My suggestion is very different from yo-yo and Fly-Gen:
A laid Savonius rotor from thin plastic sheets, held by a plastic ring,
lifted by a drone (then the rotation can provide lifting force),
and a tether loop transmits down the perimetric movement (high speed, high force)
Can be big (20 m rotor length, 400 m elevation, MW-performance).
Can be built quickly, at very low costs.
There are several options yet (cross-wind, blade shapes, etc.).
Searching for a team to build prototypes.
Welcome to the forum @kerati.
Please can you provide a sketch of what you intend to do?
Some AWES concepts based on Savonius rotor type has been discussed in the forum, and sometime realized:
Hi Pierre,
Roddy told you will be interested. The drawing:
Yes, similar to Magenn rotors, but I suggest reverse rotation (to get more lifting force).
And a ring holds the blades, avoiding large torque (so that a thin sheet can handle the wind with its tension strength only) and it can provide maximal tether speed.
Hi Attila,
You could replace the drone with a lifting kite.
As it provides lift by Magnus effect, reversing rotation would lead to a negative lifting force.
Pierre, i think he is talking about the rotation in “the drawing”, which shows a slack tether going to the tension side, and a tensioned tether going to the slack side, which makes no sense as a start. Regardless, I think he means reversing the supposed rotation direction in that one drawing, to yield lift like a flettner/magnus rotor or a Sharp rotor, with the top of the cylinder traveling downwind, rather than upwind. Whether a Savonius would give similar “lift” to a Sharp rotor or Magnus rotor, I do not know. As we know, with wind being invisible, we can imagine it doing whatever we want, so I won’t speculate on whether a Savonius rotor can give lift in whichever direction it spins. I should know this I guess, but i don’t, although I’ll bet somebody does!
(Pierre could build one and test it with the change in his pocket, and so could anyone else if they just tried.)
Savonius is the least-efficient type of wind turbine commonly discussed, dating back thousands of years, before the concept of aerodynamic “lift” was implemented, which was about 1000 years ago when modern, bladed wind turbine rotors using airfoils first appeared. Not that we don’t all have our pet Savonius ideas, but just to mention the fact that it is not very efficient regarding energy capture.
That drawing of the stacked Savonius-looking rotors labeled as “Magenn” seems nice on paper, but how long would the various rotors hold their position and spacing, considering that any persistent slip, of even a fraction of an inche per rotation, would add up pretty quickly.
If someone believes in this idea, it should be fairly simple and affordable to build a small prototype and see how well it works. If the results look in any way promising at that point, that would be the time to start increasing its size and see how well a bigger one fares. The big mistake companies like Magenn and so many others make is immediately raising a lot of money based on a mere idea, the hiring so many people and spending so much money, so quickly, that even if the idea turned out to be a good one, the company cannot continue due to debt burden too great to move forward. And usually the idea turns out to be not-so-great, at which point you would avoid the entire cycle of hiring people to do renderings, hiring a team, renting office-space and a shop and equipment, issuing inaccurate press-releases announcing your future success ahead of any fact, on and on and on with “The Professor Crackpot Syndrome”. Start small and see what you’ve got and go from there. You will have more fun and less bother, and maybe change your design approach very quickly and move on to a better one that you are not locked into from too much hype over a design that turned out to be not very effective.
Hi there @kerati and thanks for sharing.
I think it is too soon to gather a team and start building. If you do, it should be understanding that you will be in the AWE or wind energy domain, but the design idea may change, maybe even a lot
One thing I could suggest at this point. Draw a better drawing with components at scale. Then look at mass and price. Maybe you can select a drone in the largest size for which you can find a price.
I believe the structure you have drawn would not work because the downwind pull will be very great. It would probably end up close to the ground, and in turbulent winds that would make it bounce around a lot.
That is at least my initial thought.
Thanks again for sharing. Maybe a good first step is bouncing ideas off this forum to see if you can improve it before building anything. And you probably dont need either a team or funding to make some prototypes. Lool for instance at the work @PierreB has been doing lately with sharp and magnus turbines. These tests give an immediate indication where you may want to move your design.
