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What is the Future of Wireless Power? 178

Posted by CmdrTaco
from the this-is-gonna-burn-my-crotch-isn't-it dept.
mfbatzap writes "According to Firdooze, we have seen various devices that can free ourselves from wires at CES 2008. The manufactures, Wildcharge, Powercast and Fulton Innovation, came out with two different methods of transmitting power from source to the devices. Wildcharge and Fulton banked on magnetic coupling while Powercast decided to go with RF (Radio Frequency). So which technology will eventually prevail to be the future of wireless power? Or will the technological setbacks from transferring power wirelessly make it unrealistic to accomplish a wire-free world?"
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What is the Future of Wireless Power?

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  • by debatem1 (1087307) on Thursday January 10, 2008 @12:43PM (#21985468)
    I have to wonder whether this announcement and the glowing pigs announcement are just coincidental...
  • by ShawnCplus (1083617) <shawncplus@gmail.com> on Thursday January 10, 2008 @12:46PM (#21985512) Homepage
    Well my laptop has wireless internet and a wireless mouse, why not wireless power? I'd gladly accept a benign tumor or two if I could get more than 3 hours out of my battery.
  • is there a way (Score:3, Interesting)

    by JeanBaptiste (537955) on Thursday January 10, 2008 @12:46PM (#21985522)
    to transfer power wirelessly without cooking whatever happens to pass inbetween the sender and receiver?
    • by gardyloo (512791)
      Probably. Just make damned sure that the transmitter produces frequencies which couple strongly only to the receiver (very small bandwidth). Things which don't resonate at those frequencies will be essentially transparent to the signals. I suggest 2.45 GHz!

    • Re: (Score:3, Interesting)

      by jdray (645332)
      From what I understand, it depends on the frequency. For instance, a microwave oven operates at whatever frequency best excites a water molecule, which leads to cooking by making the water in everything hot.

      There was a long-running experiment in California back in the seventies or so that transmitted kilowatts of power over a few kilometers. They were doing the test as a lead-in experiment to figure out whether or not satellite-based power generation and transmission was feasible.

      I'm not confident that we
      • Re:is there a way (Score:5, Interesting)

        by Otto (17870) on Thursday January 10, 2008 @01:51PM (#21986722) Homepage Journal

        From what I understand, it depends on the frequency. For instance, a microwave oven operates at whatever frequency best excites a water molecule, which leads to cooking by making the water in everything hot.
        That is incorrect, but you're forgiven because it is a common misconception that's even in a few encyclopedia's and such.

        Microwaves work by producing an alternative electric field (using non-ionizing microwave radiation) that acts on molecules which have electric dipoles. Water is one of those, but so are many others, including fats and such. The process is called Dielectric Heating.

        Basically, the molecule being heated is a dipole. It has a positive charge at one end, and a negative charge at the other. In an alternating electric field, it rotates as it tries to align itself with the field. This causes motion, which translates to heat. The heat spreads as the molecules hit other molecules and transfer the energy to them. Now, this process works really good on water because water is a very strong dipole, but it does not operate solely on water, and it doesn't have anything to do with water in particular.

        See, the frequency doesn't actually have much to do with it. Normal kitchen microwaves operate at 2.4 Ghz or close to that. Industrial microwave devices tend to work at 915 Mhz. Also, if the frequency had something to do with it, then 2.4 Ghz would be the wrong one. The resonant frequency for water is somewhere in the 20 gigahertz range. The only reason 2.4 Ghz is used for microwaves is that it's a free bands of frequency (ISM frequency bands) that can be used worldwide.

