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Power Hardware Science

Rubber Boots Charge Your Phone 111

Posted by CmdrTaco
from the put-on-your-lead-boots dept.
andylim writes "UK wireless provider Orange and renewable energy experts GotWind have come up with a prototype pair of power-generating rubber boots. Inside the power-generating soles of the boots are thermoelectric modules constructed of pairs of p-type and n-type semiconductor materials forming thermocouples, which are connected electrically to form an array of multiple thermocouples (thermopile). They are then sandwiched between two thin ceramic wafers. When the heat from the foot is applied on the top side of the ceramic wafer and cold is applied on the opposite side, from the cold of the ground, electricity is generated."
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Rubber Boots Charge Your Phone

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  • by Drakkenmensch (1255800) on Monday June 07, 2010 @09:33AM (#32482878)
    Now you can look goofy AND charge your phone all at once!
    • Re: (Score:3, Funny)

      by rickb928 (945187)

      Corrections:

      Wellies are back in style for men. Supermodels and grannies have never left the fold.

      And of course, you can now look goofy, have cold feet, and get electrocuted all at once.

      Nice. The British, ever helful. Spot on, I say!

      • Re: (Score:1, Funny)

        by Anonymous Coward

        The British, ever helful

        I'm not sure if that was a typo or not, but bravo, sir.

    • by Virmal (1281900)
      Now everyone can look like Mr.Smart with your shoe phones. I wonder if TSA would let you through screening...
      • Say: "That's not a bomb. That's a charger for my iPhone." and see how fast you get tackled to the ground...

    • Reminds me of the song "These Boots Are Made for Talkin"... OK the original title has "Walkin".

      I'm too lazy to mangle the lyrics accordingly. Perhaps someone else can? :).
  • Slow news day? (Score:5, Insightful)

    by elrous0 (869638) * on Monday June 07, 2010 @09:33AM (#32482880)

    Periodically someone will come out with one of these "Clothing that generates electricity" (usually based on kinetic energy, in this case on body heat) inventions and the press will briefly cover it as a novelty item, then forget it. The clothing product in question will always be expensive, uncomfortable, prone to break and malfunction, and unable to generate enough electricity to be of any practical use. People either don't buy it at all or stop buying it the second the newspaper story fades from view. They stop buying it for the same reason that I ditched my "generator powered" light on my bicycle when I was a kid (you remember, the one that attached to the tire and used its kinetic energy to power the bike's headlight)--because it doesn't work worth a damn.

    I just hope those much-touted wind turbines that are all the rage now work a lot better than my old bike light at converting kinetic energy to electrical.

    • Re:Slow news day? (Score:4, Informative)

      by datapharmer (1099455) on Monday June 07, 2010 @09:45AM (#32482996) Homepage
      If the light didn't work well for you it was adjusted poorly or you weren't riding fast enough. The only problems with them were:
      a) You had to ride relatively quickly to generate much light
      b) It added a significant amount of friction to your wheel meaning you had to ride harder and
      c) The light stopped when you stopped.

      That said, a few modifications such as adding a capacitor to even out the light (acting as a voltage regulator), changing the light bulb to LED, and lowering the friction caused by the generator wheel and it would probably work phenomenally well. I was happy even back then though.
      • by MrNaz (730548)

        Indeed. Today's LEDs are vastly more efficient at producing light from low current sources than yesteryear's incandescent bulbs. Furthermore, capacitors are far better at storing larger amounts of energy and discharging it evenly than those of years gone past. Look at the Faraday light, (which I can't call anything other than a WanikLight) which uses a capacitor, magnet and coil to produce light. If they were built with decent build quality, they should be able to last several decades without malfunction.

        To

        • Re: (Score:2, Interesting)

          by Anonymous Coward

          Today's tech would make bike dynamos work so well that I have no idea why they don't make them any more. Perhaps battery tech is so good that there's little advantage?

          Around here (Sweden) they're generally replaced by a generator integrated into the front hub resulting in far better efficiency (thus much less drag) than relying to force a small diameter wheel to spin by gripping against the possibly wet/muddy/snowy tire.

          With a small integrated battery/super-cap you also get light while stationary (at least for a while).

