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Cellphones Communications Handhelds Power Hardware Technology

Talk-Powered Cell Phones Won't Need Batteries 197

alphadogg writes "It's possible that in the future conversations on your cell phone could generate enough electrical power to run the phone, without batteries. That's one possible outcome of recent work by a team of Texas researchers, who appear to have discovered that by building a certain type of piezoelectric material to a specific thickness (about 21 nanometers, compared to a typical human hair of 100,000 nanometers), you can boost its energy production by 100 percent. And the technology could power not just phones, but a whole range of low-power mobile devices and sensors. The breakthrough is an example of 'energy harvesting' that can convert one kind of energy, such as vibrations or solar rays, into electricity."
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Talk-Powered Cell Phones Won't Need Batteries

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  • by Mike-the-Mikado ( 889632 ) on Wednesday December 03, 2008 @07:51PM (#25982681)
    That's why people are always shouting at them?
    • by earlymon ( 1116185 ) on Wednesday December 03, 2008 @08:19PM (#25982949) Homepage Journal

      I see you've met my sister. She comes through clear as a bell from 8 states away. Next time, I'll have her turn her phone on...

      • Re: (Score:2, Informative)

        It takes 1000 screaming people to generate a watt's worth of energy (one joule of energy per second).
        • 1000 people screaming only makes one watt? I have no proof of my own, but I'm not so sure on that one. Take two different auditoriums, one with 1000 screaming people in it, and one with a sound system in it.

          You're telling me that I could power the sound system with ONE WATT, and duplicate the sound energy of the auditorium that has 1000 people in it?

          I need a little more info to see how that would be possible...

          Granted, I'm betting that there is something interesting that happens to the piezoelectric
      • by M1rth ( 790840 ) on Wednesday December 03, 2008 @09:42PM (#25983767)

        If she's that loud, her vocalizations could probably power other "battery operated" devices she may use...

    • by EmbeddedJanitor ( 597831 ) on Wednesday December 03, 2008 @08:21PM (#25982965)
      to anywhere near low enough to work with the piezo then you might as well use a very small battery.

      Current cell phone technology is perhaps four orders of magnitude away from piezo power. At ten times the piezo power level, say 10mW, you may as well use small cheap batteries. One non-rechargable AAA cell would run for approx 700-800 hours at those levels.

      • by sexconker ( 1179573 ) on Wednesday December 03, 2008 @08:46PM (#25983215)

        Your math. It is very wrong.

        A typical AAA battery is 1.5v @ about 900 mAH.
        Round that up and you get 1500 mWH.

        1500 mWH / 10 mW = 150 hours.

        • by MaceyHW ( 832021 )
          No, his point is that if cell phones became efficient enough to be powered by piezo power, it would make more sense to stick a AAA in and get 700-800 hours of use.
          • No, his point was that the power required for a cell phone is orders of magnitude (4, according to him) higher than what you can get out of piezo electric funstuffs.

            He then assumed an amazing case scenario of a cell phone needing 10 mW. He said at that power level (draw), you may as well use small cheap batteries.

            He then said a single AAA would run for about 700-800 hours (at that power draw).

            Given that a typical rechargeable AAA is 1.2v @ 800 mAH, it's a fair high-end estimate to say that a standard AAA (

      • Re: (Score:3, Interesting)

        by rolfwind ( 528248 )

        I don't talk enough on the phone to power it for standby. But what about one powered by motion, much like an automatic watch? Does it generate enough power?

        I personally hate batteries, at least the current technology. Perhaps ultra-capacitors one day...

        • by Firehed ( 942385 )

          I don't look forward to the contract attached to the carrier subsidy for a Rolex phone... though I still like the idea.

      • by Chapter80 ( 926879 ) on Thursday December 04, 2008 @04:21AM (#25986139)
        According to my calculations, no battery is required and this article poses an excellent solution, with a few minor modifications and innovations.

        If you assume normal human speech is about 60dB. We know dB = 10 log(I/I0) where I0 is 10^-12 W/m^2. So 60dB works out to about 10^-6 W/m^2 -- that's a microwatt per square meter. With 100% efficiency and a mike of 1 cm^2 collecting area, that's around 10^-10 W -- 0.1 nano-watts. (Thanks phliar [] for the calculations.)

        Then utilize this energy using recent advances in String Theory, and you have a workable solution.

        Here's a picture of a prototype. []

    • by billstewart ( 78916 ) on Wednesday December 03, 2008 @08:22PM (#25982987) Journal

      Hey, my phone's running low on power, let me find some heavy traffic and big trucks so it'll be loud enough for me to hear you!"