        So, there you go. Now you know.
        • Re: (Score:3, Insightful)

          by Sarutobi (1135167)
          As long as we're getting in the scientifically correct... Frequency does matter. If the frequency is too high, the dipole won't be able to follow and you'll see other phenomena pop up. That is, for instance, why water is blue. The frequency of the electrons around the dipole allow them to absorb a bit of red light. If you go even higher, it will stop interacting altogether. If you go too low, the energy transfer will be hindered.
        • by tprime (673835)
          Did you research all of this or is this something you already knew? If it is the latter, I really need to go back to school and figure out what the hell I missed.
        • by jdray (645332)
          Thanks. Much more informative. I always had a sense that the explanation about the frequency and water was suspect, but have read it several times, so went with it. So much for the Fox News approach to research...
    • sure power can be sent wirelessly a number of different ways, with outcomes other than cooking
      • Sound waves carry energy, result: deafness
      • Visible Light waves carry energy, result: blindness
      • Positron beams waves carry energy, result: random explosions/ unexplained disappearance of electrons
      • Re: (Score:3, Funny)

        by spun (1352)
        Couldn't we attach batteries to hamsters and let them carry the electricity where it's needed? Just set up hamster base stations with battery chargers and hamster food, and place small pellets of hamster food in the battery compartments of the device needing power. It's so simple and easy, I'm surprised no one has thought of this before.
        • by Zaurus (674150)
          Hmm...if you did this with a pair of hamsters (1 male, 1 female), perhaps you would have a perpetual power machine...
    • by Stooshie (993666)

      ... without cooking whatever happens to pass inbetween ...

      Don't worry. If you wear a foil hat you will be protected!

    • by grumpyman (849537)
      That's right, soon you can place your tv dinner between your monitor and the no-battery wireless keyboard, surfing the web and see the meal cook right in front of you :)
    • You could use a highly shielded antenna long enough to reach between the sender and the receiver.
  • Out of curiousity... (Score:5, Interesting)

    by Krinsath (1048838) on Thursday January 10, 2008 @12:49PM (#21985588)
    Does anyone know how much power is "wasted" (if any) due to using wireless methods versus wired connections?

    Off my limited knowledge, it would seem to be akin to one of the problems with biofuels...they currently take more energy to produce than they store. So will using this technology to charge a device result in taking two or three times more energy to transmit the same amount of power to the device, or is there no discernible difference between wireless and wired?

    Just wondering is all...
    • by mblase (200735) on Thursday January 10, 2008 @12:56PM (#21985694)
      Off my limited knowledge, it would seem to be akin to one of the problems with biofuels...they currently take more energy to produce than they store.

      If I remember my Second Law of Thermodynamics correctly, this is true in any case.

      (Yes, I know what you meant.)
    • by tjstork (137384) <todd.bandrowsky@NOSpAM.gmail.com> on Thursday January 10, 2008 @01:00PM (#21985760) Homepage Journal
      All fuels take more energy to produce... in a sense, our present fossil fuel predicament is because we are using stored energy from the sun over millions of years. That we can even think about creating biofuels or really, any sort of fuel, efficiently, says a lot for how far the technology has come. But we'll never be able to just "create" a fuel, and the world's going to have to accept that.
      • by timeOday (582209)

        we'll never be able to just "create" a fuel

        Nuclear does "create" energy (unless, I suppose, you think of mass as energy). Granted, that energy is still not coming from nowhere, but when you get c^2 (the speed of light, squared) working in your favor, you're doing pretty darn well for yourself. I realize nuclear is still very hampered by practical issues, and I'm not particularly taking a stand for nuclear power over more dissipated forms (solar, biofuels)... but when you step back and think about releas

        • Nuclear does "create" energy (unless, I suppose, you think of mass as energy).
          This is true of fusion, but fission is solar energy in the same sense that fossil fuels are. The energy was put in to the heavier-than-iron elements by fusion reactions in stars a few billion years ago.
        • by chgros (690878)
          Nuclear does "create" energy (unless, I suppose, you think of mass as energy).
          You know, E=mc^2 is valid for chemical energy, too. So by that same token, gasoline "creates" energy. Of course it's a much smaller fraction of the mass of the fuel.
      • by snowraver1 (1052510) on Thursday January 10, 2008 @01:49PM (#21986678)
        200 years ago people would never fly.
        150 years ago it was impossible to talk to someone in another town
        125 years ago it was impossible to own a car
        50 years ago it was impossible to own a computer (except for banks, schools, and gov't)

        You never know what the future might hold. Cold Fusion might prove to be possible. Zero point energy might be proved and harnessed. Maybe someone will figure out a way to take the heat out of the atmosphere and make electricity from that.