          Not that totally battery-powered lights are uncommon, but IME rechargeables tend to die rather abruptly and Murphy will assure it happens just when you n

        • Re: (Score:2, Informative)

          by Anonymous Coward

          Dynamos still exist; in fact, new models are being produced all the time:
          http://www.peterwhitecycles.com/shimano3n70.asp
          http://www.peterwhitecycles.com/schmidt.asp

          They tend to have pretty good efficiency (~60%), generally use a clutching system so there is no drag when the lights are turned off, and have capacitors that will run the lights for at least five minutes. The problem is the expense - a good hub-mounted generator system runs around $100 and requires a rebuild of the wheel to install (around $50 in

      • Re: (Score:1, Interesting)

        by Anonymous Coward

        If you built it into the bicycle's hub, it might not cause nearly as much resistance.

        • Re: (Score:3, Informative)

          by Insightfill (554828)

          If you built it into the bicycle's hub, it might not cause nearly as much resistance.

          My wife has one of those. Specialized brand made the "Vienna Deluxe" [specialized.com] line last year. You can feel the drag when you hit the switch, but it's very subtle.

      • by elrous0 (869638) *
        The Simpsons episode "Bart's Comet" (in which Bart is shown struggling to pedal with one of the damn things and with it still only producing a weak/sporadic light) pretty much sums up my experience with these dynamos when I was a kid. They may have gotten better since, but no amount of adjustment to the one I used 30 years ago would have made it not suck.
        • by xaxa (988988)

          Two years ago I started cycling to work (I realised it was faster than walk+train+walk). Of course, I bought lights. Come winter, my parents gave me a big pack of batteries. I didn't realise why, until I found my dad's 1998 bike light in his garage: it sucked, and while sucking it sucked batteries dry. My LED lights need new batteries about every nine months, and are brighter.

    • by tepples (727027)

      They stop buying it for the same reason that I ditched my "generator powered" light on my bicycle when I was a kid (you remember, the one that attached to the tire and used its kinetic energy to power the bike's headlight)--because it doesn't work worth a damn.

      I wonder why wheel-powered bike headlights don't use regenerative braking to charge a battery that runs the headlight. It might work better.

      • by skids (119237)

        Regenerative braking is a bit more expensive to engineer than a small DC genset. The genset has to create a lot more power, since you are only braking 1% of the time compared to when you are moving -- two orders of magnitude difference.

        Might as well go full e-bike, though even some of those do not have regenerative braking, mostly because bicyclists are very efficient about choosing the paths with the least braking.
         

      • by Rogerborg (306625)

        I wonder why wheel-powered bike headlights don't use regenerative braking to charge a battery that runs the headlight.

        It's an interesting idea, but I can see 2 problems with it:

        1. The cost and complexity would see it only used by Serious Cyclists.
        2. Serious Cyclists rarely use their brakes.
        • by Protoslo (752870)
          I own a Serious Bicycle, and it would be a faux pas to put a kickstand on it, much less regenerative braking! You might as well chuck your all-carbon frame and make it out of steel tubing.

          I think you would have more luck appealing to self-hating middle aged people with plenty of money who only use their cycles twice a year.
          • There are several flavours of serious bicycles. You roadies seem to think that you're the only ones, but touring folk also like to kit out their bike. Indeed we do use steel frames and kickstands, and always have good lights.

      • Re:Slow news day? (Score:4, Interesting)

        by biryokumaru (822262) <biryokumaru@gmail.com> on Monday June 07, 2010 @09:52AM (#32483098)
        Because regenerative braking would be several orders of magnitude more complex and expensive to implement than a simple permanent magnet generator.
        • by drinkypoo (153816)

          Because regenerative braking would be several orders of magnitude more complex and expensive to implement than a simple permanent magnet generator.

          Just to be clear, we're talking about adding a button to the brake lever, and a battery and a diode to the design. Done. If you integrated the dynamo into the brake assembly such that the dynamo was applied when the brake was applied, you wouldn't even have to do this. If you want to use a nice battery that is optimally efficient you will need some electronics to handle charging; I suppose any design ought to have some sort of voltage regulation. This is still minimal. Further, dynamo lights blow anyway; la

          • Just to be clear, we're talking about adding a button to the brake lever, and a battery and a diode to the design. Done.

            Oh. Sounds pretty simp

            If you integrated the dynamo into the brake assembly such that the dynamo was applied when the brake was applied

            le.

            Oh sorry, I thought you said we were done.

