New Zealand To Test Wireless Power Transmission

Nikola Tesla wanted to beam power without wires. NASA talked about building power-generating satellites that would do the same thing. But now New Zealand’s second-largest power utility — Powerco — is working with a start-up company to beam energy to remote locations. There have been several news releases, but possibly the most technical detail is from an interview [Loz Blain] did with the founder of the startup company.

It isn’t really news that you can send radio waves somewhere and convert the signal back into power. Every antenna does that routinely. The question is how efficient is the power transmission and — when the power levels are high — how safe is it? According to [Greg Kushnir], the founder of Emrod, the technology is about 70% efficient and uses ISM frequencies.

According to [Kushnir], the technology relies on metamaterials that are very efficient and a beam that sends all the power to the receiver, possibly through some passive relay stations [Kushnir] claims are like lenses and nearly lossless. Reading between the lines, it sounds like a modern take on the MASER with very good receiving antennas.

The relay antennas allow you to send power beyond your line of sight. Apparently, the power density is not enough to be very harmful if you intersect the beam for brief times, but a laser sensor can stop some part of the energy flow if something obstructs the beam.

Is it real? We don’t doubt it is possible. Their existing prototype sends a few watts about 40 meters, which is not a big deal. The new system will transmit “a few kilowatts” for a longer distance. The real question is can you safely operate at power levels that make economic sense based on actual efficiency. Honestly, 70% isn’t that great and even that sounds like it would be difficult to achieve over a long distance. But Powerco must see some promise in the technology, so we’ll wait and see how it goes.

Based on a tower we saw in Milford, Texas, we think Tesla had a different method in mind. We did recently see a Tesla coil-powered bike, though.

82 thoughts on “New Zealand To Test Wireless Power Transmission

    1. I imagine that you could modulate a constant carrier E-M field, capture the signal at a distance with a resonant structure, bandpass filter to select just the carrier, and downconvert the modulated signal.

      Oh wait.

  1. I hope they don’t use smart power meters… some of the concerned types will be worried about the RF from the power meters… which they read about on social media on their Qi charged phones…

  2. i just get annoyed at all these people yelling conserve save the planet etc…. but give me wireless everything even though the efficiency level compared to just using wires is beyond horrible. but hey if it is wireless it has to be great right….. so lets go boys

    1. It’s the same people that drive the constant demand for thinner devices necessitating delicate micro-miniaturized power connectors. Perhaps wireless charging will allow them to realize their dream of all smartphones being nothing but a thin sheet of glass, expensive enough to satisfy anyone as a show of status and so delicate you have to buy another one any time you breathe on it.

    2. IFF such a system can be made efficient enough it could work out much greener than running wires. It just won’t be the right fit for every location – but in areas that running wires requires huge infrastructure projects to get through and its likely to get damaged and need frequent repairs or replacements wireless can make sense even though its less efficient as a transmission method.

      Its the whole system efficiencies that matter – much like that new Tesla isn’t greener than an early petrol car by some metrics – all that new steel, aluminium and lithium refined at great energy cost all to build a vehicle that ends up charged by burning fossil fuel indirectly (if you are not charging your electric vehicle by renewable its just burning something somewhere else!). So while the new car, big power plant and small transmission losses might take the same chemical potential energy and go further than the early car, carbon per mile over their current lifetime including the production costs the old beast is almost certainly winning (and possibly will never loose – as battery recycling is very energy intensive too).

      That said I think Electric Vehicles are certainly a part a better for the planet future, just that they don’t automatically win on every count.

