Earlier quoted context omitted.
IANAP, but a layman's understanding: the materials that we have available today to conduct electricity at or around room temperatures largely do so in an inefficient manner. As electricity moves through the material, some energy is wasted in the form of ejected heat. To circumvent this, physicists discovered superconductivity: a state in which a material is a perfectly efficient conductor of electricity. Thus far, to…
"Inefficient" is a rather relative term here, since batteries, motors, and transmission wires are >=95% efficient already.
We lose it to HEAT and that has a lot of limitations like the stuff melting and exploding.