After decades of technical development, superconductors – materials that can carry far more electricity than similarly sized copper wires – are being integrated into electricity transmission and distribution grids.

On Monday, American Superconductor Corp. (NSDQ: AMSC) announced its biggest sale yet of superconducting wire meant to transmit electricity at high voltages across long distances – 80,000 meters of wire going to South Korea.

The wire will be used by LS Cable to make cable for a distribution system for national utility Korea Electric Power Corp., expected to be up and running in 2010. It's the single biggest superconductor wire order ever, meant to create the longest-ever superconductor distribution system, nearly a half-mile long, American Superconductor announced.

While the Devens, Mass.-based company was founded in 1987 to commercialize superconductors, it now makes most of its money licensing its wind turbine designs to other manufacturers – mainly Chinese companies at this point – and selling ancillary power equipment (see American Superconductor: The Quiet Wind Player).

Still, the company's superconductor wires, which can carry up to 150 times more electricity than similarly sized copper wires, are in use in a number of grid applications.

In 2006, utility American Electric Power installed superconductor cable using American Superconductor's wires for distribution-level system. And in July, New York's Long Island Power Authority started up the first underground transmission voltage level superconductor cable system using the company's wires.

Despite the extra cost of making and cooling the high-temperature cables, the savings in delivering power in a narrow underground right of way, rather than through massive overhead transmission lines, made it worth the utility's while, said Jason Fredette, American Superconductor director of investor and media relations.

That project, along with the South Korea project, puts the company "on the threshold of commercial success with superconducting cables," he said – though he added that he expects utilities to wait for such projects to be proven in the field before that happens.

Beyond transmission, superconducting cables have characteristics that suit them for use as fault current limiters to prevent current surges caused by grid breakdowns. That's because superconductors actually stop being superconductors and start resisting current when that current grows too great.

London-based superconductor company Zenergy Power (AIM: ZEN) announced Monday that it had landed a contract to provide a superconductor fault current limiter to Consolidated Edison.

The New York utility wants to test the system as part of the $39 million, Department of Homeland Security-funded project HYDRA, which aims to give New York City's power grid the ability to withstand disruptions either natural or man-made.

IN 2007, Zenergy subsidiary SC Power, based in Sam Mateo, Calif., got $500,000 from the California Energy Commission, along with $11 million from the Department of Energy, to study the technology for California's power grid.

That DOE funding round also included a total of $21.7 million for American Superconductor to develop fault current limiter and power delivery equipment, and the company has worked on project Hydra as well.

Of course, utilities are notorious for being slow to adopt new technologies. Both American Superconductor and Zenergy have faced losses in recent quarters as they've sought to build up their utility business.

American Superconductor in February reported a loss of $17.9 million for the first nine months of fiscal year 2008, compared to a $23.6 million loss in the same period in 2007. Revenue for the first nine months of 2008 grew to $109.8 million from $62.5 million in the same period in 2007.

Zenergy reported a loss of €2.5 million ($3.2 million) on revenues of €1.04 million ($1.3 million) for the first six months of 2008, compared to a loss of €1.8 million ($2.3 million) on revenues of €94,000 ($122,000) in the first six months of 2007.