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Water balloon energy storage

For agriculture, fill preasure-tank balloons with water in floor level containers
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NOT the underwater pressure tank energy storage project (which stores air)

Friends of mine run a farm using a total of 750 kw (100 hp) water-pumps (10 pumps, approximately 75 kw each), working around the clock, typically at 20 Atmospheres, and pumping water to the fields 24 hours a day, for about 7 months a year, to a total of 6M cubic meters annually (the last number I'm not sure of).

This is standard for many similar farms of that size, and probably the same for areas around the world with dry periods during the year, such as North Africa, the Middle East and many of the landlocked states in the US.

They pay for extremely low cost electricity at off- peak hours and it has been seriously calculated that gravity energy storage would pay off well. But, luckily for the wildlife's sake, they lack the permission to create a water reservoir on the tree covered mountains nearby.

So:

A system of many water balloons in a set of containers in a warehouse, hold stacked pressure-tank balloons, digitally controlled (a digital pressure measuring device can cost less than 1 cent), each balloon is filled under pressure, bottom to top, and emptied top to bottom.

The system returns the water under pressure during peak hours.

The water had to pumped up to ground level in any case, and, hopefully, only a small amount of energy will be lost to heat. Costing much less than the extremely expensive and complex pressure and heat retrieval systems needed with air or gas compression.

pashute, Nov 23 2012

Your friends may want to consider this http://www.youtube....watch?v=Sddb0Khx0yA
if power is the only price pressure. [4whom, Nov 29 2012]

[link]






       //24 hours a day, for about 7 months a year, to a total of 6M cubic meters annually (the last number I'm not sure of).//   

       If that figure is trustable, I make it you would need 6,000,000 * 12/7 / 365 = 28180 cubic meters per day. That's equivalent to a cube approx. 30.4 metres to a side. Is it a big farm?   

       The basis that your plan seems to be that you can run the pumps part-time the whole year round, so saving on pumping capacity. As far as I can see, this has two main potential draw-backs:
1) The pumps may well not be easy to turn on and off. The stop-start cycle may reduce their mean time between failures.
2) At the start of the irrigation period you will need to have storage for 6,000,000 * 5/12 = 2,500,000 cubic metres of water. This volume is equivalent to a cube approx. 135.7 metres to a side ... quite large to store with your proposed relatively technological method.
Loris, Nov 23 2012
  

       Its a collective farm, therefore quite large, in Israeli terms.   

       A Texan farmer visited Israel. The Israeli proudly showed him his farm: See det line of trees zerr, end de brrokne traktore on de road, zerr? All dees eez mine! The Texan says: Well, it takes me a good two days to get from one saad of maa property t'the other saad of it! The Israeli is silent for a minute and says: Yes. We used to hev broken car like det.   

       I only store for peak hours - 6 hours a day. Digital control makes it quite easy, including balloon failure and maintenance when empty, and the whole thing shouldn't cost too much. A large warehouse would do the job.
pashute, Nov 23 2012
  

       //I only store for peak hours - 6 hours a day.//   

       In that case - why store the water at all? You'd need to increase the pumping capacity either way. (In fact you'd need less additional power to use the water directly; loss to friction and back-pressure will be lower.)
Loris, Nov 23 2012
  

       Have they considered an old-fashioned water tower? Or a new-fashioned one (they come in a variety of sizes and take up far less ground space than a lake).
Vernon, Nov 23 2012
  

       So the energy-storage medium here is actually the rubber of the balloons? The water is just a handy way to distribute the pressure around, right? This is equivalent to stretching elastic bands?   

       Or am I missing something, and is the weight of the water somehow the primary storage medium? Are the balloons just bags under no tension?   

       Because giant water balloons capable of storing energy in their stretchiness sound quite expensive. Non-stretchy bags that just hold water sound like needless tank liners.   

       I've seen giant water bags used as emergency water tanks, but they had maybe six feet of pressure head, and took up a lot of ground area. And were very expensive---making them out of stretchy rubber would cost many times more.
baconbrain, Nov 23 2012
  

       I can't see why not to use a water tank.
piluso, Nov 24 2012
  

       Why not switch the plants off during the day?
pocmloc, Nov 24 2012
  

       I store at night when off-peak electricity is at least 1/9th the price of the 6 hour peak price.   

       I use the elasticity to achieve the desired pressure. Yes the energy-storage medium is the "rubber" of the balloons, which are under tension. The water is both the pressure distributor and what will be used for the fields, pumped at night time from a well. The space they take is limited by the containers they are sitting in (so the tension is mostly "UP DOWN")   

       Custom made balloons at a commercial quantity are not expensive. Even pressure tank balloons.   

       A water tower will need special permits, will not give the desired pressure, and in any case is impractical for such a large amount of water. And, in all practicality, a warehouse filled this way, is in fact a water tower. Except that the water on the top is leaning on more water lower below.
pashute, Nov 25 2012
  

       //Why not switch the plants off during the day?// You can almost literally do that with CAM plants, such as cactuses. They can happily take up all their water and carbon dioxide at night.   

       Is there a problem with simply irrigating at night (as [Loris] suggested)? Can the soil not hold 6 hours worth of water?
spidermother, Nov 25 2012
  

       Nope. This farm works around the clock. They also have livestock, a dairy farm, a winery and more. And as I wrote, there are many many places around the world with a similar need.
pashute, Nov 25 2012
  

       //NOT the underwater pressure tank energy storage project (which stores air)//   

       How about the underground pressure tank energy storage project (which stores water pressurized by air) ? Might be worth the waste heat: Hydraulics 101 with real hydra.   

       Or, if there's such a thing as a temperature sensitive dessicant, put an inch of that on the fields, water it at night when it's cool and the substance soaks up water, then during the day the heat causes it to unhydrate into the soil.   

       Meanwhile //1/9 the price//, seriously ? Sounds like an opportunity for battery farms. Or something sneaky and Escheresque with the water-gas reaction.
FlyingToaster, Nov 26 2012
  

       Pressure generated by tension of the balloon would be inverse cube, in a perfect world. You would get far less than that in the real world, and even less so as you scale up. Far better to store electrical potential energy as per link above.
4whom, Nov 29 2012
  
      
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