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Power Wireless Networking Hardware

Wireless Power Over Distance: Just a Parlor Trick? 215

Posted by Soulskill
from the efficiency-is-a-harsh-taskmaster dept.
Lucas123 writes "Companies like U.S.-based WiTricity and China-based 3DVOX Technology claim patents and products to wirelessly powering anything from many feet away — from smart phones and televisions to electric cars by using charging pads embedded in concrete. But more than one industry standards group promoting magnetic induction and short-distance resonance wireless charging say such technology is useless; Charging anything at distances greater than the diameter of a magnetic coil is an inefficient use of power. For example, Menno Treffers, chairman of the Wireless Power Consortium, says you can broadcast wireless power over six feet, but the charge received will be less than 10% of the source. WiTricity and 3DVOX, however, are fighting those claims with demonstrations showing their products are capable of resonating the majority of source power."
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Wireless Power Over Distance: Just a Parlor Trick?

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  • by Anonymous Coward on Wednesday October 31, 2012 @05:01PM (#41835845)

    i mean, the amount of effort it took you to make that rock round and then roll a log over it? you could have carried 10 logs in that time. quit with the making new shit, gorg, it isn't useful at all and it isn't like anyone will ever find a way to improve on it. ...
    oh, nice vette, gorg.

  • As it was before (Score:5, Insightful)

    by MakerDusk (2712435) on Wednesday October 31, 2012 @05:02PM (#41835851)
    Back in the day, Tesla had achieved even greater success. Though if you can charge from anywhere, how can you be billed? That is what will permanently stop this type of technology.
    • by CanHasDIY (1672858) on Wednesday October 31, 2012 @05:06PM (#41835889) Homepage Journal

      Back in the day, Tesla had achieved even greater success. Though if you can charge from anywhere, how can you be billed? That is what will permanently stop this type of technology.

      Exactly.

      It's not that wireless power distribution is a "parlor trick" - rather, the problem is that the profiteers are doing it wrong.

      • No it isn't (Score:5, Interesting)

        by Sycraft-fu (314770) on Wednesday October 31, 2012 @05:30PM (#41836131)

        The problem is inefficiency. Power drops with the square of distance. That means you need a bigass transmission source to get a small amount of power any distance away, hence why things like FM stations have 5 digit wattage transmitters.

        Yes we have been able to transmit power wirelessly for a long time, no it is NOT practical or efficient. If you are enthralled with Tesla, spend some time reading some actual books on him, not just the silly piece by the Oatmeal. He was a fascinating man and worth your time to learn about, but you need to learn about him if you want to go spouting off.

        He didn't invent some magic transmission technology we can't replicate, he invented an inefficient transmission technology that we can replicate, but don't, because he was not able to solve the efficiency problems (and it may not be physically possible to).

        • Re: (Score:3, Informative)

          by StripedCow (776465)

          Power drops with the square of distance.

          Not if you have a directed beam of energy.

          The beam could be directed based on some set-up protocol between the energy-source and the energy-consumer.
          And you can easily direct beams by using some antenna array.

          Such direction-sensitivity could also be used to (partly) solve the billing problem.

          http://en.wikipedia.org/wiki/Antenna_array_(electromagnetic) [wikipedia.org]

          • by bug1 (96678)

            Power drops with the square of distance.

            Not if you have a directed beam of energy.

            An Antenna array is lots of antenna, and in each one "Power drops withe the squar of distance".

          • Re: (Score:3, Informative)

            by Anonymous Coward
            Even directed beams drop off with distance squared once you get outside the near field. A directed beam is a lot more efficient than an omnidirectional beam, but for any given directional beam, power will drop off with distance squared, and narrowing the beam will require larger antennas setups.
            • by Shavano (2541114)

              Even directed beams drop off with distance squared once you get outside the near field. A directed beam is a lot more efficient than an omnidirectional beam, but for any given directional beam, power will drop off with distance squared, and narrowing the beam will require larger antennas setups.

