In 1911 Heike Kamerlingh Onnes discovered that if he cooled mercury to –269º C its electrical resistance disappeared completely: he had just discovered superconductivity .
This happens with certain types of compounds when they cool down to a temperature, called the critical temperature; from that moment they do not offer any resistance to the passage of electricity. This means that they do not heat up and, therefore, there are no energy losses when carrying the current from one place to another, something that is priceless for any electric company. In fact, it is estimated that discovering superconducting materials at room temperature would save 20% of the losses in the energy that is transported from power plants to homes.
The drawback is in the critical temperature itself: to get a material to become superconducting it has to be cooled down a lot, down to about 250 degrees Celsius below zero.
But in 1986 it was discovered that not only metals and metal alloys had this property: at IBM Laboratories in Zurich they discovered that when copper and lanthanum oxide, which is an insulator, is doped with barium, it becomes superconducting at -237º C.
Since then , superconducting substances have been intensively sought at room temperature , as there is no theoretical impediment to this. It is possible that we will see it in the near future and then we will be able to carry current densities 2,000 times greater than what a copper cable does. Many optimistic scientists think that by 2025 50% of electrical generators, transmitters and transformers will be superconducting . Unfortunately, this search is done almost blindly, with probatins, because the question of how superconductivity appears in a material at high temperature is one of the most important enigmas that the physics of condensed matter has to solve. And, despite the efforts made since the 1980s, the phenomenon eludes any attempt at explanation.