        My point is, and I do have one, that nothing is impossible. There is more that we don't know then we know... Chew on that.
      • and the world's going to have to accept that

        Screw that! Lets just build ten mile wide/long automated tankards that go into space and collect chemical energy from the sun/solar winds/asteriods/???, and then bring it back to earth. When we get this working really well, the only waste will be heat - which we can actively concentrate and pump into space (with no net loss of mass for the process since we took on a lot from the tankards).

        We can probably do a few dozen terajoules that way, and keep it up until t
    • by MBCook (132727) <foobarsoft@foobarsoft.com> on Thursday January 10, 2008 @01:01PM (#21985770) Homepage
      I'd think you'd have problems with RF, it'd be easy to waste power that way. The magnetic people mentioned in the article say they've hit 98.5%, which is great.
    • by Abeydoun (1096003) on Thursday January 10, 2008 @01:02PM (#21985788)
      Here's the Wiki [wikipedia.org] I found on general wireless energy transmission.

      From the wiki article

      "WiPower [1] technology is a very recent example of inductive charging technology. The charging pad allow users to charge multiple electronic devices that are placed on its surface. It is insensitive to the position or orientation of the devices under charge. Unlike most inductive charging systems, the WiPower system uses air-core technology which allows the system to be integrated into very small electronic devices. The efficiency of the system actually exceeds many corded chargers which have a median efficiency of 57%."

    • by caseih (160668)
      You had better believe there's a difference between transmitting energy wirelessly vs on a wire. The reason is that a wire simply transmits the energy end to end; the energy is essentially limited to the physical space of the wire. So some minor losses happen due to resistance, etc. But to transmit the power wirelessly means you have to radiate it in all directions. The amount of energy required to do wireless power transfer over a certain distance is basically governed (upper bound) by the inverse-squa
      • by yulek (202118)
        that's not entirely true as the target device could be targetted with a "power beam". i do agree however that it is still likely to be terribly wasteful. better local storage of energy is definitely a better idea.

        i'm amazed at the battery life of the ipod classic, for example, as compared to that of the 4th generation ipod (in just 3 years went from 16 real hours to real life 30+ hours and it's smaller to boot)
    • Re: (Score:2, Informative)

      by Monkier (607445)
      Seems every one is more interested in your comment on biofuels. Me too :)

      "A team of US researchers also found that switchgrass-derived ethanol produced 540% more energy than was required to manufacture the fuel."
      http://news.bbc.co.uk/2/hi/science/nature/7175397.stm [bbc.co.uk]
    • I suspect the standby losses will be more than the 500-750mW allowed by efficiency standards [energy.gov]. These standards were set to challenge the manufacturers of conventional wire-connected power supplies. To meet them, the engineers must reduce losses wherever possible. Copper conductors can deliver power to the load device with efficiency better than 95% (less than 0.25V drop for a 5V adapter, etc.). Wireless couplers would be hard pressed to come anywhere close to that. It seems like a step backwards in the battl
  • by Ancient_Hacker (751168) on Thursday January 10, 2008 @12:52PM (#21985644)
    Wireless power is not going to happen.

    Shooting photons across a room to deliver significant power just ain't gonna be practical. If you use an omnidirectional antenna, the losses will be huge. If you instead have like a parabolic dish that tracks the receiver, the losses will be lower, but what happens to kitty or your eyeballs if they get in the way? Cooking your eyeballs to a nice firm egg-white consistency is not going to fly.

