POWER TRANSMISSION Wires spun from carbon
nanotubes could carryelectricity farther and more efficiently. Richard Smalley
toys with a clear plastic tube that holds a thin, dark grayfiber. About 15 centimeters long, the fiber comprises billions of carbonnanotubes, and according to the Rice University chemist, itrepresents the first step toward a new type of wire that could transform theelectrical power grid.Smalley's lab has embarked on a four-year project to create a prototype of ananotube-based quantum wire. Cables made from quantum wires should conduct muchbetter than copper. The wires' lighter weight and greater strength would alsoallow
existing towers to carry fatter cables with a capacity ten times that ofthe heavy and inefficient steel-reinforced aluminum cables used in today'saging power grid. The goal is to make a wire with so little electrical resistance that it doesnot dissipate electricity as heat. Smalley says quantum wires could perform atleast as well as existing superconductors -- without the need for expensivecooling equipment. The reason: on the nanometer scale, the weird properties ofquantum physics take over, and a wire can carry current without resistance. Butuntil a couple of years ago, no one knew whether this amazing property wouldhold up when
nanotubes were assembled into a macroscopic system. Then JianpingLu, a physicist at the University of North Carolina at Chapel Hill, calculatedthat electrons could travel down a wire of perfectly aligned, overlappingcarbon nanotubes with almost no loss of energy.Smalley's group has already produced 100-meter-long fibers consisting ofwell-aligned nanotubes. But the fibers are mixtures of 150 different types ofnanotubes, which limits their conductivity. The best wire would consist of justone kind of nanotube -- ideally the so-called 5,5-armchair nanotube, named forthe arrangement of its carbon atoms. Existing production techniques generatemultiple types of nanotubes, indiscriminately. But Smalley believes that addingtiny bits of a single carbon nanotube at the beginning of the process couldcatalyze the production of huge numbers of identical nanotubes -- in essence, cloningthe original tube.