About a year ago, I first talked about
the Aeromine rooftop wind turbine and its unique “motionless” design. Now,
a new rooftop turbine is hitting the scene. Norwegian company Ventum Dynamics
just released its shrouded wind turbine, the VX175, to the market in February.
It’s also deployed in the same way as the Aeromine: along the edges of large
industrial and commercial buildings. What makes the VX175 so different, though, is the
lantern-like structure wrapped around the body: a shroud. Shrouds are anything
but a novel idea. Researchers have experimented with amplifying a turbine’s
power output by covering the rotor for decades. What is new is a misunderstanding that Ventum’s
approach is tethered to an even older concept: a Darwinian invention, to be specific. Well, yes,
but actually no. What we’re about to dive into is more than an overview of the VX175. I always
like to put these technologies into context, especially older concepts that get
revived with new approaches. However, this one really threw my team and I for
a loop as we learned about the origins. How did that even happen? And how much
of the VX175 is a rehash, if at all? I’m Matt Ferrell … welcome to Undecided. This video is brought to you by
Surfshark, but more on that later. We’ve featured a lot of fascinating wind
power designs here on the channel, from a mega-flyswatter containing multiple mini-rotors
to a track with “wings” flying laps around it. But we’ve yet to cover… a covered turbine. This
story isn’t just about fluid dynamics or design, though. It’s a lot more convoluted, and
it starts in the 18th century. Kind of. Before we get into that, let’s set the stage.
For a variety of reasons the primary goal of wind turbine construction has pretty much
always been pushing the limits of size. However, it’s becoming less practical to build
them this way, between the nail-biting logistics and the terrifying consequences of mechanical
failure. While the industry changes its approach, decentralizing our power supply through
smaller wind turbines also has significant benefits. One major motivator? Even if
we were to perfect monolithic turbines, we still can’t fit them into most areas. That’s where rooftop turbines can come in, and
after five iterations and about six years of development, the VX175 has made its debut. What
makes the turbine so noteworthy is immediately clear: the “shroud” that encases the rotor. In
Ventum’s words, it “accelerates the wind, allowing a greater volume of air
to pass through the turbine.” We’ll discuss how that works later. For now,
I want to focus on that burning question: what’s Charles Darwin got to
do with it? Well, nothing, actually. The Darwinian windmill at hand
was developed by Erasmus Darwin. That’s the English physician and notably less famous
grandfather of none other than Charles Darwin. Yep — that’s not Photoshop or a DALL-E AI
generated image. What you’re looking at is a photo of a museum display showing a model of
one of Erasmus’ many inventions at the Darwin House in Lichfield, England. And here’s
a drawing of his creation. Look familiar? To be clear, this patent diagram is for
a prior version of Ventum’s turbine, not the one that was just released
to market. But even more importantly, despite the fact that the two may seem
deceptively similar, there’s a lot more than eras setting them apart. No, the VX175
we know today is really a new form of this… …the IMPLUX turbine, which was originally
invented by engineer Varan Sureshan. And neither Sureshan nor the Ventum team
based their work upon Darwin’s. I know this for sure because, well…we asked. As
Sureshan himself said in an email interview: “I would be lying if I said I was inspired
by the Erasmus turbine, or any other turbine, as there was no internet or any search engines
when I started working on some of my ideas.” To put things into perspective, neither I nor
my team had ever even heard of Erasmus until a viewer suggested I look into Ventum. In
their email, they referenced a YouTube video that identified Ventum’s models as
Darwin turbines. My lead writer took this information at face value and threw himself into
researching 18th century history. For weeks, he prepared a sweeping, dramatic narrative
about the sociopolitical woes that might explain why the shrouded windmill had effectively
remained trapped in parchment…until now. Later, while scrolling through Google Images results, he
stumbled across the IMPLUX and thought to himself: “What the hell is that?” So why did I ever bring up
Erasmus Darwin in the first place? Before I get into that connection, I need
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below and thanks to Surfshark and to all of you, for supporting the channel. So why did I ever
bring up Erasmus Darwin in the first place? The answer is simple: because if it weren’t
for the false notion that Darwin had laid the groundwork for Ventum’s new turbine, I wouldn’t
be talking to you about it at all. We wanted to investigate why Ventum adapted such an old idea,
and why it had been left in the dust for so long. In reality, there was no adaptation. There’s
no connection between Darwin and the VX175. To make a long story short, our confidence in
the misinformation stemmed from the fact that it wasn’t just anybody comparing the
VX175 to ole windmill. It was someone from an engineering background who had been
studying the Darwin design for over a year. And you gotta admit…the resemblance to the
