On April 22, 2008, the world's first high-temperature superconductor (HTS) power transmission cable system in a commercial power grid was energized on Long Island.

The 138-kV system, which consists of three individual HTS power-cable phases running in parallel, is operating successfully in Long Island Power Authority's (LIPA; Uniondale, New York, U.S.) Holbrook transmission right-of-way. The cable system, including six outdoor terminations for connection to LIPA's grid, was designed, manufactured and installed by Nexans. The cable uses HTS wire produced by American Superconductor Corp. The 2000-ft (610-m)-long cable system is cryogenically cooled using a liquid nitrogen refrigeration system from Air Liquide (Paris, France).

The U.S. Department of Energy previously funded US$27.5 million of the $58.5 million total project cost, which advances the department's ongoing efforts, through the Office of Electricity Delivery and Energy Reliability, to modernize the nation's electricity-delivery infrastructure.

The cable system contains hair-thin, ribbon-shaped HTS wires that conduct 150 times the electricity of similar-sized copper wires. This power-density advantage enables transmission-voltage HTS cables to use far less wire and yet conduct up to five times more power — in a smaller right-of-way — than traditional copper-based cables. When operated at full capacity, the new HTS cable system is capable of transmitting up to 574 MW of electricity, enough to power 300,000 homes.