            • The generator is on a small spring that keeps it away from the wheel until you apply the brakes. The brakes are cable operated. You add an additional cable that pulls the generator hub to the wheel simultaneously with the braking action. Just a lever and a pivot. It would be a typical idler/simple clutch looking arrangement.

              It's actually a good idea, combined with rechargeable batteries. Of course I am also in favor or just having an integrated small solar panel someplace to keep the batts topped off while

              • Could you build one? Could you build a reliable one, such that the friction kicks in seamlessly when necessary? More to the point, could you produce them for a price that people were willing to pay?

                Yeah, just this, only that, a simple matter of the other.

                • Maybe it's not something you could retrofit, but at the manufacturing stage, it wouldn't be that hard to include an electric signal when the brakes were applied.

                  You couldn't completely eliminate the friction, but the majority of the resistance comes from the generator, so you'd have some loss of power all the time, but only a significant loss of power when you're breaking (when you actually want it).

                  The show-stopper is that it would produce bugger-all power, coz bikes don't travel fast enough and stop way t

            • by elbarney (876344)

              I think that's what the button in the brake lever is for.

      • As long as that is in addition to drawing power from normal pedalling - otherwise when you're out on the open road cycling for miles with no need of braking, you're going to have no power. Then you have to consider the extra weight of a regenerative braking system and a battery..

        • by drinkypoo (153816)

          As long as that is in addition to drawing power from normal pedalling - otherwise when you're out on the open road cycling for miles with no need of braking, you're going to have no power. Then you have to consider the extra weight of a regenerative braking system and a battery..

          It's dumb to do at all. It's solar that should be used to charge bike lights. Dynamos are heavy, thin-film PV is light. Charge during the day, and you can ride at night. Even if you need to plug in to charge it's still going to save you weight.

          • Dynamos are heavy, thin-film PV is light.

            Batteries are...

            • Re: (Score:3, Interesting)

              by drinkypoo (153816)

              Batteries are...

              ...not made with big lumps of iron, and thus lighter than a dynamo when you're talking about powering an LED bike light. The dynamo has a certain minimum size if you want it to be durable. But a bike light can easily be powered by a couple of AAA batteries these days, or some even smaller solution. For example I have a 5 LED hand-crank flashlight that has a battery pack that looks like three cells half the size of a AAA each. It runs for many hours on a full charge. To be fair it has a very small and light

            • by Yvan256 (722131)

              going, and going, and going...

          • by Iskender (1040286)

            It's dumb to do at all. It's solar that should be used to charge bike lights. Dynamos are heavy, thin-film PV is light. Charge during the day, and you can ride at night. Even if you need to plug in to charge it's still going to save you weight.

            While this might work in many places (I still like hub generators better because they're awesome), it would probably suck in northern (/southern) places. In the winter it gets dark enough that solar energy is very close non-existent. I suspect only lead-acid batteries would survive living in the cold for that matter (and aside from being heavy, those too are happy to die when the temperature goes down to -30 C).

            A generator is a pretty smooth concept in that it only requires the rider to be there for power.

        • Yeah, if only someone would design, say, a pair of boot that would..oh wait.
          • I really doubt they're going to provide enough power even for an LED headlight, especially when the soles are not in contact with a cold surface.

    • Re:Slow news day? (Score:5, Interesting)

      by wwwillem (253720) on Monday June 07, 2010 @09:46AM (#32483004) Homepage

      I ditched my "generator powered" light on my bicycle

      Those are not a temporary fad that doesn't really work. In Holland (where there are more bicycles than people) those dynamo's [wikipedia.org] are the standard way (at least were before LED lights) of powering bicycle lights.

      It was the next progression after the carbid lantern, so I guess that started around WWII, maybe even earlier. At least I'm from 1957 and I can't remember anything else.

      • Re:Slow news day? (Score:4, Insightful)

        by SharpFang (651121) on Monday June 07, 2010 @10:22AM (#32483440) Homepage Journal

        ...yes, and essentially only inexpensive white LED put an end to them.

        The battery-powered lamps were a gimmick, too expensive in use (expensive batteries, note rechargeables were scarce, expensive and poor capacity back then too!) and too short-living (bulb energy draw) for any longer routes. The dynamo was the standard, sure it put extra friction but finely tuned the friction was well within acceptable standards and the light strength was unparallelled.

