MIT Produces Electricity Using Thermopower Waves

MikeChino writes "MIT scientists have discovered a never-before-known phenomenon wherein carbon nanotubes can be used to harness energy from 'thermopower waves.' To do this they coated the nanotubes with a reactive fuel and then lit one end, causing a fast-moving thermal wave to speed down the length of the tube. The heat from the fuel rises to a temperature of 3,000 kelvins, and can speed along the tube 10,000 times faster than the normal spread of this chemical reaction. The heat also pushes electrons down the tube, which creates a substantial electrical current. The system can output energy (in proportion to its weight) about 100x greater than an equivalent weight lithium-ion battery, and according to MIT the discovery 'opens up a new area of energy research, which is rare.'"

Comments

So basically they cut out the middleman

[Shadow of Eternity]

Instead of having a Lion battery that explodes we now have a deliberately exploding battery.

Re:That's some hot stuff...

[profplump]

Refueling could be as simple as pouring more fuel on the nanotubes. But it may also be irrelevant -- not all power systems need to be reusable. For example, an emergency beacon is not likely to be used frequently, so refueling is not nearly as important as shelf life. And even in applications where refueling is desirable, the increased power density may be worth it -- if you phone battery lasted 200 days instead of 2 days you might not care that the battery can only be refueled with special equipment.

That being said, 100x might well be optimistic. Or it might be wildly conservative. Since this is a brand new field it seems unlikely that an estimate will be terribly accurate.

Re:That's some hot stuff...

[jellomizer]

For some perspective that is about the heat that a filament in a lightbulb is at.

Fricken Lasers

[Gotung]

This sounds like a niche energy product. Basically nano-combustion that very quickly creates a very strong electrical charge.

Doesn't sound too great as a battery. But as "ammo" for hand held laser weapons? Could be perfect for that.

Re:Fricken Lasers

[girlintraining]

Basically nano-combustion that very quickly creates a very strong electrical charge.

EMP in a suitcase.

Link to the Nature Materials article

[reverseengineer]

The orignal article may be found here- subscription to Nature Materials or payment required for full text. Abstract:

Theoretical calculations predict that by coupling an exothermic chemical reaction with a nanotube or nanowire possessing a high axial thermal conductivity, a self-propagating reactive wave can be driven along its length. Herein, such waves are realized using a 7-nm cyclotrimethylene trinitramine annular shell around a multiwalled carbon nanotube and are amplified by more than 104 times the bulk value, propagating faster than 2 m s-1, with an effective thermal conductivity of 1.28±0.2kWm-1K-1 at 2,860K. This wave produces a concomitant electrical pulse of disproportionately high specific power, as large as 7kW kg-1, which we identify as a thermopower wave. Thermally excited carriers flow in the direction of the propagating reaction with a specific power that scales inversely with system size. The reaction also evolves an anisotropic pressure wave of high total impulse per mass (300 N s kg-1). Such waves of high power density may find uses as unique energy sources.

The "fuel" used, cyclotrimethylene trinitramine, may be better known as the explosive RDX.

Re:Link to the Nature Materials article

[garg0yle]

Yeah, I doubt that I'm gonna be able to bring a laptop on a plane with RDX in its battery...