      1. Let’s call the “greenness” between the construction/delivery of an electric vehicle (EV) and an internal combustion engine vehicle a push (for argument’s sake). The point, and I’m guessing you actually do realize this but neglected to type it, is that rather than waiting for the power plants of the world to go sustainable THEN buying EVs, the buying of EVs can be done now knowing that power plants/grids are working on moving greener. Plus, depending on where you are, “personal” solar is becoming much bigger. (And, obviously, R&D continues to improve the efficiency of solar.) So, you buy an EV today. Some part of your “fuel” WILL come from renewable energy (at least in the US, there are solar/hydro/wind generating stations everywhere) and over time that percentage will increase (probably eventually to the point where you’re generating all of it on your own roof). It’s all upside. :-)

  3. A few Watts is a far cry from what is output down a HVAC 220kv transmission line in waste heat alone. So does that inefficiency scale with the increase of voltage then what happens when other factors come into play such as heat shimmer, misting/heavy fogs, parallax error, wind loading and worse case earthquakes effecting the aim of the plyons/towers over extreme distance?

    Is it practical to cover distances over impassible/difficult terrain (expensive)? Or if found efficient enough and cost effective to build upon the existing grid if an easier and more cost effective than the current HVAC lines and pylons.

    Also most homes (in my area of NZ) have smart meters that are definitely digital not that many bother to check. Probably depends on the council/district and the utilities. There was only a few 5g towers mildly damaged up on the North Island. Not bad for a sub 5mill population. Wonder what the numbers are like world wide for stupid actions like that.

  4. 70% may sound bad, but one has to remember that cables have losses too. I seriously doubt this will ever be practical though. And, I don’t beleive they will even reach anywhere near 70% efficiency under real conditions. This is most likely a scam to suck a bit of money out of the power company.

    Also. Cables are great for transferring power and data. Wireless doesn’t make everything cool. Wireless is good for mobile devices. Stationary ones are better off with cables.

    1. In the linked page the distance is “40 meters (130 ft)” and the power level is a “few watts” (so say more than 2 and less than 7).

      The free-space path loss at 2400 MHz over 40 meters would be:
      20xlog(40)+20xlog(2400) – 27.55 dB = ~72 dB

      So on paper all they need is for the transmit and receive antennas to provide 72dB of gain :)

      I would never say that something is totally impossible, but extremely unlikely is sitting firmly on the tip of my tongue.

      1. at 2.4GHz, an ideal 4M dish gives +40dBi of gain….
        put one on either end, and we’ll have +8dB (630%) system efficiency……
        why bother with cold fusion, we just need a series of 4M dish repeaters……

        seriously, though, you can run the numbers on this without building it.
        The diameter of the dishes on both ends should scale by approximately sqrt(range) once the beamwidth of one dish is wider than the other.
        At 40 meters, you’ll need 2M dishes on either end to get anywhere near 50% efficiency.
        Want to do 4km? You’ll need 20M dishes.
        You might get around this by building a series of lenses along the path, or a waveguide…
        Which leads us back to where we started… Infrastructure between points A and B.
        The most efficient infrastructure between 2 points for moving power? wire.

  5. 70% efficient sounds like it will be worse than just a regular pair of wires to be fair…

    Especially if all we move is a “few kW”. Sending that over a 3-14 kV line wouldn’t require all that many amps, and therefor rather low resistive losses along the way.

    Though, the question is if these remote locations could just use solar power (or wind?) + some batteries instead.
    “Off the grid” is rather practical if the grid itself isn’t a thing for miles around.

    One can though still drag over a wire, as to have additional redundancy, not to mention a higher peak power for those times such is needed.

    1. Well, let’s say you want to move 5000 watts, single phase 1 Km. Say, a pump in an outbuilding on a farm.

      10 gauge wire wold have a loop drop of 6.5 ohms.

      Using typical North American primary distribution levels of 2Kv that’s about 2.5A for a 17 watt drop.

      Assuming you’re powering the head end from the primary drop on a power pole, and the load end needs a transformer for a typical load voltage of 240 volts, you can still do the trip at 97% efficiency.

          1. Yes, at 50/60 Hz, the skin depth is rather deep…
            9.2 mm for 50 Hz, and 8.4 mm for 60 Hz
            (Where the depth is defined as: the depth where the current density is just 1/e (about 37%) of the value at the surface)

            So a 10 AWG wire at 2.588 mm diameter won’t be noticeably effected by the skin effect.