older proofs of concept is a bit uncanny. Another element at play is that we don’t
know everything. A lot of the time, we approach video topics with very little
prior knowledge of the subject. This channel is as much about science communication
as it is taking you with me on learning journeys. That’s why I have science and
engineering advisors that help fill in the gaps. The research for this script in
particular took a lot of twists and turns. Now, the elder Darwin did tinker with shrouded
windmills when he wasn’t busy tending to patents, writing plant romances, or designing mechanical
spiders. But to say that the VX175 represents an evolution of one of Darwin’s many side projects
simply isn’t true. The people who created the turbine weren’t aware of the comparison until a
few years ago…when they watched the same videos that inspired this one. The VX175’s actual
origin story is an interesting example of humans thinking alike across time, just not
in the way that we had initially believed. Hold that thought, though, because the
scientific experimentation Darwin dabbled in outside his medical career is legitimately
fascinating. So, for the sake of keeping things chronological (and not letting
my poor writer’s research go to waste), let’s dig a little deeper into his windmill and
where exactly this comparison came from. One thing that the two designs do have in common
is the potential for increased power output. Take it from the man himself, who wrote
this in his 1800 book “Phytologia; or the Philosophy of Agriculture and Gardening”: “And as the height of the tower may be made
twice as great as the diameter of the fail, there is reason to conclude that the power of this
horizontal wind-sail may be considerably greater, than if the same fail was placed nearly vertically
opposed to the wind in the usual manner.” According to historian Jennifer Uglow,
Darwin claimed that his horizontal windmill produced a third more power than
the…run-of-the-mill…vertical mills of his time. And like Ventum’s VX175, the
windmill worked omnidirectionally, meaning it could take in winds from all
angles. On its journey to the sail, wind would push through the slatted boards that made
up the shell of the turbine. You get the drift. But that’s pretty much where a comparison
to Ventum has to end. Setting aside the fact that the tech is more complex and
that the applications are worlds apart, there’s a couple critical differences between
the designs. First of all, the VX175, as a unit, is a new form of turbine. The novelty
of Darwin’s creation was that octagonal, “smoke jack”-style tower: an air catcher. Not
a turbine. Sureshan explained it like this: “...The IMPLUX works because it is
part of the group of wind turbines where there is a "static turbine"
and "dynamic turbine" combination, which enables much higher power extraction well
beyond the "catcher" turbine concept…Whilst increased air flow is important, it does not
lead to automatic increase in power efficiency.” On top of this, the VX175 is, like
the Aeromine, entirely stationary besides the rotor. As Ventum’s COO, Rebekka
Stumpf, described it in an email interview, one of the main objectives in designing the
turbine was promoting air capture while also preventing air leakage, regardless
of the wind direction. In her words, that meant “no physically closing or opening
mechanisms, such as air shutters.” Meanwhile, the tower of Darwin’s windmill was composed
of flaps that fluttered in the breeze. Well, did it work? It would seem that it did just
fine, considering it was actually put to use. In 1778, Darwin’s colleague Josiah Wedgwood installed
it at his pottery factory, The Etruria Works, in Staffordshire, England. There, the mill
mixed clay and grinded materials like flint and enamels for a solid 14 years, until it
was eventually replaced by another engine. However, we don’t remember grandpa Darwin
as a kooky scientist for a reason. He feared for his reputation as a physician and very
intentionally opted to keep his engineering pursuits to himself. I think it says a lot that
he published Phytologia in 1800 and died in 1802. But while I can’t say what was going through
Erasmus’ mind when he designed his windmill, there are multiple advantages to shrouds. Part
of the reason why the wind industry places so much emphasis on taller and taller towers
is because the higher you go, the faster the winds you can capture. The faster the winds
you capture, the more power you can generate. The thing is, in the U.S. the majority
of the country only receives average wind speeds between about 3 and 5 meters
per second (or about 6 to 12 mph) when measured 10 meters off the ground. In
Norway, Ventum’s country of origin, the windiest areas range from 5 m/s
to 8 m/s at that same 10-meter mark. Of course, this becomes a problem in areas
without much room, vertically or otherwise, to place towers that can reach for the
good stuff. That’s why companies like Ventum are seeking ways to make use of
the low wind speeds that are accessible from rooftops — especially in more
densely populated areas like cities. And one possible way of doing just that is by
creating turbines with shrouds…or diffusers…or lenses…or ducts. Whatever you want to call it,
this type of turbine is a class of its own: a DAWT, or diffuser-augmented wind turbine. Y’know,
like a HAWT or a VAWT. That’s “horizontal axis wind turbine” and “vertical axis wind turbine.”