        A dynamo gives about 5W at 5V on standard use. That is 1 Ampere, which means state-of-the-art(then) 1000mAh rechargeables, or a set of standard 3 bulky A-size 1.5V batteries could run the lamp at the same strength for about a hour. Which was pathetic.

        Even today dynamo still has its place - as a backup. If batteries die in your LED lamp, you can switch to dynamo. If you ride downhill, you can ride faster because the faster you ride the stronger the light is (and it's much stronger than your average bicycle LED lamp), and it gives an extra braking power. And normally you switch it off.

        • by LWATCDR (28044)

          Actually I just carry a spare battery powered light for my road bike in the winter. I just ride for fun so I get to pick when I ride. My off road bike has a monster gel cell powered setup and I leave that battery when it is daytime. It is a beast.
          In Holland I can see why a dynamo could still be of use.

      • Re: (Score:2, Interesting)

        by overlordofmu (1422163)
        Ah, yes. The carbide lantern. Which carbide? Answer: calcium carbide

        And how does it work? Well, you put it into water which is inside of a copper lamp and one of the the resultant compounds is a gas named acetylene which you light on fire as it squirts from an opening in your lamp. The burning acetylene is the light for you to coal mine by.

        I have my grandfather's carbide lantern. Can you imagine being a coal miner? Can you imagine being a coal miner with an open flame on your head your whole work
      • by elrous0 (869638) *
        Well, not sure how well the modern versions work, as I haven't used one since I was a kid (and it was certainly awful back then). If they've worked out the kinks and achieved decent efficiency, good on them.
    • by delinear (991444)
      I thought I remembered a quote about achieving even 50% efficiency being a pipe dream at this point, but actually it's not easy to find solid efficiency figures for wind turbines (I can't remember when or where I heard the quote so hopefully things have moved on since then, plus I guess so much depends on location, season, etc making it hard to give definitive figures, but it would be nice to at least know, when running in optimal conditions, what the conversion rate was like). My favourite quote from Answe [answers.com]
    • Re: (Score:3, Informative)

      by thermopile (571680)
      If you didn't like the dynamo for your bike, you're definitely not going to like the in-boot charger. Thermopiles have notoriously hideous efficiencies, like 2-5%.

      Note also that it relies on a heat difference between your foot and whatever is outside. So on a hot day, you're going to have a hard time generating much of a delta-T, and your efficiency will drop even further.

      Despite the fact that my nickname is one of these devices, I'm not very hopeful. A piezo-electric based device that uses the me

      • Or a scaled-up version of the generators used in Seiko's kinetic watches.

      • So, how little power are we talking? With the flushless toilets I see more of, I wondered what sort of power could be generated from the 98.6F urine against the porcelain and concrete wall behind it (or incoming water lines for sink/flushables). Figured there was some cistern below with a boyant liquid topper that could sit for a while and give heat. Gives a new meaning to 'trickle charge'.
      • by BillX (307153)

        Sadly, piezo generators are not great either for any serious tasks like charging phones or plugging laptops into your shoe. (Disclaimer: I'm an EE at one company that makes these things.) They would power a shoe-embedded pedometer / sensor mote, or maintain the realtime clock of some device, but you only get 10s of mW average from a typical device under ideal lab conditions. (Plus, in a shoe-generator scenario, that 10mW is coming right out of your body's forward-motion power budget - probably not noticeabl

    • Re: (Score:3, Interesting)

      by Hurricane78 (562437)

      They stop buying it for the same reason that I ditched my "generator powered" light on my bicycle when I was a kid (you remember, the one that attached to the tire and used its kinetic energy to power the bike's headlight)--because it doesn't work worth a damn.

      You mean a dynamo? What do you mean “it doesn’t work”? It works great. In rain, snow, everything. And with it, I don’t look like an idiot who’t replacing batteries or having to recharge the thing all the time, while still only having three weak flickering LEDs.
      What? But it goes off when you stop, you say? Not anymore. That’s solved with capacitors since at least a decade ago.
      And no, they don’t slow you down like in the olden days anymore.
      Also, they don’t slip,

    • by Silly Man (15712)

      I'm freezing already! You insensitive clod!

    • Re: (Score:3, Interesting)

      by Locutus (9039)
      I still have one of those on one of our old bikes and it gets used a few times a year without problems and it works well. So before you publish that something doesn't work, you might want to check if you have one of the many models which just aren't made well.

