For the first time in the world super conducting wires are moved beyond the laboratories and into the power grid, at Amager Koblings station. Since February engineers from Copenhagen Energy, NKT Cables, NKT Research and DTU have worked on installing three pieces of super conducting wire at Amager Koblings station, and reported that they are ready to supply great parts of Amager with power.
Super conducting cables will be used to supply electricity to consumers.
This is a demonstration project (proof of concept) that through daily maintenance will show whether super conduction techniques are read for the terms of reality. the cables need to withstand the large fluctuations in power and voltage, that occur from time to time. Three cables at each 30 meters of length have been spliced into a section of the normal power grid, on the distribution side, where the voltage is 30 kilovolts.
The initial phase is careful, but as Amager Koblingsstation is capable of supplying power to all of Amager's 150000 inhabitants, the supercables will have theirs to see to.
"Initially the supercables will be in charge of 20 percent of the ordinary power, for as long as we're comfortable using them. Later the load will be increased", says integrational project manager Svend Korning of Copenhagen Energy.
Waste is halved
Not only the cables are on test. An important part of the cooling facility that's needed to keep the super conductors below their critical temperature, minus 160 degrees celcius (-256F), where electrical resistance disappears.
When the test phase is over, the new supercables are to be used across larger distances, typically 4-6 kilometers (1.6-3.75 miles). This is where money is to be made in comparison to traditional power cables, that become 70-80 degrees celcius hot (158-176F) when fully loaded. The dug down cables heat the surrounding ground to no use, that waste will disappear completely when using super conductors.
"In stead there's going to be an extra power usage in the maintentance of the necessary cooling facilities, but that usage is only half the wast of the traditional cables" says project manager Dag Willen of NKT Research.
"The society can save energy on super conductors, but to the power companies it's more interesting that the cables are cheaper to install, as this helps then to be competitive on price. So far things look good. With cables that are several kilometers in length, expensive high voltage transformers which have been necessary so far, can be saved when the power is to be transported. Furthermore, the supercables are smaller and bend easier" he says.
The demonstration project at Amager has costed 10 million Danish Krona (~$1.25m), but there are more possibilities of doing this cheaper next time. For example, the cables can be produced to take up less space, and allow larger maximum current.
"But for the first round, we've purposely produced a simple cable with the same dimensions as the old" says Dag Willen.
Energy savings, increased grid capacity and cheaper electricity for consumers are in prospect as a result of new technology that is about to undergo full-scale testing in Copenhagen.
Super conducting cables will be used to supply electricity to consumers. Some 150,000 residents in the Amager district of Co-penhagen will in future have their electricity supplied by this new technology. Until now, superconducting cables have only been tested - by laboratories and by the organisations across the world that have been competing for more than a decade to develop the technology for practical application. "We have focused on placing ourselves among the five technologically leading manufacturers of supercables. Not specifically on being first past the post", says Dag Willén, Project Manager of NKT Research. And indeed, for a long time it looked as though first place would go to a project in Detroit. But in the end Danish technology proved quickest to overcome the legion of theoretical and practical challenges posed by supercable development.
5-7% energy saving
Discovered as far back as 1911, the phenomenon of super conductivity occurs at extremely cold temperatures and causes almost all electrical resistance - and thus also energy loss - to disappear. However, within the last 15 years new materials have been discovered that only require cooling with liquid nitrogen (minus 196° Celsius). The Danish technology group NKT has been involved in the research race since the end of the 1980s. With widespread use of superconducting technology in grid 'highways' energy consumption can be reduced by 5-7%, which means an equivalent reduction in CO2 emissions from electricity generation. But supercables can also become part of a simplification of the electrical infrastructure. This is because they can transmit massive currents, something which can further be utilised to reduce the number of voltage levels (fewer transformer substations). At the end of the day this will enable cheaper electricity for consumers.
Three 30 metre supercooled cables Copenhagen's new supercable is only 30 metres long, but that is ample for practical full-scale testing in the public supply grid. The cable is installed at 'Amager Substation', a central hub in the Danish capital's energy supply system. The supercable is capable of supplying electricity to the whole of Amager district and will be tested under all operating conditions. No operating experience exists elsewhere of superca-bles installed in a public supply grid, and in particular the use of extremely cold liquid nitro-gen to cool the cable is a totally new element in electricity supply. The new cable has three phases, ie. it consists of three separate super conducting cables each 30 metres long spliced into the grid where the voltage is 30 kV. The supercable has a 2000 Amp current rating.
The future electrical infrastructure
The increased energy consumption expected in the future would demand expansion of the power network and in many cases - especially in the industrialised part of the world - also investments in replacement of existing networks. As technology evolves high capacity super-cables at still more competitive prices will gradually play a more important role in the future infrastructure. City of Copenhagen's Environmental Mayor Bo Asmus Kjeldgaard stresses the importance of Copenhagen pressing ahead with development of new environment-friendly technology: "All new technology is expensive at first. Like solar cells in the past, superconducting material is currently very expensive. That means it will have to come down in price to compete with conventional technology. But I am certain that if this project produces the right results, we will see the superconducting material used not only in cables but also, for instance, in coils and transformers."
The supercable project
The actual power transmission in supercables takes place through super conducting tapes. These tapes are the key component of the cable, and the NKT subsidiary company NST (Nordic Super conductor Technologies) is among the world's three or four leading manufacturers of these products. The tapes are used in a large number of electrical applications, such as engines, generators, current leads and MRI scanners. The high tech superconducting cable was fabricated by NKT's cable company NKT Cables, and will now undergo full-scale testing by Copenhagen Energy.