As you know a Sharp rotor provides more lift but less torque than a horizontal Savonius rotor. The lift of a Magnus rotor depends on its spin ratio (relatively to the wind speed).
I did it. An horizontal polystyrene foam Savonius rotor (a little like the device on the video) which flew like a rotating kite during little time.
True.
Thin sheets of plastic or fabric could be light enough to perhaps compensate for the low efficiency, but the structure to hold this would be heavy, above all when the device scales up. Perhaps said structure could be inflatable balloons (in addition to the central beam of the Savonius rotor) settled at each end (and providing some additional Magnus effect taken from the power of the Savonius rotor), the Savonius rotor being settled in the middle, a little like this but by replacing the Darrieus rotor in the middle with a Savonius rotor, then using bottles of constant diameter to hold the rotor as on the sketch on Flettner balloon and VAWT side by side - #4 by PierreB.
As the Savonius rotor is already not very efficient, especially in a more or less flexible version, and it takes energy to stay in flight, we should not expect great results from the generator.
Pierre,
Yes, the kite needed for the lifting force (sorry, missing from the draft, it was below the drone). But the drone can help keep stability at take-off (both in testing and in automated work), when the wind is turbulent or isn’t strong enough. And it can drive the looping.
Magnus effect is too small, as the perimetric speed is less than the (cross-)wind speed. So it is negligible here, only the kite should be responsible for the lifting force (1 MW needs around 10.000 kp tether force at 10 m/s speed).
Hi Doug,
Yes, Savonius is not too efficient. But the „fuel” is costless, and the inefficiency can be compensated by inceasing the size (larger blades). Or it can be replaced by a Darrieus one (increases TSR but needs more expensive rotor blades).
Many stacked rotors can really cause problems with their motions and different tether forces. Separated rotors (around 100 kW each) in a matrix may be more usable (and needs smaller kites and tether force). And it could do decentralized power generation (helping avoid network overloads).
Hi Tallak,
Thanks for the instructions. I agree, but I’m a pensioner mathematician, without a workshop, so even a two-meter long rotor with a small drone is hard for me to build and test (funny, but no wind tower installations allowed in my country).
That’s why I’m searching for experienced partners to check the ideas. This forum seems helpful as well.
I think time flies fast, so there is no time for spending years with large, expensive AWE solutions. I hope this one is so cheap and needs no special machinery (plastic foil, plastic tether, plastic rods and a small, fast generator). Calculated LCoE is less than 10 EUR/MWh.
Could also be good for cargo ships (works even in upwind, providing water jet mechanically) and offshore (fast installation on buoys, no danger, easy energy storage).
And theoretically 200 million 100 kW turbines needed to make the global power generation green.
Even with a low spin ratio (below the wind speed) the Magnus effect is significant and allows rotating
kites to fly, like the Savonius rotor which is on the video and that I tested, flying at about 45 degrees of elevation angle. This effect increases with the area of the rotor.
By reversing the rotation you will obtain a negative lift requiring to be compensated with a lifting force still higher.
[quote=“kerati, post:8, topic:2628”]
Yes, Savonius is not too efficient. But the „fuel” is costless, and the inefficiency can be compensated by inceasing the size (larger blades). Or it can be replaced by a Darrieus one (increases TSR but needs more expensive rotor blades).
People from outside of the world of wind energy, especially if they know they are “smart”, such as being a mathematician, for example, tend to assume their initial first impressions of the factors involved in wind energy are a correct interpretation, but in fact, it is almost worse to come in knowing you are “smart”, due to this tendency to assume your first impressions are accurate.
OK the fuel is costless, right? Everybody knows that about wind energy (although the land, tower, taxes, installation, interconnection, ongoing labor and maintenance costs, and the cost of the apparatus itself are not free, so yes, no fuel needed, but wind energy can still be very expensive).
