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A little under a year ago, I heard about an interesting wind power project from an engineer-friend of mine: wind turbines that look like trees. While the actual wind turbines, known as Arbre à Vent®, didn’t look exactly as I’d imagined, I had to admit they were closer to an organic design, and they did have the ability to be integrated into the urban landscape, as the company, New Wind, had planned. Evidently, the company’s founder Jérôme Michaud-Larivière “came up with the idea while in a Paris square, when he ‘saw the leaves tremble when there was not a breath of air.’” The goal of each Arbre à Vent is to “exploit small air currents flowing along buildings and streets.”
I’m skeptical as to whether the efficiency, which Michaud-Larivière admits is “low compared to [accessing] more consistent currents higher up,” could stand up to traditional wind power, but I love the idea. If nothing else, these “trees” could help change public opinion about wind power—that it necessitates skyline-obstructing monstrosities (which I happen to think are strangely elegant).
I was reminded of this Parisian project when I read an article on Engineering360 about a device that attempts to harness “piezoelectric energy generated when wind bends a specialized plastic built into the leaf stalks” of their specially created leaves.
The leaves of Iowa State University’s project look much more leaf-like than those on the Arbre à Vent, as they were modeled after cottonwood leaves. If you’ve ever seen a cottonwood tree in even the slightest breeze, you will probably understand why, as the way each of their leaves flutter in the wind is memorable. The researchers say “their flattened leaf stalks compel blades to oscillate in a regular pattern that optimizes energy generation by flexible piezoelectric strips.”
Moving away from the idea of a wind turbine blade allowed Iowa State’s researchers to move away from the clunkier “Aeroleaf®” of the Arbre à Vent, making them more recognizable as, well, leaves. In fact, while the Iowa State leaves are comparable in size to actual cottonwood leaves, the Arbre à Vent leaves would dwarf even the leaves of the bigleaf magnolia (if not those of the raphia palm).
The trunk and branches of Iowa State’s “tree,” however, leave much to be desired—instead resembling “a metallic trellis.” Curtis Mosher, a co-author of the paper written about these leaves, said that even without the structure of the tree conceptualized in the prototype, “it’s not that great of a leap … to a much more convincing artificial tree with tens of thousands of leaves, each producing electricity derived from wind power.”
Now, the researchers plan to work toward better efficiency, something that Mike McCloskey, an associate professor of genetics, development, and cell biology, who led the design of the device, says “means finding an alternative means of mechanical-to-electrical transduction, or a scheme for converting wind energy into usable electricity” as the piezo method didn’t achieve that efficiency.
While each project has its shortcomings, they both signal wind power moving to a smaller, personal scale. Maybe in the not so distant future, wind turbines will be as common as trees—and they might look like them too.
I've often noticed leaves on the trees shaking in just a little breeze and suspected that the leaves have evolved an airfoil shape to shake off insects.
I wrote that news item for Eng 360 -- had no idea about the wind turbines! Really interesting that different scientists/engineers are thinking alike. To me that's the most interesting aspect of this story: great minds thinking alike.
I didn't include in the short article the reason the Iowa State guys used the cottonwood leaf, out of all the leaves they could have chosen. MaggieMc alluded to it: cottonwoods move in the slightest of breezes.
The wind turbine-as-piezoelectric-generator might make more sense, given the height of a turbine's tower. Thanks for this blog, MaggieMc!
That was pretty much the researchers' conclusion about piezoelectricity. Here's a link to the press release that goes into more detail. They're looking for other kinds of electricity to generate.
Two problems are that there is very little power captured from the wind and that the "generators" have high internal impedance, i.e., all voltage and very little current.
This might be useful for sensors that use low power CMOS circuits that draw hardly any current.
I read with great interest your statement, " They're looking for other kinds of electricity to generate."
That would be truly revolutionary, indeed.
I worked on a project once that cancelled vibrations by applying current that is 180° out of phase to piezoelectric actuators. Not too much amplitude, but good response.
That statement does sound sorta dumb. I should have said "different ways to generate electricity" since piezoelectric wasn't making enough juice. Electricity is electricity, after all .
Yeah, I've got one of those a few miles from my house as well. Not a very convincing tree but, much less abrasive to the eyes than a normal cell tower.
Those are actually quite attractive. Unlike the other multicolored ones in your other post. Looking at them, I'm waiting for the clowns to jump out. They look like they belong in the circus. Those white ones, however, kind of resemble ice covered trees in winter. Much more elegant.
Nice as a garden feature, for parking areas, but quite impractical when versed against the cost.
If they really wanted cheap electricity, there are many city roof tops that can accept solar panels and an array of smaller turbines to catch the wind. One does not need big diameter blades spinning around.
Personally as someone who has actively played around with wind power since I was a kid I find these designs to be somewhere between humorous at best and a general insult to the concept of RE power.
The single most insulting thing I find in every RE concept is the overwhelming lack of basic numbers to show their sales and operational costs VS their power output capabilities for whatever life expectancy they are to suposedly have.
Of which with these trees I have suspicions they are carrying a price tag in the tens of thousands of dollars with a realistic power production of a few hundred watts or less at any given time making their ROI as a RE source totally unrealistic.
Oh for Pete's sake, a few of these are experiments, the rest is 'art.' You know as well as I do they know how to build efficient turbines and have been doing it for years. Chill, mate, you'll live longer.
I'm practical minded so to me this sort of artsy fartsy stuff under the weak claim of being 'green/environmentally friendly' or whatever is not just lame but an insult to properly designed and purpose built tech.
It's like being around people who spend $50K+ on a 'eco friendly green vehicle' to 'save the planet' and $300 or less a year on fuel while they turn around spend $1000 or more a year on insurance and everything else for it over what their older vehicle cost and figure it's some sort of badge of honor that shows how much 'smarter and more efficient' they are than everyone else.
having built wind farms on and off shore, they don't have a long life span. Normally around 10 yrs max depending on the environment, sea/land based. And they can be purchased 2nd hand for as little as $8000-$35000 and some refurnished units for much more. These would have 17m to 55m blades
New from Vestas is a small fortune and the crane hire for the nacelle and tower lift is not cheap. Building the road for the blade and nacelle is not cheap for the bigger units.
Re: Trees as Turbines
