Original URL: http://www.theregister.co.uk/2009/11/19/quantum_crumble/

Boffins try to get closer to hot bodies

Quantum dots: making electricity from waste heat

By Pratik Desai

Posted in Science, 19th November 2009 15:02 GMT

Scientists at the Massachusetts Institute of Technology have found a way of of increasing the amount of energy that can harvested from a hot body*. If the discovery lives up to the hype then it could possibly pave the way to devices that can use waste heat as a power source.

Pointing out the potential of wasted heat, the press release states:

More than half of the energy consumed worldwide is wasted, most of it in the form of excess heat. This new technology would allow conversion of waste heat into electricity with an efficiency several times greater than existing devices. That kind of waste-energy harvesting might, for example, lead to cellphones with double the talk time, laptop computers that can operate twice as long before needing to be plugged in, or power plants that put out more electricity for a given amount of fuel.

The new technology relates to more efficient versions of thermophotovoltaic devices, or TPVs - devices that capture infrared light from a hot body and turn it into electricity. TPVs are usually limited by the amount of energy being emitted from the hot body - you can't catch more than is being thrown at you.

The boffs at MIT state in their research paper that they were motivated by a "challenge" from MTPV Corp colleague, Bob DiMatteo. DiMatteo asked them to exploit his discovery which showed that a hot body had a lot more potentially useful energy close to the surface.

Using quantum dots - imagine energy trapped in a box so it can't go anywhere - the boffs were able to couple the energy out of a hot body and convert it to useful electricity. Crucially, they demonstrated that it was possible to surpass the previous limits on the efficiency of TPVs.

The findings show it might be possible to use quantum dots to build high efficiency, high throughput TPVs, which could then be used to capture and utilise waste heat in a myriad of different products. But the quantum dots must be incorporated into a useful structure first. This is highlighted in the press release:

The new technology depends on quantum dot devices, a specialized kind of chip in which charged particles are very narrowly confined to a very small region. Such devices are under development, but still a few years away from commercial availability.

So we are still a fair way from the heady claims of double run-time batteries, but this is not to detract from the achievements of the MIT techno-boffins. Their work is novel and exciting stuff, but perhaps they need to keep a brake on their PR machine.

As well as the press release, the techno-boffin factory even has its own beta service news site with an evangelising story about the new research. ®

* Of course, when they refer to 'hot bodies', the researchers mean any object emitting a significant amount of heat, not just attractively proportioned individuals. It is not noted if the heat emitted by such individuals would be sufficient to classify them as 'hot bodies' in the strictly scientific sense.

If it were, it would be getting dangerously close to Matrix-like bioelectric technology. As we have seen from the popular Keanu Reeves vehicle, this would ideal for facilitating a machine takeover, and would be but a simple step away from allowing the use of humanity as mere fleshy battery packs for our new robot overlords.