There is another one in Germany since 2014, https://phys.org/news/2014-05-longest-superconducting-cable-worldwide.html https://phys.org/news/2014-05-longest-sup

There is another one in Germany since 2014, https://phys.org/news/2014-05-longest-superconducting-cable-worldwide.html https://phys.org/news/2014-05-longest-superconducting-cable-... As I've read from other sources (in german) it's not perfect, more of a prototype, because it "leaks". The tanks need to be refilled with about 30 metric tons of LN2 every 3 weeks. Anyway, at the time of building (2013) the cost was 13.5 million Euros for its length of 1000 meters, for 3 phases and up to 40 megawatt capacity at 10.000 volts. The operators say it works reliably, and the leakyness could be avoided with the next builds, which are planned. And would make sense, because it's more compact, and enables more efficient 'smart grid'. Especially in densely built up areas, like downtown, where this is.