    Magnetic fields are dipole fields, that means the little wavy lines leaving the North pole want to curl back as quicly as possible to the South pole. Which means they have very little extent in space. The strength drops off as the CUBE of the distance, so any significant distance is a no-go.

    • Maybe this is a good thing. I don't want my neighbour leeching my wireless internet AND my wireless power! Besides, I think a practical application of this would be as a laptop dock with no electrical connection. Place your laptop on the charging pad, and your laptop will start charging without having to plug in!
      • by Fred_A (10934)

        Besides, I think a practical application of this would be as a laptop dock with no electrical connection. Place your laptop on the charging pad, and your laptop will start charging without having to plug in!

        At least if there's one thing we can be sure of judging from the last century or so of appliances is that each and every gizmo will have its own charging pad which will be absolutely incompatible with any other gadget you own. Those charging pads will also have "wall wart" transformers that only work with the pad they came with.

        Ah, progress, it's so exciting !

    • Re: (Score:3, Interesting)

      by farkus888 (1103903)
      it may not make a replacement for everything, but unless I am mistaken I have already seen electric toothbrushes that use something similar over very short distances. the advantage is they don't have to insulate any leads or connectors from the water it will inevitably be exposed to. a sealed case is always better than a sealed case with a rubber plug over the one opening where you give it power. range is not an issue because you are still dropping it into a charging dock [sitting it right on the transmitte
    • by Jeff DeMaagd (2015) on Thursday January 10, 2008 @01:06PM (#21985864) Homepage Journal
      For the reasons you state, I'd put the people demanding wireless power among the people demanding pony-sized unicorns, at least for the forseeable future. I think pony-sized unicorns is more likely given how genetic engineering is going, but then the people that say they want them are going to say they won't pay more than $1500 for those.
      • I can see a HUGE market for those.

        Or ponikeys, for the guys.

        Isn't it enough to know that I ruined a pony making a present for you?
    • by Lumpy (12016) on Thursday January 10, 2008 @01:21PM (#21986106) Homepage
      you dont need to shoot it across the room, just charge the device when set on a table. Make ALL your tables charging stations and now you attain the "wireless power" illusion.

      I did this way back in the 90's for one of my EE projects. I created a charge mat and charge adapters to make devices charge from the mat. worked great, erased tapes , credit cards, and discs though... All you did was set the device down and it started charging. worked great and could supply 100ma of charge current to 3 devices.
    • An average laptop consumes about 50 watts. Using the back of a 15" screen as receiver (0.07 m^2), the intensity is about 50 / 0.07 = 714 watt/m^2. As a reference, "a site in Eastern Oregon receives 600 watts per square meter of solar radiation in July". http://zebu.uoregon.edu/disted/ph162/l4.html > See, it's just like walking by an unshaded window in a summer's day.
    • by Toonol (1057698)
      Yeah, those methods seem inevitably lossy to me. But what about lasers? How efficient are they? It seems like a microwave laser would transport energy efficiently... but I don't know how efficient the creation of the maser is in the first place.
    • by evilviper (135110)

      If you instead have like a parabolic dish that tracks the receiver, the losses will be lower, but what happens to kitty or your eyeballs if they get in the way?

      I've passed under 100W light bulbs, and direct sunlight, millions of times in my life, and yet my eyeballs continue to function just fine.

      The strength drops off as the CUBE of the distance, so any significant distance is a no-go.

      Only true with onmidirectional... A high-gain antenna, or collimated beam like a laser, and you can get very good distance

      • >> If you instead have like a parabolic dish that tracks the receiver, the losses will be lower, but what happens to kitty or your eyeballs if they get in the way?

        >I've passed under 100W light bulbs, and direct sunlight, millions of times in my life, and yet my eyeballs continue to function just fine.

        A "100W" light bulb puts out like 2 watts of actual light, and in every direction. Try taking 50 of those light bulbs, with reflectors, and look into those. No, don't.

        Just a few watts of m

  • by Anonymous Coward
    Good news everyone!

