
Sheerwind - jeena
http://sheerwind.com/technology/how-does-it-work
======
weland
I am not an expert in wind turbines, but I am technically an EE, so I have
seen a thing or two. I have mixed feelings about this.

On one hand, the principle of operation superficially looks OK. The weird
shape probably gives more flexibility in the design (I say _probably_ because
I honestly don't know anything serious about fluid mechanics). The data they
provide seems usable.

That being said, the website is fairly scarce in terms of actual details (e.g.
the "collected wind is channeled to pick up speed" doesn't seem to be
explained anywhere -- _how_ exactly is that done, and how much speed would the
wind gain?), and the only paper they published looks rather meagre -- from the
works they cite to the dubious editing of the paper (e.g. last sentence before
"Conclusions": "The total energy production of INVELOX over 8 days is about
314%" would _not_ have made it past decent peer reviewing).

I don't know enough about mechanics to make a proper assessment of this, but
my bullshit detector is bleeping, though shyly.

Edit: BTW, the website also seems to casually glance over _what_ the (up to)
600% improvement improves upon. If I read their article correctly, it's an
improvement over using the same turbine, but without the funky tunnel. In that
case, I kindda doubt the economical feasibility of this design.

~~~
bigiain
"I don't know enough about mechanics to make a proper assessment of this, but
my bullshit detector is bleeping, though shyly."

Mine too…

One of the fundamental problems regular wind turbines need to deal with is the
"V cubed" term in the power contained in moving air. For exactly the same
reason that you need eight times as much power to make a car go twice as fast
– if you build a turbine that can produce it's "nominal power" output in, say,
10m/s (~22mph) of wind, it'll need to be able to somehow deal with the turbine
operating at 8 times nominal at 20m/s (45mph, a not unreasonable occasional
windspeed in many places) and 27 times nominal power at 30m/s (a high, but
certainly not yet "beyond reasonable safety design limits" speed).

My problem is with the numner on their Field Data page - they say they get an
average "speed Ratio" of 1.8, and their turbine is rated at "600W at 12.5m/s".
Ballpark extrapolation follows. I'll assume that's 12.5m/s at the turbine, or
12.5/1.8 = ~7m/s wind speed. About 15mph. At half that windspeed, there's 8
times less energy available, so 7.5mph of breeze will generate 75W, halve it
again and output at 4mph drops down under 10W, and 2mph means low single digit
Watts of output.

Now think about what happens to their turbine in a stiff breeze of 30mph?
Where does the 4.8kW go? and when the once-in-5-years 60mph storm comes
through, somewhere the best part of 40kW needs to be dealt with. Who engineers
things with almost two orders of magnitude margins of safety?

It doesn't smell right to me.

~~~
mgraczyk
This is where the 4.8kW will go if they haven't thought of the possibility of
high winds.

[http://www.youtube.com/watch?v=_e9uRSVun30](http://www.youtube.com/watch?v=_e9uRSVun30)

~~~
traviscj
This seems precisely like an argument for a smaller turbine-based design
INSTEAD of huge and (relatively) heavy blades. Turbines for car turbochargers
and airplane engines can regularly (if I remember correctly) operate in the
regime of ~100k RPM.

And like other commenters say: I think it would be much easier to restrict
flow in the "funnel" part and most things I can imagine for a freestanding
wind machine.

------
gscott
I applied to ycombinator with this idea two years ago, I read an article about
how the wind turbines were driving people who live near them crazy with the
noise they create. Having a funnel that would capture the wind, then put it
through a turbine, plus the ability to channel the wind, seemed like a good
idea. However I am not an engineer, never finished college, and am over 35
which may have hurt my application :)

