Wireless Electricity

[ted id=619]

[Eric Giler] has a talk available over at TED that discusses and demos delivering electricity without wires. Called WiTricity, these methods were developed by a team at MIT a few years ago who were working off of the concepts of Nicolai Tesla. The facts shared about our current energy delivery system are a bit shocking; we’ve spent over $1 trillion in infrastructure and produce more than 40 billion disposable batteries each year.

The demonstration in the video starts about 6:30 into it. At first we see a flat panel television powered wirelessly from about 6 feet away, then the T-Mobile G1 powered from the same distance. The thought of new TVs coming with WiFi and WiTricity standard would mean just hanging it on the wall with no cords to run. We can also image cellphones that have a battery only for backup purposes when you were not near a transmitter.

The power transfer occurs between two coils that resonate at the same frequency and only that frequency. This remind us a bit of Orson Scott Card’s fantasy communications device from the Ender’s Saga.

78 thoughts on “Wireless Electricity

    1. yeah! Witricity sucks!. Tesla had done it more efficiently. and at a distance of miles not just feets. Tesla doesnt use anoter coil. Tesla use earth’s magnetic field to transmit electical energy. and lastly Tesla is a missionary his invention is free for all!!! Witricity will sell their gadget for a couple of hundreds bucks. Sucks!!!

      1. well tesla spent millions of dollars, and i guess you can use his huge machine that shoots lightning at ur house to charge ur iphone and then die from cancer, witricity tries safe, small wireless electricity thats why it is only few feet first. then it can increase over time.

  1. Really, every few years it seems like somebody puts their own minor spin on this concept and claims it is a new discovery. Tesla had the thing essentially all wrapped up, there is precious little modern scientists need to do with this technology beyond further miniaturization.

    Had Tesla’s funding held out, there is a good chance all of the demonstrations shown here would be everyday items for us now.

  2. pffft. This is stupid. My TV is wireless already. Its a projector screen. I’m sending the power from 14′ away. I broadcast the power through something called a ‘lens’.


  3. The issue with wireless power is that you are wasting a huge amount of power to broadcast it everywhere, rather than deliver it directly to the destination as batteries do. What is needed is better rechargeable batteries and a standard DC interface to recharge devices with.

  4. what i want to know is do I need both devices to be in plane with each other, all of the demos show them that way. If I bought one, I want it big enough to power 2-3 laptops, a similar number of cell phones and maybe my electric cars.

    Also I wonder how much power it consumes just to have the transmitter on without a receiver coil.

    I heard they had a mat that did this for the electric cars. I wonder if it like getting covered in road salt and water and ice in the winter, and works while sitting on a relatively uninsulated slab.

  5. Around 5 minutes in: “It doesn’t radiate. There are no electric fields here, only magnetic fields.”

    Magnetic fields ARE electric fields. It’s just a different perspective on the same phenomenon.
    Also, this isn’t green at all, the transfer efficiency is disgustingly low, and you can’t get around 1/r^2 no matter what you do. I’m going to have to agree with loren and tom here, this isn’t new.

    I’m not an RF engineer, but I’m pretty sure antenna design has used this tech for years, and I *know* antennas are simply inducing a current from a changing field, which is being created by another antenna. Guess what? That’s wireless power transfer.
    I digress.

  6. It’s awfully hard to bill someone for electricity if it’s “transmitted.” That is why Tesla’s funding dried up. There may be a market for short range transmission though. We will see.

  7. A coil consumes only reactive power and no real power. So it does not “broadcast” any power, not more than an unloaded transformer (the coil is not perfect so there’s always be small losses). Energy is only consumed when loaded. However the problem is that the coupling coefficient between the main coil and the receptors is very small, especially if the magnetic fields have to travel through air. That’s why several techniques have to be used. First, have the two coils have the same resonant frequency. Much more energy is transmitted this way. This is the basis of most of Tesla’s work. Second, try to get as much flux to couple between the two coils, and for this you must use collinear coil arrangements like shown in the picture. This makes it difficult to apply to mobile applications, where wireless power is the most needed.

    Eric Giler lies a little in the video probably to lower the fears of the public. It does radiate, it’s not emitting gamma rays but it is emitting energy in some form. Also, high frequency, high intensity magnetic fields are nothing like the Earth’s natural field. Low frequency magnetic fields are generally seen as safe but we don’t have nearly has much background with high frequency ones.

  8. hehe. yeah everybody respects the tesla. if his ideas and theories were fully realized sustainability and efficiency wouldn’t be a problem. he wanted to harness energy from “cosmic sources” of some kind (solar, geothermal) and turn the atmosphere/ground into a giant tesla coil and cage. that’s why he built them, to test the theory. cool stuff. but the idea of having a never ending ion storm seems like it may have consequences…

    but alas efficiency is a problem and this tech isn’t gonna be worth it, ever. just a dead end technology that may have a less inbred cousin that will work as soon as he is born.

