[cogman10]

The crux of the problem for superconductors used as power delivery is the "critical field" problem. [1]

Super conductors are superconductive to a point. Once that point is crossed they turn into regular conductors. (I've seen ~1A cited. For context, EVs charge at around 500A).

To make them useful for power transmission, you'd have to up the voltage to insane levels to avoid collapsing the field.

[1] https://en.wikipedia.org/wiki/Critical_field

[floxy]

Superconductors have a critical current density (Ampere/m^2) that varies with temperature and external magnetic field[0]. So if you want more current, you need to use a bigger wire (and/or make it cooler). YBCO HTS tapes have enough current density for power transmission[1].

[0] https://en.wikipedia.org/wiki/Yttrium_barium_copper_oxide#/m...

[1] https://www.amsc.com/comed-and-amsc-announce-successful-inte...

[Eduard]

or just go the straightforward way and use several transmissions in parallel, as it is already done for existing superconducting lines in production.

The AmpaCity project in Essen, Germany, gives insights about the implementation details, as the involved parties were required to publish their work.

https://www.enargus.de/pub/bscw.cgi/?op=enargus.eps2&q=%2201...

for the specific aspect under discussion, the Karlsruhe Institute of Technology report is of interest:

https://www.tib.eu/de/suchen/id/TIBKAT:872231372/Ampacity-10...