              Yes, that can be done. But the collectors are very large if you want to catch most of the power. And they also suffer large efficiency losses compared to a wire and low frequency.

        • The problem is inefficiency. Power drops with the square of distance.

          That's when the transmitter is essentially a point source radiating in a sphere. I have a tiny bit of experience with very high powered radars that use beam-forming to narrowly direct their transmission. In the past that sort of beam-forming required lots of bulky equipment, but apparently that's changed in the last decade or so. I wouldn't be surprised if something similar could be used to direct wireless power with much better efficiencies.

          • Re: (Score:2, Interesting)

            by Anonymous Coward

            Beam forming is just the correct use of interference patterns, and it is very useful for *information* transmission, and an useless piece of crap for *power* transmission: you still leak power like a sieve. The math is not even complex, in fact it is downright simple.

            The only way to increase efficiency is to redirect the wavefront and concentrate it where you need it instead of letting all that power go somewhere else it is not useful. This means you need to *reflect* it, maybe *guide* it (using waveguide

        • Looked at one of the demo videos. There is a 4000watt transmitter (in middle of floor, nevermind the radiated power someone is gonna trip on it!) a few feet away from most of the stuff and i don't see 2000w worth of stuff.

          Don't know how it works, don't care so much to look. I don't plan on adding a 4000watt transmitter to each room, seems like a half dozen power cords would be a bit cheaper. Not that i have any interest or hope for anything called 3D power...sigh.

          But...Does the green carpet in the one vid p

        • tesla was the genuine article: a mad genius

          so there's the genius

          but there's also the crazy part to

        • I thought the resonating magnetic field solved the efficiency problem for Tesla.
          These guys aren't charging the planet at the right frequency.

        • Tesla Worship (Score:5, Insightful)

          by elrous0 (869638) * on Wednesday October 31, 2012 @09:07PM (#41837727)

          Personally, I think the Tesla worship among geeks has gotten WAY out of hand in recent years. Yeah, I know the Evil Rich Guy Edison vs. the Poor But Plucky Tesla makes for a great literary narrative. And I don't discount the guy's work (particularly with alternating current, which he was right to argue for over DC as a practical means of long range electrical transmission). But he wasn't a god, he wasn't 100 years ahead of his time (as some recent hyperbole would have it), he didn't invent anything which subsequent engineers haven't since replicated and improved on, and he didn't certainly didn't invent EVERYTHING (the list of claimed inventions seems to get longer every year, in spite of the fact that he remains decisively dead).

          I think we do him an honor to recognize his REAL work. But we do him a dishonor to exaggerate, or even mystify, his accomplishments.

          • by MickLinux (579158)

            I dunno, it isn't Tesla worship: but at least his real work, good , bad, or useless, was real work, and was really his. I think Edison once pointed out that Tesla would never be great because he didn't know how to steal. That from a man who did steal, and kill, too. Seems to me that after TARP, you would have had enough of great men. If that wasn't enough, there's the quadrennial election.

            Tesla's inventions may not be practical for various purposes, but they did have a use within their own limits.

        • The problem is inefficiency. Power drops with the square of distance. That means you need a bigass transmission source to get a small amount of power any distance away, hence why things like FM stations have 5 digit wattage transmitters.

          Yes we have been able to transmit power wirelessly for a long time, no it is NOT practical or efficient. If you are enthralled with Tesla, spend some time reading some actual books on him, not just the silly piece by the Oatmeal. He was a fascinating man and worth your time to learn about, but you need to learn about him if you want to go spouting off.

          He didn't invent some magic transmission technology we can't replicate, he invented an inefficient transmission technology that we can replicate, but don't, because he was not able to solve the efficiency problems (and it may not be physically possible to).

          Radio stations use that kind of power because they want to broadcast a signal hundreds of miles in a very noisy RF environment. True, it's inefficient but you could definitely transmit power a few feet and use the power to run some device. Charging most cell phones for example only requires about 500ma at 5vdc. Even at 10% efficiency it's doable; just inefficient.

