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Power Technology

Wireless Power Demonstrated 124

Posted by kdawson
from the spooky-action-at-a-distance dept.
Necroloth and other readers sent in the story of Witricity's latest demo at the TED Global conference in Oxford, UK. The company is developing a system that can deliver power to devices without the need for wires. The idea is not new — electrical pioneers Thomas Edison and Nicola Tesla assumed that power would be delivered wirelessly. The BBC quotes the inventor behind Witricity's tech as saying that Tesla and Edison "...couldn't imagine dragging this vast infrastructure of metallic wires across every continent." eWeek Europe notes some hurdles the technology must overcome: "The 2007 experiment it is based on had an efficiency of only around 45 percent, but [Witricity's CEO] promised power delivered wirelessly would start out 15 percent more expensive than wires, and improve on that." Intel has also demonstrated wireless charging.
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Wireless Power Demonstrated

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  • A wireless Taser?

    • by EdZ (755139)
      Only if the person you're aiming at happens to have hooked the correct resonant antenna into their muscles.
      • Re: (Score:3, Interesting)

        by powerlord (28156)

        Okay ... so what about a taser that works by firing the "head" of the taser but without the trailing wires.

        Heck, if that sort of approach worked (a huge "if" personally), the next obvious steps would be to miniaturize the "heads", perhaps make them burn out after a single use (cheap materials, built in resistor that burns out as the current crosses it) ... ... then pack a few of them into a magazine and we've created a rather nice "Assault Weapon" when you're trying to keep casualties to a minimum and are o

        • Re: (Score:1, Interesting)

          by Anonymous Coward

          Okay ... so what about a taser that works by firing the "head" of the taser but without the trailing wires.

          check out the Tetanizing Beam Weapon [archive.org]

        • by EdZ (755139)
          So, essentially the piezoelectric shotgun rounds that are already in development then.
        • by Quothz (683368)

          Okay ... so what about a taser that works by firing the "head" of the taser but without the trailing wires.

          Not what you meant, but you can fire the whole thing [wired.com]. From a shotgun.

    • Try UV lasers to ionise a path through the air and send your taser pulse down that.

  • by elwinc (663074) on Friday July 24, 2009 @05:16PM (#28812961)
    Resonant transfer is great stuff, but what we need even more is a standard interface so that all our rechargable devices can recharge at the same source.
    • Thinkgeek has sold wireless extension cords for a long time [thinkgeek.com]. I wonder if Witricity has solved the issue about domestic cats getting in between the source and destination...

    • This is only a good idea if the standard included a communication bus and spec for voltage, polarity, and amperage negotiation. Without these things, we would have a lot of burnt out equipment. Unfortunately, this would also increase the complexity and cost of the small devices and chargers, but hopefully the volume of the components used would lessen the expense.

      • by dgatwood (11270) on Friday July 24, 2009 @06:35PM (#28813995) Journal

        I think that's massive overkill. Just provide a 12V rail, a 5V rail, and a ground using a polarized plug. Heck, you can probably dispense with the 12V rail. A 5V rail by itself should cover the vast majority of portable electronics these days. Amperage negotiation? Build the supply so that if it is under too much load, it sheds power connections, then periodically switches which jacks are shed. That's much cheaper to design, and it doesn't unnecessarily add to the complexity of the devices that use it.

        • That would be great, if 1.5v-3v devices could automagically operate safely with 5v. Essentially, your concept requires the device to convert DC voltage, which isn't cheap, and generally very wasteful. However, on the charger end, they could have an switchable transformer and produce the desired voltage.

          • Re: (Score:3, Insightful)

            by vivian (156520)

            DC to DC regulators are very cheap, for low power needs - which is what you are talking about for most small devices that use wall warts.

