Pretty cool article about using superconductors for commercial power. In a nutshell, superconductors are materials that have a zero electrical resistance below a threshold temperature. These particular "warm" cables have to be maintained between 65-75 K, which is still pretty cold. Electrical current can flow indefinately without a power source meaning that you don't "lose" any power during transmission (i squared r loss). From a practical perspective in the energy industry, this technology allows great amounts of power to be transferred over physically small lines. Also beneficial for safety, is the fact that superconducting properties are quickly lost during "fault circuits" - reminds me of built in nuclear reactor safety mechanisms where the system can't function when it goes to a certain range out of spec.