      Next thing you know you'll have to shake your phone to get features to work (oh, wait...)

  • by infonography ( 566403 ) on Wednesday December 03, 2008 @07:52PM (#25982691) Homepage

    Just set it in a Pyramid and use pyramid power to keep it topped off. That is what they ancient Egyptians did.

    Don't forget to call your Mummy.

  • by liraz ( 77590 ) * <> on Wednesday December 03, 2008 @07:52PM (#25982695) Homepage

    Most modern phones are probably much too power hungry to be get enough energy from audio vibrations, even you manage to ramp up the efficiency close to 100%, which is unlikely to ever be practical.

    Where this could be useful is in specialized low-power devices that get bundled into emergency survival []

    OTOH, future cellular devices might incorporate enough improvements into power efficiency (e.g., e-ink displays []), such that you could significantly extend battery life and perhaps even power a very basic subset of the phone when the battery runs out.

    Also, harnessing vibrations efficiently might be very useful in surgically implanted medical devices where replacing the battery can be rather inconvenient [].

    • by InlawBiker ( 1124825 ) on Wednesday December 03, 2008 @07:55PM (#25982715)

      Mmmm, I dunno. If this turns out to be true my wife could talk on the phone enough to power the whole grid.

    • Re: (Score:2, Informative)

      by orkybash ( 1013349 )
      Regarding your last idea, I've interned in the medical device industry so I might have some perspectives... basically, if something like this couldn't power a cell phone it certainly couldn't power sustained operation of a pacemaker! Charge a battery for a defibrillator maybe, but even then you're taking huge risks with rechargable batteries with regard to memory. Basically, even if you were able to use this to increase battery life, you would still decrease *predictability* of the battery life, which is
    • His heart implant is failing hand me a vibrator stat!

    • Yeah, but maybe, in the future, they might find that the convenience of never having to charge your phone is worth more than having the ability to watch TV/videos, browse the web, listen to music, get directions on a map, download ringtones, take pictures, and purchase all kinds of other pointless stuff to do on your phone. We're in a recession afterall, priorities people! Plus I imagine that such a phone would probably be ubersmall and uberlight.

    • I'm pretty sure that when you have an active call going on a modern phone the radio gear is the most significant power drain especailly if you are a long way from a base station (with radio power required is roughly proportional to the square of distance).

    • Re: (Score:2, Informative)

      by caladine ( 1290184 )

      OTOH, future cellular devices might incorporate enough improvements into power efficiency (e.g., e-ink displays []), such that you could significantly extend battery life and perhaps even power a very basic subset of the phone when the battery runs out.

      IMO, future cellular devices will probably use something based on IMOD display technology []. It has all the power benefits of e-ink, but considerably faster switching. They're also already available, albeit at pretty small sizes. There's also color versions of these IMOD displays avaliable, but they also suffer from the current size problems.

      The Wikipedia article is somewhat short on the details, so the Qualcomm PR page is here []. Like I said, it's really a PR page trying to promote their solution, but the whit

    • For emergency equipment, wouldn't it be easier and more effective to just put a damn hand crank on the thing? If kids in third world countries can power a laptop with a handcrank I think I can power a phone long enough to call 911.

  • by HtR ( 240250 ) on Wednesday December 03, 2008 @07:55PM (#25982719)

    Wonderful. I can just imagine being in a restaurant or an elevator with a group of people with phones all saying "Low Power - please speak louder."

  • by ( 142825 ) on Wednesday December 03, 2008 @07:57PM (#25982739) Homepage

    And, no I am not talking about the crossed my mind.

    I remember there was also a digital watch that worked on body heat. I could not find that one, but I found another, non-digital. [] .

    • by Tuidjy ( 321055 ) on Wednesday December 03, 2008 @08:18PM (#25982939)

      Why would you want one? We have watches working off the constant motion of our body/arm/wrist/whatever. Mine takes a few days before it winds down. I think that anyone that stays immobile for that long will not be doing so great in respect of body heat, either.

    • by sribe ( 304414 )

      The harvesting of heat energy always depends on the temperature differential between two materials. The temperature differential between your body and ambient air is so low that it can only be used to produce very, very, very little power. It just so happens that a watch can be designed to run on very, very, very little power--way less than required by a cell phone, you know with its little transmitter and all that kind of stuff ;-)

  • by Anonymous Coward on Wednesday December 03, 2008 @08:01PM (#25982777)
    Lets assume that a minimum channel capacity (bits/s) is required to support a conversation, even if we use the absolute best vocoder that eliminates all redundant information. Shannon's Law [] then says that for a given noise power (set by the environment) there is a minimum signal power which must be transmitted to get error free transmission. Again we are assuming we have an optimal codec, which achieves Shannon's bound. This sets the absolute minimum power consumption of an ideal radio telephone. A real life phone will use more than this. My guess is that this theoretical minimum power is greater than the power which can be harvested from the human voice.
    • "Won't need batteries" may be a bit of an exageration, but even if the new tech only increases time between required charges a bit, it seems like a win to me.