          Tv's and electric cars, though.. that sounds like a huge stretch. I wonder if the FCC has properly studied this stuff - at the transmission l

          • Charging most cell phones for example only requires about 500ma at 5vdc. Even at 10% efficiency it's doable; just inefficient.

            Can't you see how crazy you sound? Smartphones are a new constant drain on electricity, and if you dropped the efficiency of the charging transmission line to just 10%, you'd potentially cost the grid GIGAWATTS of capacity.

            Here are my thoughts:

            Current worldwide sales of Smartphones were 154 million units in 2012 [techcrunch.com]. If they continue to grow like last year, in 2013 they will move 220 m

            • LOL! Electricity exists almost exclusively so people can be lazy. For example, you're wasting electricity posting on slashdot when you could be writing a letter or doing something else. Just because your idea of what it's okay to use electricity on is different than someone else's doesn't make you right. Unreasonable attitudes like yours are a problem in today's society. You don't want to do it, and that's fine. It doesn't mean that I don't want to do it or won't do it. If I charge a phone that way e
        • He did solve those efficiency problems... Something called Alternating Current. It's gonna be big!

          Of course without Tesla's work on wireless power, we wouldn't have "radio" (and various technologies) either. Marconi's famous radio patent used more than 20 Tesla patents...

          • by necro81 (917438)

            Of course without Tesla's work on wireless power, we wouldn't have "radio" (and various technologies) either. Marconi's famous radio patent used more than 20 Tesla patents...

            Yes, because in the 100+ years since, no one, I mean no one could ever have invented the stuff that Tesla did. There's no way that we would have radio, even today, without that man.

        • If you are enthralled with Tesla, spend some time reading some actual books on him, not just the silly piece by the Oatmeal. He was a fascinating man and worth your time to learn about, but you need to learn about him if you want to go spouting off.

          He didn't invent some magic transmission technology we can't replicate, he invented an inefficient transmission technology that we can replicate, but don't, because he was not able to solve the efficiency problems (and it may not be physically possible to).

          Well, had you read some actual books on the topic, instead of spending your time coming up with snarky responses to satisfy your narcissistic need to baselessly denigrate others, you would know that Tesla had a solution indeed - many towers, spread strategically about the globe, creating a worldwide network of wireless power stations.

          Had his brilliance been recognized at the time, we wouldn't be playing catch-up on century old technology. Let that be a lesson to the world - today's mad scientist may just

        • Re:No it isn't (Score:4, Insightful)

          by WolfWithoutAClause (162946) on Thursday November 01, 2012 @10:26AM (#41842493) Homepage

          > The problem is inefficiency. Power drops with the square of distance.

          Wrong!

          That's how radio works.

          Actually the resonant schemes DON'T use radio, they use inductance; which is just magnetic fields; and they work at much lower frequencies.

          By contrast, radio is a particular mixture of magnetic and electric fields that propagate to infinity, and you tend to lose them. That was the genius of Marconi, to get the mix right.

          But magnetic fields on their own don't propagate, that's partly why magnets don't go flat. The energy hangs around the transmitter and can be absorbed by a suitable receiver.

        • by zzyzyx (1382375)

          You're correct that power drops with the square of distance, however it does not mean efficiency follows the same relation. It can be improved through resonance. This phenomenon allows the power of the magnetic field to be much higher than the electrical power put in the antenna. Think of somebody pushing a child on a swing. This works because an induction antenna does not simply send energy into space, but it sets up a magnetic field that can be recaptured and reused in the next cycle, adding up the energy

      • ... if you can charge from anywhere, how can you be billed? That is what will permanently stop this type of technology.

        Exactly. ... the problem is that the profiteers are doing it wrong.