            The far thicker 5 AWG wire at 4.621 mm diameter would also not be majorly affected by the skin effect. (And that would only have a round trip resistance of about 2 ohms, for every 1 km, a lot lower than even a 10 AWG wire, though at a higher cost.)

            Though, I also do have to point out that a 10 AWG wire indeed does have 6.5 ohms of resistance.
            But with a 2.5 amp load, it will actually burn about 40 watts. (A trivial mistake on SteveS’ part. (They forgot to square the current. R*I=V and V*I = P Thereby: R*I^2 = P))

            Now, one could also just increase voltage to have less current to start with, but eventually stuff like corona discharge and other static effects starts to become a real problem… (And eventually one needs to start bundling wires with spacers, as to make the wire “look” thicker than what is actually is, as to reduce said static effects, due to charges having a tendency to accumulate at sharp protruding edges…)

    1. Not *that* hard. The key is they’re not really going that far, and the total power capacity’s small. It’s just optics. We send signals with equivalently high receiving efficiency and super-low loss using creative optics all the time. We just call them optical fibers.

      The sketchy part to me is the claim of near-lossless relays. That seems a bit marketing-ish. I mean, if he said “they’re 95% efficient” I’d say OK, sure, that’s not nuts. Limits you to 4-5 hops in distance practically, but still kinda interesting, and I can definitely think of some use cases. But he seemed to imply that the losses were so small as to be trivial, like 99% efficient, and that seems way too good to be true.

  6. 70% efficient sounds…unikely.

    Inverse Square Law’s gonna bite ’em. And how are they going to keep the radiated power from energising things they don’t want energised…like fences, cars, bicycles, etc?

    Every few years we get a bright startup that promises wireless power transmission, and then we never hear from them again. Tesla could never make it work, I doubt this startup will be able to find a way around the laws of physics either.

    1. I always check the date when I see stupid.

      “Emrod uses beams in the ISM (Industrial, Scientific, and Medical) band with frequencies commonly used in WiFi, Bluetooth, and RfID.” (ref: )

      WiFi could be:
      900 MHz (802.11ah)
      2.4 GHz (802.11b/g/n/ax)
      3.65 GHz (802.11y)
      5 GHz or 5.9 GHz (802.11a/h/j/n/ac/ax)

      Bluetooth could be:
      2.402 GHz to 2.480 GHz

      RfID could be:

      What frequency could the be using ? Is it 2.4 GHz, why did they they not mentioned microwave ovens.

    1. There are a couple of reasons that come to my mind:
      a) They can fall down due to intentional or accidental actions of humans, animals, or weather.
      b) They need maintenance. Maybe not that often, but physical stuff wears over time.
      c) Many (or “most”) people think they can mar views. If you’re lucky enough to have a few trees outside of your window, having power lines (and poles) in your frame is sub-optimal.

      Now, if you wanted to bury the lines instead of putting them on a pole… :-)

  7. Hello yes who is this. Oh this is the inverse squared relationship between distance traveled and power.

    Power density = (Power output * gain)/(4*pi*distance^2).

    Hello yes we would like 70% power efficiency. Well so would energous, Ubeam, and every other wireless power HACK. It is a lie, there is no avoiding this reality. Qi chargers are wireless power with a range of about 4inches and they barely can crank out 70% efficiency. To get enough power to someones house to turn on a heater you would need to make the transmitter have a 100meter death radius no one could stand in.

    1. Oh I just noticed they did the same trick every other cancerous startup in this field does.

      Hey look we could transmit a pittance of power over a short distance. Now all we do is wave the magic engineering wand of scaling and job done.

      What scaling is literally the whole problem with this idea? That’s redicilous, if I just hire more engineers they can fundamentally alter physics no problem.

    2. LASERs and MASERs don’t follow the inverse square relationship, though, as the beam divergence is so low.

      I guess this could make sense if one needs to get a few hundred watts of power to something that is on top of a big hill – a cell tower or similar.

