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Buoyancy Engine Energy Storage For Ocean Windmills

Huge air tank pulled down with cables, then released when needed.
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The air tank would probably be in the form of a donut shaped tank around the windmill's tower.

In off hours, the buoyant tank would be pulled under water, several hundred feet deep storing potential energy.

When the energy is needed, the tank is released to pull the cables turning 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.

doctorremulac3, Jun 09 2020

Couple of kinks to iron out. https://www.youtube...watch?v=dbRhUWGd98I
But all in all a pretty successful first deployment. [doctorremulac3, Jun 09 2020]

Working out the kinks https://clideo.com/editor/reverse-video
Feed it the URL from previous link and wait a bit. [whatrock, Jun 09 2020]

floating windmill https://www.nytimes...climate-change.html
[kdf, Jun 10 2020]

US20100107627A1 https://patents.goo.../US20100107627A1/en
[xaviergisz, Jun 10 2020]

DE102014117018A1 https://patents.goo...DE102014117018A1/en
Buoyancy energy storage [xaviergisz, Jun 10 2020]

[link]






       I think there'd be too much hydrodynamic drag - energy expended pushing water out of the way rather than spinning the turbine.   

       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.
kdf, Jun 09 2020
  

       I'm thinking the release of this would be very slow so drag woudn't be an issue. So if it's submerged to say, 150 feet and you wanted to tap that saved energy for say, 3 hours, during peak load or low wind times, you've got something traveling at about 10 inches a minute.   

       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.
doctorremulac3, Jun 09 2020
  

       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)
doctorremulac3, Jun 09 2020
  

       Presumably the cable:motor/generator setup would be more efficient than water:pump/turbine?
pocmloc, Jun 09 2020
  

       Yea, you're directly putting that energy into the system 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.
doctorremulac3, Jun 09 2020
  

       see link on floating windmills, mainly notable for costs and challenges on installing things offshore.
kdf, Jun 10 2020
  

       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?
bs0u0155, Jun 10 2020
  

       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?
pertinax, Jun 10 2020
  

       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 dozen windmills.   

       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.   

       What do you think 8th?
doctorremulac3, Jun 10 2020
  

       OK, have a modification. Basically the whole windmill is the energy storing float. See addendum.   

       Not sure if this needs a new post.
doctorremulac3, Jun 10 2020
  

       // 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?
whatrock, Jun 10 2020
  

       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 wind levels.
doctorremulac3, Jun 10 2020
  

       I'll bun that.
whatrock, Jun 10 2020
  

       //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.
bs0u0155, Jun 10 2020
  

       I am probably just confused by I am somehow reminded of grandfather clocks having two weights.
beanangel, Jun 10 2020
  

       One weight powers the hands of the clock, the other powers the chiming mechanism.   

       This needs factored in for chiming wind turbines
pocmloc, Jun 10 2020
  
      
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