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Electricity demand continues to rise worldwide. Utilities are challenged to find economical, sustainable solutions. Losses due to fault current limitation are common. Nearly 50% of the electrical losses between generators and end-users occur in transformers. High-temperature superconducting (HTS) cables can transport current with low losses and a very high power density. Incorporating HTS into electrical generators and equipment increases system efficiency, reliability and safety. Policies and measures to enable HTS to become commercially available include continued support for R&D and sustained public and private research partnerships.
The aim of the ETI focusing on superconducting cables for electricity (HTS) is to identify and evaluate the potential benefits of superconductivity and the barriers to achieving these benefits. HTS participants keep abreast of the state-of-the-art and industry standards regarding HTS component manufacturers, cryogenics research, laboratories and trade organisations. There are 13 Contracting Parties, including Israel, and two Sponsors.
HTS cables have clear benefits for the electric power sector. They reduce space in urban environments, and when cooled to -200°C, HTS cables can transport nearly three times more electric power than conventional copper cables with much fewer transmission losses and without generating magnetic fields.
HTS works actively to identify new applications and projects using this promising technology. In Essen, Germany (a Contracting Party to the HTS), a two-year “AmpaCity” project is testing a resistive HTS fault current limiter and the world’s longest HTS cable - 1 kilometre (km).
The HTS cable is laid between two 10 kilovolts (kV) urban substations. Power is transformed from the high-voltage line (110 kV) to a 10 kV current limiter, then transmitted by HTS cable to the city centre. This eliminates the need for a MV substation.
Type testing has recently been completed. A two-year study found that despite needing a flow of liquid nitrogen to cool the HTS cables, it is actually more cost effective to install the cables and operate over a 40‑year period than to install conventional high voltage lines, which require high levels of maintenance and additional network infrastructure. The smaller space needed for the cables enabled the distribution company to develop a simplified network configuration, further reducing the amount of land used. A 2012 study conducted by the AmpaCity partners found that a typical urban network including 20 transformers could be reduced to 15 using HTS cables, significantly reducing costs.
Project sponsors include the German Federal Ministry of Economics and Technology, the KarlsruheInstitue for Technology (KIT) and the project sponsor Jülich (PTJ), and Nexans, as manufacturer of cables and cable systems. Installation will be completed third quarter 2013.
* Photo courtesy of Nexans.
For more information: www.superconductivityiea.res-web.it
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