Superconductors can be used to build ultra-powerful electromagnets. These are what you'll find in particle accelerators and experimental fusion reactors (tokamaks) as well as MRI machines. All of these devices are extremely large and very expensive, partly because of the equipment used to maintain them at cryogenic temperatures.

If you could build a room temperature superconductor, you could shrink these machines and reduce their cost and complexity by a large amount. Additionally, you would open up new applications for superconducting magnets, such as maglev trains.

As others have said, reducing electrical transmission losses is another huge benefit. It's only the beginning of the potential applications of room temperature superconductors though.

Current power transmission losses can be between 8%-15%, cutting those to 0 would be a pretty big deal.

https://blog.schneider-electric.com/energy-management-energy...

Our NMR machine that was used for discovering the structure of biomolecules had a superconducting magnet. The whole machine was pretty impressive (massive steel chamber filled with cryo-cooled magnetic coils). You'd "inject" current once in a while and it would swirl around for weeks/months at a time.

well you're not wrong but a room tc superconductor would indeed enable us to cut down on transmission costs of power. I'm not sure if this is obvious but the only reason national powergrids are AC and not DC is because you can step down AC current and therefore have much lower heat dissipation through the transmission lines. So at the minimum you'd get cheaper power by eliminating all the resistive losses and stepper circuits . But also superconductors are used in MRI machines where right now they're kept below Tc using liquid nitrogen, which is hard to control (search MRI quenching). So room temp superconductors would make MRIs cheaper, which would be a boon to the developing world.

Novel magnetic effects, efficient power transfer, some special forms of supercomputers. Room temp super-conductors would change the world in interesting ways assuming of course that they could also be manufactured at scale.

Most importantly it would require an unlocking of fundamental properties in electromagnetism, chemistry, and quantum physics that as of today is still very much unknown.

High powered magnets - these will improve scanners (see comment below), turbines, motors, generators. YBCO superconductors can be fabricated into a flexible tape which is then useful for creating these kind of devices, but YBCO needs to be cooled with liquid nitrogen.

You could have a world-wide power grid; you could power all humanity's energy needs by having a couple of "tiny" (100kmX100km) solar farms spread between world deserts located on different timezones so you won't need any storage.

Using for energy storage would be a big deal see superconductive storage rings. Potentially the holy grail of batteries.