~~~
CmonDev
Did you present a plan of how to inflate the price of the start-up rapidly for
a quick sell-off?

~~~
gscott
That was the challenge, I couldn't think of a way to make everyone in the
whole world want the product but it seemed like an interesting problem because
giant blades spinning just can't be the future of wind energy. The blades take
out too many birds and make too much noise. There is a wind energy project
maybe 40 miles from me, the installation of the towers and movement of the
dirt has caused dust storms for the local residents. A funnel system could be
longer and have more support of a wider area, requiring less digging. Big
corporations would only switch if they can build it for less and make more
money through additional production from each unit so it is unlikely there is
big money in developing it, it would have to be a Bill Gates type save the
world project and give the designs away for free.

------
eliteraspberrie
As others have mentioned, the air increases in speed because of the Bernoulli
principle: the decreased cross-section increases the dynamic pressure.
However, most of the power will be lost in friction, during the "channeling"
part -- and the increase in speed will not make up for that loss.

The friction is relatively high because the flow is turbulent, not laminar.
The friction factor can be calculated with the Colebrook equation, implicitly;
if they did the calculation they would realize that the distance between the
intake and the turbine is a mistake (especially the height difference, which
doesn't make sense for atmospheric flow).

It would be better to use natural land features that create the kind of flow
you need, such as mountains. Look at the figures here for inspiration:

[http://journals.ametsoc.org/doi/pdf/10.1175/1520-0469%281973...](http://journals.ametsoc.org/doi/pdf/10.1175/1520-0469%281973%29030%3C0801%3AATSOTF%3E2.0.CO%3B2)

------
rikkus
Was a bit worried until I saw 'Wind returns to environment.' Thought they were
going to keep it.

------
alfor
No, it doesn't work.

The same principle have been posted many times. The only important thing, is
the surface area of the collector, that where the energy comme from.

In this case, think about the cost of all this structure vs the same area
swept by a blade. The cost of the simple blade is always lower than the same
area of 'concentrating funnel'.

Right now they are building turbine with blade of 90m of diameter, imagine
building a concentrating structure of the same size.

~~~
jpadkins
Right, but is the mfging and installation costs of the 90m blade vs. the
structure of the same size?

I see this as a cost optimization, not a way to get more energy from the same
source.

------
aquadrop
If it really works it's amazing. But I won't believe it until more information
is disclosed and some independent experimental data provided.

------
dojomouse
This is an absolutely awful idea, as it was every other time someone's had it.

Consider the following:

a) The _maximum_ amount of energy you can get from some wind is a function of
the velocity and density of the air and the projected area of your generator.
You can't go above 59.3% of the original kinetic energy content. Conventional
three axis turbines get pretty damn close to this limit (80% or so).

b) That being the case, getting cheaper or better power is a matter of getting
a large projected area for a low cost while still keeping pretty good
efficiency.

c) If you cover a large projected area with a small amount of material, and
can point your projection to face the wind... you will do quite well. This is
what conventional turbines do.

d) If you cover a large projected area with an even smaller amount of material
you may do VERY well. This is what Makani power acheived before they were
absorbed into GoogleX.

e) If you cover a small projected area using an astronomical amount of
material, which doesn't turn but is rather built for every direction, you can
expect to do really really badly... no matter how many bullshit mystery air
acceleration tubes you include.

It's bullshit.

*edit: I know nothing about the people who are proposing it. They may be doing so in good faith and not realize it's a terrible idea. But it's still a terrible idea.

------
chrisfarms
> The unit is about 50% shorter than traditional wind towers

This is the same thing people say about VAWTs... but they don't build HAWTs
really tall just for fun, the wind speed is faster and more consistent up
there. So all they are really saying is "the one we built isn't very big"

I think the biggest benefit to this design is that it looks like it could be
dirt cheap to make and maintain since it appears to have very few moving parts
exposed to the elements.

------
JackWebbHeller
Why is the funnel intake octagonal? Making it circular would be more
aesthetically pleasing, or is there a technical reason why having 8 'separate'
entrances is required?

Secondly, paint the funnel intake and top section green, and the 'trunk'
brown, stick these on top of a hill, and from a distance it could pass for a
tree. Much more visually pleasing than a traditional wind turbine.

~~~
moocowduckquack
I doubt that the aesthetics are the prime design consideration. This is to
generate electricity, not to stick in a gallery. Power generation isn't
generally pretty, but it keeps people alive in the winter.

~~~
elithrar
> I doubt that the aesthetics are the prime design consideration. This is to
> generate electricity, not to stick in a gallery. Power generation isn't
> generally pretty, but it keeps people alive in the winter.

They are _a_ design consideration though. You can't just stick things where
you want: there are political and community issues to consider. Many rural
communities might object to functional-but-ugly wind turbines littered about
"their countryside".

