June 10, 1991

Article at Reuters

Superconductors only years away from practical applications

Professor Shi Xue Dou, centre, with colleagues

By Wilson da Silva

SYDNEY – Super-fast computers, trains that float magnetically on their tracks, high-resolution medical scanners and cheap power transmission – such is the promise of superconductors.

After years of tinkering, scientists are mustering to break superconductors – exotic materials that can carry huge electric loads with no loss of energy – into the commercial world at last.

Japan’s Sumitomo Electric Industries is leading the charge, having shown off the world’s first superconductor magnet in March. The company called the advance a breakthrough and said sample shipments could start in a year or two.

The profit potential is huge. World demand for superconductors could reach $1 billion in four to five years, and $10 billion by the year 2000, the U.S. Department of Commerce recently estimated.

Sumitomo’s superconductor is made of the same ceramic materials that four years ago astounded scientists with their ability to superconduct at higher temperatures than existing theories seemed to allow.

But scientists say the application of superconductors has been stalled because the ceramics from which they are made are extremely brittle, making the manufacture of wires, coils and other devices an engineering nightmare.

As of last week, the problem appeared closer to solution. Researchers in Australia announced they had produced ceramic superconductor wires that were flexible enough to twist into relatively tight coils.

“We are getting results very comparable with Sumitomo’s, and in some aspects,  we are ahead of them,” Professor Shi Xuedou of Sydney’s University of New South Wales told Reuters.

“This convincingly indicates there is large commercial potential in high-temperature superconductors.”

Although groups in North America and Europe have spent millions on research, Shi says no-one except his group has replicated Sumitomo’s results.

Shi’s team of three Australian and two Chinese researchers say their wires, thin strips 3.0 mm wide, can be bent up to 10 times without losing any of their “critical current density” or electricity carrying capacity.

Their work is partly supported by the Australian cable, wiring and engineering company Metal Manufactures Ltd, which is applying for patents on the team’s behalf. The Australian government has also contributed funding.

Mal Clark, one of the company’s technical managers, said by telephone from Melbourne that functions requiring a current to be carried a short distance were likely to be the first practical applications.

These included computers, magnetic imaging scanners for hospitals and other devices that needed super-fast electrical switching. Clark said applications could appear by 1995, with more difficult ones appearing by early next century.

“There are some niche markets that can be developed early, and they would be the markets I would expect us to enter,” he said.

Superconductors are important because they can carry huge currents with no loss in power. Normal copper wires become extremely resistant as the amount of electricity they carry rises, eventually melting if too much power is applied.

Scientists have known for 80 years that some materials lose resistance as they approach absolute zero, or about minus 273 degrees Celsius (minus 523 degrees Fahrenheit). Because materials only did this at super-cold temperatures, the phenomenon was largely treated as a scientific curiosity.

But in 1987 it was found that some ceramics showed no resistance at the much warmer temperature of liquid nitrogen – minus 196 degrees Celsius (minus 385 degrees Fahrenheit).

Dubbed “high-temperature” superconductors, they were still hundreds of degrees below 0 degrees Celsius (32 Farenheit).

Liquid nitrogen used as coolant is 20 times cheaper to use than the previously used liquid helium, and easier to handle.

Shi said power transmission costs, estimated at $200 billion a year in the United States, could be cut by 10 to 15 per cent using superconductors.

Superconductors would also allow electricity storage for use during peak demand times, and would allow nuclear reactors to be built far from cities but still be able to deliver electricity with no drop in power levels, he said.

A reactor could be built in Australia’s Simpson Desert and superconducting wires could carry the power to Sydney, 1,700 km (1,060 miles) southwest, without power loss, or allow power to be carried from the Nevada desert in the United States to New York, he said.

The team’s so-called silver-clad wires are made of metal-sheathed, bismuth-based ceramic superconductor sheets, and can be wound into small coils without losing superconductivity.

Coiling of wires is essential if superconductors are to be applied practically.