But just pointing out the already-known fact that the “fuel” is costless does not negate the facts of wind turbine design, cost, longevity, material used, etc. How many Savonius turbines do we see in windfarms around the entire world? Not one. Why? Because they may look cheap to the uninitiated, but they cost more per unit power, so they are never used. Why do they cost more? First, the active surfaces travel WITH the wind, reducing relative speed, lowering the power to about 1/4th of what a regular turbine would make in the same space. But that’s only one half of the machine. The other half is traveling upwind, USING power, so you end up with a paltry fraction of the available power, but it gets worse:
Every place gets storms. Even solar panels need to be constructed and mounted to withstand 100 mph winds. So constructing a Savonius from light materials is likely to result in destruction in the first storm.
There is a whole, predictable “syndrome” here, and the next typical step is for the inventor to say “Well, we’ll just take it down when strong winds are predicted.” But
Anyway, like the story of, what was it, The Three Little Pigs(?) where the Big Bad Wolf said “I’ll huff and I’ll puff and I’ll blow your house down!” - the house made of straw blew away, the house made of sticks blew away, with only the house made of bricks still standing.
Anyone who has built any new wind energy device and run it for any time at all, will know this happens repeatedly to any new installation, requiring multiple modifications over years, until you get it right. Using large sheets of thin plastic is not going to accomplish this.
The reason regular propeller-style rotors are the result of 3000 years of wind turbine design evolution is it uses the least material to gather the most energy, and tends to survive, and even then, survival remains a challenge.
Regarding machines using Darrieus-principle blades, they always break down eventually (within a year for the best examples), are less efficient per unit of intercepted area, and require literally many times the blade material of regular propeller-style turbines, for the same power, because they need to “sweep” 3.14x the intercepted area.
Look at this piece of junk,
55kW Vertical Axis Wind Turbine | Renewable On-Grid & Off-Grid Energy (ryse.energy)
and imagine how many regular propeller-style turbines of the same or larger size you could build using the same amount of blade material! I’d guess you could get maybe 5 or 6 regular turbines, some sweeping even more area, from the incredible amount of blade material going into this vertical-axis (Darrieus?) turbine. And I doubt you could find many, if any, actually operating at this moment. With forces reversing twice with every rotation, they don’t last long. I posted a photo here before of one down the street from me that looked indestructible, but in a storm, it lost a blade - in less than a year. The Italian winery owner whose house it was installed at was so disgusted he left California and moved back to Italy
The power curve on those babies make me envious!
I think @dougselsam makes some good points here. Why should the suggested design be better than tried and trusted designs. There is little in terms or arguments to why you would want large plastic sheets, a drone and a savonious design, rather than a huge composite HAWT (horizontal axis wind turbine). Why would that be likely to have a lower LCOE. I think if you find it hard to come up with solid arguments, there is a good chance its not a great idea.
This may seem harsh but keep in mind this idea, like @dougselsam points out, does not seem very unique and other similar ideas come and go like mayflies. We are just trying to help you out by first challenging you to spend more time on your idea.
Thank you, I was wrong with the direction.
Magnus effect works well on the surface of a cylinder, but this Savonius rotor has 3 open blades only, so it may provide smaller lift on them.
As the profile of the Savonius rotor is similar to an extreme Sharp rotor, I’d like to know if its Kramer effect can provide some lifting force, as a vertical component of the large forces affecting the blades (100 kW needs around 1000 kp lifting force on a rotor).
True, and a spin motor generates and increases the spin ratio sometime beyond wind speed, increasing the lift coefficient.
A Savonius rotor or a Sharp rotor are self-rotating devices of which the spin ratio is 1 or lower. The lift coefficient of a Sharp rotor is good, but not the torque: so it is used to produce lift.
And the lift coefficient of a Savonius rotor (or something similar) can be good enough to allow it to fly like a kite, the Magnus effect being provided by open blades. See for example this:
See also this:
But powering a generator using this method is another matter.
