

The Future of Wind Turbines: No Blades - eurvin
http://www.wired.com/2015/05/future-wind-turbines-no-blades/?mbid=social_fb

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JackC
OK, so: Betz's Law says that the maximum energy that any wind turbine can
extract is 16/27 of the kinetic energy contained in the wind that it blocks.
Modern three-blade wind turbines reach 75-80% of the theoretical maximum,
across the entire area their rotors sweep out.[1]

That's why the classic windmill design is so classic: its efficiency scales
with the _square_ of the length of the rotors. The energy extracted by a
windmill is (very roughly):

    
    
        wind_speed * 16/27 * 0.8 * π * rotor_length^2
    

But then the wind speed also increases with height.[2] So the game to design
an efficient windmill is to sweep out as much cross-sectional area as
possible, as high up in the air as possible, and that's how we get the iconic
windmills we have.

I don't know anything about anything -- I just read this stuff on Wikipedia.
But until a third-party engineer says otherwise, I'm super skeptical that a
device like this with minimal high-altitude cross-section is anywhere in the
game.

[1]
[http://en.wikipedia.org/wiki/Betz%27s_law](http://en.wikipedia.org/wiki/Betz%27s_law)
[2]
[http://en.wikipedia.org/wiki/Wind_profile_power_law](http://en.wikipedia.org/wiki/Wind_profile_power_law)

~~~
mst
My first thought was "even if this is less efficient, the silence and lack-of-
bird-killing means it would be viable to install places where NIMBYism etc.
mean that traditional turbines can't be".

i.e. it may be sufficiently in the game to compete effectively against "no
turbines" even if it can't compete against turbines directly.

~~~
PopeOfNope
It also seems like you'd be able to fit more of them into the same space. The
company also claims that they're (allegedly) cheaper to manufacture and are
(allegedly) cheaper to maintain. Even if the efficiency is less than those of
a traditional windmill, it would still make sense to use them from a cost
savings perspective alone.

That's if everything the company claims is true. Too many other alternative
energy companies have made similar claims and failed to follow through for me
to take this with anything other than a grain of salt.

edited for clarity.

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ColinWright
Substantial discussion of the concept and technology over here:

[https://news.ycombinator.com/item?id=9523877](https://news.ycombinator.com/item?id=9523877)

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hannob
I followed the debate about renewables for quite some time and I heared
stories like this before. A new design for wind energy with so obvious
advantages. And you can read pretty similar stories for new solar or water
power tech also pretty regularly.

I remember that already in the 90s I heared people saying that future wind
turbines will have a funnel to focus the energy. Later kite-like flying
turbines or turbines in donut-shaped balloons became a thing.

But wind turbines still basically look very similar than they used to be all
the time, the biggest change is that they became much bigger. There's a reason
for that: The design worked well and has been improved in details over the
years. It's much easier to improve in small steps than to reinvent a
completely new tech, which will have many downsides that the enthusiasts
inventing them don't want to see.

That's not saying that it's entirely impossible that a completely new design
of wind turbines will some day emerge. But I don't think it's very likely. And
before I believe it I want to see them built at scale for a reasonable price.
(Because one of the biggest advantages of the existing wind turbines - appart
from them being environmentally friendly - is that their price dropped rapidly
in the past years.)

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zackmorris
Similar to the windbelt:

[http://www.instructables.com/id/Windbelt-Redux--21st-
Century...](http://www.instructables.com/id/Windbelt-Redux--21st-Century-
Micro-Power-Generatio/)

Fluids tend to move as vortices so often reciprocating motion can be at least
as efficient as rotary motion. For example it is (currently) difficult to
replicate the efficiency of birds and fish with propellers.

Potentially (ahem) it's possible to extract work from ions in a flow, and if
it's laminar there would be no vortex losses. Just for fun, here is an
electrostatic turbine, which works a bit like an electrohydrodynamic (EHD)
drive but in reverse. From what I understand, it's difficult to extract more
work than it takes to ionize the fluid, so this cheats a bit by using liquid
droplets:

[http://www.wired.co.uk/news/archive/2013-04/3/bladeless-
wind...](http://www.wired.co.uk/news/archive/2013-04/3/bladeless-wind-turbine-
ewicon)

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dm2
I personally like the idea of wind turbines being tethered high-altitude
blimps.

I assume the high-altitude ones could be higher than birds fly.

They could even be used as in-flight recharge stations for drones.

~~~
gweinberg
It's amazing how high birds can fly
[http://en.wikipedia.org/wiki/List_of_birds_by_flight_heights](http://en.wikipedia.org/wiki/List_of_birds_by_flight_heights)

~~~
dm2
Unfortunately it's likely that many many types of animals take advantage of
low-altitude wind-streams, especially during migrations.

But maybe we could place several of them into the jet-stream (at 10-15 km)
which is higher than all birds except one type of vulture.

Edit: Nevermind, Google is working on exactly that:
[http://www.gizmag.com/google-x-makani-power-airborne-wind-
tu...](http://www.gizmag.com/google-x-makani-power-airborne-wind-
turbine/27668/)

The cable seems to be the most difficult part:
[http://en.wikipedia.org/wiki/High-
altitude_wind_power](http://en.wikipedia.org/wiki/High-altitude_wind_power)

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digi_owl
I find myself thinking of a grassy field swaying in the wind.

I wonder if they should try painting them deep green or something.