------
ancientrepeat
The physical rationale is fundamentally flawed. It assumes that all wind that
is "caught" will enter on the big opening and all of it will leave on the
small opening. But that is wrong, the smaller of the narrow region the less
wind enters the entire construction.

The fundamental flaw of the rationale is that it confounds the concept of an
engine to that of wind entering the tube. If you suck cold air into a
compartment via a valve and provide heat inside it the air expands rapidly and
must leave because it does not fit inside anymore. But note how we spend a lot
of energy to expand the air and turn that internal energy into mechanical
energy. There is absolutely no way that you could get air freely inside of a
tube and have it "speed" up without actually pushing back on the air that is
coming in.

Imagine that you close the narrow part completely. What happens? Will the
construction blow up, of course not? Will the the pressure inside rise to a
high value? Of course not. It will simply fill up with air and will experience
as much pressure as the wall of the building is subjected to. Can you make the
closure experience more pressure than any other part of the building? No that
is not how pressure works, it is uniform inside the building.

Now imagine that you make a teeny tiny hole in the closed area. Will that lead
to air leaking at insane speeds? No it will be barely noticeable, almost no
air would be coming out. There is no reason whatsoever that the air would
voluntarily go into a building than on it is own choose to leave on the tiny
hole instead of leaving the same way where it got in (basically it is not
getting in at all because the pressure inside is the same as outside)

Does it work, of course to some extent, take the area of the building that
catches wind, multiply it with the speed of the wind and density of the air
and you get the the mass and volume of air that is moving. Air is actually
pretty light, you would be surprised how big the area needs to be.

------
bmatthews60
Why is this better than just putting a big cone around a small conventional
wind turbine?

That would also 'concentrate' the wind.

~~~
scblock
It's being done, actually. Company called Ogin (was FloDesign Wind Turbine) is
developing a 100 kW shrouded wind turbine that is similar to that idea. But it
only works on small machines, can you imagine a 100 meter rotor with a shroud
around it?

[http://oginenergy.com/](http://oginenergy.com/)

------
lotsofcows
"Wind returns to the environment"? Ahh, running wildly as wind should.

Presumably, they mean, "some wind returns to the environment"? Currently, I'm
reading that as, "massively inefficient".

And it doesn't really "return to the environment" anyway, does it? It's
channelled, focused and ?most? of the power is removed.

------
__alexs
This design optimises for low-wind speeds by exploiting the Bernoulli
Principle but the problem with doing that is that there is very little energy
available in the wind at low speeds to begin with.

It's more practical to aim at higher wind speed sites (e.g. off-shore, or
simply by being much taller) simply because there is vastly more energy.

------
malandrew
I'm not specialist in fluid dynamics or wind, but isn't some energy going to
be robbed by the intakes on the sides not receiving the brunt of the wind? I
would imagine that the passive sides would rob the tunnel of pressure.

However, if this problem exists and does reduce efficiency, I reckon it's an
easy fix that just requires adding dampers for each of the channels and
opening them for the ones receiving wind and closing them when not receiving
wind.

Out of curiosity, what's the fluid dynamics equivalent of a parabola for
energy rays? i.e what shapes are known to concentrate and accelerate fluids
best? I know a venturi nozzle is one such shape for acceleration of already
collected fluids. What's the best collector shape?

~~~
ars
They would _have_ to use dampers. Otherwise the wind will enter one side, flow
down the tube, then right back up the other side since there is less
resistance that way compared to pushing a turbine.

You could use passive dampers - just a flap basically.

------
fpp
There has been a lot of hype on low wind speed energy production for years and
Sheerwind is just one of the "contestants" of _challenging the laws of
physics_ \- i.e. there is only so much energy per m3 air / wind power density
provided with low wind speeds and you can't harvest more than 100% - also see
Betz's law.