You’re right, I’m really just an outsider, but I’d like to help with my weird ideas. I appreciate your patience.
Collected the points that might be useful, compared to an airplane kite (yo-yo devices do not provide constant energy):
No aircraft needed, with composite propellers and flying generator, the drone can position the rotor.
The “swept area” can be up to 400 m2.
Plastic sheets (2 m wide polycarbonate strips) are available in stores, can be recycled and easily replaced if damaged.
The support bars and the ring can be simple steel plates, only the ring needs a rubber cover for better adhesion of the rope.
The rope can be Dyneema, it does not have to conduct electricity.
The efficiency increases if the inner edge of the rotor blades can move freely, in which case the return blades are bent by the wind (droplet cross-section), so their air drag is greatly reduced. And they can be secured in this bent position in a very high windstorm (or maintenance) with one click.
I don’t have exact prices right now, but I think a drone, some boards, rods and rope are not too expensive to produce 1 MW (last time I calculated 10 EUR/MWh LCoE).
They are not “weird ideas”, so much as very typical beginner ideas. Wind turbines started out similar to Savonius, at least 3000 years ago. Somewhere near 1500-2000 years ago they discovered 100% cross-wind rotation. 1000 years ago they discovered crosswind airfoils.
All beginners start out thinking “The wind can push a surface - that I can understand, so that must be a superior way to do wind energy, which, somehow, all the experts have overlooked, until I came along with my infinite wisdom”.
Plastic sheets etc. are fine for initial prototypes, but not suitable for strong winds or serious power production. Being “available in stores” is not a relevant factor for anyone but a part-time tinkerer. It’s not an industrial-level consideration.
Then we get into irrelevant, politically-correct-sounding details like “plastic sheets can be recycled!” - well, actually, most plastics are not economically recycled. They are “recycled” to avoid being accumulated on the roadside, but actually dumped into landfills anyway most of the time these days. Only HDPE is economic to recycle, but most milk jugs have no rebate value, and are simply thrown away.
Yeah, yeah, yeah, every new idea starts out quoting some ridiculously low, completely unrealistic “levelized cost of energy” (LCOE). Just the land and permits, cost of generator and supporting infrastructure, inverters, grid connection and underground cabling, substation, roads, labor, maintenance, on and on and on, are major cost drivers. Let alone replacing “plastic sheets” and repairing a failed MegaWatt turbine that self-destructed when a plastic sheet ripped apart and caused the rotor to become unbalanced when God forbid a seriously strong wind hit the system.
AWE People tend to always imagine the tower as the main cost driver. Not really. it’s a factor, but only one factor of many. Meanwhile, you want to make the most power using the least material, which means using propeller-style rotors.
People talking this way have no idea how silly and redundant it sounds to those with experience, not only with wind energy, but with reviewing the predictably repetitive ideas of newbies. Sorry to say, we all start out this way, wishing everything were so simple, but the realities of wind energy are not intuitive, and must often be learned the hard way.
Even PhDs supposedly educated in aerodynamics (and “educating” others!) are apt to make beginner mistakes, such as “Professor” Dabiri, fixated on vertical-axis turbines, for the politically-correct-sounding “reason” of “biomimicry!”
Out of 1000 “new” (usually old or even disproven) wind energy ideas, you will normally find zero (0) that are effective enough to bother with. Like walking into a casino and thinking you will soon be rich, the odds are against anyone coming into wind energy with such talk of plastic sheets, Savonius turbines, etc. Hey, we’d all love to build a Savonius - seems like fun, but don’t expect much power.
Sometimes amateur tinkerers find unique angles. The guys here at Harmony have it all figured out.
