. Its performance will then be evaluated for a year. As well as conducting verification tests the three companies are keen to reduce production costs in order to have the new superconducting cable ready for full-scale introduction as soon as possible, perhaps by 2016.
According to Tepco, 4.8% of its generated electricity is lost en route between power stations and homes over the existing power grid. For all of Japan, that amounts to some 50 billion kwh of electricity, or the combined output from around 10 of Japan’s 54 nuclear power plants. Superconducting cable could dramatically reduce these losses.