Sumitomo Electric Develops Superconductive Cable With 50% More Efficiency

Sumitomo Electric Industries Ltd. has developed wiring than can conduct about 50 percent more current than existing superconductive cables, targeting power producers and medical equipment makers seeking more efficient delivery of electricity.

The wires, known as high-temperature superconductors, are made using the metal bismuth and have zero electrical resistance, Kenichi Sato, a chief engineer at the Osaka-based company, said Sept. 21 in an interview. Sumitomo, whose customers include Tokyo Electric Power Co., Asia’s biggest power producer, in 2004 started producing wires capable of delivering up to 200 amperes.

“We’ve confirmed that we can increase the electrical current capacity by about 1.5 times,” Sato said. Sumitomo will start selling the cables “within a year,” and will announce the development at a conference in Tsukuba, north of Tokyo, in November, he said.

Bismuth-based high-temperature superconductors can transmit 200 times the electrical current of copper cables when cooled with liquid nitrogen, resulting in less wiring being needed to transmit power, Sato said. The technology allows for more efficient connections with renewable energy sources such as solar and wind, he said.

Customers could benefit from the efficiency of the wires because liquid nitrogen costs about 50 yen (59 cents) a liter, which is cheaper than mineral water, Sato said.


“The technology that Sumitomo have announced is an incremental improvement on first generation high temperature superconductors,” Thomas Rowlands-Rees, an analyst at Bloomberg New Energy Finance in London, said in an e-mail. “Even with this one-third saving in cost, the technology is always going to be prohibitively expensive.”

Sumitomo now produces about 500 kilometers (311 miles) of superconductive wiring a year and targets doubling production “within one or two years,” Sato said. The company aims to create Japan’s first power grid using superconductive cables at Tokyo Electric’s plant in Yokohama, outside Tokyo, as early as next year.

Superconductivity was discovered in 1911 by Dutch physicist Heike Kamerlingh Onnes and is the phenomenon of zero electrical resistance when certain materials are cooled to very low temperatures, according to Sumitomo’s website. In 1988, Japanese researcher Hiroshi Maeda developed the bismuth-based high- temperature superconductor, which has zero electrical resistance when cooled to -160 degrees Celsius (-256 Fahrenheit) using liquid nitrogen.

Sato said he expects the technology to be applied in several areas, including energy production, motors for boats and magnetic levitation trains, and medical equipment such as magnetic resonance imaging scanners.

To contact the reporter on this story: Masatsugu Horie in Osaka at Adam Le in Osaka at

To contact the editor responsible for this story: Drew Gibson in Osaka at

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