Miracle material: Super for some cases

Superconductors transport electricity without energy losses. They have the potential to make a significant contribution to saving energy. However, a great deal of research is still needed before superconductors can be used on a large scale.

Munich is boldly leading the way. If everything goes as planned, the city’s municipal utilities company Stadtwerke München (SWM) will put “by far the longest high-temperature superconductor in the world” into operation by 2030 at the latest. A 15-kilometer cable is planned, running from the main substation in Menzing to the district of Sendling. A prototype was put into operation in Menzing in October 2024. The aim of the project, called Superlink, is to save millions of kilowatt hours of electricity. “If we are successful with this, it could set an example for cities around the world. After all, everyone is facing the same challenge: the constantly growing hunger for energy,” says Helge-Uve Braun, Technical Managing Director of Stadtwerke München.

Behind the high hopes lies a technology that is keeping engineers, technicians and researchers alike busy. Superconductors can transport electricity without energy losses. Compare this with standard electrical cables made of copper, for example, which produce an energy loss of six to seven percent – a costly inefficiency given the vast amounts of electricity consumed every minute.

The Dutch physicist Kamerlingh Onnes first observed the phenomenon of superconductivity more than 100 years ago, when he discovered that the electrical resistance of mercury disappears under certain circumstances. The big drawback is that superconducting materials, such as lead, have to be cooled to almost absolute zero: zero kelvin or around minus 269 degrees Celsius. Onnes achieved this with liquid helium. At zero kelvin, physical particles come to a standstill. All disorder disappears, and with it the resistance in superconducting materials. Since such cooling is extremely complex and consumes a great deal of energy, superconductors are not suitable for everyday use.

To solve this problem, a number of research projects have focused on increasing the required temperature. The less cold superconductors have to be in order to function, the more possible applications there are.

The German physicist Georg Bednorz made a decisive contribution in the 1980s. Together with the Swiss physicist Karl Alexander Müller, he discovered the superconducting properties of ceramic materials. in 1987, the pair were awarded the Nobel Prize in Physics for their work. While the new superconductors are known as high-temperature superconductors, the term “high temperature” is relative. It still takes extremely low temperatures for electrical resistance to disappear. However, conductors that do not require cooling below 77 kelvin (minus 196 degrees Celsius) can still make a vast difference. This is because such temperatures can be achieved by using nitrogen instead of the comparatively expensive helium for cooling purposes.

Metallic superconductors are already in use today, for example in medicine. Because superconductors can also generate very strong magnetic fields, they are used in magnetic resonance imaging (MRI) to scan the human body. This application shows that small-scale use of superconductors already makes sense today.

Stadtwerke München sees another such use case in its Superlink project. To transport the same amount of electricity as a conventional conductor, a superconductor requires a much lower voltage. That makes it ideal for cities. The necessary substation would be no larger than a double garage. The power line itself is also extremely compact and therefore well suited for densely built-up areas, as it can be installed at much lower cost.

If large amounts of electricity could be transported over long distances using superconducting cables, this would have an enormous positive impact on climate change. “Fewer power plants would be needed, fewer greenhouse gases would be released and costs would fall sharply,” says Stadtwerke München. However, the utility provider also admits: “A large-scale, supra-regional network of superconductors is not economical at the temperatures currently required.”

“We won’t be able to achieve the necessary conversion of Munich’s electricity grid with the existing technologies.” Helge-Uve Braun, Technical Managing Director of Stadtwerke München

| Vauel

Demonstrating the opportunities offered by superconductor technology and promoting its commercialization is the task of ivSupra, a semiconductor interest group. ivSupra brings together companies in the sector and scientific institutes. Its members advocate for “the systematic promotion of lighthouse and pilot projects that are suitable for accelerating the spread of superconductor technology.” The VDE entered into a collaboration with ivSupra in 2023. “It is our job to bring the networks and communities together and to report on the advantages and disadvantages of innovations in a technology-neutral way,” says VDE CTO Dr. Martin Hieber.

Due to the high cost of cooling, the use of superconductors is only economically viable under certain circumstances – the transition to mass production is therefore still a long way off.

“If we want superconductors to make a significant contribution to the energy transition, we quickly need to bring this technology onto the energy market on a large scale,” says Dr. Michael Bäcker. He is a professor at the Bonn-Rhein-Sieg University of Applied Sciences and Managing Director of MaTech-Consult. The company advises companies and investors on product and process development with a focus on materials for energy technology and efficient coating technologies. Bäcker is also a member of the ivSupra board. The necessary step towards mass production is not yet in sight, he says, as funding projects are few and far between. The search is underway for companies brave enough to take part, like Stadtwerke München.

Is the Munich project particularly courageous – or simply pragmatic? Munich has two main substations, but their output will not be sufficient to supply the region with electricity for much longer. “If we don’t succeed in using technologies such as superconductors, we will have to build a third main substation to meet the city’s energy requirements. This will require space, a scarce commodity in cities, and cost a lot of money,” explains SWM Managing Director Helge-Uve Braun. “As part of the energy and heating transition, we need to expand and modernize Munich’s electricity grid enormously over the next 20 years,” Braun continues. “We won’t be able to achieve that with the existing technologies. The superconductor can play an important role in this.”

Miracle material: Super for some cases

Struggling for every degree

Due to the high cost of cooling, the use of superconductors is only economically viable under certain circumstances – the transition to mass production is therefore still a long way off.