Bladeless wind turbines--big and small

[samclem]

A Spanish startup has developed a wind turbine that uses the pressure differential caused by vortices passing a single mast to generate power, replacing the blades on a conventional wind turbine. They say the benefits are:
Lower noise
No dead birds
53% reduction in manufacturing costs (compared to large conventional wind turbines)
80% reduction in maintenance costs (no rigid parts rub against each other, no periodic lubrication, etc)
More at this link: Forbes article
They are planing to build big ones, but also 100W units for remote villages in the 3rd world and a 40' tall, 220 lb unit with a capacity of 4KW for use by off-grid homes (together with solar).

Compared to regular wind turbines, this design collects 30% less energy for the same swept area, but the devices will be cheap enough to build, install, and operate that they say it will reduce the cost of wind power by over 50%. Time will tell.

Investment opportunities will reportedly be available, obviously any money plunked down on this would be highly speculative. But the tech is interesting.
Unfortunately (to my eye), a field of them would be just about as ugly as regular wind turbines. Still, if I had an off-grid house, I'd much prefer a few of these at the edge of my property than a spinning wind turbine. The company's web site is obnoxious, but contains this bit about how it works. It just oscillates a bit in the breeze, that produces the power.

Video of Bladeless Wind Turbine

 

[Fermion]

Interesting! It is like the sway in skyscrapers (which are designed to sway)

I wonder how they capture the energy? I would probably try rare earth magnets on the swaying shaft somewhere near the bottom and fixed coils of wire (any change in magnetic field passing through a wire will generate current in the wire, it doesn't have to be in the form of a traditional rotating motor/generator).

Sounds like something you could build in your garage in a few hours.

 

[samclem]

I wonder how they capture the energy?

I dunno either. I was guessing it might be some type of piezoelectric gizmo.

 

[ERD50]

Very interesting - this video has some English, and it says electromagnetic:

I like the fact that they are not hyping the efficiency, they admit it is lower, but expect the cost to be even lower on a $/W basis.

The prototype runs in low winds (3-15 mph), and we know there is very, very little power there. They say their next proto shoots for operation in 7~ 33 mph winds. So hopefully they get there.

I'm curious just where they capture the motion to drive magnets.

I think they have the right plan - if this works, combine with solar and batteries, and you have some complimentary power sources (so smaller battery, and/or longer storage time) for 3rd world, off-grid use. Long way to go to see if it can compete with the big blades.

-ERD50

 

[Brat]

Vestas should be on alert. If this system can be made cost effective it will be a game changer.

 

[audreyh1]

Very cool!

 

[NW-Bound]

Conversion of mechanical motion to electrical energy is of course by electromagnetic means, but I could not find any description of how they do it. But I suspect that they have internal counter-oscillating masses, similar to flashlights that are powered by shaking. See: Mechanically powered flashlight - Wikipedia, the free encyclopedia.

The oscillating airfoil must face the wind properly, and as the wind changes direction, the structure must have a bearing at the base for rotation. There are still moving parts, and so this interesting design will have different problems to solve, such as fatigue of various restraining springs or internal parts.

PS. I am not an aerodynamicist to know if the oscillating structure can be designed to be symmetrical, but their inverted cone appears to be. If so, it can respond to wind from any direction (the plane of the oscillation will be perpendicular to the wind direction). Then, it would not need to rotate to face the wind, but extracting the power from the motion is going to be trickier because the plane of the motion is not fixed.

PPS. I found the following presentation that talked of having the electrical generator all at the base. Initially, they used some piezoelectric material, but that provided very little power. So, they are working with a new "linear generator" design using magnets. Not much more details or diagrams were provided.

 

[samclem]

The oscillating airfoil must face the wind properly, and as the wind changes direction, the structure must have a bearing at the base for rotation.

