European Organization for Nuclear Research known as CERN developed the first 60-metre-long power transmission line made with magnesium diboride (MgB2) superconductor. It can transport electricity at a much higher current densities than ordinary cables without any loss. The line operates in Helium gas (He) up to 25 K (-248 degree Celsius) as the cooling system so reach its superconducting state.
Like a metal python, the huge pipe snaking through a CERN high-tech hall is actually a new electrical transmission line. This superconducting line is the first of its kind and allows vast quantities of electrical current to be transported within a pipe of a relatively small diameter. Similar pipes could well be used in towns in the future.
Catch the video on Phys.org.
(Image Credit: CERN)
In more general electrical transmission, only a small fraction of power is lost to the resistivity of the cable (transmission in general is 94-95% efficient in the US, and there are other losses involved too). Where superconducting cables would be most useful though is for buried lines in dense urban areas. Most transmission lines can minimize losses with higher voltage and sometimes switching to DC. But that causes problems for buried lines requiring very expensive dielectric oils to insulate the cable and a complicated system for moving the oil around as it doesn't work as well if not constantly moving. Even with the cryogenic insulation, a buried superconducting cable could be smaller for the same power carrying capacity. In the end, it will come down to which of the two approaches is less of a PITA and costs less.