Experimenting With Vibratory Wind Generators

We’ve all got a pretty good mental image of the traditional wind-powered generator: essentially a big propeller on a stick. Some might also be familiar with vertical wind turbines, which can operate no matter which way the wind is blowing. In either case, they use some form of rotating structure to harness the wind’s energy.

But as demonstrated by [Robert Murray-Smith], it’s possible to generate electrical power from wind without any moving parts. With simple components, he shows how you can build a device capable of harnessing the wind with nothing more than vibrations. Alright, so we suppose that means the parts are technically moving, but you get the idea.

In the video after the break, [Robert] shows two different devices that operate under the same basic principle. For the first, he cuts the cone out of a standard speaker and glues a flat stick to the voice coil. As the stick moves back and forth in the wind, the coil inside of the magnet’s field and produces a measurable voltage. This proves the idea has merit and can be thrown together easily, but isn’t terribly elegant.

For the revised version, he glues a coil to a small piece of neoprene rubber, which in turn is glued to a slat taken from a Venetian blind. On the opposite side of the coil, he glues a magnet. When the blind slat starts vibrating in the wind, the oscillation of the magnet relative to the coil is enough to produce a current. It’s tiny, of course. But if you had hundreds or even thousands of these electric “blades of grass”, you could potentially build up quite a bit of energy.

If this all sounds a bit too theoretical for your tastes, you can always 3D print yourself a more traditional wind turbine. We’ve even seen them in vertical form, if you want to get fancy.

[Thanks to Itay for the tip.]

40 thoughts on “Experimenting With Vibratory Wind Generators

  1. If this was real, he would have shown the meter’s screen — if that’s standard Fluke meter, he appears to have it on the mVDC scale — he’s not measuring the AC output at all. Secondly, you can’t efficiently extract useful electric power (rectify) a random AC signal with just mV of amplitude.

    I don’t believe handheld wobbling bits of magnets, rubber and windings is doing anything useful.

        1. Think bigger, supersized coil, rattle the iron core of the earth up and down. Just need to hack the Chinese power grid, switch off everything in the middle, route it all round the outermost lines in an approximate circle… just need a small injection of seed financing…

  2. Piezo versions show more merit and ruggedness -they periodically turn up in “power generating shoe” projects! However such environmental energy harvesting is small beer compared with using ambient solar – if light’s available -and if course PV is already DC too.

    1. Did they get any further than 12mW do you know?

      It occurred to me that if you constrain it at both ends, you force those to be nodal points whether it does half lambda oscillation or higher harmonics, so the ends have the lowest energy. The highest energy is at 1/4 lambda, whether that’s half way or at thirds or quarters depending on oscillation modes.

      So what I’d want to do, is determine tension for the broadest range of windspeeds to keep the fundamental frequency, and stick a low mass magnet in the middle and use a pickup coil there. (IDK if bass guitar pickups would be worth a try)

      It would be “cool” to have these strung along the side of your house if you could make power worth bothering with, IDK where that starts, a watt each??? Made from something simple like dollar store ratchet straps, and with close spacing they would shade the side of your house a bit, and reduce AC load as well as generating. However, I don’t think they would be quite as noise free as imagined in brisk to high winds, probably start to notice the low frequency hum and whoowhoowhoooo wind noises.

      1. Well you could call even a single watt hours over a whole day useful – Depends so much on what you wish to achieve – but a few lower power LED lamps or small remote sensing project could get useable working time on very little. Doesn’t power your PC/Fridge/Freezer/Air-conditioning/heating systems at all. But hey at least you have some light or can keep that air quality monitor sending data every so often etc.

        I’d think you would do better making the wave out of coil rather than magnet on the wave and put the magnet(s) where they will do you most good.

        Can’t say I think the method looks particularly practical though – if you are going to have moving parts and so have mechanical wear why not just go the highly efficient motor style generator and flappy aerodynamic thingies to make it spin?

  3. He says the first wobbling blade thing generates 12-18V, which sounds way to high to me. Obviously, the meter isn’t drawing any significant current (it’s probably 10 megaohm input impedance). The current would be limited by the coil impedance; that is, the vector sum of the resistance and reactance at the given frequency. I have no clue what the order of magnitude of the inductance would be, so I can’t estimate the current or power. Also, drawing a current would generate a resistive force on the coil, which would dampen the resonance of the blade, which would reduce the amplitude, and therefor the voltage.

    The second prototype seems very inefficient; rubber is a very lossy spring, and the orientation of the magnet and the inductor core causes a relatively small change in flux in the inductor for a given amount of relative movement.

    I doubt something like this would ever generate a significant amount of power, to be worthwhile to feed into to grid or into a home battery bank, but it may be useful as an energy scavenging method, for off-grid, very low power devices, such as sensors in remote locations. Even if it just produces a milliwatt, it might be useful, and if constructed properly, it might be much more reliable than other methods (solar panels get dirty, rotating generators foul).

