Moving Electricity via Super-Cold Cables Wins Influential D.C. Ally

Increasing reliance on renewable energy from wind and solar farms might not necessarily mean the construction of thousands of new transmission towers stretching across the American landscape.

That’s because of a technology called superconducting cable, that could be the recipient of federal assistance that would speed its deployment.

Superconducting cable has for at least two decades struggled to prove its mettle and win big utility contracts from the power industry, which is notoriously slow to adopt new technology.

But the technology won a powerful friend this week when House Majority Leader Steny Hoyer’s introduced on Tuesday two bills (HR 2347 and HR 2348) that authorize the federal government to cover half the cost of high-voltage transmission projects, at least 300 miles in length, that employ advanced cable technology. Mr. Hoyer, a Maryland Democrat, also would offer accelerated depreciation (five years, not 20) and special incentives for domestic manufacturing of advanced cable systems.

Superconducting cable, one type of advanced cable, is able to move large amounts of energy in a small space and more efficiently because bundles of special, low-resistance wire run through pipes chilled with liquid nitrogen which brings the temperature down to minus 321 degrees Fahrenheit. In effect, it provides a more slippery medium for moving electricity than conventional copper or aluminum wire whose efficiency degrades as they heat up.

Power losses are reduced by about two thirds with superconducting material, according to American Superconductor Inc., one of the companies that designs superconducting wire and would benefit from advanced cable deployments. Another possible benefactor is Sumitomo Electric Co. of Japan. Other companies that make composite cores with ceramic-like material also could gain more visibility.

Currently, wire designed by American Superconductor is being used by three utilities — Long Island Power Authority, American Electric Power Co. and National Grid—in small projects in New York and Ohio. The distances are short and voltages aren’t as high as what would be necessary to move large sums of electricity from, say, wind farms on the Great Plains to large cities in the east or from solar farms in the desert Southwest to cities on the Pacific Coast.

American Superconductor, based in Devens, Mass., says it can move as much electricity through an underground cable system with a 25-foot right of way – out of sight and out of mind – as would otherwise require a 600-foot-wide right of way for a 765-kv overhead transmission system with giant towers.

Use of superconducting technology could nip objections from many landowners who don’t want unsightly transmission towers marching across their line of sight.

With the proposed federal subsidy, the cost could be equivalent, too, according to American Superconductor.

American Superconductor says it figures its systems would cost $8 million per mile for a single superconducting cable capable of carrying 5,000 megawatts of electricity and $13 million per mile for two pipes able to move 10,000 megawatts. It estimates the cost of 765-kv transmission towers and lines at $7 million to $10 million per mile.

An update: American Electric Power says it has tested superconducting cable with good results concerning reliability. But transmission experts there are doubtful the technology will be used in long-distance transmission projects of 300 miles or more because the liquefied gas used as coolant requires pumps and refrigeration units every mile or so. That adds to the cost and maintenance challenge.

The most logical use for superconducting cable, AEP engineers say, would be for short distances in dense urban settings where space is at a premium, such as between substations. The utility, based on Columbus Ohio, intends to test superconducting cable, in the near future, in association with one of its 765-kv lines, the highest voltage found in the U.S. electric grid.