        J.P. Morgan figured he'd stick with the General Electric/Westinghouse business model and eschew the more efficient new technology, as it would not provide the market needed for his copper business.

        • ... if you can charge from anywhere, how can you be billed? That is what will permanently stop this type of technology.

          Exactly. ... the problem is that the profiteers are doing it wrong.

          J.P. Morgan figured he'd stick with the General Electric/Westinghouse business model and eschew the more efficient new technology, as it would not provide the market needed for his copper business.

          J.P. Morgan is, in many circles, considered one of the greatest Americans ever.
          It never ceases to amaze me how much praise and adulation the people in this country can heap upon the fantastical image of a person who, in reality, was far more concerned about maximizing his own bottom line than he was about advancing humanity, and was essentially a self-serving traitor to mankind... perhaps that's a testament to the human tendency towards selfishness.

    • by Nidi62 (1525137) on Wednesday October 31, 2012 @05:22PM (#41836049)

      Though if you can charge from anywhere, how can you be billed?

      Don't worry, I'm sure you'll be charged for the amount of power sent, and not the small amount of power received

      • Re:As it was before (Score:5, Interesting)

        by Telvin_3d (855514) on Wednesday October 31, 2012 @10:05PM (#41838199)

        If anyone went through with this kind of thing they SHOULD be charged by the power sent. It is, after all, taking that much power to charge your device. The wastage is your problem for being too lazy to plug in your phone.

        • by rok3 (1133003)
          I wish I still had some mod points. You are making too much sense to ignore.
        • by necro81 (917438)

          If anyone went through with this kind of thing they SHOULD be charged by the power sent. It is, after all, taking that much power to charge your device. The wastage is your problem for being too lazy to plug in your phone.

          And I propose an additional surcharge of 100% for using such a ridiculously inefficient and wasteful technology.

    • by Randle_Revar (229304) <kelly.clowers@gmail.com> on Wednesday October 31, 2012 @06:12PM (#41836497) Homepage Journal

      Yeah, and Tesla also cloaked a navy ship and accidentally sent it back in time! And the world is run by Illuminati Lizard-men!

    • by geekoid (135745) <dadinportland AT yahoo DOT com> on Wednesday October 31, 2012 @06:14PM (#41836513) Homepage Journal

      No he did not.
      Tesla needs props, but the Tesla myth does not.

    • by flyneye (84093)

      Lack of imagination seems to stop it pretty well.
      I could see residential communities utilizing this complete with meters and billing.
      Especially if it can be dispensed at a specific frequency.
      Even without metering, the electricity only goes so far and a fair communal price for usage could be instituted based on general usage and on a flexible rate.
      Hey, radio waves go everywhere, but they seem to be able to charge for XM/Sirius with no problems. Satellite T.V., Wifi, sure there are some using it for free, but

    • by necro81 (917438)
      How can you be billed? You get billed for the 4 kW of electricity you are pumping into the 3DVox's transmitter to be able to enjoy the innumerable benefits of having one room without wires. What a glorious new age we live in! Where we can waste gobs of power to avoid the awful burden of plugging things in!
    • by VoidCrow (836595)

      Assuming you could make the power transfer practical, there's nothing to stop you from implementing an identification protocol over the inductive connection. Sure, it could be spoofed, but at the end of the day, *anything* can.

    • Except that now the device can have chips in to measure the amount of power being supplied, and if somebody hasn't paid, can cut it off.

      And actually the original problem about how you can be billed was solved by television broadcasters; mostly it relied on people being honest, and occasionally driving around with a truck with equipment to sniff out people that were stealing.

  • Have they tested its ability to charge the phone of someone with a pacemaker or other medical device? Sure, it charged the phone, but he was no longer around to make a call...