    1. I was thinking, what if you had a couple of beams with a dozen of these on, and lowered them either side of your boat at anchor to scavenge power from currents, eddies and wave action, wonder if that would be worthwhile.

      1. Just let the prop spin in the water? I know some sailboats will deliberately do that on the move as a generator. Can’t see why you can’t do the same with the tide/currents, just need to point your propeller into the flow correctly. Which in general you would want to do anyway!

        And if you have a boat – it almost certainly already has and needs a prop. So you are making it work for you in two ways rather than building another thing that serves no additional purpose. How easy retrofitting passive power generation into the drive system is a possible issue, but hardly going to be insurmountable. I also wouldn’t expect much energy out most of the time – small prop and slow flow etc. Expect its as good as this though.

    2. The limiter for milliwatt scale power generators is a rechargeable laptop battery is both not terribly big nor heavy and stores on the order of 100K milliwatt-hours, although non-rechargeable can do somewhat better. So if weight is not an issue you need to build a mechanical generator capable of 100K+ hours of unattended unmaintained operation to beat the performance of a lump of a battery that has wires coming out of it. Aside from operation, merely surviving outdoors in the weather for 100K hours is a pretty good challenge. Some roof materials in some climates struggle to achieve 100K hours without maintenance. And the mission has to last longer than 100K hours to even meet the breakeven point and 100K hours is about a decade, so …

  4. Colin Kapp, a delightful 60s Brit SF writer, wrote a few short stories about “The Unorthodox Engineers”, a group of engineers sent around the galaxy to try to solve weird problems with no resources and even less support.
    His story “the Subways of Tazoo” has a substantial bearing on this post – I won’t spoil the story by revealing any details but it really is worth a read just for the confirmation that there’s nothing new under the sun, now as ever.

    1. People do harp on about the obscure sci-fi they read… just kidding, read it a few months ago. Was pretty good, if a tiny bit obvious and plodding. Had no idea there were other stories though, my copy was in an assorted anthology, will have to look them out.

  5. Ofcourse you can get energy from this setup, but only small amounts, it’s determined by physics.

    If anybody tries to sell you this as the big break through and that it just needs some tuning, please remember that wind energy is relatively easy to understand, with 9th grade math and physics:

    The energy wind has, is kinetic energy: E= 1/2 * m * v² (and according to betz’ law you can only use ~59%)

    1.) mass
    2.) square(velocity)

    m = is determined by volume (times) air_density

    Now make your calculation for the volume of this singing leaf -> it’s very very very small and it’s swept area is changing from end to end.

  6. This should also work under water, perhaps in a river or tidal area.
    There’s also another option, take a ping pong ball and put it in the plug hole of your sink and add some water. It’ll vibrate rapidly with little to know effort to get it started and it’s pretty efficient as far as flow rate goes.

    1. There was an experiment years ago with a cylindrical obstacle to shed vortices and one or more sideways moving vanes to capture the energy. The video was on YouTube.

  7. ” … it’s possible to generate electrical power from wind without any moving parts. ”

    “As the stick moves back and forth in the wind, the coil inside of the magnet’s field and produces a measurable voltage.”

    ?

  8. This title is so confusing. I thought, how can you generate wind in a vibratory way? Maybe reversing the principle of a brass instrument’s reed? But the turbulent nature of moving wind doesn’t lend itself to reversal. (Something flowing fast enough creates turbulence, as explained in https://youtu.be/5zI9sG3pjVU, but turbulence doesn’t cause flow) Maybe some new discovery, or a way of ‘steering’ the turbulence in *just* the right way to cause flow? Maybe just something like the non-intuitive dynamics of a bumblebee’s wings?

    It wasn’t about a wind generator at all, but about a wind-generator.

  9. When a voltage is created an idea pops to mind, harness sound. Rather the sound waves which can also be harnessed. Combining both in wind chimes as an experiment? How about some input from all of you?

    1. but wait, let’s think about the huge forces that made that bridge fail….. Surely with such huge oscillations and appropriate generation coils/magnets loads of power should be extractable. The key here seems to be not so much flutter but resonance. The second video shows it clearly, it’s way more intense. So in real life some way of dynamically tuning the tension would be required…a type of electromechanical mppt system. With some historical data the tension could be predicted and just fine tuning be done to maximise the resonance. Maybe also the location of the generation coils could be tuned to be at the appropriate wavelength as mentioned in some comments. As usual there is a sweet spot with not a whole lot happening when not in it. Of course for low power harvesting for say a sensor then the reed approach might just be a ticket but for a remote power or grid feed thats a different situation.

  10. “But if you had hundreds or even thousands of these electric “blades of grass”, you could potentially build up quite a bit of energy.”

    And a buzz like a bazillion angry bees. Ever heard a breeze blowing through Venetian blinds?

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