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The table below shows some of the parameters of common superconductors. X:Y means material X doped with element Y, T C is the highest reported transition temperature in kelvins and H C is a critical magnetic field in tesla. "BCS" means whether or not the superconductivity is explained within the BCS theory.
In the past, experimental AC synchronous superconducting machines were made with rotors using low-temperature metal superconductors that exhibit superconductivity when cooled with liquid helium. These worked, however the high cost of liquid helium cooling made them too expensive for most applications.
The suburban Long Island electrical substation is fed by a 2,000 foot (600 m) underground cable system which consists of about 99 miles (159 km) of high-temperature superconductor wire manufactured by American Superconductor chilled to −371 °F (−223.9 °C; 49.3 K) with liquid nitrogen, [dubious – discuss] greatly reducing the cost ...
A substance with a high critical temperature will generally have a higher critical current at low temperature than a superconductor with a lower critical temperature. This higher critical current will raise the energy storage quadratically, which may make SMES and other industrial applications of superconductors cost-effective. [22]
The construction and operating temperature will typically be chosen to maximise: Critical temperature T c, the temperature below which the wire becomes a superconductor; Critical current density J c, the maximum current a superconducting wire can carry per unit cross-sectional area (see images below for examples with 20 kA/cm 2).
If a new superconductor works out, its 100% efficiency will make the worldwide grid even more of a no-brainer. Paul deLespinasse: Room temperature superconductors, the worldwide grid, solar energy ...
The most famous ReBCO is yttrium barium copper oxide, YBa 2 Cu 3 O 7−x (or Y123), the first superconductor found with a critical temperature above the boiling point of liquid nitrogen. [10] Its molar ratio is 1 to 2 to 3 for yttrium, barium, and copper and it has a unit cell consisting of subunits, which is the typical structure of perovskites .
Breakthrough would mark ‘holy grails of modern physics, unlocking major new developments in energy, transportation, healthcare, and communications’ – but it is a long way from being proven