The Cold Reality of Power

This article highlights large-scale applications of high-temperature superconductors (HTS), based on copper-oxide ceramics, which have begun to occur in the United States. A number of major electric-power application projects have been undertaken as partnerships between the US Department of Energy and various companies. Superconductors are particularly appropriate for electric power applications because of the total lack of resistance in direct current applications and very low losses in alternating current. The low losses allow use of much higher current densities than can be achieved in normal conducting metals, such as copper or aluminum. An HTS transmission line has been operating at the Southwire Co. in Carrollton, GA, since January 5, 2000. Since then, the three 100-foot-long above-ground cables have supplied 1250 A at 12.4 kV to three manufacturing plants at the Southwire headquarters. During its first year of operation, the line supplied more than 5000 hours of operation at 100% load. Southwire’s HTS cables lose only about 0.5% of power during transmission, compared to 5 to 8 percent lost by traditional cables.