We may never give high voltage power cables a second thought, but there’s a lot that goes into their construction that could be improved.
High voltage cables are typically made from a steel core and an aluminum shell. Aluminum is the 4th-best conductor of electricity after gold, silver, and copper, but doesn’t make a good cable on its own. The problem with aluminum is it is too ductile and it would stretch too much just under its own weight. In order to solve this problem, the steel core helps to keep its shape.
Because an alternating current travels on the aluminum skin, the steel core is basically dead weight. The steel core doesn’t even do that much in conducting direct current through the body because it’s worse than 10th place in conductivity.
Finally, steel and aluminum expand at different rates under tension and temperature changes, eventually leading to breakage and separation. In order to lighten high voltage power cables, researchers at the US Department of Energy’s Ames Laboratory have turned to the 5th-best conductor, calcium.
A composite nanocalcium-aluminum high voltage cable would be lighter than current steel-core aluminum cables. Making the cables lighter could eliminate the number of suspension towers, which make up nearly half the cost of a power line installation. Under direct current, it would also be about 10% more efficient.
The new composite material wouldn’t suffer the problems associated with dissimilar metals expansion and contraction rates. Finally, researchers expect that the new high voltage power cables wouldn’t cost any more than current cables.