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The air tank would probably be in the form of a donut
tank around the windmill's tower.
In off hours, the buoyant tank would be pulled under
several hundred feet deep storing potential energy.
When the energy is needed, the tank is released to pull
a generator as it floats up.
The bigger the tank, the more energy could be stored. If
necessary it would be expandable by adding more
sections to the tank to increase buoyancy.
ADDENDUM: The energy storage float is what the
windmill is built on top of. When there's strong wind,
energy that isn't directed to the generator is put into the
cables that pull the whole windmill down under water.
At times of less wind, the float rises and powers the
generator. And there's a bonus to this
design, as the float rises up to provide more power, the
windmill rises up where there's more wind.
Couple of kinks to iron out.
But all in all a pretty successful first deployment. [doctorremulac3, Jun 09 2020]
Working out the kinks
Feed it the URL from previous link and wait a bit. [whatrock, Jun 09 2020]
[kdf, Jun 10 2020]
[xaviergisz, Jun 10 2020]
Buoyancy energy storage [xaviergisz, Jun 10 2020]
||I think there'd be too much hydrodynamic drag - energy
expended pushing water out of the way rather than spinning
||In any case, a donut is probably the wrong shape for this idea.
You want to minimize surface area and maximize volume for
best effect. A sphere would do that but maybe you want this a
bit more like a vertical torpedo shape to reduce drag.
||I'm thinking the release of this would be very slow
drag woudn't be an issue. So if it's submerged to
150 feet and you wanted to tap that saved energy
say, 3 hours, during peak load or low wind times,
you've got something traveling at about 10 inches a
||Of course to get any useful spin in your generator
you'd have to get a pretty honkin' gear ratio going,
but you're dealing with several tons of lift here so
it might be useful.
||Another thing you could do is have something the
size of a ship and pull it down and let it move with
the flow of the current rather than having it
locked onto a vertical path. Then you've basically
got a motor/generator at the bottom of the ocean,
a buoy the size of, you name it, the Titanic, but
with an issue of tying that thing down. Even if
you're down to solid rock those are going to have
to be some pretty big anchors.
||Could even have these mounted out of range of
the windmills so you don't have to worry about the
current crashing them into each other. You're just
extending undersea power cables so no reason to
have them close to the windmills.
||Yea, our first deployment saw a minor glitch or two. Some houses were very slightly affected but nothing
a couple of paint touchups can't fix. (link)
||Presumably the cable:motor/generator setup would be more efficient than water:pump/turbine?
||Yea, you're directly putting that energy into the
rather than losing some of it through friction and
inefficiency of pumps and turbines. Basically like
compressing a spring.
||Plus you can charge the system directly, just have
gears from the windmill pull the buoy down then let
it pull the motor when it floats back up. Skip having
a motor do it to be more effecient.
||see link on floating windmills, mainly notable for
costs and challenges on installing things offshore.
||Some numbers? Is this ballpark reasonable? Say 500
tonnes of buoyancy at the surface, 5000000N
through 1m is 5MJ. Or 5MW for 1s. Hmm, a big wind
turbine is about that range, so it seems reasonably
well scaled. You'd want to move slower, which
means a bigger float, stronger cable and more
gears. Between water resistance and gearboxes, I'd
expect 30% losses. How is it moved? Independent
motor-generator? More capital, more loss. Why not
use a wave generator instead?
||I wonder, would this be extra-useful in the Dead Sea, with
its extra buoyancy, assuming that in this case the windmills
would be in the surrounding hills?
||Looking at those patents, I'm wondering about the
practical issues of having a free floating member
like that. Especially what I'm proposing which is
basically a sunken ship sized float servicing several
||Might be better to keep it in place with multiple
cables, although if the area has been determined
to be ok to have a float the size of the Titanic
floating around un-predictably it might be ok.
||OK, have a modification. Basically the whole
windmill is the energy storing float. See addendum.
||Not sure if this needs a new post.
||// When there's strong wind, energy that isn't directed to
the generator is put into the cables that pull the whole
windmill down under water //
||If the whole windmill is hauled underwater wouldn't it
defeat the purpose of having it spinning in strong wind?
||I'd add the height. Basically take a 500 foot tower and
add 200 feet of float below it. Have the lower portion be
cone shaped so it'll remain stable as it rises.
||Then you've got this massive thing up at 1,000 feet both
generating electricity and pulling the whole monster
down to store potential energy.
||Easy to deploy, just tow it out from the shipyard that
built it, anchor it in place and push the go button.
||When winds kick up to destructive levels, the tower
stores the energy and drops down to more manageable
||//I wonder, would this be extra-useful in the Dead Sea,//
||You would gain energy density, but on the downside the Dead
sea is a spectacularly non-windy place. It's a hole in the
ground in an already non-windy part of the world.
||I am probably just confused by I am somehow reminded of grandfather clocks having two weights.
||One weight powers the hands of the clock, the other powers the chiming mechanism.
||This needs factored in for chiming wind turbines