  • by MichaelSmith (789609) on Wednesday October 31, 2012 @05:19PM (#41836009) Homepage Journal

    I think these are a great idea and I would not be surprised if Apple start to support them in the future. A phone could be built with no open connections at all. Just wireless data and inductive charging. But over longer distances the laws of physics catch up with up. Obviously the shorter the wavelength the less doffraction you get over a given distance so if you direct power with a laser and convert it into electricity with a photovoltaic cell then you could easily get more efficiency over a few metres than with induction. Maybe in the future it will be considered normal to transmit power that way.

  • by Anonymous Coward

    ...but, the further you go the more it resembles eating your lunch sitting on power lines.

    At the one end, there is no measurable danger in charging handset on a pad charger. But do you really want to spend all your television watching hours in a room where 200 watts of power is being beamed to your TV (and 19x being radiated) from the wall to save you the bother of the unsightly cord?

    If you have magnetic wave energy, you have electric wave energy, which means you have RF. You can shape the way you transmi

  • They've seen people who live under high voltage power lines seem to have a higher rate of cancer [stanford.edu]

    So I would think it would be possibly dangerous to come close to fields where energy is passing through your body. The more energy involved the worse off I'd think people would be. I don't tend to worry much about low energy fields like cell phones or wifi. Yet if a job powered all the computers with remote energy so I'm exposed all day long, I'd have to decline that job. No sense risking cancer for any
    • by metaconcept (1315943) on Wednesday October 31, 2012 @07:16PM (#41837001)
      From the very PDF you link to, Question 1, right at the beginning:

      • the more recent epidemiological studies show little evidence that either power lines or "electrical occupations" are associated with an increase in cancer (see Q19);
      • laboratory studies have shown little evidence of a link between power-frequency fields and cancer (see Q16);
      • an extensive series of studies have shown that life-time exposure of animals to power-frequency magnetic fields does not cause cancer (see Q16B);
      • a connection between power line fields and cancer is physically implausible (see Q18).

      ... Overall, most scientists consider that the evidence that power line fields cause or contribute to cancer is weak to nonexistent.

      (Emphasis mine.)

      • The magnetic field drops off rapidly with distance. At very close range, south American monkey in treetops near the line during winter range, there is so much induction that there is enough heat to be felt so the monkies kept warm. A field strength that high was the cause of many miscarriages among women that used poorly shielded RF plastic welding machines in the USA in the 1950s-60s. You've got to be almost close enough to worry about arcing to get that much RF from a power line, but there are known pr
  • I'm as big a Tesla fan as anyone, but I'm also a practical electrical engineer.

    Someone above already raised the end-point billing issue the utilco's will have, so we needn't bother with the bean-counter side of things. MBA's, rest easy. Your obscene profits are safe.

    However, going from a theoretical ability to blast x amount of joules across an air gap to capturing a useful fraction of x without frying the adjacent wildlife and neighbors is quite another thing. As TFA points out, they seem impressed with a

  • There seems to be some confusion on this thread between magnetic resonance, which is the type of power transfer used by WiTricity and others, and radiative RF which is the radio technology we are used to. For example, received power does not fall off with the square of distance in the case of magnetic resonant systems. There are definitely a ton of challenges to this technology, but it is good to keep in mind that they are NOT talking about transmitting a high power RF signal and having it received at range
  • by HizookRobotics (1722346) on Wednesday October 31, 2012 @08:08PM (#41837397) Homepage
    There are a lot of hard engineering problems to overcome, even if the system was efficient... For example, a second resonant load nearby severely de-tunes the system, antenna mounting considerations are of supreme importance (good luck putting one on a laptop full of metal), and antenna alignment is absolutely crucial! The whole WiTricity concept might be sound in theory, but the engineering challenges are monumental.
    • Now THAT is actually interesting. Finally, some discussion of the practical aspects of resonant systems. I'd never heard anybody mention system detuning if there's more than one load.

      I had heard about the alignment problem before, but when you're talking about most gadgets, they have an obvious antenna orientation because they generally have one particularly slim dimension and two broader ones. I'd assume you'd build the plane of the antenna to correspond to the broader dimensions, since it apparently ne

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