Multi rotor wind

A seminar on multi rotor wind turbine systems in Glasgow this week

Thanks @tallakt for pointing out that I should have shared this earlier

We need some new category choices for post writing on this forum


OK this is really weird: Google returns basically nothing when you type in Heronymus Windship

Not that anyone here has probably ever heard of him, but…
Bill Heronemus of UMass was considered the father of wind energy:
Here was one of his early designs - a floating multirotor wind turbine
Offshore turbine design
You might notice, he promoted onboard hydrogen production, but placed the hydrogen tanks at the BOTTOM of his early idea for a floating wind turbine installation. It’s easy to see that the above design would simply capsize. One wonders what Bill might have been smoking way back then!

In reality, Bil’s ideas were half-baked, but nonetheless, his students ushered in the modern wind energy industry.

The Life and Work of Bill Heronemus, Wind Engineering Pioneer | Wind Energy Center (

Oddly, his best drawings return NOTHING using a Google search! I’m very puzzled. Google used to return many many of Bill’s drawings! What’s going on with Google??? Even UMass only has some thumbnails of his major design, the “Windship”:
drawing4 drawing2

It used to be easy to find large versions of the above drawing in color! WTF??? Could this be some sort of “cover-up”?

Anyway, as some here may know, I was awarded patents on the basic idea of floating foundations for a SINGLE wind turbine (usually multi-rotor, but with a single moving part), after all of Bill’s floating multi-rotor drawings.

Yes, and don’t forget:
I’ve been offered 10,000 for this domain more than once!


I reckon Doug’s gonna pop his head out from behind the curtain half way through the first presentation with a wink and a roar of applause from the audience
That’s why I’m going

In his AWEA 1999 acceptance speech (for a lifetime achievement award), Bill said:

“There is an absolute requirement for the Earth to remain in thermal balance within our solar system. There is only one ultimate solution to the global warming problem: total reliance upon solar energy. And the most productive of all solar energy processes is the wind energy process.” He continued, saying, “Wind power needs to be developed at a steady and appropriate pace, but the free market capitalistic system that we hold so dear will not do the job. There is need for massive governmental interference. If we wait for the private sector to reduce the greenhouse gases linked to our fossil fuel use, it will be too late.”

For more information about WEH, see the full article and other of his papers.

William Edward. Heronemus, Captain,. USN (Ret.), Professor Emeritus, University of Massachusetts at Amherst, born April 16, 1920, died November 2,2002

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Funny Pierre! “Big News!” This is a really old idea. It has been done many, many times. All these guys have done is buy a few super-cheap, (probably about to fall apart, while producing a fraction of their stated output) Chinese turbines and mounted them on a frame. They act like it is a new concept! Then of course they go right on into “global warming”… (yawn)

Many large turbine manufacturers have built much larger and more sophisticated versions of this basic concept.

I agree the basic idea could be very fruitful, but so far, the problem has been inter-turbine oscillations and vibrations, transmitted through the common frame, etc., plus the fact that by the time you have all the required support structure for all the small turbines, they end up using the same amount of material as one larger turbine, but then you have the problem of the harmful oscillatory interactions, plus you have several turbines to maintain instead of one.

And they operate at a lower Reynolds number, hence slightly lower efficiency.

Here’s one by Vestas, in a video with a lot of music, but you might note, they DO NOT SHOW IT RUNNING!!! WHY? Probably because you would see it trying to rip itself apart!
4-Rotor Concept Turbine (

The strange thing is, every time some new group mounts more than one turbine side-by-side on a common support frame, (or just says they will) they pretend it is some new idea!!! It’s actually one of the OLDEST ideas!

And while I would not say it is “disproven” because I still like the concept, it has NEVER been successful! And that is with some pretty large versions having been built and run, by major manufacturers!

So, for “real wind people” this is really really old (antique?) news - as the old saying goes “Nothing to see here folks, move along”… :slight_smile:

(If “topics” is so important here, why do we suddenly have two (2) topics on multi-rotor turbines?)

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I think the actual answer is much more complicated

The answer to: «Why dont wind turbines look like this in 2024»

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That riam complete with annular rings is a classic… make the ring and the wind will come

These are NOT “multi-rotor turbines”. They are “multi-turbine arrays”. Or, if you consider the yaw bearing as a "rotor, you could call them “multi-turbine rotors”. The point is, the rotor is just part of what is called a complete “wind turbine” - it also needs a generator, and in the case of the Myriad prototype, they even kept the original tails on each turbine.
A true multi-rotor turbine would require multiple rotors somehow incorporated into a single total turbine.
So what is being called “multi-rotror” here should instead be called “multi-turbine”.

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I would like to point out that Bill Heronemus, in spite of being known to have catalyzed early interest in wind energy among his students, exhibited several symptoms of “The Professor Crackpot Syndrome”. One such symptom is ruining a perfectly good invention by adding a bunch of other inventions.

For example, I’ve heard him described as a marine engineer. But if you look at his drawings, they are visibly top-heavy and would NOT stand upright in the water, but capsize, even in zero wind! All the heavy stuff is up high, with a long lever arm, while the floats are at the bottom, underwater, with no ballast or other means to keep the structure upright! (???) What kind of “marine engineer” doesn’t understand basic floating stability?