I hope this post was sarcastic. I really hope the person posting was joking. I think we covered this drag-based vertical-axis disaster before, because when I pulled up the video, it was already part way through playing, indicating I had already been watching it, and I recognized the people in it. Then when I saw the geared overspeed protection I remembered it more clearly. This is a very typical Savonius extreme-know-nothing-newbie waste of time and money. They will probably never even have a product available. As it is now, you can buy a coffee cup, a sweatshirt, or a hat: Collections – Harmony Turbines
I’m actually surprised these guys are wasting the time to interview this company. Know-nothings, interviewing know-nothings, with even more know-nothings promoting the video, and still more know-nothings investing in the company. Well, that should not surprise us at this point, since, as we’ve been finding out, most people know nothing about wind energy, and even PhD’s make all the typical beginner mistakes.
The desperate tactic of showing of a picture of a real wind turbine on fire (very rare) and denigrating regular wind turbines as “stupid” is typical for such projects. As though that rescues them from the first stupid move - placing any turbine in someone’s backyard, between houses and trees, at a low height. Let alone promoting one more Savonius. Tempting to build, but aerodymanically, the numbers are way, way, way against the design.
The talk of how it is better because “the owner wants to see it spin” even while admitting it is making no power at low wind speeds, is also a desperate dodge of reality. What they are tacitly admitting is it is nothing but a feel-good backyard decoration - a kinetic sculpture that pretends they are saving the world by wasting time and materials to create no energy.
They still have no product available, and as usual "all progress is “in the future” (and always will be). They are now looking for a machine shop helper. That’s because of all the steel and gearing being wasted on this monstrosity. And like all the rest of these - dare I say it(?) - idiots - they have the nerve to call regular wind turbines “ugly” whereas theirs is really nothing but an opaque and complicated-looking eyesore.
I’m pretty sure I’ve already debunked this lack-of-a-breakthrough here in the recent past. Amazing how they are just all the same - one idiot after another, always with the same “new idea”, over and over. Obviously it will never end. Obviously the world will never run out of wind-energy-idiots. And it is self-inflicted idiocy, since anyone could take the time to learn about wind energy and the mistakes of the past.
OK, so, once again, I’ve done my duty. And I’ll say it again, because sometimes sarcasm doesn’t come thru in written text: I truly hope the person posting this debacle was joking! In the company of real wind people, this is nothing but comedy, but it also has a sad note to it.
On the one hand it makes us feel good that we know more about wind energy and would never fall for something like this… right? RIGHT??? But on the other hand, it is sad to see so many otherwise possibly-intelligent people talking such stupid and uneducated nonsense. Even the amount of material going into this hunk-of-junk should be a big red flag.
Everything described in the initial post, except the passage I quoted and some other things (there is no drone, no rope drive, the generator being aloft, and the Magnus effect is used), was produced by Magenn Power:
My sarcastic hue comes from not knowing whether to laugh or cry. The psychology of slowly spinning ornaments is endlessly fascinating though. There must be a primal attraction to spinning objects that predates humans. The tendency reveals itself in dogs chasing their tails and herds of sheep running in circles. The amount of money and labor invested in the contraptions is absolutely amazing to me. Our world would be a different place if golf majors were required to learn basic science and engineering.
Ok I am relieved. I agree - the fascination is hard to resist. Even I would love to build a Savonius turbine. A compound Savonius - really long, with a lot of swept area. Maybe oriented horizontally. But then reality kicks in: You could make an equivalent regular turbine using a tiny fraction of the materials, at a fraction of the cost. And forget about backyard installations in compact, crowded neighborhoods.
Even certain species of tree will not survive here in a wide-open area at the edge of the Mojave Desert, due to the dryness, hi summer temps, and ridiculously high winds. But a mile away, in a crowded neighborhood, they will do fine in a backyard, simply because of less wind.
By the way, to your point, I think the market for decorative, nonfunctional windmills, for gardens and yards, is way way larger than the market for power-producing small wind turbines, since more people (basically everyone) are allowed to “install them” anywhere, and people just like the look of them.
A hang-gliding friend of mine had always kept wondering why I didn’t just make decorative turbines since they sell in such large numbers. Funny, but around here, even the decorative turbines end up laying on the ground broken, from our strong wind resource. But in most locations they will be fine, and you would seldom have to worry about warranty returns and repairs!