            Here's a bunch of devices, with datasheets & prices.
            ahref=http://www.semiconductorstore.com/pages/asp/category.asp?id=56rel=url2html-27418 [slashdot.org]http://www.semiconductorstore.com/pages/asp/category.asp?id=56>
            They start at about $1 and go all the way up to 3.86 for a device that can do dual power rails of exactly that spec - 5v to 3.3v.

            Of course, if you don't care quite as

          • any electronics running as low as 1.5V is going to need to be supplied from a local regulator (either linear or switcher depending on whether the manufacturer cares more about cost or efficiancy) anyway because that is the only way to keep the voltage stable enough.

            Notice that this is how PCs are done nowadays, 12V supply from the PSU to local switchers that provide the high current low voltage power needed by the CPU(s) and GPU(s)

      • by node 3 (115640)

        This is only a good idea if the standard included a communication bus and spec for voltage, polarity, and amperage negotiation.

        That's electricity. All that matters here is frequency and amplitude. It'll be up to the receiving device itself to manage voltage and polarity. Amperage is a matter of the transmitter having a sufficient amplitude at its particular frequency, nothing more (power = amps x volts).

    • by HalAtWork (926717)
      But then, many devices also want their own USB cable interface...
    • > Resonant transfer is great stuff

      Yeah, especially if you're living in an apartment, you get to borrow your neighbour's power (and vice versa).

      Do you get arrested if you keep forgetting to turn on your "power sender", but leave your "power receiver" on?
    • First came free internet now comes free power.

  • Thomas Edison ??? (Score:4, Insightful)

    by nurb432 (527695) on Friday July 24, 2009 @05:17PM (#28812967) Homepage Journal

    Electrical pioneer my ass, he just got lucky once and was able to afford to hire good talent ( like Nikola ). But i totally agree that Tesla proved it was possible ( and WAS a pioneer ). But he also proved that it takes more then tech to make such a project work, it also needs funding. As brilliant as he was, a businessman he wasn't, and we were set decades behind on projects such as this.

    • by slimak (593319)

      Edison has gotten far more coverage in the history books (at least US ones), He was probably best at business, although he is known as an inventor. On the other hand, Tesla was, without a doubt, the greatest engineer that has ever lived. He is proof that a formal advanced education is not necessary for scientific greatness. It is too bad that most people don't realize the impact he truly had.

      • by nurb432 (527695)

        ya, i should give Edison credit for his business savvy.

        Just was irritated to see his name in the same sentence as Tesla in this context and went off on a mini-rant.

    • Re: (Score:3, Interesting)

      by lawnboy5-O (772026)
      My grandmother worked for Thomas Edison - so I the FUD on Edison I can speak to directly as she was my intellectual mentor growing up - and yes we spent hours and hours talking about that crazy Edison.

      Some points you should know:
      Most of the consumer devices you use today are direct descendants of Edison's inventions.
      Edison was no Crook either - even if only paying my sweet grandmother ~17 cents a day around the 1920's.
      He was indeed eccentric toward the later years of his life however, and experienc
      • by nurb432 (527695)

        Most of the consumer devices you use today are direct descendants of Edison's inventions.

        They were 'his inventions' only because his employees created them. So i guess technically you are correct, but that is stretching intellectual honesty. Sort of like saying Bell Labs invented the silicon transistor, when it was actually employees of the labs that did..

        . ...and by the way - it was Marconi that invented most of what was later attributed to Tesla... and returned to Marconi only recently by world courts.

        I call BS. And even if its true they gave them back, Marconi used Telsa's work to achieve it, AFTER Tesla did, so Tesla earned the credit and should retain it.

        • Your admiration/enthusiasm for Tesla is not unwarranted - his genius was original, but you need to loosen up on the others.... Marconi did it before Tesla but both indpendently, actually. And as far as Edison goes, he was indeed hard to work for, but to claim he raped his employees for everythng is far too fetched, and outright false. He did indeed depend on his employees more in his later years, but his genius was legit, and his Inventions genuinly his own.
      • Re: (Score:2, Insightful)

        by kliklik (322798)

        ...and by the way - it was Marconi that invented most of what was later attributed to Tesla... and returned to Marconi only recently by world courts.

