Friday, November 13, 2009

Long Lines

Technology Review reports on progress in Making Carbon Nanotubes into Long Fibers

A new method for assembling carbon nanotubes has been used to create fibers hundreds of meters long. Individual carbon nanotubes are strong, lightweight, and electrically conductive, and could be valuable as, among other things, electrical transmission wires. But aligning masses of the nanotubes into well-ordered materials such as fibers has proven challenging at a scale suitable for manufacturing. By processing carbon nanotubes in a solution called a superacid, researchers at Rice University have made long fibers that might be used as lightweight, efficient wires for the electrical grid or as the basis of structural materials and conductive textiles.
Yep. It could be a very good replacement for copper or aluminum wires. And the base material is rather abundant. Coal mines are full of it. On the other hand petroleum or natural gas might be easier to process.

But we are not quite there yet.
So far, the group has made fibers that are highly conductive but not as strong as other carbon materials. Pasquali says the strength of the fibers could probably be improved tenfold by using longer carbon nanotubes. "We're now working on a project for making electrical transmission lines," says Pasquali. "Metallic nanotubes conduct electricity better than copper, they're lighter, and they fail less often."

One important hurdle for large-scale manufacturing of carbon nanotubes remains: Today, there aren't any good methods for making the nanotubes themselves in large, pure batches. In order to make nanotube transmission lines, for example, the Rice group would need to start with a large batch of nanotubes containing all metallic nanotubes and no semiconducting ones. Last month, chemists at the Honda Research Institute published a paper in Science describing a method for making large amounts of metallic nanotubes that Pasquali says is promising. "For transmission lines you need to make tons, and there are no methods now to do that," he says. "We are one miracle away."
And that miracle may have already happened.

What remains to be done after the breakthrough: making enough Carbon Nanotube (CNT) wire to build a test section into the grid. Developing methods for joining the wire to other non CNT segments of the grid. Developing methods for joining CNT segments. Testing it against weather and lightning strikes. And at least 10,000 other details (hand tools among them) will need to be worked out including crew training. Miracles take time to unfold.

And power lines might not be the prime candidate. Lowering the weight of wiring harnesses in automobiles might be a more favorable initial application since weight reduction is worth real money.

H/T GPecchia at Talk Polywell