Conventional superconducting cables are lighter than those made of copper, but they are still so heavy that they have to be buried underground, van der Laan says. “Researchers are looking at options for using them as overhead lines instead of underground,” he says, “but conventional cables have been too heavy to use overhead. One benefit of our cables is they’re much more lightweight.”
Until now, it was assumed that you could not make superconducting cables so thin, says Venkat Selvamanickam, a mechanical-engineering professor and high-temperature superconductivity expert at the University of Houston. “The concern was whether the tapes could be bent at such small diameter cores and still maintain high current carrying capacity without any damage.”
David Larbalestier, a scientist at the National High Magnetic Field Laboratory in Tallahassee, Florida, says the new cables are a perfect example of good engineering. “There’s no new rocket science here. They have applied perfectly standard techniques to make a cable.” Larbalestier does not think the new cables will easily find their way into power transmission, though. “Many people would love to use high-temperature superconductors to revolutionize the electric utility industry,” he says. “But the industry is relatively conservative and not used to cryogenics. On the other hand, the big multibillion-dollar market for superconductors is making magnets that consume very little power.”
Today’s superconducting magnets contain niobium-titanium wires wound into coils that can provide at most 25 Tesla magnetic fields. Magnets made using the new high-temperature superconducting cables could give higher fields while potentially requiring less power for cooling. .
The low weight and flexibility are especially appealing to the military as a replacement for the bulky copper cables that carry large amounts of power from generators to weapons and devices on board aircraft and ships. “If you look at replacing standard copper cables on a Navy ship, you have to be able to pull the cable through existing conduits with many sharp bends,” van der Laan says. He is now making a demonstration cable for the U.S. military. Researchers at CERN (the European Organization for Nuclear Research) in Switzerland are also interested in using the thin cables to feed the several thousands of amperes of current to the magnets used at the Large Hadron Collider.