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In the framework of the High-Luminosity LHC project, experts from the CERN Superconductors team recently obtained a world-record current of 20 kA at 24 K in an electrical transmission line consisting of two 20-metre long cables made of magnesium diboride (MgB2) superconductor. This result makes the technology a viable solution for long-distance power transportation.
"The test is an important step in the development of cold electrical power transmission systems based on the use of MgB2," says Amalia Ballarino, head of the Superconductors and Superconducting Devices section at CERN. "The cables and associated technologies were designed, developed and tested at CERN. The superconducting wire is the result of a long R&D effort that started in 2008 between CERN and the manufacturer, Columbus Superconductors in Genova, Italy.
Its superconductivity was discovered by the group of Akimitsu in 2001. Its critical temperature (Tc) of 39 K (−234 °C; −389 °F) is the highest amongst conventional superconductors. This material was first synthesized and its structure confirmed in 1953, but its superconducting properties were not discovered until 2001.
Though generally believed to be a conventional (phonon-mediated) superconductor, it is a rather unusual one. Its electronic structure is such that there exist two types of electrons at the Fermi level with widely differing behaviours, one of them (sigma-bonding) being much more strongly superconducting than the other (pi-bonding). This is at odds with usual theories of phonon-mediated superconductivity which assume that all electrons behave in the same manner. Theoretical understanding of the properties of MgB2 has almost been achieved with two energy gaps. In 2001 it was regarded as behaving more like a metallic than a cuprate superconductor.
Columbus Superconductors SpA is a world leader in cutting-edge magnesium diboride (MgB2) technology and the transformation of this superconducting material into long, versatile and highly reliable superconducting wires. The company is vertically integrated, from R&D to applications and from production to sales.
Columbus Superconductors was established in Genoa in 2003 following successful cooperation involving ASG Superconductors, CNR-INFM (the Italian National Research Council) and a group of researchers. The company’s staff were some of the first to develop long wire prototypes and in 2005 set the world record with the first 1.6 km MgB2 tape. This milestone event paved the way to industrial applications for MgB2-based wires and their large scale production.
Cooling to what temperature? Current technology doesn't cool power transmission lines to superconducting temperatures.
EasyPleaseMe
reply to post by Arbitrageur
For high load cables, especially underground ones, cooling costs are typically 50% of the I^2R losses.
Arbitrageur
Cooling to what temperature? Current technology doesn't cool power transmission lines to superconducting temperatures.
EasyPleaseMe
reply to post by Arbitrageur
For high load cables, especially underground ones, cooling costs are typically 50% of the I^2R losses.
Cooling costs to cool to superconducting temperatures will be much greater, right?edit on 15-4-2014 by Arbitrageur because: clarification
That is correct, but to further emphasize the contrast, the cooling costs could be more than a million times the I^2 R losses, right? I'm not sure if the i^2 R losses can even be calculated.
mbkennel
Well, the heat flux from I^2 R losses would be practically zero, a totally different situation. You'd have to overcome losses from imperfect insulation, but you won't have an intrinsic heat flux to dissipate.
originally posted by: Arbitrageur
That is correct, but to further emphasize the contrast, the cooling costs could be more than a million times the I^2 R losses, right? I'm not sure if the i^2 R losses can even be calculated.
I do think there would be some economy of scale in cooling conductors carrying relatively large current for relatively short distances, as in cities, which might make it economical in certain situations. However when transmitting more modest currents over much longer distances through the countryside, I'd be surprised if the economics of cooling such long stretches of wire to superconducting temperatures plus maintaining the cooling apparatus would work out favorably.
originally posted by: EasyPleaseMe
originally posted by: Arbitrageur
That is correct, but to further emphasize the contrast, the cooling costs could be more than a million times the I^2 R losses, right? I'm not sure if the i^2 R losses can even be calculated.
I do think there would be some economy of scale in cooling conductors carrying relatively large current for relatively short distances, as in cities, which might make it economical in certain situations. However when transmitting more modest currents over much longer distances through the countryside, I'd be surprised if the economics of cooling such long stretches of wire to superconducting temperatures plus maintaining the cooling apparatus would work out favorably.
Yes only the highest current conductors such as city feeds and grid interconnects are economical to replace with superconductors at the moment.