      1. That is a bit of an oversimplification. An ideal (aka pretend) laser does not follow the law. However, real lasers have beam divergence and so the power loss is proportional to r^2. Now that said it is also a function of the beam divergence so if you can keep that reaaalllllllyyyyy low then over kilo meters the power loss may be somewhat not insanely bad. You would still have the reality that if anything walked through that beam it would be cooked.

      2. The idea that the inverse square law does not apply to lasers (and MASERs) is a very common misconception.

        Nowhere does it mention explicitly that they are using a MASER (other than an educated guess by the author Al above), they are using lasers to detect anything entering the RF beam, that should not be there for safety, so that they can power off the RF to avoid slow cooking. Although at only a few watts spread over what looks like a meter it might take quite a while to warm anything up.

        Plug “MASER” into your search engine of choice, and you will not find any mention of it. A parabolic antenna at microwave frequencies will typically produce the highest gain, or achieve a narrow beamwidth. Why add the complexity of of needing to cool things down with a cryocooler typically needed for a MASAR, that will not help to improve the efficiency.

        1. There’s nothing special about lasers and masers in this regard. It’s exactly like whisper dishes at any science center: so long as your receiving device captures and refocuses all the energy, there’s no loss.

          Another way of saying this is that the inverse square law is just for far-field. With a laser, because the beam is so tightly collimated (and it’s optical) a small lens is still in the transition region.

        2. A Horn o plenty antenna (yes, that is its real name) can have slightly higher efficiencies than a parabolic dish. The problem is that they’re expensive, unwieldy, and difficult to mount.

          In decibel terms, it’s not much. But if you’re sending power, every watt counts. So the difference between 50% and 60% efficiency is worth something.

    3. Read the interview and understand what the product is before commenting please. This isn’t magic “power everywhere” wireless, this is a directed beam that’s meant to replace sections of physical power lines where the construction and maintenance of the lines is problematic (islands, mountainous regions, etc). They’re not using a light bulb on a string, they’re using a focused flashlight through a series of lenses. It may be a scam, but at least get a basic grasp on the concept before yelling about it. Unless you’re an “Inverse Square Law Bot”, in which case I need a nap, because the internet is exhausting.

      1. Yeah, I get that, but the client base for “I just need to power the Jacuzzi on my island separated from the mainland by a thousand-foot-deep ferry channel, but fortunately I can erect a small microwave tower on either side” is pretty slim.

          1. Yeah, but they also have these things called solar cells and batteries. They work pretty well too, given the power requirements of most communications equipment.

    4. You are using a formula for an isotrpic antenna, emitting in all directions.
      If the beam is focused, you must take into account directivity of the antenna. Laser or non-coherent focused sources are good examples.
      However, I have no clue, how you can accurately focus a high energy beam in GHz range.

      1. Same way you focus anything, with a reflector or a refractor of the right shape. At microwave frequencies you can compress the beam pretty tightly with a reasonable parabolic dish, and the diffraction’s not too bad. It’s still just a wave.

    5. You might want to look up where the inverse square law comes from: it’s intensity, not power. Formulas that use it for power (like Friis’s equation) only are for the far field.

      Sound waves follow an inverse square law in the far field, too, but little kids play with whisper dishes at science centers all over. Why? Because they’re not far field.

      Surround the Sun with a Dyson sphere. How much power do you get? All of it.

      Make the Dyson sphere twice as large in radius. How much power do you get? *Still* all of it. There’s no inverse square law for total power. The solar flux drops, sure. But not total power.

      Same here. It’s not magic. Just optics. Beam power out tightly, make sure you collect all the power (and refocus if necessary), and you’re fine. You’re of course limited by diffraction, so you can’t infinitely focus the beam. Hence why you do it at high frequency.

  8. How could have engineers at Powerco got into this nonsense? Or maybe it is all political and they didn’t have a word in it. When talking about remote area it usualy imply small villages, low density population where wind turbines or solar panels would fit best.

    1. Wind turbines and solar panels are truly great things for remote areas.
      Especially together with a bunch of batteries.

