Use of oil with tetra ethyl lead causes much pollution, with lead containing carbon monoxide, nitrogen oxide and policyclic nitro hydride.

Since the cuprates first appeared, a variety of other high temperature superconductors have been discovered one is a simple compound of magnesium and boron, and another involves a mixture of iron and arsenic. Although none of them superconduct at temperatures as high as liquid air, they may ultimately be better materials with which to work.

We've been working on this, actually, as an alternative energy source, starting way back with Johnson Johnson, to run an iBOT, because the best batteries you could get 10 watt hours per kilogram in lead, 20 watt hours per kilogram nickel cadmium, 40 watt hours per kilogram in nickel metal hydride, 60 watt hours per kilogram in lithium, 8,750 watt hours of energy in every kilogram of propane or gasoline which is why nobody drives electric cars.