    Radio-Fuel autos may solve gas problem!" [jalopnik.com]

    All you do, you see, is you put this big coil above your car, and several gigawatts RF transmitters embedded in the roadway! Waste heat from the transmitters (and the melted tires, and the roasting humans) can even be used to ensure that ice never accumulates on the road!

  • Wireless power certainly should have a future if a single standard was achieved. It would be nice to be able to sit my child's toys near the charging station and have them charge themselves. No more fuss with changing batteries every month. No risk of losing the AC adapter.

    And it can certainly be made efficient and safe by using a focus beam to the device being charged. We are surrounded by RF signals everywhere we go. What is one more RF signal?
  • How do you prevent arcing with wireless power? Seems to me that wireless power pretty much means arcing through the air of some kind for any high-power applications... sounds dangerous in the proximity of the broadcast and receiving antennae.
  • I'm not in the field. I'm not officially qualified to decide. But this is /.

    Wireless (RF) worries me. You either have to confine it to a little beam (then why not just set the device down somewhere?) or pump a ton of power into it (most wasted). There are a few limited applications where it might make sense (the Wii, since we already know you'll be standing in front of the TV). I'm also worried about health concerns (really high frequencies can solve this, to a good degree) and interference (this is what I

  • by Kuukai (865890) on Thursday January 10, 2008 @01:01PM (#21985782) Journal
    Wireless power was simply never meant to be. Nikola Tesla tried it, and look what happened to him. He's DEAD!
     
    I wouldn't touch wireless power with a ten foot, umm... wire.
  • Can someone explain if this is a matter of transferring electrons between two devices, eg the source and recipient of the energy? Wouldn't we be better off either A: improving batteries, or B playing with an source that creates an event that would cause a pendulum of sorts to charge a device?
  • by BoRegardless (721219) on Thursday January 10, 2008 @01:06PM (#21985850)
    There is s vast difference between a universal wireless charging "surface" or "plate" where your electronics go at night versus recharging at a distance of 10 feet.

    Then there is also a difference between the "idle" power loss versus "zero" while turned OFF & of the transmitters efficiency in getting power to a remoted device. I could imagine only 25% or less of the transmitter's input getting to the remote device.

    Time matters. Batteries are going to get better quicker if A123Systems & others are right, meaning charging with a standard cord may be the cheapest & best method giving a 5-10 minute recharge, as opposed to overnight.

    Ain't going to be easy. Lots of VC money is going to be burned up. The good news is the U.S. government is not picking and funding a single winner, as they tend to do when they back a "bill".
  • Wireless power? (Score:4, Insightful)

    by Gavin Rogers (301715) * <grogers@vk6hgr.echidna.id.au> on Thursday January 10, 2008 @01:06PM (#21985854) Homepage
    Already invented. Next!

    http://en.wikipedia.org/wiki/Tesla_Coil [wikipedia.org]

    • Re:Wireless power? (Score:4, Insightful)

      by thatskinnyguy (1129515) on Thursday January 10, 2008 @01:14PM (#21985996)
      Even better than that, Tesla was able to power stuff at great distances. He was doing stuff like this as early as 1891. Really people ought to start giving Tesla his due and stop claiming his concepts for themselves. More on his wireless power experiments here [wikipedia.org].
      • Re: (Score:2, Informative)

        by Anonymous Coward
        Telsa was an absolute prodigy. It's a damn shame he is not more often mentioned in the history and school books!

        Don't know who he is? Take 10 mins. and see that he is an equal to names like Einstein and Newton:
        http://www.youtube.com/watch?v=gt8Y93k0pB0 [youtube.com]

        Really, just do this, open your eyes!

        He had wireless power working with his 'radiant energy' approach... almost with zero loss.

        There is not a single student being taught the complete thing when it comes to EE. Maxwell's original theories have been simplified b
      • Re: (Score:2, Insightful)

        by aix tom (902140)
        Yep. And then Westinghouse got wind of it, and thought "Wireless energy? How the hell will we be able to bill people for using it?" and axed the project.