        Actually, it's the other way around. Check [wikipedia.org] your [tfcbooks.com] facts [wikipedia.org].

        • This is interesting - but wiki is wrong here IMHO. The credit in question on many of the conflicts between Marconi and tesla have been on going for decades... Discovery and History both in recent docmentations claim the opposite... And give Marconi the credit... As do some governing bodies and courts. But i guess we will have to wait for more compeling evidence for the truth to be known ( if wiki is correct).
          • by paganizer (566360)

            There is actually some interesting insight into this debate at the University of Kentucky Library in Murray, KY (of all places).
            I'm not going to go in to details, as I've been labeled a crank a few times to many lately, but if you have access check out the Stubblefield papers in reference to Tesla, ignore the respective wiki article, and form your own opinions.

            plug: gotthefire.net

            • I agree - u need to read the reasearch - the debate for origin is well alive and no last word is offered.

              My only real point was sharing the stories of my grandmother - sharp as a tack - and memory like a steel trap. Edison was real, and his inventions so wide spread you can not live in the modern world without them. And yes, many of them were engineering inventions - one of my favorites being his joint project with Henry Ford in creating Charcoal (the same stuff you use to cook burgers on) as Henry w
      • Edison invented one major thing:

        The mass production of inventions.

        Everything else was either stolen or subcontracted.

        Did you know Edison didn't believe in Ohm's law?

      • by Warshadow (132109)

        Edison not a crook? Oh now there's a good one. I suggest you do some reading about the man and his actions instead of relying on the words of someone who was under his employ. "Le Voyage dans la lune" might be helpful in your search for accurate information on the man.

    • by Heed00 (1473203) on Friday July 24, 2009 @06:29PM (#28813923)
      Bah. He came up with that cool electric hammer that was recently discovered as well as the extra hinged legs on chairs to stop you falling over if you lean back too far.
    • Re: (Score:3, Informative)

      by westlake (615356)

      Electrical pioneer my ass, he just got lucky once and was able to afford to hire good talent

      Luck favors the prepared.

      1869 Stock ticker

      1874 Quadruplex telegraph [wikipedia.org] [Polar modulation]
      Rights sold to Western Union for $10,000. [about $170,000 in 2005 dollars Historical Value of U.S. Dollar [mykindred.com]]

      Menlo Park was in the business of invention. That in itself was a new idea.

      1877 Phonograph

      The most interesting thing about the phonograph is that no one saw it coming.

      1880 Incandescent lamp.

      Edison needed a lamp which could be w

      • The Stock ticker is merely a different telegraph. The Quadruplex telegraph was based on J. B. Stearns duplex telegraph. The incandescent lamp was invented by Swan. The phonograph was probably the only thing major invention in that list that he made a major contribution to.
        • The Stock ticker is merely a different telegraph. The Quadruplex telegraph was based on J. B. Stearns duplex telegraph. The incandescent lamp was invented by Swan. The phonograph was probably the only thing major invention in that list that he made a major contribution to.

          The improved stock ticker.

          Edison's improved stock ticker included his key contributions to printing telegraphy. His most significant improvement was a mechanism that enabled all of the tickers on a line to be synchronized so that they pri

  • by roc97007 (608802) on Friday July 24, 2009 @05:18PM (#28812987) Journal

    ...but as geeks we should remember that Heinlein cautioned against it.

    • by Nethead (1563)

      Are you talking about "Blowups Happen" or "Magic Inc."?

      • by roc97007 (608802)

        No, Waldo. "Blowups Happen" was a (premature, somewhat unwarranted) cautionary tale about nuclear power. Magic Inc could be a cautionary tale about... lessee... nationalized health care. Yeah, that works for me. But Waldo (usually bundled with Magic Inc) was (at it's core) about human physical deterioration brought on by widespread broadcast power.