      A current example of this are the crank up flashlights. We recently lost a nice one we've had for a few years and started looking for a new one. Let me tell you, that are _not_ all the same. I now see so many which just have a little DC motor inside wh
    • by PingSpike (947548)

      These prototype boots sound like a great idea to me. However, rubber boots don't keep my feet very warm. That's why I plan to wear battery powered heated socks at the same time to alleviate the problem!

      Hey...I've got a great idea, why don't we rig the battery powered heated socks to the power generating boots so I don't have to replace the batteries in the socks all the time.

      Patent time!

    • by cpscotti (1032676)
      Yep.. everything that can charge a cell phone (namely an iPhone) turns into news nowadays (even if it takes 100hrs to charge it to last only 2hr).

      I'm even surprised how it is taking so long for people to make up an all-metal, torture-equip-looking gadget that you use with "your partner" while making "love" to seamlessly charge your iPad.
  • That sounds like a good way to solve energy problems and overweightness.
    • by delinear (991444)
      Well apparently the latest scheme being trialled in the UK is to pay the overweight to lose weight [telegraph.co.uk], maybe get them to exercise hooked up to a generator, pay them a fee for doing so and sell the electricity back into the national grid to fund the project...
  • by Anonymous Coward

    Assuming the laws of thermodynamics are still intact, they also keep your feet cool. So, not so good for cold climates - which is unfortunate, because that's when the temperature gradient is highest and they'd work the best.

  • by dtmos (447842) * on Monday June 07, 2010 @09:39AM (#32482922)

    The term for this type of electricity generation is the Seebeck effect [wikipedia.org]. Typically a very small voltage is generated per pn junction, so many hundreds of junctions are placed in series to generate a significant voltage.

    • Would it be possible to put them on a condom?

      Guy in bar to babe: "Hey. My phone died. Would you like to go and charge it?"

    • by skids (119237)

      The quantum well stuff they are playing with should allow the piles to be strung on-chip aa well as improve the K value significantly.

      If we can ever get these things or thermophotovoltaics up to 35% or so conversion efficiency we might see some natgas "solid state" power plants for plugin hybrids, but I think we are still short of that even with current lab bench prototypes.

  • Remember LA Gear shoes? The ones with the flashing piezoelectric lights that blinked when you took a step? If we can harness the power of millions of sugar-crazed kids, we can solve the world's energy problem! There is probably already enough HFCS to power this revolution.
  • If you fill your rubber boots with a manure and urine blend, seal the tops, walk around a bit, and have tube connected to

    this [gizmodo.com]

    then you could warm your feet and charge your phone. Or fill a fanny pack with the mix, so it is contained.

  • . . . the story becomes slightly more amusing.

  • New technology aside, I've always found rubber boots to be excellent for generating what I like to call "zapping power".
  • Unfortunately (Score:4, Insightful)

    by NtwoO (517588) on Monday June 07, 2010 @09:50AM (#32483066) Homepage
    It'll cool your feet in the winter when it works at its best and in the summer the difference between warm sidewalks and the inside of the boot will not generate any electricity. This means that when you don't mind to wear it, it does not work. When it works, it causes so much discomfort that you choose not to... Mmm.
    • by Thelasko (1196535)

      in the summer the difference between warm sidewalks and the inside of the boot will not generate any electricity.

      You haven't met my wife. Her feet are ice cold in any weather.

      I've been telling her I'm going to use her feet as a sink [wikipedia.org] for a heat engine. It looks like today is the day!

  • by drinkypoo (153816) <martin.espinoza@gmail.com> on Monday June 07, 2010 @09:51AM (#32483082) Homepage Journal

    Boots that don't keep my feet warm because they depend on heat flowing across a thermocouple as quickly as possible to produce electricity? That sounds great! I'll take two.

    • Re: (Score:3, Informative)

      by solevita (967690)

      Boots that don't keep my feet warm because they depend on heat flowing across a thermocouple as quickly as possible to produce electricity? That sounds great! I'll take two.

      There are many inventions like this that suggest you can pull energy from nowhere. Of course you can't, it has to come from somewhere. In this case, it's your body heat powering the phone. You'll have cold feet and you'll have to put more energy into yourself everyday to power the phone in the form of calories. No such thing as free energy, just different ways to transfer it about.