I’m not trying to sound like the Cat in the Hat. “Shroud” and “duct” and “diffuser”
can be used interchangeably, but I’m going to keep using “shroud”
because it sounds the coolest. The main idea here is power augmentation. Think
about it like this: urban and residential areas have enough wind to spare, but oftentimes it’s
not fast enough for turbine installations to be worth it. In other words, you wouldn’t be
able to justify the costs vs. power output. What if we could somehow speed up that wind?
So, in theory, shrouds have this to offer: Concentration of wind energy
Low exit pressure, which leads to increased airflow and faster wind speeds
Avoiding what are known as tip losses, which are reductions in efficiency caused by
vortices that form at the tip of turbine blades Overall increased efficiency
Overall increased power output Basically, shrouds increase speed — and increased
speed means increased power. As early as 1956, studies have shown over and over again
that shrouds can increase power output, and the numbers sound impressive. Figures of
approximately “2 to 5 times increase in power output” get thrown around a lot in scientific
literature. But I probably don’t have to tell you that sounding impressive is different from
actually being impressive. Of the papers we reviewed, most are based upon simulations
or experiments conducted in wind tunnels, which aren’t fully representative of
the much more chaotic outside world. And as you might have already guessed, a
consistent drawback is cost. From discussions that took place at the United States’ 1979
Wind Energy Innovative Systems Conference to conclusions drawn from extensive wind tunnel
tests in the present day, researchers have repeatedly indicated that shrouds just aren’t
economically practical. However…a lot of these observations are also made within the paradigm of
your typical turbine. Attaching a component that heavy and that big to an already massive tower
would threaten the structural integrity. Of course it would be ludicrous to stick a shroud on one
of these. But that’s not what Ventum is doing. In any case, it seems like shrouds become trendy
on a cycle, like jeans. For example, in the 1920s, inventor Dew Oliver created his “blunderbuss”
ducted turbine, which might seem like a far cry from anything we’d see today…except it
looks somewhat like the SheerWind INVELOX. I wouldn’t be giving you the full story
if I didn’t mention that both designs were ill-fated. Oliver ended up convicted of fraud,
and SheerWind filed for bankruptcy in 2017. Anyway, if the superficial similarities between
Darwin’s work and the VX175 didn’t already convince you that researchers have tested
variations upon shrouds for a while now, I don’t know what will. But
if neither the IMPLUX nor the VX175 were created with Darwin
in mind, how did they come to be? Here’s where the accurate comparisons really
lie. Over the course of his engineering career, Sureshan designed systems like a
hybrid rooftop air-conditioning units, and took note of the bountiful supply
of wind available atop buildings. So, after over 25 years of similar projects,
he founded Katru Eco Energy and began developing the IMPLUX, with some of
the earliest patents filed in 2005. Unfortunately, despite successful prototyping
— including Honda’s Formula 1 team taking it for a spin — the IMPLUX never made it to the
market. Manufacturing and installation stopped not once, not twice, but three times across three
different years in three different countries. You could say that the IMPLUX was too ahead of
its time. According to Sureshan, the problems that prevented its commercialization were political,
not technical. And after three attempts, it’s understandable that he and his company’s investors
were hesitant to try again. So, that’s one way the IMPLUX specifically is like Darwin’s windmill.