        • Well, we haven't listened to Gibson about the "black shakes" caused by too much RF - heck we put RF gear near our heads daily.
          Why would we stop now when we can charge it while wearing it? (cancer? naaaaaaah)

        • by Nethead (1563)

          That's right, it's been decades since I've read them. Time to dig in the book pile again.

          Thanks.

    • by Chyeld (713439)

      Heinlein also wrote about a character that was effectively immortal. Banged his daughters, his sisters, his clones, went back in time and banged his mom and his dad, gave his best friend a sex change so he could bang it, got the AI running a planet and the AI running his ship bodies cloned from him (so he could bang them) and really pretty much humped everything that moved, while being a bigger bad ass than the illicit love child of Dirty Harry, Chuck Norris, and Vin Disel.

      A good wordsmith, but not exactly

  • Mmmm; I'm under the impression that the problem with contact-free power is a significant loss in efficiency. So, if I have to use 25% more power (for example) to charge all my devices just so I don't need to connect a wire, that sounds like a great way to make stuff cost more due to increased electricity demand.

    If I were building power plants, of course, this would sound like fantastic news.

    • Mmmm; I'm under the impression that the problem with contact-free power is a significant loss in efficiency.

      I, on the other hand, always thought the problem with contact-free power was cancer.

      • Mmmm; I'm under the impression that the problem with contact-free power is a significant loss in efficiency.

        I, on the other hand, always thought the problem with contact-free power was cancer.

        Considering the large amount of EMI emitting transformers and oscillating devices found in the common nerd's dwellings, I doubt adding a little more would hurt all that much, relatively speaking that is.

  • by Corson (746347) on Friday July 24, 2009 @05:20PM (#28813021)
    I don't know about Edison but Tesla certainly carried out experiments proving that wireless energy transfer is possible.
    • Re: (Score:3, Informative)

      by n3umh (876572)
      It's not only possible, but really damn easy to do.

      You can build a reasonably efficient resonant power transfer doohickey in your backyard out of some copper tubing, some low loss tuning capacitors, a RF power generator, and some diodes and filter caps on the far end to turn the received RF into DC.

      I've built one to couple 4MHz pulses across to a rotating experiment for ultrasound measurement: http://n3ox.net/files/us_ring.jpg [n3ox.net]

      You couple 'em that tightly, and they're like 99% efficient at transferr
      • Re: (Score:2, Interesting)

        by Ryvar (122400)

        But even with Tesla aside, this isn't new... it's just not as vastly useful as people re-discovering it seem to think it is. It doesn't work over gigantic distances, only moderate ones, and there's no engineering you can do to get around that.

        The misunderstanding a lot of people have is that they think Tesla was chasing *truly* wireless power - when in fact this was probably never his goal. Tesla was always chasing after something he called "longitudinal waves" in an attempt to perform worldwide "wireless"

  • Retarded. (Score:5, Insightful)

    by girlintraining (1395911) on Friday July 24, 2009 @05:27PM (#28813121)

    Blasting large amounts of EMI solely to avoid the need to put a battery in something is stupid. Right now EM radiation is controlled to the lowest levels it can practically be in order to achieve some transfer of information between two or more points. Any power transfer system is going to muck up what's already in the air. It's called Shannon's Law -- and no matter how you sex up the technology, the fact is you're raising the noise floor doing this.

    Bad engineer. No cookie for you.

    • Re: (Score:1, Insightful)

      by n3umh (876572)

      It's called Shannon's Law -- and no matter how you sex up the technology, the fact is you're raising the noise floor doing this.

      Bad engineer. No cookie for you.

