Randall Parker at FuturePundit has a post on superconducting power cables, in which he notes their benefits over copper:
Superconductor power cables can carry three to five times the power of conventional copper cables. Compact, underground superconductor cables can be used to expand capacity and direct power flows at strategic points on the electric power grid and can be used in city centers where there is enormous demand, but little space under the streets for additional copper cables.
High-temperature superconductor technology is also being used in transformers, to great effect. The company mentioned in Randall’s post, American Superconductor, is doing pioneering work in this field, and has run some successful pilots with Detroit Power & Light. Another important feature of HTS that Randall didn’t mention is that they have no line loss, unlike copper cables (power loss increases with the square of distance traveled, in copper cables), so that means less total power generation to get a given amount of power delivered from A to B.
What, you mean technological change promotes energy conservation? I’m shocked, shocked to hear that! (note: heavy sarcasm)