Not content with simply introducing turbines supported by floating foundations, Heronemus felt compelled to promote floating ARRAYS of turbines, mounted on a lattice structure, producing hydrogen onboard by electrolysis, for onboard storage and later transport away from the array. This is where the “crackpot” part comes in:

  1. A lattice array supporting multiple turbines is ONE invention.
  2. Using electricity from a wind turbine to produce hydrogen is another invention (with hydrogen wasting at least 75% of the power produced, ESPECIALLY at that early date)
  3. A floating foundation for a wind turbine is yet another invention.
  4. Having the electrolysis unit mounted ON the floating foundation (implying that transporting hydrogen away from the unit is more efficient than transporting electricity to shore) is yet another invention.
  5. Having hydrogen STORAGE on the floating foundation, using t for floatation, is YET ANOTHER “invention”

ALL FIVE of these inventions were unproven. So, combining all five severely reduces the odds that any aspect of the resulting agglomeration of inventions could be successful. (More failure points) But crackpot inventors can’t seem to grasp the concept of simplicity, or of proving ONE aspect of an idea at a time, Nope, they are so in love with their possibly flawed or incomplete “vision”, so convinced they are “a genius” and that every passing thought is “a surefire breakthrough”, that they combine them ALL into a single, unworkable mess.

Example: Heronemus never proposed a floating foundation for a single turbine, That was left to me. As I recall, Heronemus never had any patents issued while he was alive(?). That was left to his relatives (wife I think) to have issued posthumously (after his passing). Result: (if memory serves) Heronemous’ patent cites my patent as prior art. :slight_smile:

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The cube-square law suggests multiple smaller rotors would use less material than a single, larger rotor.
Here are the tradeoffs as I’ve always interpreted the situation:

Yes the larger rotor will weigh more per unit swept area, BUT…

  1. the support frame for an array of smaller rotors might end up using a similar total amount of material.
  2. the single larger rotor operates at a higher Reynolds number (better efficiency)
  3. Larger generators are also more efficient than smaller generators.
  4. the lattice or other support structure will tend to block (slow) the overall wind flow. Could be a problem, especially in storms.
  5. the ENTIRE SUPPORT STRUCTURE will then be required to ROTATE to AIM toward the wind. With high leverage against the ground or water, and a high rotational “moment of inertia” that could require a lot of active support structure!
  6. unfavorable mutually destructive oscillations have turned out to be a major factor for multi-turbine arrays on a single support structure.
  7. Increased maintenance costs with multiple turbines, multiple generators, etc.
  8. difficulty accessing the multiple nacelles - just look at the stairways on the Vestas attempt.
  9. once you have a tower, it takes a lot less material to simply balance the heaviest part of a turbine (often with a super-heavy cast-iron hub) directly on top of that tower, rather than having to build a complicated support structure to distribute that weight AWAY from the supporting tower, which only increases the azimuthal “moment of inertia” of the entire structure, increasing the difficulty and apparatus required for aiming into the wind!

Result? It’s far simpler, and probably uses less total material, to build a single large turbine. Oh well, back to “The La Brea Tar Pits”…

So, while I’m always dreaming of ways to combine several turbines on a single support structure, and I do think it could have use-cases, it’s not a slam-dunk solution. There are many reasons turbines are the way they are.

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Im thinking more like death by a thousand cuts [practical stumbling blocks] and loss of management support. But I know nothing about what actually happened. I doubt they arrived at a final design where they said «this is not as good as our other options»

Hi Tallak: Well I keep thinking of more reasons - as I was just out watering some trees and thought of a few more that I had forgotten to include, I came back inside and edited my post to add more - maybe re-read it now that I’m up to 9 reasons.

Yes, death by a thousand papercuts is a good way to describe the overall situation, because there are a thousand reasons why the arrays seem to turn out to be more of a problem than a solution, and I’m pretty sure the big manufacturers realized what they were already doing was better than the array, due to all of these compounding detractive issues. At least they gave it a try! :slight_smile:

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Hi Doug, on the video below there is an example of a “multi-rotor turbine”, with several rotors and only one generator, unlike a “multi-turbine” which comprises several times one rotor for one generator, right?

The series of good comments from you on this subject, could illustrate the structurally simpler solution of a SuperTurbine ™ compared to a “multi-turbine”.


Thanks Pierre: Nice to see this old video! :slight_smile:


A “multi-turbine” is suitable for a Kitewinder style industrial system where all turbines are connected to a single cable drive. It has two major advantages, firstly, employing counterrotating, turbines, neutralizes transverse torque in the system so the whole device will not tend to rotate around the tether axis. Secondly, the use of different size pulleys can be substituted for a gear reduction system which greatly reduces the weight of the airborne system.

At the end of the multi rotor seminar it was said several times… We should be more like those airborne wind energy folks. they’re super organised, they arrange loads of funded projects, they have AWEurope, they have …

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Yeah, let’s emulate those people who have spent 15 years wasting a billion dollars, with still nothing running on a regular basis!
If anyone knows what they are doing, they will simply do it, rather than have yet another “conference”.


they should look to someone successful. Why copy someone struggling?

Anyways; does the idea «multi rotor» hold the same potential as AWE? It seems more of an incremental development… funding/activity/actors should reflect that