Superconductors at a stretch

Research from the National Institute of Standards and Technology suggests that next-generation, high-temperature superconductor wire can withstand more mechanical strain than originally thought.

As a result, superconductor power cables employing this future wire may be used in power grids.

Projected to become available in three to four years, the superconductor wire (known in the industry as second generation HTS wire) is expected to cost less than the HTS wire used in today's superconductor power cables.

Superconductor power cables can carry there to five times the power of conventional copper cables. Compact, underground superconductor cables can be used to expand capacity and direct power flows at strategic points on the electric power grid and can be used in city centres where there is enormous demand, but little space under the streets for additional copper cables.

One important challenge in using this next-generation HTS wire in such applications is the need for sufficient strength and resiliency to withstand the stretching and bending that occurs during power cable fabrication and installation.

Using superconductor ceramic coatings on metallic substrates fabricated by American Superconductor and Oak Ridge National Laboratory, the researchers tested the material's electromechanical properties.

They found that these advanced wires could stretch almost twice as much as previously believed without any cracking of the superconductor coating and with almost no loss in the coating's ability to carry electricity.

The team also found that strain-induced degradation of the superconductors' ability to carry electricity is reversible up to a certain critical strain value.