Explosive stuff

A team of scientists at MIT has discovered a new way to generate power with carbon nanotubes. In a paper titled "Chemically driven carbon-nanotube-guided thermopower waves" published in Nature Materials, they describe how they made "thermopower waves" flow through the nanotubes, generating a significant amount of power relative to the size of the nanotubes.

In the new experiments, each of these electrically and thermally conductive nanotubes was coated with a layer of a reactive fuel that can produce heat by decomposing. This fuel was then ignited at one end of the nanotube using either a laser beam or a high-voltage spark, and the result was a fast-moving thermal wave traveling along the length of the carbon nanotube like a flame speeding along the length of a lit fuse.

Heat from the fuel goes into the nanotube, where it travels thousands of times faster than in the fuel itself. As the heat feeds back to the fuel coating, a thermal wave is created that is guided along the nanotube. With a temperature of 3,000 kelvins, this ring of heat speeds along the tube 10,000 times faster than the normal spread of this chemical reaction. The heating produced by that combustion, it turns out, also pushes electrons along the tube, creating a substantial electrical current.

What's surprising about this is that the amount of power released is much higher than what standard thermoelectric calculations predict. Something is going on with carbon nanotubes when they are heated up that isn't happening on the same scale with other semi-conductors. But if the fuel is toxic and the nanotubes are hard to re-coat, do we want this on a large scale?