For a good overview of _novelty_ wind energy approaches (taken with a grain of
salt) - [http://barnardonwind.com/2013/06/03/good-and-bad-bets-new-
wi...](http://barnardonwind.com/2013/06/03/good-and-bad-bets-new-wind-
technologies-rated/)

~~~
msandford
This is an optimization, they're not trying to extract more energy than the
wind contains. They're taking 500sqft of wind and channeling it down to
100sqft where their 100sqft wind turbine is. 2mph*500sqft/100sqft = 10mph
ignoring all the viscous losses and backpressure, both of which there will
certainly be some of. So perhaps instead of 10mph you get 8mph.

What they've done is made a 100sqft wind turbine which would have a high cut-
in speed effectively a 500sqft wind turbine with a lower cut-in speed. No
magic, just a bit of clever engineering provided that the tower is cheaper
than the 500sqft wind turbine.

------
yardie
According to my old aeronautics professor, 2-blade turbines are the most
efficient when pointed directly into the wind. They've tested 3-blade,
5-blade, and vertical turbines and couldn't get the same amount of output.
These experimental turbines look great on paper but rarely scale up.

The reason why 3-blade is the most common design is 2-blade turbines induce a
lot of harmonics at high speed. 3-blade cancels it out but are slightly
noisier from the blades slicing through the spoiled air.

~~~
neumann
Actually it is the opposite [1]. Efficiency is theoretically increased with
_more_ blades. The three-bladed turbine is the most popular because of the
cost benefit of building blades vs efficiency gain of extra blades - although
the case of harmonics for even number of blades does hold true.

[1]
[http://onlinelibrary.wiley.com/doi/10.1002/we.274/abstract](http://onlinelibrary.wiley.com/doi/10.1002/we.274/abstract)

------
forktheif
Interesting, but I'd like to hear from someone other than the company that's
making them. I'm kinda suspicious when I only hear the upsides to something
like this.

------
tzaman
The first question that popped my mind is how long until the amount of
produced energy exceeds the amount needed to build such a device.

------
varjag
The mechanical power carried by wind is normally a cube function of its speed,
which suggests that the surface area to generate substantial output from slow
winds have to be enormous.

This doesn't seem to be the case here. Until there's an independent
confirmation (and there seems to be none so far), I'd file it next to cold
fusion folder.

------
lafar6502
Ok, the air would flow into the channel facing the wind, but wouldn't it also
be sucked out by the side channels as the wind passes by? A movement of air
creates a pressure drop proportional to the speed of wind so there would be a
sucking force on both sides of the tower (Venturi effect) - did they address
that?

~~~
jeena
I assume you could have something which only lets air in but not out, like a
[https://en.wikipedia.org/wiki/Check_valve](https://en.wikipedia.org/wiki/Check_valve)
but for wind.

~~~
lafar6502
Yes, but they aren't mentioning that, and I suppose this is quite an important
ommission. And btw, valves would create additional drag and reduce efficiency
of the device.

~~~
jeena
In their FAQ they say:

\- What are the details of the system inside? Sorry, we do not comment on the
details of the inside of our INVELOX system because they are part of our trade
secret.

So it is not unreasonable to assume that they have something in there. And
they could be needing the valve anyway to close the tube if the wind is too
strong to protect the turbine.

~~~
lafar6502
There's a paper published by sheerwind, detailing the principles of operation
- [http://sheerwind.com/wp-
content/uploads/sheerwind/2012/10/Al...](http://sheerwind.com/wp-
content/uploads/sheerwind/2012/10/Allaei-Andreopoulos_ASME-ES-
FuelCell2013-18311.pdf). There's no mention of any valves, too. But there's a
more interesting claim they make: "(...) INVELOX captures the wind kinetic
energy and uses the pressure differentials to increase the kinetic energy
available to a turbine". I wonder how they manage to increase the kinetic
energy of air flow without any external energy source.

~~~
jeena
The more I read about it the more I get the feeling that their goal is to get
as much funding as possible without letting anyone test it, kind of like
Andrea Rossi and his cold fusion reactor.

------
kermorvan
This looks much more difficult to clean, think of all the bugs, birds and
sediment that will stick to the INSIDE of that funnel structure. Cleaning the
blades of an ordinary wind generator seems much simpler.

On the other hand, if this is as tall as they will get, it seems a lot safer
to work on than the current behemoths.

~~~
VLM
In northern areas I think freezing rain would be extraordinarily exciting.