I'm not sure about that. The units in their video and picture don't appear to have a "normal" airfoil (with a leading edge, trailing edge, camber, etc). It's just a tube or in other instances a slightly tapered cone, and that would be able to use wind from any direction without needing to pivot, no bearings, etc. But it does oscillate, so likely there's a spring or a flexible (?composite?) section that might eventually fail due to stress. Still, with the right material choices and engineering, that could take a LONG time.
Blades on conventional turbines also bend and probably have fatigue life limits, too. A failure of one of those would be a lot more dangerous and lot harder to mitigate through mechanical means than a failure of the mast on this new design (Whatever comes off won't be traveling any faster than the wind, and likely to fall pretty close to the base. Not so with a conventional turbine blade.).

 

[cantlogin]

Let's glue some branches and leaves on it and call it a tree.

 

[ls99]

Let's glue some branches and leaves on it and call it a tree.

Right. With the added surface area more wind is captured, bigger deflection, more power. The moving parts would need to be more robust to handle the additional loads.

See, bigger is better.

 

[ERD50]

But will he have a patent battle with Claes Oldenburg (this is the Batcolumn, some 'artwork' in Chicago)? Maybe it can be upgraded to produce energy?

I'm not sure about that. The units in their video and picture don't appear to have a "normal" airfoil (with a leading edge, trailing edge, camber, etc). It's just a tube or in other instances a slightly tapered cone, and that would be able to use wind from any direction without needing to pivot, no bearings, etc. But it does oscillate, so likely there's a spring or a flexible (?composite?) section that might eventually fail due to stress. Still, with the right material choices and engineering, that could take a LONG time. ...

I also thought it was non-directional. Here's some science on the effect:

http://en.wikipedia.org/wiki/Vorticity

And I wonder about fatigue also, seems to be a lot of bending going on, but then again, distributed along most of the lengthen. That's an engineering/materials problem, so it can be answered by the right people with the right information.

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.

It's also interesting that they found a second one near the first created more energy, due to the vortex from the first, though they don't know how far this will scale up.

So their 4KW model is ~ 40' high - not small by any means, but if it hits a capacity factor of 25% (seems conservative from a little googling), that's about enough to power a home.

Let's glue some branches and leaves on it and call it a tree.

Right. With the added surface area more wind is captured, bigger deflection, more power. The moving parts would need to be more robust to handle the additional loads.

See, bigger is better.

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

 

[NW-Bound]

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!

 

[Fermion]

I have toyed with the idea of building a wind generator based on sailing. Advantage would be it could work in extremely light winds (say 4 or 5mph) and could be scaled up with a taller mast and sail.

The mechanism needed would be something to spill the wind in the "jib" and sheet it in for the next linear power stroke. Then a simple linear motor wired as a generator to capture the energy from the stroke.

 

[NW-Bound]

Designs that work well in light winds will break when the wind gets strong. You can't win.

 

[ERD50]

Designs that work well in light winds will break when the wind gets strong. You can't win.

It could be possible to have a design that would actively pull in the 'sail' (or other mechanism) as the wind increases. They do that on sailing ships, don't they?

I'm not saying it is practical, just possible.

-ERD50

 

[Fermion]

Designs that work well in light winds will break when the wind gets strong. You can't win.

You could use a roller furling to lessen the surface area of the jib during high wind.

 

[imoldernu]

Bladeless windmills opens a whole new science.EWICON bladeless wind turbine generates electricity using charged water droplets

 

[Lakewood90712]

I better read up on this , as I seem to be in an Inherit the wind situation .

 

[NW-Bound]

It could be possible to have a design that would actively pull in the 'sail' (or other mechanism) as the wind increases. They do that on sailing ships, don't they?

I'm not saying it is practical, just possible.

-ERD50

You could use a roller furling to lessen the surface area of the jib during high wind.

Yes. But it creates more things to fail. Things that start out simple are no longer so.

 

[stepford]

Compared to regular wind turbines, this design collects 30% less energy FOR THE SAME SWEPT AREA

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.

 

[ERD50]

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?

-ERD50

 

[Fermion]

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?

 

[ERD50]

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.


-ERD50

 

[ls99]

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.

 

[ls99]

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