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Old 05-08-2015, 12:27 PM   #21
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But since these are very skinny structures isn't the swept area of one of these devices much less than that of a conventional turbine of similar height?

It does look like a cool idea, but I wonder if one would need to use a LOT of these to replicate the output of a turbine.
I was wondering about that swept area comment as well. I looked it up, and swept area for a turbine is just what you would expect, Pi*r^2 for the blade radius. Not sure what is equivalent for this thing - how wide of a path is it 'sweeping'? But it would seem like a small fraction. It will be interesting to see if their numbers hold up with their 4KW model. I guess we could find 4KW wind turbines for comparison (again, assuming their projections are even close).

I have to admit, it's tough to imagine something oscillating in the wind being anywhere near as powerful as something with blades. Little whirly-gigs spin pretty fast in a light breeze, how much motion/force can you really get from this?

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Old 05-08-2015, 12:35 PM   #22
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I have to admit, it's tough to imagine something oscillating in the wind being anywhere near as powerful as something with blades. Little whirly-gigs spin pretty fast in a light breeze, how much motion/force can you really get from this?

-ERD50
Oscillations can bring down bridges and buildings...seems like a lot of energy?
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Old 05-08-2015, 12:43 PM   #23
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Oscillations can bring down bridges and buildings...seems like a lot of energy?
That was a lot of force, but was it a lot of energy (force times distance)? I don't know, could be both.


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Old 05-08-2015, 07:11 PM   #24
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I don't think so. Adding stuff to it would just make it get pushed over, they want it to oscillate in the wind.

-ERD50
Trees sway in the wind.

I have lots of 80 to 90 footers at my camp, with crowns around 20 feet in diameter, they deflect to about 15 feetm naybe even more, I'll measure one of these days, from vertical in 30 to 40 mph winds. Surely some smart mechanical engineer along with carbon fiber designers can make an analog to that.
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Old 05-08-2015, 07:15 PM   #25
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Oscillations can bring down bridges and buildings...seems like a lot of energy?
From wiki:



Collapse of the Tacoma Narrows Bridge



Tacoma Narrows Bridge Collapse Tacoma, Washington
November 7, 1940
by Rachel Martin


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Old 05-08-2015, 07:21 PM   #26
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Trees sway in the wind. ...
Sure, but is that the optimal configuration?

These guys don't strike me as dummies. For now I'll assume that if adding 'branches' to that structure would improve the power output, they would have designed it with 'branches'.

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Old 05-08-2015, 08:56 PM   #27
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I'm guessing the energy is harvested with a disk towards the base (he pointed to the linear alternator as being ~ 1/4 of the way up I think). I picture the disk/magnets being horizontal, and the coils in a fixed toroidal arrangement above and below the disk, so any movement of the disk has the magnets moving in relation to those coils and creating a current.
I'm trying to figure out what type of setup could harvest an appreciable amount of electrical energy from such a slow, high-torque mechanical motion--without using gears to get the speed of the armature (or magnets) up. It would seem to me that, without high speeds, the coils and magnets would have to be very robust to produce appreciable electricity. The info from the company mentioned some type of electronics that artificially mimic mechanical gearing.

It's impressive that these three guys hit on two complementary and apparently novel ideas simultaneously--this vertical mast that produces the oscillatory motion due to wind/vortices, and the electromechanical means to turn that relatively slow motion into electricity. I'm pretty sure this won't be the final evolution of this concept, but it's pretty cool as-is (if it's even close to the claims).
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Old 05-09-2015, 08:45 AM   #28
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Lots of fascinating approaches being explored - though cost, "energy" storage and intermittent sources remain the larger obstacles (vs generating while sources are available) IF we expect to maintain our current 24/7 access to "energy."

Reading the discussions here reminds me: All truth passes through three stages: First, it is ridiculed; Second, it is violently opposed; Third, it is accepted as self-evident. - Arthur Schopenhauer

Saphon Energy
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Old 05-09-2015, 09:27 AM   #29
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Lots of fascinating approaches being explored - though cost, "energy" storage and intermittent sources remain the larger obstacles (vs generating while sources are available) IF we expect to maintain our current 24/7 access to "energy."