        Which will still be a problem today, even when they overcome the technical problems.
      • by LWATCDR (28044)
        Tesla was a brilliant nut. Wireless transmission of power was EXTREMLY inefficient. In other words just like his Tesla turbine it has limited applications and really isn't better than what our scientists can do now. No magic, no strange conspiracies just reality. Not as much fun but it is the truth.
  • by Original Replica (908688) on Thursday January 10, 2008 @01:12PM (#21985964) Journal
    So where does the power go, that doesn't make it into the device? In this day and age of energy efficiency and conservation, this seems a step backwards. Maybe that energy is slowly heating the room or maybe it's slowly increasing my risk for cancer, but either way if the vast majority of the power isn't going into the device it's being wasted. Tis tech might have some specific applications where the wirelessness is of true overall benefit, but everyday hand held devices aren't it. As global energy demands continue to grow using something like this to charge your cellphone will become a hallmark of bourgeois ass-hattery.
  • I like wires! (Score:2, Insightful)

    by jabjoe (1042100)
    I want to see what is connected to what in a nice clear visual way, i.e wires. I want soild connections, i.e. wires. I want secure connections I could see no one else is using, i.e wires.
  • by Thuktun (221615) on Thursday January 10, 2008 @01:16PM (#21986018) Homepage Journal

    will magnetic coupling destroys your HDD
    Oh, noes! They be destroying my disks!
  • by sluke (26350) on Thursday January 10, 2008 @01:25PM (#21986166)
    I'm relatively pessimistic about both of the technologies mentioned due to the inherent limitations that they pose (large leakage of radiated power or short range). I'm looking forward to seeing products based on the wireless power idea that came out of the Joannopoulos group at MIT in 2006.
    The idea was that you can setup an RF wireless power transmitter in such a way that it does not actually transmit any power unless it resonantly couples to a precisely shaped receiver. This way there is little to no leakage and they claimed that the power transfer was quite efficient. I'm sure this was posted to slashdot, but I can't seem to find it. Here's a link to the paper if you are somewhere with access to Science: Science 6 July 2007: Vol. 317. no. 5834, pp. 83 - 86 [sciencemag.org] and here's [mit.edu] a link to the press release by the MIT news office (no subscriptions required).
    • by 12357bd (686909)
      Tesla was the master of Magnetics and Resonance. That paper states just a 60W 40%efficient 2mts power transmission setup, sorry but for now MIT guys just look like amateurs.
    • As I mentioned elsewhere, the BBC named it as one of the 'technologies of the year' - The technology with impact 2007 [bbc.co.uk]
      • by sluke (26350)
        Thanks for the info, I did a quick search to see if it was being commercialized and found nothing. That link showed something that makes me pause though, the receiving coil looks HUGE! I am assuming that to get to a smaller coil they would have to use a higher frequency field which I'm assuming will decrease range. Hmmm. I guess I should just do the math myself and see....
    • Yea, this group is doing what tesla did a hundred years ago, but it's still neat. They currently are on what would be considered "the cutting edge" of this field, no pun intended. The thing that's been a killer in the past has been the power generation and conversion efficiency (30%). The trick is getting power electronics to switch at ~10MHz without losing 60% of your total power input. The thing that makes all of this so interesting, is that advances in SiC (silicon carbide) technology are just opening up
  • There is one of two ways you can get power wireless with RF radiation:

    1. Send it out in all directions. Incredibly wasteful and, because of the inverse square law, has to be so powerful it will interfere with other stuff.

    2. Send it out in a narrow beam. I really wouldn't want to be standing in between a laptop and an outlet if this were the method...

    Either way, I prefer living in a home that isn't a microwave oven.

