Zero electrical resistance for new applications

How superconductors transform energy management

 A potential game-changer for Nexans

New processes developed in universities and national or industrial laboratories have enabled the fabrication of thin superconducting films.

These films are made of flat ceramic crystals, with the current running inside the crystals along parallel planes. The thin films are perfect, simple crystalline models, and have allowed us to understand that the connectivity and the alignment of the crystals are driving the high-voltage performance in all superconducting ceramics, whether in deposited layers like Yttrium cuprates, or in melt casts, like bulk bismuth cuprates (from Latin cuprum, meaning copper). 

At lab scale, if we extrapolate the current obtained on a micrometer (µm) coated layer to a 1 cm² cross-section, we can achieve the equivalent of several million Amps in an optimized superconductor using technologies similar to those used in microelectronics. This vastly exceeds the few hundreds of A/cm² possible in bulk ceramics obtained by melt casting.

In terms of cable systems, the key step forward was combining and adapting know-how in wire manufacturing, cable design and production to this new type of material.

The most recent and largest test site of the LIPA (Long Island Power Authority) project is a powerful demonstration of a collaborative effort to which Nexans’s cable know-how and manufacturing skills decisively contributed.

This collaborative effort culminated in a 600-meter-long cable, connecting two substations and operating at –200°C (liquid nitrogen). It is able to transmit 600 MVA – i.e. 3 times more power than existing lines using the same right-of-ways – with lower environmental impact (fig 2).

Superconductive applications are now slowly emerging from the laboratory to the operational world, with cables and new types of devices in actual operation in power grids. At a time when energy concerns are making headlines, superconductivity is becoming a practical alternative to regular devices, since they are smaller, lighter and more efficient.

The technology is relevant for several applications:

  • HV transmission in critical paths with more energy and lower environmental impact
  • Fault current limiting to reduce fault damage to equipment and help secure the grid with easier circuit breaking (fig 1)
  • Power storage (or compensation) using high inductance superconducting coils with low losses
  • Highly-efficient compact power conversion chains (generators-cables-motors) for offshore energy, all-electric ships or airplanes

While it still remains difficult to work with current HTS materials, intense activity on the scientific front hints at possible major discoveries in the near future with upscale production of film coating techniques as electrical engineers are getting familiar with superconductivity. Even minor improvements in superconductor materials, reproducibility and performance could significantly speed-up the development and generalization of superconducting applications. Nexans’ experience in turnkey superconducting systems could allow customers to quickly take advantage of superconductivity potential to achieve new breakthroughs.
 

supra2
fig 1: Medium fault current limiting units
to render secure a German industrial site

 

 

supra1
fig 2: LIPA project: World’s first HV superconducting HTS cable