Well, based on the paper presented LK99 isn't <i>very</i> useful, think of it as a demonstration of a concept rather than that it is an immediately widely applicable thing, the currents mentioned in the original paper are modest (ok, tiny) and it would require a big step still before using this becomes practical assuming it all holds up.<p>If such a step is ever made then for starters anything that currently uses superconductors would see an immediate improvement in efficiency because the cooling requirement would disappear as well as much reduced engineering complexity. Right now the superconducting wire or ribbon is the simple part, the rest of the complexity is given over to cooling it and keeping it in place under immense stress. The latter part will stay.<p>Then you can start to think about other real world applications such as in power transmission (no need for high voltages to reduce losses), motors, generators, storage systems and so on. There probably isn't a field where electricity is used that would not be peripherally or directly affected by this invention if it all holds up and the current limit is dealt with. Of course it also needs to be fabricated cost effectively (a 'mere matter of engineering'), but given the price of current superconductors that may well be possible. Right now it's more of a matter of whether it can be done or not, not yet whether it can be done cost effectively and in bulk.
Every day stuff:<p>* Frictionless bearings<p>* Incredibly efficient wind turbines<p>* Incredibly efficient motors<p>* Magnetic Grid Storage<p>* Even mor gianter particle colliders<p>* The usual futuristic crap like maglev trains<p>* All sorts crazy applications in everything from Heavy Industry to Mining to Medicine to Recycling<p>I think the most exciting application is widely available superconductors unlock a new region of physics. I look at superconductivity as the garden gate... Once we're inside the exotic garden, we don't even know what we don't know.<p>Think about it... if we could induce superconductivity with a light switch, what other particles in nature have a similar states or effects? Likely once we have a toehold we can use to study superconductivity with, we'll discover even more stuff we didn't know about.
I've been following this on Twitter all week and I am _very_ excited but I must admit, I don't think I'm fully grasping all the ways that this could change our world.