      • Re: (Score:3, Funny)

        by fotbr (855184)

        Ooh, weight loss boots! Get some washed-up overweight celebrity to market them, and this idea can't fail!

  • So pathetic (Score:3, Informative)

    by Ancient_Hacker (751168) on Monday June 07, 2010 @09:52AM (#32483096)

    So pathetic. This is not a way to generate electricity, but to destroy it.

    You see those "p-n" junctions did not appear out of thin air-- they're the result of using scads of electricity to heat silicon to the melting point, extract it into perfect crystals, then slice it, anneal it again in an electric furnace, then more hours at 1200C to diffuse in minute amounts of p and n dopants, then more electricity to slice, dice, solder, and cement these into usable devices.

    And in the end you have some very expensive, in both dollars and energy used, heat to microamps of electricity converters. And you can easily compute exactly how much electricity you get back given say a 10 degree temperature difference between the warm and slightly less warm sides. It's miniscule. Microwatts per square centimeter. Even if you wore these for 10,000 hours, you're nowhere near making back the amount of electricity, not to mention the $$$, it cost to make these things.

    • So pathetic. This is not a way to generate electricity, but to destroy it.

      You see those "p-n" junctions did not appear out of thin air-- they're the result of using scads of electricity to heat silicon to the melting point, extract it into perfect crystals, then slice it, anneal it again in an electric furnace, then more hours at 1200C to diffuse in minute amounts of p and n dopants, then more electricity to slice, dice, solder, and cement these into usable devices.

      Yes, yes, we are all aware of the laws of

    • Wrong. The P-N junctions in thermogenerators contain no silicon whatsoever. In early thermogenerators the junctions were created by using two different metals, and later thermogenerators use bismuth telluride in place of one of the metals. See the Wikipedia page on "Thermogenerator" for more detail.

      If you want a valid argument on environmental costs, compare the environmental cost of using a thermogenerator to the environmental cost of the batteries it replaces. Balance that against lifetime: thermogenerato

  • My momma said these are my magic shoes...

  • So, under ideal conditions (exercising in a cold wet environment) you get 1 hour of "charging" - say, how much is that in use time? - for 12 hours of activity?

    It's a sad state of affairs when you can't even market your snake oil convincingly. Heck, if you're going to get some free advertising from a joke product that you have no intention of making, you might as well push the boat out and claim that it heals the ozone layer and turns CO2 into unicorn burps.

  • Add these with your nylon socks and underwear and wearable solarpower packs and you'll never need to juice up again. Screw wierding modules, just point your hip mounted crotch sock and fry the enemy with your static charge. Maaaau'dii*ZAAAAP*$%%"£..
  • Of course it only works in bloody cold, damp England!
  • by Anonymous Coward

    In my own experiments with themoelectric generation, I was unable to get more than a few tens of milliwatts from such a setup.

    I connected up a cheap peltier module (TEC1-12709), 4cm * 4cm (1.5in * 1.5in), to a heatsink+fan with some heatsink paste, and pressed my palm against the other side, the maximum power output was a few milliwatts, and additionally my palm got cold very quickly (I altered the resistive loading to ensure I reached the maximum power point.) When I used a metal tray of boiling water ins

    • by jubei (89485)

      You got a few milliwatts of output using a heatsink and a fan. How much power was the fan using?

  • So maybe we'll all be (re)booting our phones on a regular basis - not just those people running WinMo!!
  • >> Rubber Boots Charge Your Phone

    They would seem to have locked up the footwear market in D.C..

  • oh dear, I had pictures of a pipe from the boots into your trousers when the firm's name of Gotwind was read....I must get out more :-)

  • Thats cool and all, but can they power my stillsuit, will they alert the sandworms of my location, and are they compatible with the foot controls of my ornithopter?

  • >> heat from the foot is applied on the top side and cold from the ground is applied on the opposite side

    Cold from the ground? I live in Phoenix you insensitive clod.

  • Next on tap... energy produced from your schwetty balls [youtube.com].
  • "Charging up!"

    Now we know what power source the Tesla Troopers used.

  • Nokia [nokianfootwear.fi] should have made these.

  • ...since they're the heaviest users of cellphones. And (at least in the US) they are, for all intents and purposes, the only ones who wear rubber boots nowadays.

    ---PCJ
  • When's the energy break even point? Are they as efficient as solar panels? If I walk a mile in someone else's shoes then ....................

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