      Except that energy transfer is not information transfer, and doesn't really require any bandwidth. Of course, every emission has *some* bandwidth due to noise, etc, but you should be able to do wireless power with very narrow band oscillators and I suspect you have confine emissions to the the ISM (industrial, scientific, and medical) bands. Maybe it needs a little bit of slow digital transmission if you need to sync devices and chargers beyond just whether or not there is another resonant device around

    • For Powercast's technology, here's the spreadsheet that can be used to calculate transmission efficiency given distance, frequency, etc.
      http://powercastco.com/wireless-power-calculator.xls [powercastco.com]
    • by kheldan (1460303)
      Hear, hear!
      We'll have practical flying cars before we have practical wireless electricity. Hell, we'll probably have over-unity energy before we have practical wireless electricity!
    • by hannson (1369413)

      How is that any different than Ethernet over Power?
       
      (I'm not an engineer, someone please explain)

      • by bugnuts (94678)

        Ethernet over powerlines noises up the powerlines, but won't add much EM interference to your wireless, e.g.. I believe the GP is saying that wireless energy transmission is going to make any wireless communication have to compete with the noise, going from a hiss to a yell, like the 2.4Ghz noise of millions of microwave ovens suddenly turning on while you're reading this on your iphone's wifi.

        In practicality, that means your phone batteries will die much faster as it has to pump out 1 bar worth of power i

    • Not that you'd learn it from this non-technical news report, but the energy transfer in WiTricity is non-radiative for this and other reasons. Indiscriminately radiating power not only will interfere with other devices (and violate FCC regulations), but also wastes power by dumping it into the environment, not to mention that people tend to dislike the idea that power is being dumped into their brains. See my other post below.
      • It's non-radiative only as long as there's no object in the vicinity which happens (by chance of it's structure) to resonate with it and form an antenna.

        If Witricity used something like coded spread-spectrum for it's magnetic waveform, that would be very unlikely, and make stealing power more difficult too. But from the little description in the articles, it looks like it depends on a simple narrow band resonance. An unlucky mechanical structure could resonate with that and radiate.

        • by stevenj (9583)
          First of all, you don't understand the meaning of "non-radiative". Whether or not there is power transfer, it is in the near field, not the far field, and hence it is not radiative. Second, it's not sufficient to have the same resonant frequency; you also have to be impedance-matched. The combination of the two is unlikely in the extreme.
          • I believe I understand the meaning of non-radiative and near-field, but I won't claim expertise.

            As a simple thought experiment, a Witricity receiving coil connected by ordinary cable to a radiating antenna resonant at the same frequency, with all three components impedance matched, would clearly be a mechanical object which passively coupled with the transmitter and produced a (radiating) far field.

            The transmitted field's shape is modified by antenna elements in the vicinity of the transmitter. With comple

    • Just because you're much closer to 102.5's radio tower doesn't mean you can't listen to 93.3.

      They're not adding the Gaussian white noise that Shannon's Law refers to, they're going to pump at some specific frequency, so you presumably get to filter it out for your communication channel.

      • Just because you're much closer to 102.5's radio tower doesn't mean you can't listen to 93.3.

        Get close enough to 102.5's tower and it does. And the farther it is from 93.3's, the farther you have to be from 102.5's tower to hear 93.3.

        Look up "receiver quieting".

        Yes they're different frequencies. But the sharp tuned circuits are AFTER the first few stages. Saturate the front end and you can forget listening to the quiet stuff.

        So things like this need to be in bands far enough removed from the signals of i

    • by msheekhah (903443)
      This method of recharging is going to be much less harmful than the power transformers... Why? High resonance frequency EMF vs. Low resonance frequency EMF. Our entire environment is magnetic. However, it's very low resonance frequency, that we are evolved to survive in. Sure, we're going to loose efficiency with this method of charging. That's why we need to focus on research to create better power sources. Also, what if we found the magnetic resonance frequency of the earth (core/atmosphere, whatever i
    • by labnet (457441)

      Actually, one the main problems they will have is dealing with ETSI EN 300 330-1, which governs the field strength of inductive based transmitters.
      The USA also has a similar FCC standard but in screwed up volts/m units.
      We develop 134kHz RFID equipment, which pushes right on the boundary of this standard, and it aint a lot of power.
      eg a 1200mm x 600mm antenna can just power a 1" RFID tag at 1.5m
      Remember near field systems loose strength from the transmitter at 1/r3.

