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Replacing a turbine, this sail or wing, permanently set on
the
roof of high rise buildings or in high-wind locations, catches
wind energy and transfers it via a cable and gearbox to an
electric generator.
For several hours the sail advances slowly by leaning forward
but only 1 cm at most
in 24 hours.
A cable transfers the power of movement
Once every few hours the sail is relaxed and pulled back to
its
original position.
Rather than "no moving parts" this is about "slow moving
parts".
The benefits over a turbine would be: 1. You have more
"wind
catching space" so I would expect you can catch more
energy
in the same area. 2. Less parts and less moving parts. 3.
Probably much cheaper to create, hoist up and maintain. 4.
Less environmental objections. Could even be set up as a
fence or roof shade.
One thing I don't understand is how much of the wind I have
to let by, so that the strongest constant difference of
pressure between the two sides of the sail is kept and what
the best shape of the sail should be. Sailships use square
sails when they want to advance with heavy cargo, but
sailboats use triangular sails when they want to go faster
than the wind, or in a direction that is not that of the wind.
When going in the same direction of the wind does that
mean they are able to recieve more energy ?
Sail generator proposal
https://greendiary....urbine-designs.html
[2 fries shy of a happy meal, May 22 2019]
A bit of real physics
https://en.wikipedia.org/wiki/Windbelt
One of those out of box inventions [wjt, May 23 2019]
Wikipedia: Betz's law
https://en.wikipedi...g/wiki/Betz%27s_law
// One thing I don't understand is how much of the wind I have to let by // [notexactly, May 27 2019]
Electric_20Galleon
[2 fries shy of a happy meal, May 27 2019]
About Catchwood's sail - actually a wind funnel
https://www.wired.c.../11/kite-like-sail/
[pashute, May 27 2019]
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Annotation:
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//the sail advances slowly by leaning forward but only 1 cm at most in 24 hours.//
There's your problem. Energy=force x distance. |
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Suppose you have a wind turbine, where the blades travel a total distance of 100km in
a day (that's very conservative), and the force acting on the blades is 1000kg or
10,000N (also conservative). That's 100,000 x 10,000 = 1e9 Joules of energy. |
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Now consider your system. Let's assume that the force acting on your almost-static
sail is 100 times bigger than the wind turbine, or 100,000kg (100 tons), or 1e6N. The
sail moves 0.01m in a day. Total energy= 10,000 Joules. |
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So, adjust the figures. Have it swing forward a couple of meters, and then feather to swing back, every couple of seconds. Better, have a symmetrical section so it can generate force in both directions. |
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Or you could attach it to an axle ... |
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As [MB] points out, [-] Bad Physics. |
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//Better, have a symmetrical section so it can generate force
in both directions.// Well, then you've essentially got a
flapping structure. Not only do you waste lots of energy in
accelerating/decelerating in each cycle, but the loads on the
support structure will be huge. |
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Put it on a trolly on rails so it can run 100km across the landscape every day, pulling a cable attached to a generator? |
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No it is a silly idea. Let us stop. |
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It can be made to work, after a fashion. |
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The mast and sail is on a trolley. The trolley runs on a track with a vane that keeps it pointing away from the wind direction. |
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From the trolley, a cable runs over a pulley and is attached to a bucket and a weight which are free to descend into a water well. |
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The wind pushes on the sail, which raises the bucket. When the bucket reaches the top, it is automatically tipped. This furls the sail. The weight pulls the bucket back down the well, and when the trolley hits the stop the sail is unfurled again; the cycle repeats. |
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More of an art installation than a practical pump. |
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Played with this basic idea for a while. Came up with the
best incarnation of it. |
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Use it for decoration and build nuclear power plants. |
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There was a Venetian blind type generator that vibrated as wind traversed the belts or 'sails' if you like. |
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Used physics textbooks really aren't that expensive... |
