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Still Suits and Body-powered Devices

Posted by michael on from the stay-out-of-the-rain dept.

Helmholtz writes: "Soon body powered devices may be a reality thanks to work being done at the Center for Space Power and Advanced Electronics, a NASA commercial center in Alabama. The article talks mostly about military and space applications, but I think it'd be really slick to make still suits, not to mention portable audio players, PDA, and even laptops that are powered by energy that we are generating anyway."

3 of 136 comments (clear)

  1. It's already here, well, kinda. by mlafranc · · Score: 4, Informative
    Seiko has been selling it's Kenetic line for a few years, even coming up with the Auto-Relay line, supposidly keeping time for up to four years.

    Seiko has the only Quartz watch of this kind, afaik.

    However, self winding watches have been around for quite a while. Now, these watches don't run off body heat, sweat, brain waves or any else NASA might be thinking of, god knows. They work from adjustments in tilt, giving off enough power to build a reserve. Just getting out of the office chair and going for coffee, or off the couch and walking the dog, should be enough.

  2. Re:That's not new by elem · · Score: 2, Informative

    This sounds remarkably like one of the things that Trevor Bailis (inventor of the windup radio) is working on. I remember reading an article or seeing an interview where he had built a pair of boots with piezo-electric strips in which he used to recharge a mobile battery.

  3. Not that much energy from heat by Roger_Wilco · · Score: 4, Informative

    They claim that 81W are waiting to be harvested from a sleeping human. This is incorrect, due to Carnot's law (a thermodynamic law). Basically if we have a heat source at Th (the body) and a heat sink at Tl (the environment) the maximum possible efficiency is

    1- Tl/Th

    All temperatures must be in Kelvin (or Rankine). So for a human at 37C = 310K, with an environment at room temperature 20C = 293K, the best efficiency is

    1 - 293/310 = 5.5%

    If they can get 3% efficiency with current materials, they're already doing extremely well. At this efficiency a sleeping human, putting of 81W of heat, can only provide

    81W * 5.5% = 4.4W

    of usable energy. It's true that 4.4W can power a fair bit of energy-efficient technology, but they're starting with a lot less available energy than they claimed in the article.