  9. Eric: Magnetic fields are not the same as electric fields. A magnetic field cannot affect an electron “at rest”, where as an electric field can. That is the distinct difference between “electric” and “magnetic”.

    nope: tesla’s idea of using the atmosphere for transmitting electricity was just fantastic… before radio was heavily used. If it was used now, lots of long range radio communications would be non existent due to the interference.

    As for efficiency, for wireless power transfer, I suggest using a directional RF method instead of magnetic. This would allow a higher coefficient of transfer due to more energy being received on the device end. This extreme directionality cannot be achieved with magnetics. Using a magnetic system, you will always have alternating field lines, and they will weaken as they go outwards.

    Yes, this system does use resonance, however, it is still a mutual inductance, open-air transformer. The difference is you are “pulsing” it in the kHz range instead of the Hz range (tuned coil). I really am sick of these “researchers” re-inventing the wheel. Yeah, great, you made 2 big coils that are magnetically coupled. Take it up with tesla you thieves.

    If you would like to see the same effect, without all of the BS “scientific breakthroughs”, just take a florescent light bulb under some power lines.

  10. It’s not even relevant if you use a resonant circuit to drive the coil or not.

    What matters is the (reactive) current that flows through the coil, be there a receiving coil with a load attached or not.

    Although you might be able to modulate the transmitted field strength to accomodate varying power demands of different load situations, the whole system just cries inefficiency.

    It’s nothing new, it wastes a lot of power, and I bet it is even dangerous if some arbitrary metal structure nearby just happens to be a near-impedance-match and heat up to incendiary temperatures. At least if tens or hundreds of watts are transmitted.

    Am I wrong?

  11. Lol ok I had to take a double look fist,l wasn’t sure what I was seeing, the future or the past. maybe both :)

    @Dave: I think your 99% right :) but I think a concentrated beam, photon or another high energy directed would work. We can have targeted energy, no need to radiate blindly. sping it in 3 axes and pulse energy, probably would be more efficient. :P

  12. @geodoom – that’s right, it’s all a *conspiracy* (never mind the physics).

    It’s sad that Tesla gets recognition for crazy ideas that didn’t work out, yet almost none for our AC power system which was also his invention – and worked out a hell of a lot better than Edison’s DC.

    quoth – Around 5 minutes in: “It doesn’t radiate. There are no electric fields here, only magnetic fields.” – unquoth

    Yep, this is simply drivel that marks it as higorant hoopla.

    What might require some thought is that *any* conductive object brought into the radiated field (including you) will have currents induced in it. Anyone spent any time around a big transmitter and noted how all sorts of things strike sparks from each other? Not in my home thanks.

  13. magnetic field declienes with 1/r^3 not 1/r^2 as the electric field does.

    Besides this thing uses more copper in the supply-coil than running 10 TVs via wire at the same distance – really very “wireless” ;)

    Transmitting Energy into a 3D volume can never be as effektive as a ~1D (wire) transmitting system.

    Maybe some day we will really have more energy than we can ever waste and this wireless “new technology” gets a market ;P

  14. All very nice. I’m an industrial electrician and the question i have is how am i to shut off certain devices or make sure there will be no power going through some of my stuff. Without having to shut down a major generator and thus cutting off ,potentially, streets, factory’s or a city.

    I develop electrical closets that control chemical processes, backup power generators, pneumatic air compressors, robotic welders and various other stuff. Now for some chemical processes you need huge amounts of power, high amps. I don’t see this technology as being able to conduct these amounts in a simple compact way as supposed to just big copper bars. Some stuff could really come in handy because it wouldn’t require to copper to physically enter the process (mechanical problems heat and movement). But it just doesn’t seem feasible at that scale.

    How am i to identify a magnetic stream from another?
    Will the magnetic stream carry an id package?
    This technology seems a goldmine for hackers and other culprits looking for free power.

    Idea’s are plentiful but implementation is everything. This will need a lot of investment, a international law/standard and social acceptance by which i mean buyers and investors.

    And the last thing i could think of was birds.
    Yes, birds as in animals, some species have the ability to see magnetic fields and navigate by these fields. If we fuck up their system we end up with another very HUGE problem. A good example is oil-platforms that had to change their the color of their light beacons because birds had mistaken it for sunlight So they became disoriented and exhausted which resulted i a lot of dead birds.

    Phew..finished sorry for any language errors or repetitions, English isn’t my first language.)

  15. @ xchip
    Boot? It didn’t boot. It went from standby to the ‘charging’ screen. That always happens that quickly.

    “It’s better to close your mouth and have people think you a fool than to open your mouth and remove all doubt.”

  16. implementation is EVERYTHING. this guy isn’t trying too hard to impress nerds like us. It’s to get potential investors interested in his startup.