Saphon Energy
Interesting - this video shows that it 'wobbles', I guess it fills with air, tilts to the side to release that air, then re-centers to be filled again. Three pistons capture the energy electro-magnetically.

https://www.youtube.com/watch?t=15&v=ml6hiN4nCDA

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... Reading the discussions here reminds me: All truth passes through three stages: First, it is ridiculed; Second, it is violently opposed; Third, it is accepted as self-evident. - Arthur Schopenhauer
I'm not following you, unless you are trying to say this idea does not represent 'truth'. Where is the ridiculing and opposition?

I see questions about how they generate the electricity, questions about stresses, but no ridicule or opposition.

At any rate, I think that quote is overused and misused. I don't think all truths or new ideas are ridiculed (overall that is - you will always find someone who is opposed to any idea). Many good ideas are accepted very quickly. Did the general public ridicule the idea of, hmmmmm, recording TV shows at home for later playback? Carrying a telephone with you? Carrying your music with you? Portable computers?

And misused because not every idea that is ridiculed ends up being a 'truth' or a good idea. Yet many people tend to think this way.

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Old 05-09-2015, 09:42 AM   #30
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Oscillations can bring down bridges and buildings...seems like a lot of energy?
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Originally Posted by ls99 View Post
From wiki:



Collapse of the Tacoma Narrows Bridge


Tacoma Narrows Bridge Collapse Tacoma, Washington
November 7, 1940
[B]by Rachel Martin
...
Looking back at the Tacoma Narrows bridge collapse, the energy was due to flutter, similar to these blade-less designs.

https://en.wikipedia.org/wiki/Aeroelasticity

In the bridge, the flutter worked with the 5 second period of resonance of the bridge. So it takes relatively little forces to create large displacements when that force is in-sync with the resonance of the system. Just like a large pendulum swings wide with very, very little pushes an each swing.

So the fact that the bridge collapsed does not say all that much about the forces involved, it says more about those existing for a long time (I think they said it was about an hour between when the oscillations were first observed and the collapse), and the flutter working in-sync with the resonance of the bridge.

Once you try to draw power from that resonance, you dampen it (lower the Q in engineering terms).

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Old 05-09-2015, 10:40 AM   #31
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Once you try to draw power from that resonance, you dampen it (lower the Q in engineering terms).

-ERD50
True, but I imagine it still would have been a fairly large electric motor to cause that many tons of concrete and steel to oscillate several meters and with up to a 45 degree twist. That has to generate heat in the steel which is drawing off some of the energy.


Even with resonance, there was probably several hundred kilowatts (maybe megawatts) of energy being absorbed by the Tacoma Narrows bridge in the 42mph wind.


It does now give me the idea of designing a windmill based on a poorly damped suspension bridge. :-)
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Old 05-09-2015, 10:48 AM   #32
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In the postscript, I corrected myself when I observed that the vibrating structure - indeed not an airfoil in the normal sense which is designed to avoid creating vortices - is symmetrical and will respond to wind from all directions. I also wondered how their "linear" generator would respond to oscillations in different vertical planes.

Anyway, any novel new design will avoid existing limitations just to create some new problems. And the designer will not discover them until he tries. And people will have to try, else we would be stuck with horse-drawn carriages. I am not a naysayer, but just try to figure out what problems he will have to solve.

And talk about vertical wind structures, how about more conventional designs like the following? I looked at a few that have been in production, figuring that if one is inexpensive enough I would buy a small one to play with in my high-country home which has lots of wind. They are more expensive than conventional turbines!


The world should be thankful it is not all populated with people such as myself. I can hear myself now if I had lived in previous times... "Nothing will ever replace the spear to kill our food".... "This automobile thing will never replace a good horse"...." These personal computer things are a fad and will soon too pass".


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