      So to obey the standards and get useful po

  • by TheNarrator (200498) on Friday July 24, 2009 @05:38PM (#28813321)
    Here's a company that's had wireless power tech since 2007:
    http://www.powercastco.com/ [powercastco.com]
    They even won a best of CES 2007 award from CNET:
    http://reviews.cnet.com/8301-12760_7-9673092-5.html [cnet.com]
    They released working wirelessly powered Christmas tree lights in December 2007 as a consumer product!
    http://news.cnet.com/8301-17938_105-9793204-1.html [cnet.com]
    So this type of wireless power tech has been available in consumer products since 2007 and it appears that there has not been a lot of interest. I am really mystified as why nobody cares. Is it because they mistake this technology for some other kind of well known technology? I can't figure out the psychology here.
    • by stevenj (9583) <stevenj.alum@mit@edu> on Friday July 24, 2009 @06:34PM (#28813971) Homepage
      There are several very different schemes currently being explored for wireless power transfer, with different strengths and weaknesses.
      • Radiative transfer: send a directed beam of energy from a source to a receiver. The advantage is that this can work over long distances, the disadvantage is that you need to either have fixed locations or some active tracking system to keep pointing at the receiver as it moves around, and you need some kind of automated kill switch to make sure you don't accidentally fry anything that walks between the transmitter and receiver or waste power when the receiver is not there. It looks like PowerCast [powercastco.com] and PowerBeam [powerbeaminc.com] fall into this category.
      • Traditional inductive, non-radiative power transfer. This works well, and does not transfer power when the receiver is absent, but is extremely short-range if you want any kind of efficiency; typically, the device to be charged must be sitting directly on or adjacent to the charger. The Wireless Power Consortium [wirelesspo...ortium.com] is pursuing this kind of approach.
      • Resonant, non-radiative power transfer. This relies on the source and receiver being electrical resonators at the same frequency, so that they preferentially transfer energy to one another rather than to other objects in the environment via resonant coupling. This is the approach being pursued by WiTricity [witricity.com], where they additionally rely on resonators that couple primarily via magnetic fields (the electric-field energy is mostly in capacitors inside the devices), which have the advantage that most materials are non-magnetic at these frequencies so the power source dissipates very little energy into extraneous objects (or people). (In contrast, Tesla coils produce strong electric fields external to the device, which interact much more strongly with matter; it's no coincidence that Tesla coils are used as lightning generators.) This operates efficiently at mid-range distances although not as far as radiative transfer (meters at most), does not transfer or dissipate power when the receiver is absent, and is not directional so does not require active "pointing" of the power at the receiver. But it is more complicated than the short-range non-resonant inductive transfer, and requires careful impedance-matching of the source and receiver.

      Full disclosure: I know Prof. Soljacic at MIT, who founded WiTricity, although I personally have no financial interest in the company; all of the above information is public and published, however.

      • If it's non directional, does not get blocked by most materials and has a range of a few meters, how well would it work if in apartments where you and your neighbours tried to use the tech?

        I can see a few potential problems with that ;)
    • by dissy (172727)

      So this type of wireless power tech has been available in consumer products since 2007 and it appears that there has not been a lot of interest. I am really mystified as why nobody cares. Is it because they mistake this technology for some other kind of well known technology? I can't figure out the psychology here.

      I'm going to place a guess that it involves price, and possibly obscurity.

      Admittedly, I am just going by the $400 pricetag on that tree from 2007, but most people that would be preparing and setting up a christmas tree today, have been doing so for awhile already and in most all cases don't see a drawback to the wires. They have wired things up before, so the process is pretty well understood and worked around.

