News from IIR members: Air Liquide

The world's longest and most powerful superconductor power transmission cable has been connected to the commercial power grid in Holbrook, New York, United States, by the Long Island Power Authority (LIPA) and American Superconductor. The 600-m long cable is cryogenically cooled thanks to the advanced technologies of Air Liquide. This project demonstrates the operation of a high voltage superconductor cable in an urban commercial power grid. Capable of transporting up to 2400 A (574 MVA in a 138 kV system), the superconductor cable is the first such high-voltage electric cable in the world to be operating in a real transmission system. This cable transports more energy than all of the previously demonstrated high-temperature superconductor (HTS) cables together and is capable of powering 300 000 homes. Besides Air Liquide, the Long Island project involved the US Department of Energy and Nexans, the worldwide leader in the cable industry. Superconductor cables can transport three to five times more energy than traditional cables. Capable of transporting electricity without resistance at a certain low temperature (in this case at -200°C), the HTS cables avoid energy loss along the cable. In order to use the exceptional properties of superconductor materials, it is necessary to keep the cables below their critical temperature through an appropriate refrigeration system using liquid nitrogen: cryogenics is thus the key to superconductivity. Air Liquide is already involved in this project's next steps to build a cable with second-generation superconductor materials that are even more powerful. In this second phase, Air Liquide will develop special very-low-temperature refrigeration technology.