Superconductors transport electricity in magnetic resonance imaging (MRI) machines and keep gigantic particle accelerators operating smoothly. At temperatures well below minus 100 degrees Celsius, the properties of the conductive materials change. Their electrical resistance falls to nearly zero, making them perfect conductors of electricity. This effect was used for a few applications, such as magnetic resonance imaging, decades ago. However, because conventional superconductors have to be cooled with very expensive helium, the technology failed to achieve a large-scale industrial breakthrough.

Exactly 20 years ago, the situation changed drastically overnight when a German and Swiss team of researchers discovered the phenomenon of high-temperature superconductors (HTS). Experts were thrilled to learn that high-temperature superconductors work at higher temperatures and can be cooled very easily with liquid nitrogen - a much less expensive and tedious procedure. Even then, experts were already promising superconductor electrical lines. However, the search for a robust, manageable, and inexpensive HTS material was a long and difficult one. Recently, advances in the field have been coming one after another. With increasing frequency, experts worldwide are presenting new HTS developments, new, more powerful HTS materials, new applications, and promising prototypes. There's no doubt that this technology is poised to make a huge breakthrough.

For the first time, top researchers and representatives of the world's leading companies are coming to Erlangen to discuss what the industry has achieved and where future developments will lead it. In line with its slogan "20 Years of High-Temperature Superconductors - Successes and Challenges," the 15th International Superconductivity Industry Summit will be held here on September 28th and 29th. This is the industry's most important summit meeting and has been held annually since 1992 in various locations in the United States, Japan, and Europe.

Along with trade organizations such as the CCAS (Coalition for the Commercial Application of Superconductors) of the United States and ISTEC (International Superconductivity Technology Center) of Japan, representatives from China, Korea, and New Zealand are also invited. Presentations will focus on a variety of current projects that are helping get the technology into the marketplace. One such project is the first generator with a high-temperature superconductor that will provide exceptionally energy-efficient propulsion of ships. The system replaces the magnetic coil with thin copper superconductor wires. This results in a significant reduction in energy losses, producing a substantial improvement in electrical efficiency. Furthermore, this type of unit is much lighter and more compact than conventional engines. The system is the size of a small van and generates 4 megavolt-amperes, enough energy to supply 200 average households with electricity.

"The HTS industry is in an unusual situation. It develops engines and devices for which there are no established markets or customers," said Heinz-Werner Neumüller, who heads the Power Components and Superconductivity Department at Siemens Corporate Technology's Erlangen research center. "Researchers and companies are entering into more and more international partnerships to share the risk of developing products to the market roll-out stage, and especially to accelerate the development process."

Neumüller, who is also the chairman of CONECTUS, is convinced that HTS technology's clear advantages will help it gain widespread acceptance in the near future thanks to its ability to save energy. Its energy savings are concentrated on power generation, transport, and distribution. The world's first HTS high-voltage line is an excellent example; after a six-month pilot phase that began in July of this year, it is now transitioning to commercial use. IGC-SuperPower, Inc. is using the liquid nitrogen-cooled line, which was developed by Sumitomo Electric Industries Ltd. of Japan, to relieve the strain on the municipal power grid in Albany, New York. American Superconductor Corporation (ASC) is also providing HTS wire for a power line system to supply electricity to the outer suburbs of Columbus, Ohio; ASC is working together with NEXANS on a HTS high-voltage transmission line for use on the Long Island Power Authority power grid. Korea is also committed to this emerging technology, and a 10-year state-sponsored project is helping a number of HTS applications in energy technology move forward. China is also actively driving a multitude of prestigious HTS projects. Experts will review various approaches to these issues in Erlangen.

In light of vigorous international activity in the field, Neumüller advocates stronger support of German HTS research in the future, especially via state-funded projects. "In the past, financial support often ended before an idea made it to the market-ready stage," the Siemens researcher said. "Because of that, international partners take over the idea and move production out of the country."

But there are positive examples as well: with the support of the Federal Research Ministry, manufacturer Nexans worked together with the Karlsruhe research center to develop the first "superconducting current limiter" for power supply grids. The device has already completed a one-year test phase of routine operation with RWE Energie AG in Netphen near Siegen. The unit was connected to the 10 kilovolt grid there. It will act as a kind of circuit breaker to protect power grids from short circuits. These medium voltage grids supply power to cities and towns. Like a circuit breaker in your home's basement, the current limiter absorbs short circuit currents that arise due to line defects, contact with trees, or lightning strikes.

To be effective, a current limiter must possess high resistance in the event of a short circuit. However, during normal operation, its resistance must be as low as possible. Superconductors meet these requirements: at low temperatures, they have zero electrical resistance up to a certain current level. However, when the critical level is exceeded, the device loses its superconductive properties within milliseconds and becomes a resistor. The advantage of this device is that its superconductive properties return automatically once the short circuit has been blocked. No parts have to be replaced, and no breakers have to be reset.

Experts predict that short circuits will become more frequent in the future as more decentralized power generators such as windmills and small combined heat and power (CHP) plants come on line. Generators are often the source of short circuits. Therefore, current limiters may well become an indispensable circuit breaker system in the years to come. Researchers are now working on a variant for high-voltage grids exceeding 100,000 volts.

Thanks to new durable, high-performance HTS materials, the number of applications will increase significantly in years to come, said Neumüller. The world's top researchers will introduce these concepts in Erlangen. Neumüller commented, "But it's also clear that there is still a lot of work to be done to be successful; we must continue to boost the performance of HTS systems while simultaneously making the systems less complex and more affordable." This will also be discussed at the conference.