      Now, as a geek I would love to have these, but for me it would be specifically for the reason tha

  • Your head explodes!

    Yay!!!

  • As a physicist... (Score:5, Informative)

    by The Master Control P (655590) <<ejkeever> <at> <nerdshack.com>> on Friday July 24, 2009 @05:46PM (#28813431)
    I'd like to be the first to complain that resonant power transfer has nothing to do with quantum entanglement.

    You'll be getting a memo from the Tesla Death Ray department shortly; Not observing it won't save you.
    • by n3umh (876572)

      I'd like to be the first to complain that resonant power transfer has nothing to do with quantum entanglement.

      Entanglement, no. Tunneling, yes... if you like to market your device by insisting on quantum descriptions of things that involve transition rates of 10^28 photons per second. A ~10MHz photon doesn't pack a very big punch, energy-wise.

      It's a classical effect but can be framed in quantum terms for "welcome to the future" cred.

  • Tesla actually demonstrated it. He just never got the chance to scale it up. So.. before going around and saying that this has just been invented, go check Tesla's patents.
    • by RobVB (1566105)
      It says Tesla assumed it would be delivered wirelessly, meaning he didn't think we'd build amazingly expensive and ugly power lines all over the world. But you're right, Tesla did demonstrate it. That just wasn't the point of the sentence.
    • by pitu (983343)
      any reference that he demonstrated this? ....besides his patents
  • Does it cause cancer yet? If it doesn't, it will because somebody will figure out some way to claim it happens.
  • ... at least in good weather during the day.

  • A company I visited as an FAE back as far (actually is it far?) as 2003 (Splashpower, Cambridge, UK) demonstrated a pad that with specially adapted battery packs would recharge any handheld electronics placed upon it, without wires. I know they didn't survive. I wonder what happened to them, anyone know? I do remember their chief engineer was one of the Atari Jaguar 2 designers, so he must have been fairly used to canned projects.. Yes that's right, the Jaguar 2!
    • by Warshadow (132109)

      "Wireless" charging was done before that. GM charged its EV1 with a "wireless" inductive paddle system. Google Magne Charge. I'm sure the technology was around before that.

  • Meh. (Score:2, Interesting)

    by djMouton (267156)

    To quote John Dvorak: "My toothbrush has been doing this for years."

    (ducks)

  • Inefficient use of an energy resource is NOT what is needed. Even if it cost as little as wire, it delivers energy less efficiently and puts more demands on resources to deliver the energy. And, no, it will never be efficient because of the square law [wikipedia.org].

    Our problem isn't the energy consumed, it's that through inefficiency we waste resources.

  • If it's only 45% efficient, and powering a 20W light bulb (guessed), and apparently doesn't radiate or heat people...

    Where is it dumping the remaining 55% (11W)? Does the transmitter just get hot safely?

  • Wireless Power gives everyone a warm fuzzy feeling... oh, wait...

  • Edison??? Really?? Puhleeze........!

  • "Wireless power system shown off" [article title]

    Well, that's one state necessary for a fully functional system, but I'd be far more impressed if it was shown on.

    Who's going to lug around the transmitter and receiving unit (if not internal to the device) when they can stuff a thin wire in their pocket?

  • Scotty is right. This idea is ludicrous. Sending power as magnetic fields is a major fail. The near-field which they're touting as a panacea, it inevitably falls off as the cube of the distance. So you need a sending coil about as big across as the distance. You want to hang a 10-foot coil on the ceiling to power your laptop in a 10 ft radius?

    And there won't be a single standards body that will approve pumping many watts of 30m waves into living spaces.

  • "electrical pioneers Thomas Edison and Nicola Tesla"

    That should be:

    "electrical pioneers Nicola Tesla and Thomas Edison"

It is wrong always, everywhere and for everyone to believe anything upon insufficient evidence. - W. K. Clifford, British philosopher, circa 1876

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