Superconducting Cables

When long-distance overhead transmission lines approach major population and load centers, the availability of right-of-way for overhead lines can become limited. Similarly, overhead lines may be undesirable in environmentally sensitive areas. Political and institutional issues can completely block construction of an overhead line.

New high-temperature, superconductor-based transmission cable technology may offer an alternative in the longer term, not just for short distances in urban areas but also for long-distance transmission (EPRI 2009) where pipe enclosed DC superconducting transmission cables can either be buried underground or placed in tunnels.

These cables use high-temperature superconductor materials instead of copper or aluminum and have substantially higher power handling capabilities at lower voltages than conventional cables. This additional power-carrying capacity allows this technology to address reliability concerns associated with long-term load growth in densely populated urban areas. When operating in DC systems, these cables exhibit zero resistance, hence zero electrical losses; however, there are parasitic refrigeration losses.