------
Gurkenglas
If the wind gets slowed by turning the turbine, shouldn't the output side
funnel of the turbine be larger than the input side funnel to be able to hold
more air? (So the additional wind coming in from behind doesn't have to waste
its own kinetic energy pushing the front air out of the system)

~~~
mgraczyk
I believe the output side should as wide as possible while still preventing
turbulent flow, as would exist if there were no output tube.

~~~
Gurkenglas
Would turbulences be prevented if 3 radial blades (3 so the 45:15=3fold amount
of air can pass without problem) divided the wind from the turbine into 3
funnels as large as the input funnel?

------
robewald
This is a nice concept. In populated areas there is quite a bit of pushback
from the population to install wind turbines due to the distracting movement
of the blades and their shadows. This idea solves that nicely by hiding the
turbine. Maybe the marked for this is densely populated Europe?

~~~
gambiting
I feel like this is worse though, as a tower like that looks million times
worse than a wind turbine. I would hate if structures like that started
appearing across the landscape.

~~~
Rizz
We already have square structures in the landscape: office buildings. These
could be put on top of regular buildings keeping the shape of the buildings,
just making them a bit higher.

------
keeran
Is this the same technique employed by the Windcatcher [1] (rapid inflation)

[1]
[http://www.kickstarter.com/projects/1484284472/windcatcher-i...](http://www.kickstarter.com/projects/1484284472/windcatcher-
inflates-in-seconds-with-no-power-or-p)

------
whage
The swept area of regular wind turbines seems enormous compared to sheerwind's
turbine's. Even the combined area of those 8 entrances look much much smaller.
How in the world is this going to compete with those giants? What am I
missing?

~~~
danmaz74
Why would the "swept area" be meaningful? It's the blades that get the kinetic
energy from the wind, not the space between the blades.

~~~
whage
don't be silly, you just claimed that it doesn't matter whether you have 3
meter blades or 30 meter ones. Of course the swept area matters.

P = 1/2 x ρ x A x v3 where ρ = air density, A = swept area and v = velocity of
the wind

~~~
danmaz74
Don't be silly yourself. What happens if you add or remove a blade, or change
their shape or pitch? The swept area stays the same, but the energy captured
changes. The "swept area" is a useful abstraction that gives us the total
energy that you can extract from - with your formula - but it's the blades
being there with their length that extract that energy.

These wind towers on the other hand capture and manipulate the whole air flow
from the area of their intake, not just the part directly interacting with the
blades of a traditional turbine. That's why it is physically possible to
extract much more power than with a traditional turbine with an equivalent
"swept area".

~~~
whage
That's right, the above formula is just the power of the wind, the amount of
energy you are able to harvest from it does depend on the characteristics on
the blade. The swept area is still a key factor. (see Betz limit for another
interesting fact)

You are right about the second part, those 'tunnels' do catch all the wind of
their area.

~~~
danmaz74
Ok, I think you got my point. To sustain it: "Theoretically, an infinite
number of blades of zero width is the most efficient, operating at a high
value of the tip speed ratio. But other considerations lead to a compromise of
only a few blades.[22]"
[http://en.wikipedia.org/wiki/Wind_turbine_design#Blade_count](http://en.wikipedia.org/wiki/Wind_turbine_design#Blade_count)

------
rpedela
600% sounds impressive, but what is the typical output of wind turbines in
absolute terms?

~~~
brazzy
If I look at [http://sheerwind.com/technology/field-
data](http://sheerwind.com/technology/field-data) it seems to me the 600%
improvement is highly deceptive: that huge funnel tower gives _up to_ 600%
(average 300%) more output than _the same tiny turbine inside it when it 's
just placed on top of a pole_.

If you want to use this technology to boost the output of a modern 100m
diameter turbine by 300%, you'd need to build a funnel tower that's over 1km
high. I kinda doubt that's cheapter than building three of those turbines.

~~~
Gurkenglas
Maybe by "the same turbine" they mean the generator at the center, having
swapped out the short blades shown on their site for a traditional set.

~~~
brazzy
Doesn't look like it, neither in the photo nor the comparison table. Besides,
I doubt that it's even built to allow that.

