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July 14, 2011

'Amplified' nanotubes another step on the long path to a nanotech electrical grid

Rice University scientists have achieved a pivotal breakthrough in the development of a cable that will make an efficient electric grid of the future possible.

Armchair quantum wire (AQW) will be a weave of metallic nanotubes that can carry electricity with negligible loss over long distances. It will be an ideal replacement for the nation's copper-based grid, which leaks electricity at an estimated 5 percent per 100 miles of transmission.

A prime technical hurdle in the development of this “miracle cable" is producing pure batches of armchair carbon nanotubes. Andrew Barron’s lab demonstrated a way to take small batches of individual nanotubes and make them dramatically longer. Ideally, long armchair nanotubes could be cut, re-seeded with catalyst and re-grown indefinitely. Up to 90 percent of the nanotubes in a batch can now be amplified to significant lengths.

NBF - I have criticized the Smalley vision of a carbon nanotube electrical grid in the past.

* Richard Smalley made the promise of a vision for a carbon nanotube electrical grid back in 1995.
* Smalley criticized the vision of mechanical nanotechnology as being scientifically impossible. However, there has be experimental proof that molecules can be moved and made to react with atomic precision
* Despite tens of millions in funding Smalley and now 8 professors and labs that continue the work have not delivered one meter of commercial carbon nanotube cable after 16 years.

Let us say the current work allows some carbon nanotubes to be produced. The world production of carbon nanotubes is 1350 tons per year now. Armchair quantum wire is probably in milligram non-pure quantities now and the breakthrough may bump it up to semi-pure gram or kilogram quantities in 5 years.


About 1 million tons of copper is used for the global electrical grid. It has taken many decades to build out the worlds electrical grids. Even if carbon nanotube cables were 60 times less carbon nanotubes that would still be over a million tons of armchair carbon nanotubes.

Meanwhile ultra-high voltage lines save 30-40% of the energy losses and are deployed now. Superconductors are being deployed to several major electric grid projects around the world

This article discussed the economics and energy benefits of superconducting wire

I think superconductors will be doing the job of making the electrical grid more efficient. I don't think rocking chair nanotubes will be able to get much market traction in 12-25 years. There would have to be massive production breakthroughs very much like the vision of molecular nanotechnology for the situation to change. Even then better molecular manufacturing would boost superconductors production and quality as well.

Nanoletters - Increasing the Efficiency of Single Walled Carbon Nanotube Amplification by Fe–Co Catalysts Through the Optimization of CH4/H2 Partial Pressures



Single walled carbon nanotubes (SWNTs) seeds are grown using Fe–Co nanoparticles on spin-on-glass. The relative efficiency of nucleation and amplification (versus etching) was investigated as a function of the CH4/H2 feedstock ratio and growth temperature. At 900 °C, maximum amplification is obtained with CH4/H2 ratio of 80:20 but 60:40 for nucleation. Amplification is further enhanced at 800 °C, compared with etching dominating at 1000 °C. Amplification of SWNTs is in equilibrium with etching; higher carbon feedstock pressure and decreased temperature increase the rate of amplification; the converse increases etching.

The latest experiments focused on single-walled carbon nanotubes of various chiralities, but the researchers feel the results would be as great, and probably even better, with a batch of pristine armchairs.

The key was finding the right balance of temperatures, pressures, reaction times and catalyst ratios to promote growth and retard etching, Barron said. While initial growth took place at 1,000 degrees Celsius, the researchers found the amplification step required lowering the temperature by 200 degrees, in addition to adjusting the chemistry to maximize the yield.



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