Does the electric power grid need a room temperature superconductor?

•High temperature superconductor (HTS) wires reach 500 A/cm-width (77 K) over >100 m.•Equipment using HTS wires has been developed for critical needs in the power grid.•Room temperature superconductors (RTS), if discovered, avoid refrigeration in use.•Short coherence length, accelerated flux creep make RTS power applications unlikely.•Given progress in HTS power equipment, power grid does not need RTS.

Superconductivity can revolutionize electric power grids, for example with high power underground cables to open urban power bottlenecks and fault current limiters to solve growing fault currents problems. Technology based on high temperature superconductor (HTS) wire is beginning to meet these critical needs. Wire performance is continually improving. For example, American Superconductor has recently demonstrated long wires with up to 500 A/cm-width at 77 K, almost doubling its previous production performance. But refrigeration, even at 77 K, is a complication, driving interest in discovering room temperature superconductors (RTS). Unfortunately, short coherence lengths and accelerated flux creep will make RTS applications unlikely. Existing HTS technology, in fact, offers a good compromise of relatively high operating temperature but not so high as to incur coherence-length and flux-creep limitations. So – no, power grids do not need RTS; existing HTS wire is proving to be what grids really need.