------
shenoybr
This reminds me of 'windcatchers' that humans have been using for centuries.
[https://en.wikipedia.org/wiki/Windcatcher](https://en.wikipedia.org/wiki/Windcatcher)

------
chrisbennet
"A single experiment is worth a thousand expert opinions."

~~~
ISL
A single _correct_ experiment, perhaps.

------
doubt_me
I just saw one being put up in Rosemont, Illinois last week

That thing was huge.

------
adamnemecek
Hate to be that guy but sounds a little too good to be true.

------
x0054
This looks like an amazing idea. How can I invest in this?

~~~
icebraining
Click on "Investors"?

------
astrobe_
Plus, in deserts one can collect water at the same time.

------
tomrod
Amazing technology!

Again I protest the design decision of light gray text on a gray/white
background. Higher contrast! :) (sorry to be a broken record).

------
arianvanp
The way it looks really gives you the feeling like this d'ni engineering.
Except this is real! Ok, back to playing Myst

------
DanBC
Is this really real, or is this something misguided like the "flowerpot candle
heater"?

------
mmcclellan
It looked good enough to Google to me. Sheerwind hoax is my 4th suggested
search.

------
jokoon
At first I thought this was a joke or some april fool.

------
monsterix
Okay so it starts with normal wind at as little as 2mph (influx) and then with
series of venturi tubes and processes the wind is sped up to 45 miles per
hour. Then the blast is shoved through a turbine generating electricity and an
exit wind at 15 miles per hour (efflux). All right.

So why not take this efflux wind at 15mph back to the top again, or even half
way with some loss of course, and achieve a perpetual motion machine [1]?

Is something missing in the introduction video about this concept?

[1]
[http://en.wikipedia.org/wiki/Perpetual_motion](http://en.wikipedia.org/wiki/Perpetual_motion)

[Okay got it: The blade area/size of a fan to turn at winds as low as 2mph is
quite high (and expensive) as compared to rotor blade size that would work
with winds at speed 45 miles per hour. This one looks like a play on lever
action of wind on fan blade area/angle w.r.t achievable influx velocity. Not
too bad it's a kind of optimization, but for the introduction video that
wasn't clear enough.]

~~~
mschaecher
You could do this without having to "move" the exhaust back up to the top I
think.

Just stack them in a line at different elevations so that one's exhaust turns
into the fuel for the next one. If speed of the exhaust increases after a
cycle you'd be creating stronger "breezes" as you go down each step.

It wouldn't be 'perpetual' but pods of 3-4 like this might be able to increase
the yield substantially.

Then again I don't know much about this and I'm just trying to comprehend it
all.

~~~
digler999
if you output one into another, the _resistance_ would back up into the first
one and reduce its output, or else the pressure would push the air backward
out one of the other tubes of the 2nd device and not spin the rotor.

~~~
mschaecher
Couldn't you space them out a little and rather than backing up it would
expand and flow like regular wind? (serious, just curious)

~~~
ars
When you say space them out do you mean open to the air?

If so then the wind will just escape into the easy air rather than push a
turbine.

If in a pipe then spacing makes not difference.

------
knowitall
It seems to lack any kind of physical explanation of why it should be more
efficient than traditional turbines? All it says is that it uses a smaller
turbine - are those more efficient? I would have expected larger turbines to
be more efficient (just on the grounds of larger fans in PCs making less
noise...)?

It seems irrelevant if the turbine is sitting on the ground or not.
"Accelerating" the wind also seems kind of irrelevant - they can't create
energy that way. However, if they manage to drive a turbine with little wind
that way that would otherwise not have worked, perhaps it is a win.

Maybe it is a good technology, just saying that I don't see any reason in the
text of why it should be. At least they could have written "small turbines are
x% more efficient than large turbines" or sth like that.

~~~
jeena
They say they can generate electricity at much lower wind velocities already,
long before a normal big blade could.

~~~
sgt
What happens with this setup when there are insanely high wind velocities?

~~~
jeena
They don't say anything about that, I assume you could close a valve or
something, that way it would be easier to controll the flow of wind then with
a normal turbine.

------
stefantalpalaru
What if the wind blows towards the bottom opening of the funnel?

~~~
stormcrowsx
The wind moving out of the opening is moving at 15 mph and the wind moving
toward the opening would be at 2 mph. The 15 mph wind will win.

