Yao Zhao Shows Energy-Efficient Nanotube Cable

Yao Zhao has conclusively shown that a cable made of carbon nanotubes can carry the same amount of electricity as a copper wire with virtually no loss of power due to heat. Nanotube cables weigh only a sixth as much as comparable copper wire, opening up possibilities for new efficiencies in a wide range of applications.

The nanotube cable is at least as strong as copper wire and can conduct electricity even when two pieces are joined by knots, Yao demonstrated in his Rice University PhD dissertation. Nanotubes can carry about 100,000 amps of current per square centimeter — about the same amount as copper — but weigh one-sixth as much. They don’t lose energy to heat over long distances, promising huge savings on power grids and efficiencies in computer circuitry. And unlike copper, carbon nanotubes don’t rust or corrode. The on metal that beats carbon nanotubes in conductivity-to-weight ratio is sodium which, however, doesn’t have the properties to allow the creation of nanotubes.

Yao built a circuit that fed electricity to a light-bulb through a nanotube cable. The cable showed no deterioration after many days of continuous use under a wide range of temperatures.

To make the short length of nanotube cable used in the experimental setup co-author Jinquan Wei at Beijing’s Tsinghua University had to grow billions of nanotubes through a painstaking chemical process, then spin the tubes into cable. They found that long, double-walled, iodine-doped nanotubes worked best. Electrons move through individual nanotubes very quickly but slows down each time they jump between nanotubes. Longer nanotubes require fewer jumps to travel a given distance of cable.

Any economical production of industrial-grade nanotubes as a substitute for wire would require the construction of large-scale plants. But before that stage, Yao says, researchers would have to show that longer, thicker cables can be equally efficient in carrying higher levels of current.

“We really want to go better than what copper or other metals can offer overall,” said Yao.

Yao’s paper appears in this week’s Nature journal Scientific Reports.