Super conductors are materials that conduct current without resistance. For this reason, this field of research has always generated enormous interest, and considerable resources are utilised on techniques that can transform these materials into good energy conductors in technical components.
Magne Runde and Niklas Magnusson at SINTEF have super conductivity as a field of research, and are testing out super conductors in the huge induction heaters utilised by the aluminium industry.
Today the industry preheats huge meter-long aluminium cylinders known as billets in induction heaters with copper conductors. When the temperature reaches 500 °C, the billet is extruded to profiles.
"This heating process leads to large losses in energy," says Runde. "Only half the energy supplied is used to heat the billet. The remaining 50 percent is waste energy. This is something super conductors can improve."
The research scientists have now replaced the copper conductors in the induction coils with super conductors. As the conductivity is significantly improved, a much higher proportion of the energy is transferred to the billet. The two research scientists have conducted laboratory tests that confirm the energy efficiency is increased to 80-90 percent.
In the basement laboratory, Magnusson and Runde proudly show the two large super conducting coils, with a 1.5m diameter. The super conducting material, magnesium diboride, is in thin, brittle filaments enclosed by a nickel matrix.
"These will be the world's largest super conducting coils made from this special material," says Runde.
In 2007, the German company Zenergy Power licensed a patent based on SINTEF's basic idea. The company has acted quickly and produced two heaters, which it has sold. The concept of super-conducting induction heaters was awarded a prize worth Euro 100,000 at this year's Hannover trade fair.
Magnusson and Runde have continued with the research in a parallel and competing race with Zenergy Power. In an EU project with eight other partners, SINTEF now has a model under construction that is expected to be cheaper than the German model. In this model, the Trondheim research scientists designed and built the super conducting coils.
"We have deliberately kept a low profile to see if Zenergy Power succeeded in building a complete model," says Magnusson. "We now believe the time is right to mark that it is in fact a SINTEF invention behind the product."
With around 500 extrusion lines in Europe, the super conductors will be a typical niche product. However, given that the industry stands to make energy savings of up to NOK 1 million for such induction heaters, the energy researchers believe there is a market for the product.