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[2 fries...] As far as I can tell, that one uses the sail more as
a "scoop" to channel more air into the turbine, rather than
using the tension on the sail mounts directly. |
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^ Interesting link. 2014 eh? I posted the idea to use wind power to vibrate cords stretched between magnetic cradles here in 2003. [link] |
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Nice, [2 fries], you may have inspired another bit of kit in the world. Just think how many words in this place have stimulated neurons, to alter actions and finally caused the manufacture something. |
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I knew Betz' law but never really understood it till going
over it again now and finally having it rap around my mind. I
think I get it, at least 59.3 %. |
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No need for a trolley or a bucket. The mast can be
connected to the roof with a hinge so it swivels forward and
backwards, and the cable catching the energy is tied to the
top of the mast. A gearbox for a winch 10 cm wide, going at
say 10 cm/minute means 1 rpm. (I'm being more realistic,
instead of the 1 cm in 24 hours) Changing that to 3000 rpm
is not impossible with a 1 to 3000 ratio gearbox. |
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As @MaxBu pointed out it is not uncommon to get 1 ton
(10kN) of power, but contrary to what he wrote, I'm pulling
a weight (or powering an electric generator) so the distance
the sail moves is not the significant factor but rather the
amount of energy passed from the wind to the generator. |
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I also re-learned the "faster than wind" sail, and realize now
that the actual explanation is that the angle of the sail is
alowing for a larger release of wind (and better Belz ratio)
which means more power and more energy, hence the
higher speed, which in the actual wind direction is still at
the actual wind's speed, but using extra energy to move the
boat additionally at an angle to the actual wind's direction. |
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A Like and laughing smily for doc @emulac3 (e mu - I
understand from digital signal processing hense the audio
equipment company name but what is lac3 referring to?) |
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Thanks to @Maxwel, @2friesShy, @wjt and @notExactly -
you remarks are highly appreciated! |
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@pocmloc, @Rayford, perhaps you are right. But I'm not
sure. This idea may still have some merit to it. |
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The "kite-sail" project from Chetwoods turns out to be a
funnel for "catching the wind and directing it into a
turbine". You guys have previously written about how and
why that would be non productive in a former idea of mine
a few years ago. [link] |
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The [+] Electric Galleon is, of course, an entirely different
idea. |
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@Maxwell and pocmloc: using 10 instead of 9.8 and
according to the book "Physics of Sailing": |
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If I have 100 kg mass at 1 m from the ground being pulled
towards earth by gravity with a force of 1000 N and
acceleration of 10N/kg, and I let it down by 10 cm, I lose
those 10 cm worth of potential energy previously stored in
the distance of the mass from the center of our planet.
With the new position I can now send a railcar attached
with a pulley at a lesser speed when reaching the ground, or
I can now raise an equivalent weight of 100 kg to 90 cm
only. |
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But If I put a sail of some size, which is stopping a constant
wind that is exerting a force of the same 1000 N on it (not
hard to achieve with a 15m2 sail in a 30km/hr fresh breeze)
and the sail moves 10 cm, I do not lose any of the energy
from the next wind coming up and still exerting 1000 N on
the sail. |
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If this wind could raise 100 kg to 0.2 m (let's disregard the
kinetic energy translated on the way, and avoid discussion
of what stopped the movement when 1 m was reached)
then the potential energy is 100 kg * 10 N/kg * 0.2m = 200j. |
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Theoretically I should be able to catch 50% of that energy,
say by raising a mass of 100 kg to 10 cm, (within 1 minute)
using rope and transmission. Is there a mistake in my
calculations? |
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//Just think how many words in this place have stimulated neurons, to alter actions and finally caused the manufacture something.// |
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More than you would think.
One-liners on talk-shows, stunts, entire sit-com episodes, speed-bumps, theme park rides... etc... |
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While I do a tiny little happy-dance every time I see something from here make it into reality I'm always disappointed that the origin is never mentioned. |
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