      • Meh, if the new tech provides an additional source of power, the phone manufacturers will simply fit batteries of lower capacity.

  • by reginaldo ( 1412879 ) on Wednesday December 03, 2008 @08:04PM (#25982801)
    I don't know if this would work for me, because I usually just end up listening on my phone.

    Yes, honey. Ok, honey. Will do, honey.
    • Ya, I was thinking the same thing. It would only work for woman to woman calls were they are able to fully duplex the conversation without pause.

      I don't think you can power any think on uh-hu, yes, maybe, ok, and goodbye.

    • Re: (Score:3, Insightful)

      I don't know if this would work for me, because I usually just end up listening on my phone. Yes, honey. Ok, honey. Will do, honey.

      Yeah, but you could sell the excess power your wife generates to the utility.

      I think women talking on cell phones will solve our future energy needs.

      • I was thinking the same thing, but the phone would have to be wired for efficient power transmission...either that or it would need a big battery to store all the juice and then return it once it's plugged in to the grid.

  • Texas (Score:3, Funny)

    by quenda ( 644621 ) on Wednesday December 03, 2008 @08:04PM (#25982803)
    Its not a coincidence that this story is from Texas. Other locales may lack sufficient vocal power.

    However Olivetti is working on a cellphone powered like a self-winding watch, by arm-motion.

  • by rossz ( 67331 ) <`ogre' `at' `'> on Wednesday December 03, 2008 @08:09PM (#25982859) Homepage Journal

    Just hand these out to teenage girls and we'll have enough power to supply the entire world for all its needs.

  • by cowtamer ( 311087 ) on Wednesday December 03, 2008 @08:10PM (#25982865) Journal

    Wow, that is amazing!!!

    Now if someone could tell me what the baseline of this increase is, we might actually learn something...

    (seriously, does anyone know what the efficiency of current nano-piezoelectric power generators are?)

    • by trongey ( 21550 )

      Well isn't it obvious? The baseline is about half of the efficiency of these new devices.
      Try to pay attention next time.

  • It is fully powered by the emanations of the mystical bs! Our marketing departments are now revenue generators (well, generators period)! Hallelujah for bspower! Finally, a cheap and ubiquitous energy source for the masses!
  • by damn_registrars ( 1103043 ) <> on Wednesday December 03, 2008 @08:22PM (#25982981) Homepage Journal
    I seem to recall a time years ago that a PC manufacturer (perhaps Compaq?) claimed to have developed a keyboard that could recharge a laptop battery by the kinetic energy of the key movement.

    Yet for some reason we don't all have those...

    Of course, very few people do much typing on their laptops now, but there are some people who presumably could have found it quite useful.
    • Might you be referring to the joke that went around about 15 years ago (at least that's when I heard it) for keystroke powered word processor. It goes on to extol the virtues of such a machine, providing direct output onto paper, and using only the power of your fingers to run the entire operation. It is, of course, the venerable manual typewriter. I googled but couldn't find the old text of the "Advertisement".

  • So I can sing to power my mp3 player while I'm listening to it? Cool :)
  • by Jazz-Masta ( 240659 ) on Wednesday December 03, 2008 @08:28PM (#25983035)

    ...I'm just charging my batteries.

    "battery's almost dying, I need to talk some more, let me call AOL and try to cancel."

  • The mW needed to transmit the cell signal? Or the power needed to illuminate the 2x2" full color screen with real-time GPS positioning, speakerphone, and fluid game play?

    The former.. possible. The latter.. only if you put the phone in a paint mixer.

  • It sounds like talking will just provide a way to charge the phone... it's still going to need some sort of power source to be running when you're not talking into it. Isn't this more like an alternator for a car?
    • it's still going to need some sort of power source to be running when you're not talking into it.

      Depends. If the user is like my girlfriend it will never be on unless her mouth is running anyway.

  • Bullshit (Score:2, Insightful)

    by lyml ( 1200795 )
    Bullshit, there is no way shouting would produce the required amount of power to operate a phone, theese things are very powerhungry.
  • Now every phone conversation can start a tornado or hurricane somewhere!

