A superconductor in Essen, Germany, has now been live for 4,300 hours. On Monday, Oct. 27, RWE and its project partners gave a positive interim report on AmpaCity’s first 180 days at work. The world’s longest superconductor has amply fulfilled expectations, transmitting five times as much electricity as a conventional copper cable. As an added plus, dissipation is near-zero. Since commissioning the 1-km-long cable on April 30, 2014, RWE has used it to deliver approximately 20 million kWh, equivalent to supplying around 10,000 Essen households with electricity.
Funding from the German Federal Ministry for Economics and Energy enabled the flagship project to go ahead. Since then, the eyes of the world have been on AmpaCity.
“The energy transition calls for bold innovation. We need to design an efficient and secure system to meet tomorrow’s energy needs. So we had no hesitation in choosing this excellent project for sponsorship under our energy research program,” explained Uwe Beckmeyer, Parliamentary State Secretary to the Federal Minister of Economics and Energy, on his visit to Essen.
Thus the Ministry has contributed EUR 5.9 million of the project’s total EUR 13.5 million costs, co-investing with RWE and its partners Nexans and the Karlsruhe Institute of Technology (KIT). For the field trial, cable manufacturer Nexans designed a superconducting short-circuit current limiter, as well as the superconductor itself, while KIT lent scientific support.
The superconductor transmits current at -200°C rather than -270°C. This “high” temperature is the fruit of research by Prof. Alex Müller and Dr. Johannes Georg Bednorz, who won them the Nobel Prize for Physics in 1987. The properties of the superconductor’s special ceramic material, coupled with cooling to -200°C, make the cable an ideal electric conductor. In Essen, the 10,000-V superconductor cable replaces a conventional 110,000-V power line. This technology makes it possible to reduce the number of substations and shift them to the outskirts, releasing valuable inner-city land.
After 180 days of operation, the project partners have now released their first summary. “Operations have so far proceeded smoothly. We have gained valuable knowledge of this technology, which has helped us improve the whole superconductor system further,” reported Dr. Joachim Schneider, technical director at RWE Deutschland. The project partners have made some changes to system monitoring, to ensure the best possible integration of the superconductor into the Essen grid protection system. They have also adapted the cable cooling circuit to AmpaCity’s special requirements.
The new technical knowledge gained from the project has elicited keen interest at home and abroad. Delegations from China, France, Ghana, Japan and the U.S. have already visited Essen to find out more about the technology on location.