Both were long-delayed for political reasons. Meanwhile, it seems like Ventum founder
Christopher Bisset-Nilsen had basically the same lightbulb moment as Sureshan
while working atop buildings in Stavanger, Norway. According to Stumpf, Bisset-Nilsen, as
he installed rooftop HVAC systems, he wondered “Why are there no turbines on the
roofs to power the heat pumps?” And the rest was history. In 2018 Ventum
filed its first patent for its V1.0, which was lovingly nicknamed the “Death
Star.” It’s easy to see why … that’s no moon. Then, in 2021, Ventum approached Sureshan for
guidance while testing one of its earlier versions of the turbine. And through this collaboration,
the Ventum team incorporated features from the IMPLUX into the VX175, eventually acquiring
the patent for the former. As Stumpf explained, the two are “basically the same machine,”
except the VX175 is optimized for manufacturing. You can definitely see where Sureshan’s
influence emerges on Ventum’s timeline. But what does this successor bring to
the table? While all DAWTs have a shroud of some kind to direct airflow through the
turbine, the VX175 has a specially engineered, omnidirectional shroud. This allows it to be
mounted on the tops of buildings and capture energy from the turbulent airflow. The idea is
to get even higher efficiencies out of higher speeds, particularly from the constantly
changing, rough winds common in cities. Here’s how Stumpf described it: “We focus on wind acceleration that
can be seen in urban environments due to wind “hitting” a wall and being
redirected upwards and accelerated. We call it the edge effect…The turbine is
built in a way that it can harness that upwards skewed wind and accelerate
it once more inside of the turbine.” Plus, the fact that the VX175 has no
moving parts other than the rotor helps keep maintenance costs down. After all, it’s
usually too many moving parts that gets ya. This feature also contributes to
a higher quality of life. Ventum’s turbine is pretty quiet, at least
at the lower end of wind speeds. It produces noise at about 40 decibels in
6 m/s (13.4 mph) winds. For reference, the U.S. Environmental Protection Agency
identifies 55 dB outdoors as being A-OK for human health and, you know, not wanting
to bang your head into the wall repeatedly. According to Ventum’s website, the system amounts to these estimated
values for annual energy production: However, there isn’t any publicly
available performance data yet. That’s a reasonable cause for skepticism,
especially in the controversial world of small wind turbines. But it’s worth
remembering that the more attempts engineers make, the sooner we can
incorporate SWTs into our arsenal. And it’s not like there’s no recent data
on shrouded SWTs. (Or SDAWTs?) In 2020, researchers at the University of Tehran
published a study comparing the levelized cost of energy (LCOE) and annual energy production
(AEP) of traditional turbines vs. wind lens turbines at two sites in Iran. They found
that the wind lens turbines “yielded an average decrease of 56% in LCOE and an
83% increase in AEP” on Kish Island, and “an average reduction of 59% in LCOE and a
rise of 74% in AEP” in the city of Firoozkooh. I’ll go ahead and say the line: this is
another example of picking the right tools for the right job. It ultimately doesn’t matter if
this turbine isn’t as efficient as a giant HAWT, as long as the installation and
operational costs are practical for bringing turbines to more populated
areas. Each is meant to serve a different markets. As for how well the VX175 can
do that, we’ll have to wait to find out. But will we be seeing these turbines on
residential roofs anytime soon? To that, Stumpf says that single family homes have better
options elsewhere. For those in apartment blocks, though, Ventum’s got you… covered. Alongside
commercial buildings and offices, the VX175 is a good fit for apartments. The company is
also in the process of releasing the VX300, a larger version of the turbine for industrial
areas like warehouses and storage facilities. In the end, if researching this
video has taught me anything, it’s that it’s worth remembering the
humanity behind the machines. What might seem like a technological failure could have
a story more complicated under the shroud. But what do you think? Do you think that DAWTs
have a place? Jump into the comments and let me know and be sure to listen to my follow
up podcast Still TBD where we’ll keep this conversation going. I’ve got to tip
my hat to my team on this one … from my lead researcher to my science advisory board
… this was a massive group effort. It was a wild ride. And thanks to all my patrons
and one of my newer Supporter + members, David Borin, for your continued
support. I’ll see you in the next one.