  • I'm filing my patent for my newly invented perpetual motion device.... in a dildo.
    I think I'll call it the "Infinibrator"

  • by Ancient_Hacker ( 751168 ) on Wednesday December 03, 2008 @08:56PM (#25983327)

    It does not matter if they improve the microphone efficiency to exactly 100% The amount of power in any reasonable voice is miniscule at best. And most of the power is in the lower part of the register, where the sound wavelengths are several meters long. And to get even a fraction of the power out of a wave, you need a microphone at least a quarter wavelength across.

    So even if cell phone microphones were a foot in diameter, they'd only capture a few milliwatts on voice peaks. And cell phones need a couple watts of power full-time to output a watt or so to the antenna. No way, Jose, and by at least three zeros after the "1".

    • by goodmanj ( 234846 ) on Wednesday December 03, 2008 @10:00PM (#25983897)

      A little help for those too lazy to do the math:

      Power per area transmitted by a sound wave:

      F = p^2 / (rho0 c)
      p = rms pressure variations in the sound wave (.01-.05 Pa or so for human voice)
      rho0 = density of air (1.3 kg/m3 typ.)
      c = speed of sound in air (330 m/s)

      I get 1 microwatt per square meter. So for a 20-cm2 cell phone, 2 nanowatts, ignoring the receiver-coupling issues mentioned by the parent post.

      No way, Jose, and by at least three zeros after the "1".

      Let's make that nine.

      • thanks. As a real-world example an old crystal microphone could put out one volt peak-to-peak into one megohm if you talked close. So that's about .3 volts rms, p = e^2/r or 10^-7 watts.
        So I get 100 nanowatts, close enough.

        You'd get 100 x more power from a one square cm solar cell, even from moonlight.

        • by RingDev ( 879105 )

          The whole thing makes me sceptical. Especially the author's personal notes he injects, like this gem:

          Wang noted that millions of these fiber pairs, each about one centimeter long, would be have to be woven into about 9 square feet of fabric (which would make for a shirt the size of really big poncho)to power an iPod.

          9 square feet is a really big poncho? That's a 3x3' square. Most adult sized rain ponchos are well over 3'. Here's one that comes in at 45x53" (over 16.5 square feet) and only covers to waist to elbo. 9 square feet is probably a lot closer to XL T-shirt size than it is poncho size.

          If the guy has issues comprehending something as simple as the size of 9 square feet, how can we trust him with the more complex

  • With this new technology, I'm pretty sure my wife can power our entire house! Of course things will get pretty dark and cold when she's not home, but that happens already anyway.
  • A little googling found that: a cell phone requires something on the order of 1W (while in use). Speaking in a normal voice produces on the order of 0.00001W of sound energy. I don't think cell phone power requirements could ever get that low (unless the cell towers were much closer together). Interesting idea, though.

  • by seeker_1us ( 1203072 ) on Wednesday December 03, 2008 @11:22PM (#25984481)
    As if millions of cellphone users cried out "bullshit!" and were suddenly silenced.
    • by rhizome ( 115711 )

      As if millions of cellphone users cried out "bullshit!" and were suddenly silenced.

      Look, it's not difficult to understand: the talk-powered phone does not require batteries. However, the thing you use to charge it with does.

  • My daughters would cause them to melt or explode!
    • by Shados ( 741919 )

      yeah, if you force my law to use this technology as an implant in all teenage girls, you can basically eliminate the need for coal/fossil fuel/nuclear fuel/etc in power plans of north america as a whole.

      That would be awesome.

  • Not enough energy (Score:4, Insightful)

    by phliar ( 87116 ) on Thursday December 04, 2008 @12:23AM (#25984841) Homepage

    Some back-of-the-envelope calculations: normal human speech is about 60dB. We know dB = 10 log(I/I0) where I0 is 10^-12 W/m^2. So 60dB works out to about 10^-6 W/m^2 -- that's a microwatt per square meter. With 100% efficiency and a mike of 1 cm^2 collecting area, that's around 10^-10 W -- 0.1 nano-watts.

    Color me skeptical.

  • I wonder if it'd work for other vibrations like those incurred while pushing keys to text. "Must Twitter faster... phone's dying!"

  • More details about the prototype of an existing voice-powered telephone system: []
  • I could charge my phone in a second: "Muad......DAVE!"
  • This technology wouldn't work for me.

    99% of my calls are from girlfriends who only want me to listen to them go on for hours about their problems. I never get a chance to say anything.

  • Oh, great, so then we'll have to listen to idiots not only talking LOUDER but screaming into their cellphones in public places... or in offices with bad reception....


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