  • Wildcharge and Fulton banked on magnetic coupling while Powercast decided to go with RF (Radio Frequency). So which technology will eventually prevail to be the future of wireless power?
    Blu-ray!
  • I bet Tesla does not get any credit for doing it decades ago.
  • The focus shouldn't be on "wireless" power per say, but in general just absorbtion of energy which doesn't require a tether, AKA solar & etc. to an extent. RF may be possible but I'd be damn weary if there weren't some massive long term safety tests first.
  • Pacemakers (Score:3, Interesting)

    by Stooshie (993666) on Thursday January 10, 2008 @01:37PM (#21986400) Journal

    One thing not mentioned (particuarly with the magnetic induction system) is how pacemakers are affected.

    At least with MRI scanners there are notices everywhere about people with pacemakers. If these things become widespread people with pacemakers are going to have to avoid a lot of places.

  • The problem with wireless power transmission is that it's hard to control where your electromagnetic fields go. They tend diverge as an inverse square law, scatter and bounce all over and be absorbed by things that are not your antenna. This is wasteful, because your wireless power ends up heating up trees, grass, and rivers rather than powering your city, and dangerous, because if a human absorbs even a tiny fraction of a gigawatt power transmission from a generation plant, he'll be cooked.

    In recent year
  • Isn't this technology very wasteful, a huge proportion of the power must just escape into the air. I would not be too surprised if it ends up getting banned.
  • What's wrong with wired power, exactly?
  • Way better ideas (Score:2, Informative)

    by Casandro (751346)
    Well first of all, the biggest untapped energy source on the planet still is an increase in efficiency. Why does my laptop need take 60 Watts of power in order to heat up my lap?
    Why do we have displays in mobile devices that waste 5/6 of the light they generate?
    Why do we still have processors that take _Watts_ of power althought alternatives with milliwatts are available?

    I believe that a 1 Watt laptop-like device is definitely possible. It won't have a colour screen nor Windows Vista, but it would do everyt
    • The Asus Eee PC is at ~11W TDP in it's current version, and the next one is rumored to drop to ~7W TDP, which should be low enough to lose the fan, and thus have no moving parts at all. And this is a proper little laptop with a color display (LED backlit, of course) and enough oomph to run Linux, BSD, WinXP and even Vista if you're feeling masochistic :-)
  • As I pointed out previously [slashdot.org], there were at least three companies demonstrating wireless charging systems. This new article lists two more, Powercast and Fulton Innovation.

    Short-range systems using long-wave near-field RF are probably the way to go. Power ratings can be quite high. The GM EV-1 charger used an inductive paddle operating at 400KHz, and could transfer kilowatts across about half an inch at 90%+ efficiency. The MIT system [technologyreview.com] operates in the 4-10 MHz band.

  • One of the big advantages to this idea is not having to have a bazillian different wall warts for every separate device. Usually unlabeled so that 6 months later, you have no idea what goes with what if you haven't rigorously kept things together and/or labeled them yourself, not to mention having to lug around a few kilos of the things when you travel.

    Except now they're going to beta/vhs us so some things need this charger and some need the other charger. If you get it wrong 6 months later, you've got a
  • I don't even understand why there's a question. Magnetic coupling is a joke, sure it's efficient, but really, is it ALL that different from a form-fitting cradle with physical contacts? You still have to put the device within inches of the charger... are people REALLY that lazy that they won't go the extra inch? I have an electric toothbrush that just sits in a cradle every night, I don't even SEE any physical contacts, and it's a good holder, so why bother? Or how about Apple's magnetic plugs, that's anoth
  • The thing I'd really like to see wireless power for? Transportation, by building this system right into the roads and billing your car for the amount of electricity used. Cars would be lighter, reducing the amount of electricity that would be required to move the vehicle. This would also eliminate the need for batteries meaning unlimited range. I'd be interested to see what would happen to automotive design if the power plant of a car was no longer necessary.

    The only problem with this is the engine/batt
  • Why wasn't this story tagged with "whatcouldpossiblygowrong"?
    Doesn't this seem dangerous.
    We still don't know whats wrong with the bees do we?

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