      Running over grid based power is an advantage, but having some self sufficiency in remote areas is generally better. Since if the power lines go down, then it isn’t going to be more than an inconvenience.

      Though, if one has an oversupply from one’s solar and wind, then it is nice to have a grid to feed it to, as well.

    2. I know someone who works for a US city department of energy who funded solar roadways.

      The engineers were given exactly 0 input on these kinds of decisions. This person collects the report that solar roadways puts out and then hopes to never think of it again because shockingly it’s a terrible idea but has great PR.

    3. The one thing Wind and Solar is not is reliable. The off-grid concept is nice, and can work for households easy enough. Its a bit harder to manage use to supply for the few hundred ish people though. Overspecing enough and lots of energy store can help – but its still not a certainty.
      So if its just a relatively low power transmission from the grid to those places to keep the lights, water and probably cellular antenna powered (i.e the essentials) when the local generation is insufficient. Wireless could well be the winner on every front – cost and efficiency – better than hauling tonnes of gas/coal/diesel up there by truck for a generator to make up the shortfalls.

      I admit I’m more that a little sceptical on their claims. But its certainly even at worse efficiencies than that potentially the best solution.

      1. Oh and I hope also transmission back from the town once the batteries are full and they have the oversupply. Even at something stupid like 90% loss getting anything ‘free’ back into the grid isn’t a terrible thing.

    1. Actually, the Industrial, Scientific and Medical bands are the exception to these rules.

      The bands were made for things like induction heaters, microwave ovens, and other high power applications.

      Stuff where filtering and shielding said noise were frankly non trivial. So legislators around the whole world decided to band together and give such applications their own space.

      Like I don’t want to start thinking of the RF shielding requirements of an arc furnace to just keep it’s emissions within an ISM band, let alone block all of its emissions…. (Though, these facilities are thankfully rarely one’s next door neighbor.)

      But in effect, the ISM bands have no limitations on max effective radiated power, nor duty cycle.
      If your ISM application requires a CW tone at 2.45 GHz, with x many kW behind it, then you are practically free to do so. (Though, one will need an actual ISM reason to do this.)

      The only real limitation is on data communications.
      There, one needs to use spread spectrum.

  9. No doubt there are a lot of if’s. I wonder if the beam is hot enough to deter vegetation on it’s own. 70% efficiency sounds bad, but depending on where you are going, what you have to cross to get there and the cost of ongoing maintenance or the lack thereof could make that figure sound a lot more appealing. Look at the wildfires that that power transmission lines have caused. Look at the ongoing maintenance the utilities have to keep vegetation away from the wires. Something to ponder at any rate.

    1. 70% doesn’t sound bad. It sounds like a figure some scam artist pulled out of his ass zu convince a gullible idiot that the beans are magic.
      And no distance given too.
      I can believe a meter or 2.
      If you believe it is much further: give me a call. i have a couple of magic beans for sale.

  10. “how safe is it? According to [Greg Kushnir], the founder of Emrod, the technology is about 70% efficient and uses ISM frequencies.”

    So… Mr Kushnir’s answered the question of “is it safe,” is to talk about something else (efficiency).

    In my book if the answer does not address the question, it means that the answer is negative.
    So, they know it is Not-safe, or they do not know if it is safe and do not want to go on record as saying it was.

  11. Sir, we are moving towards Distributed Generation is this system efficient enough to cooperate with smart grid?
    Second question… In this system there’s no chance of back to back tripping…right?
    Third one… Can it cause interference with other frequencies?

  12. This has been touched on my other commenters, but I wonder just how tight the beam is and what the sidelobe pattern looks like. I guess an ~6×6 meter (~~40m^2) phased array could have a pretty tight pattern, but (a) phased transmitter arrays are pretty expensive, no? (I dunno, maybe a design with a fixed beam direction wouldn’t be, as it’d just be a matter of having the right fixed phase delays between elements, and (b) when you’re transmitting 10s of KW, even small leakage could have long-term health effects.

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