    Normal consumers don’t give a shit how blackbox systems work, only that they do work and it stays the hell out of their way. This product whether new or not fulfills both requirements. If it can get past the “we’re gonna die from radiation” scare then I could see it having a good chance at succeeding.

  17. It’s can have rly bad influence for environment.
    I mean not only birds(btw-some fishes using magnetic field too! -like sharks for hunting), but for whole magnetic field of Earth.

    So video looks cool, but it’s ONLY a VIDEO ;D
    MIT -Like to make a lot of noise about nothing ;)
    This technology still needs a lot of HARD WORK to works good without bad influence for environment.

  18. makes me sick to promote a mechanism that wastes 50% of the power while justifying it because batteries are wasteful.

    I mean if you plug in your electric car (which needs batteries to store the power) and that saves you 50% of your electricity bill vs driving over an induction charging mat – just because you’re so darn lazy you can’t plug it in. (same with your wall mounted TV) Its literally crazy talk.

    It has its uses – no denying it – but wasting 50% of the power because you don’t want rechargeable batteries is just plain laziness. Not the business model I was hoping for :(

  19. >>”So, if it is not 100% efficient, and also does not create radiation, then where does the missing energy leak out to?”

    heating you plumbing pipes and messing you TV

    50% or more loss is already happen in any circuit
    because of independence math and we cant do nothing about, waist another 50% from those 50 is insane

  20. Im not as concerned about new perspectives on existing knowledge or technology. Where would we be without such things? I do have some questions about the magnitude of the electromagnetic fields produced by these componenets and their range. There are important government regulations about the filed strengths we, as humans, should limit ourselves to in order to avoid health problems. So much like nanofibers, which seem to affect us like asbestos, we really should ensure its implemented in a way that will not compromise our health.

    Otherwise, sounds pretty cool. Im fed up with all the cords, cables and adaptors I am stuck with.

  21. I like how they mention Tesla briefly, then take credit for “discovering” this technology. Tesla basically did all the work. Inductive power certainly isn’t new. We use resonance constantly to broadcast signals. So what are they taking credit for, exactly? Running an experiment that’s already been done?

    Don’t get me wrong, this is an awesome post. I enjoyed the video and I think wireless transmission of power is pretty interesting (even if it’s not really practical due to lack of efficiency), but it was just a bit too much of the guy “selling” the idea and not enough technical discussion.

  22. its a shame how all of Nikola Tesla’s work is being forgotten here on long island, the building behind which he was building the giant tower which should have been able to transmit not only power, but pictures, music, and videos as well is no being sold for a few million dollars

  23. 50% loss compared the the efficiency of solar panels or energy output of gasoline engines. There is waste everywhere but always improvement. 50% might be a good place to start.

  24. @jack
    “50% loss compared the the efficiency of solar panels or energy output of gasoline engines. There is waste everywhere but always improvement. 50% might be a good place to start.”

    The problem is that wireless transmission of power is _not_ an alternative to gasoline or solar. It doesn’t _produce_ or _contain_ power of any sort. It is an alternative to power cords, which are _very_ efficient.

  25. Phones need to boot after they get power, they don’t instantly power on to the Home screen when you plug the battery in.

    My guess is the phone was running off battery, but the screen was running off the coil, probably because they can’t get the coil need to power a whole phone small enough to look good in a demo.

  26. Look silly humans, its not about wifi here on earth. Its about solar panels in space in sunlight 24 hours a day beaming power to us 24/7. No burning oil, or natural gas anymore. Imagine the change that will bring!

  27. Someone said billing is the big problem and I’d have to agree. Can I be sure my neighbours wall hung TV isn’t leaching off my supply through the relatively thin party wall?

    Visitors to my home with their pockets loaded with rechargable gadgets, do I ask them to empty their pockets and shut them in a metal box till they leave? I know people who are that tight!

    Also how is the total appliance load calculated, distributed – if I decide to fill the room with witricity appliances, how will I know I’ve got too many, apart from when they stop working correctly?

    I think the potential niggles can easily overwhelm the ‘romance’ of the concept and prevent any chance of ubiquity for a long time.

  28. I’ve been watching this video. Coming to definition of suck (2:29) there is something else that sucks too, that is to be precise, works really bad. It’s the tuned loop antenna as an transmitter antenna. Ask your HAM neighbor about that.

    The physics says when used as transmitter antenna, small tuned loops can’t work as efficient as an dipole. It is because tuned coils have very low radiation efficiency.
    In the demo, it works because the distance is fairly small, compared to the dimension of the antenna.

    So it might recharge the mobile phone, it might recharge the laptop ( looking forward to see the actual charging pad ) but I’d not expect whole house powering units any time soon.

    As for the safety, find volunteer with pacemaker, and also ask someone working on maintenance of high power transmitters about their experience on health related effects of strong high frequency magnetic fields.

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