Body Heat Could Charge Your Cellphone 94
An anonymous reader writes to mention Nature is reporting that scientists have discovered a much more efficient way to use silicon to convert heat into electricity. This offers the possibility of many different applications including possibly charging your portable electronics just by wearing them close to your skin. "The concept of converting waste heat into electricity isn't exactly new, but it never really materialized due to efficiency hurdles. Now, scientists from the U.S. Department of Energy's (DOE) Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California at Berkeley think they may have found a key [to] increase the conversion efficiency by a factor of 100."
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Wonderful! (Score:1)
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So... (Score:5, Funny)
Snap Crackle & Pop (Score:2, Funny)
I claim dibs on Rice Crispies-powered phones
So...Portable Monica. (Score:1, Funny)
I believe Bill Clinton has one of those.
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And with solar power, we have at least one argument to get girls to masturbate outside.
Downsides (Score:5, Funny)
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Hm, I've got a great new policy with a noble rationalization. I've needed one ever since my "recycling menstrual blood" fell through.
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I had to read it again.
Re:Downsides (Score:5, Funny)
I'm sure plenty of people here have at one point thought that way about your mom.
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Why just cellphones? (Score:5, Insightful)
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CPU fan? (Score:2)
I want to see the users manual (Score:5, Funny)
Brett
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I can't wait to get my Apple iShove, or maybe the less expensive inema.
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http://www.youtube.com/watch?v=136cNGNd7Yg [youtube.com]
Not quite the same thing, but I saw this today and had to share
Needs a temperature gradient (Score:3, Insightful)
Re:Needs a temperature gradient (Score:5, Insightful)
Also TFA mentions "...the discovery will depend on whether these rough nanowires will be efficient enough to make commercial sense." So yeah, I don't see it (soon) being any more energy efficient to manufacture heat converting nanowires for my iPod Nano than it would be to say, construct a battery. But maybe they have something that could better convert a massive heat gradient into electrical energy cheaper for the purposes of co-generation. Who knows, maybe even cut down on heat pollution.
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Your balls are usually a couple of degrees cooler than the rest of the body. So the 'inserting' joke might not be too far off.
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Maybe you weren't aware, but the human body runs at a significantly higher temperature than the world around it. You'd have a hard time finding a place that that temperature gradient didn't exist. All this means is there has to be a large air-access radiating surface. No more phones the size of a stick of gum, since your hand would cover the cold spot. We don't need a magic cold c
Think of the poor elderly gadget freaks... (Score:1)
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I think I'm missing something about this concept (Score:1)
is the sun's heat not enough to generate a substantial amount of energy? what would encasing one of these in a sealed dark glass box at lower latitudes do... or even inside of a hot car for that matter
Re:I think I'm missing something about this concep (Score:1)
Nothing. It needs a thermal flow to work, i.e. a hot end and a cold end. Just putting it in a uniformly hot environment is useless.
Basic physics: no. (Score:5, Insightful)
Human body thermal output is about 120 watts on average, skin surface area is 2 m^2, so a 50-cm^2 cell phone body can intercept 0.6 watts of body heat. BUT, the laws of thermodynamics place a limit on how much of that heat can be converted into useful work to charge the batteries in the phone. That limit depends on the temperature of the heat source and sink.
Suppose one side of the phone is in contact with your skin at 32 C (305 Kelvin), and the other side is in contact with room-temperature air at 27 C (300 K). (In practice, the temperature difference will be smaller, because the air near your body will be warmed above room temp.) The maximum efficiency one could get from these thermodynamic efficiency is (305-300)/300 = 1.7%.
And that's the theoretical maximum possible conversion efficiency. Real systems rarely come close to that.
SO, the most energy we could possibly get out of this generation system is 0.6 * 1.7% = 10 milliwatts. My iPhone's battery holds about 2400 mW-hours of juice, so if I installed this charging system and held it against my skin 24/7, it would take about 10 days to charge in the theoretical best case... and in practice, much longer than that.
This idea's dead in the water at the basic physics stage, before we even get to the engineering considerations.
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You put a lot of thought into that message, but it is negated by just RTFA which says that the potential applications include "...personal power-jackets that could use heat from the human body to recharge cell-phones...". They aren't talking about the cell phone itself drawing the power, but potentially the entire inner surface of a piece of clothing (which would also have the entire outer surface of the piece of clothing as the cooling surface for differential).
However, this does sound like we will only
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(T_hot-T_cold)/T_hot
Using your numbers: (305-300)/305 = 1.64%
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Actually, 10mW is loads. You're not going to charge batteries off that or run a GSM phone, but it's more than ample for powering things like wristwatches, calculators or medical sensors; and with appropriate design, there's no reason why you couldn't build a PDA that worked at that kind of po
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The article is talking about using the technology in the clothes and using the energy from that to power a cellphone. This would give you a lot more surface. And I don't know where you live, but "room temperature" here is not so tropical. So the theoretical maximum according to your calculation would be more like ((305-295)/295) * 120 = about 4 watts. Not a lot, but my telephone charger can provide about 2.2 watts and my battery i
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Oh wait!
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So crank up the air conditioner and make the room cooler. Or just use Peltier elements to drain heat from the cold end of the generator. Coming to think of it, you could simply have a closed compartment, use Peltier elements to move heat from one side to the other, and run the generator - and power the Peltiers - from the resulting temperature gradient forever and ever.
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However you are forgetting the first two, pre-physics stages: Marketing and Investment.
