American Superconductor Corporation (NASDAQ: AMSC) and Nexans, the worldwide leader in the cable industry, have successfully tested the world’s first power transmission cable made with second generation (2G) high temperature superconductor (HTS) wire. The cable was produced by Nexans utilizing AMSC’s proprietary 2G HTS wire known as “344 superconductors.” 344 superconductors are AMSC's new 3 ply, 4.4 mm wide second generation HTS wires.
This 30-meter-long, transmission-voltage cable was tested at a Nexans high-voltage facility in Hannover, Germany. Operated at 138,000 volts (138kV), the cable contained only 33 hair-thin 344 superconductors, yet it demonstrated the capability to transmit 435 mega-volt-amperes (MVA) of power – enough electricity to power over 250,000 homes.
AMSC’s 344 superconductors were designed as a drop-in replacement for customers currently using 1G HTS wire. The 344 superconductors comprise 2G HTS wire clad with ultra-thin strips of copper or stainless steel. 344 superconductors offer significantly higher power density and efficiency compared with similar copper-based wire products. As a result, electrical systems that incorporate HTS wire are dramatically smaller, lighter and more cost effective than comparable systems based on copper wire. The applications for HTS wire include power transmission and distribution cables, propulsion motors and generators, degaussing cable systems, synchronous condensers and fault current limiters.
“The ability to carry a large amount of electricity through small corridors is incredibly appealing for urban and metropolitan power grids. Transitioning from first generation to second generation HTS wire proved to be seamless for our cable manufacturing team, and we are very happy with the cable’s performance. Based on these results and the anticipated success of the first generation 138kV HTS cable system we are installing with AMSC in the commercial grid of Long Island Power Authority, we are clearly on a path to finalize development and introduce HTS cables made with 344 superconductors in utility power grids” said Pascal Portevin, Executive Vice President, Strategic Operations for Nexans.
This demonstration confirms that 344 superconductors are a drop-in replacement for first generation HTS wire. First generation HTS wire has been utilized to manufacture all prototype HTS power cables worldwide over the past 10 years. AMSC said it expects to initiate volume production of 344 superconductors in December 2007 to meet the expected demand for HTS wire for power cables and other applications. High-capacity superconductor power cables are expected to be utilized first in cities and metropolitan areas, where demand for electricity continues to grow and has strained existing power grids.
The company’s pre-pilot production line began operating in September 2005 and produced and shipped approximately 10,000 meters of 344 Superconductors for customers in the fiscal year ending March 31, 2007. Orders for essentially all of this wire are now in hand. AMSC plans to scale up a pilot manufacturing line with a gross production capacity of approximately 720,000 meters per year by the end of 2007.
HTS are materials that can superconduct at higher temperatures than Low Temperature Superconducting materials (LTS). However, even these materials need to be cooled down to at least 125 K to superconduct. AMSC's HTS wires operate below 115 K and nominal operating temperatures range from 20 K to 77K.
The second generation (2G) coated conductor HTS wire wire has a different form than the 1G multifilamentary HTS wire that was AMSC'a previous wire product. The superconducting material developed using the coated conductor technology is the YBa2Cu3O7-x material. The wire’s architecture looks similar to a thick film technology.
More details of AMSC's 2G HTS wire can be found at their website here.
AMSC has suspended production of 1G wire and is now in the process of scaling manufacturing capacity for its 344 and 348 superconductors. The company believes manufacturing costs for this next-generation wire will be up to five times lower than 1G, making it an attractive drop in replacement for customers who have developed applications with first generation wire.