The hot air (and subsequent thermal gradient) from these stages should allow thermodynamics to power these devices for at least as long as it takes the stock to tank.
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27C room temp??? Think not (Score:2)
Assuming a more *NORMAL* room temp of 21C, the updated calculation is (305-294)/294 = 3.7%, or 21.76 milliwatts.
That is 4.5 days to charge fully from 0.
And you're also forgetting the point of this is not to take a dead battery from 0% to 100%, it is to MAINTAIN your current battery. As such I think this system could theoretically easily make it so you would rarely
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The inverse makes silent sub air-conditioning (Score:5, Interesting)
Hope that wasn't classified or anything - but then Dad passed away a while back.
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Re:The inverse makes silent sub air-conditioning (Score:5, Insightful)
Actually, at least here in the US, you probably should still worry about it being classified information.
For example, various historians have mentioned that the Rosenbergs were executed for giving "secrets" to the Russians that apparently were available in a number of college-level physics textbooks at the time.
Decades later (but still a few decades before today), I did an end-of-chapter exercise in a physics text that was something like: Using equations E and F from this chapter, and table T in appendix A, calculate the critical masses of the following isotopes
The US government's security agencies don't consider previous publication in school textbooks to be a restriction on their right to classify information.
For another example, google for RSA encryption. I have one of those t-shirts that has the 4-line perl implementation of RSA, and on the back "Warning: This t-shirt is a munition" plus a reference to the appropriate regulation. I never had the nerve to wear it to the airport on an international flight, though I did wear it to a number of techie meeting where there were non-citizens. I kept wishing someone would get arrested for wearing one, since the trial could have been entertaining. But I suppose now they wouldn't bother with a trial; you'd just disappear to an undisclosed location in an unstated country for a few years and then dropped off on a hillside in Macedonia when they're done with you.
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Well, that's technical advance for you! I'll have to find that code. I expect it'll look like pure line noise. Also, I was being a bit generous with my original "4-line" description, since I counted the first #!/usr/bin/perl line, and that's not really what you could call perl code. Others only count it as three lines.
I did like the "-export-a-crypto-system-sig" comment in the original. Like many perl geeks, I have used it as a sig off
Thank you for your support. (Score:2)
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Hope that wasn't classified or anything - but then Dad passed away a while back.
Let's just say I doubt it. Especially if it was "a while back". Won't say why, but trust me.
Anyway, the sea is an awesome heat sink - especially if you go down a bit in the right oceans. Just put your soda can on any seawater pipe. It's not th
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The problem with this is that you don't want to conduct heat into the surrounding seawater. It leaves an easily detectable heat plume.
In fact, you want to heat the interior of the sub relative to the surrounding sea. So you make the hot side of the thermoelectric pan
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Secondly, think about it. Everything in the sub from the bodies to the machinery makes heat. It has to be transferred out and the only place it can go is into the sea. The only question (and it's not a question, I know how it is done, or was, anyway) is how.
reversible? (Score:4, Interesting)
should be (Score:2)
It ought to be.
The problem with Peltier cells is the conduction of heat across the cell by means other than the charge carriers that perform the heat pumping/thermoelectric generation. This breakthrough is a drastic reduction in heat conduction. So it ought to be applicable to both heat pumping and generation. In fact the efficient thermogenerator ought to be an efficient heat pump as well.
There is a better way. (Score:3, Interesting)
Have you seen those ever lasting flashlights. Which use a magnet, a coil and a capacitor. The same concept could be used here. It might not keep the phone charged for heavy users but it could be a nice supplement to the charger.
Maybe if they really got creative they could reuse the coil and magnet as the vibrator.
OH and I didn't read the article. These are both interesting idea's but how much power can we really extract.
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But some of the hype in TFA DOES violate the laws of thermodynamics - exceeding the carnot cycle limit, sometimes by several orders of magnitude.
One of the other responses, for instance, calculates the power available from skin heat to a normal-sized cellphone at 10 mW. And the whole POINT of "waste heat" in a power plant is to dump it to ambient without restrictions that would raise the dump temperature and thus
Personal Thermonuclear Generators (Score:3, Interesting)
Re:Personal Thermonuclear Generators (Score:4, Interesting)
I've seen this suggestion any number of times, often with snide comments about how engineers have missed something obvious. This usually causes some engineer to simply mention that there's a better way. No matter how your water heater is powered, it's always more efficient to add insulation to the water heater, and use the fuel that you save to directly power an electrical generator. This skips the stage of extracting power from the water heater's heat loss, and can thus extract more electricity from the fuel (or use less fuel to generate the same electricity).
Unfortunately for such schemes, it's only practical to extract energy from a heat gradient if the heat gradient is going to be there anyway. Then, if the extra weight isn't a problem, you might be able to use some of the heat you're losing to produce a small amount of electricity "for free" (i.e., at no additional fuel cost).
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But I'm a bit dubious about the thought of a small nuclear power plant in the basements of my neighbors' homes
For longest time, I wouldn't belive it... (Score:1)
Incredible, I thought about this just yesterday (Score:1)
This, combined with a limited form of fusion... (Score:1)
Cure for obesity? (Score:1)
(fun intended)
Bring 'em on ! (Score:3, Funny)
Next up: Lap-powered laptops (Score:2, Funny)
Seebeck effect (Score:2, Interesting)
Copper Top (Score:5, Funny)
Not thought through..? (Score:1)
Charge Phone While Driving (Score:2)
Laptop Heat ! (Score:1)
This is gonna happen through the impantable market (Score:1)
New use for silicon? (Score:2)