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Author Topic: Why can't we use water weight to create energy?  (Read 8599 times)

Offline doppler1

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Why can't we use water weight to create energy?
« on: 13/01/2010 10:15:49 »
What is stoppingus from using water at depth to drive energy creating devices?

In essence at 1000meters depth, water pressure is in the region of 100 Bar which is quite high. There must be a way to drive pistons  by allowing the water pressure to act on surfaces of varying areas to drive a motor of sorts? Surely this is a realaitvely cheap source of energy and I would not think that the technology required to capitalize on this energy would be so expensive. Any comments???


 

Offline Don_1

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Why can't we use water weight to create energy?
« Reply #1 on: 13/01/2010 10:25:59 »
The pressure, at any depth, will be uniform. To drive a piston, you would need to apply the pressure to the pistion head only, then remove that pressure. Since the energy required to remove that pressure would be greater than the energy produced by the piston's down stroke, you would have a net loss of energy.
 

Offline Bored chemist

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Why can't we use water weight to create energy?
« Reply #2 on: 13/01/2010 10:27:48 »
We do, they call it hydroelectric power, but the important thing is that there has to be somewher "downhill" for the water to go to. Once you are at the bottom of the sea there's nowhere for the water to go but up and it can't do that without something adding energy to it.
 

Offline doppler1

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Why can't we use water weight to create energy?
« Reply #3 on: 13/01/2010 10:31:43 »
Can we not force movement by applying the same force against two opposing but different areas?
 

Offline doppler1

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Why can't we use water weight to create energy?
« Reply #4 on: 13/01/2010 10:33:20 »
Sorry, actually meant the same pressure against two dissimilar areas as this should result in two different forces..or am I mistaken?
 

Offline Don_1

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Why can't we use water weight to create energy?
« Reply #5 on: 13/01/2010 12:38:29 »
I think I get your drift, you are talking about alternating the surface area of two pistons. This would also require changing the bore of the chamber. The amount of energy required for this would be far in excess of any energy created.
 

Offline doppler1

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Why can't we use water weight to create energy?
« Reply #6 on: 14/01/2010 04:32:29 »
Hey Don_1, what I am thinking of is more havingan isolated units which could have sealed air chambers in which the air is simply transfered from one chanmber to the next and the pistons (which have a set surface area) are then activated via solenoids or something to let the water pressure act on them. In essence, the solenoids could divert the pressure from one piston to the next to drive the motor. the air in the unit would be used to ensure that the piston that is being driven has a nice Delta P. Anyway, just a bit of a thought and have not spent much time thinking about it.
 

Offline Don_1

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Why can't we use water weight to create energy?
« Reply #7 on: 14/01/2010 08:24:55 »
Think about it. The air in the 1st chamber would be compressed by the sea pressure. If the sea pressure were 10 bar it could only pressurise the air to something ≤ 10 bar. To evacuate the sea water from this chamber you will need air pressure > 10 bar. You do not have sufficient pressure to do this.
 

Offline doppler1

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Why can't we use water weight to create energy?
« Reply #8 on: 14/01/2010 08:45:22 »
Point made. Thanks for the input.
Cheers for now
 

Offline Don_1

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Why can't we use water weight to create energy?
« Reply #9 on: 14/01/2010 09:18:54 »
Point made. Thanks for the input.
Cheers for now

Good. But don't be put off, keep thinking, you just might hit on a brilliant idea next time.

The oceans are a source of great energy, the trick is finding a way to unleash it to our advantage.
« Last Edit: 14/01/2010 09:23:02 by Don_1 »
 

Offline doppler1

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Why can't we use water weight to create energy?
« Reply #10 on: 15/01/2010 12:37:32 »
Thanks guys, the main thing that attracted my thought was that the weight of water is available without any inputs to begin with and the efficiency of water versus air due to its non compressability seems to make it quite a good option if we can create the differential. can you tell me how if the air inside a diving bell is replenished and if so, how is it done, IE, if the diving bell is sitting at say 1KM below the surface which is not really that deep for a diving bell and deep sea operations, surely you do not need 100 bar worth of air pressure supply to change the air?? or is it done locally with a similar arrangement to submarines??
 

Offline Geezer

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Why can't we use water weight to create energy?
« Reply #11 on: 15/01/2010 20:46:33 »
er, well, the air in the diving bell is not highly pressurized. It's held at close to atmospheric pressure.
 

Offline doppler1

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Why can't we use water weight to create energy?
« Reply #12 on: 16/01/2010 11:38:24 »
If the air in the diving bell is kept at atmospheric pressure, why is it not also compressed by the outside water pressure as it is then an area of low pressure?
 

Offline Geezer

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Why can't we use water weight to create energy?
« Reply #13 on: 16/01/2010 17:14:01 »
That's what the bell is for. It withstands the water pressure so that there can be a great difference between the inside and outside of the bell.
 

Offline doppler1

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Why can't we use water weight to create energy?
« Reply #14 on: 18/01/2010 12:31:57 »
So what you are saying is that using a similar concept to the diving bell, we can in fact have a situation where a huge Delta P can exist and is sustainable in an environment of high pressure under the correct circumstances. If water is spilled or dumped inside the diving bell, will it fill up and displace the air or will it proceed down the exit/entrance and just become part of the high pressure water outside the bell?
 

Offline doppler1

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Why can't we use water weight to create energy?
« Reply #15 on: 18/01/2010 12:34:02 »
Just a thought, if the pressure inside the bell is only atmospheric, what prevents the deep sea divers from getting air bubbles in their blood as they come out of the water? Or do they have some sort of decompression chamber that theygo through before actually getting into the low pressure area?
 

Offline Bengaman

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Why can't we use water weight to create energy?
« Reply #16 on: 18/01/2010 22:06:20 »
Just a thought, if the pressure inside the bell is only atmospheric, what prevents the deep sea divers from getting air bubbles in their blood as they come out of the water? Or do they have some sort of decompression chamber that theygo through before actually getting into the low pressure area?

I believe this is the case, someone correct me if I'm wrong
 

Offline Geezer

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Why can't we use water weight to create energy?
« Reply #17 on: 19/01/2010 03:47:57 »
Oops! Possible confusion. When you say "diving bell" do you mean the old fashioned variety where the bottom is open to the water? I was thinking of something more like a bathesphere, which is sealed.
 

Offline doppler1

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Why can't we use water weight to create energy?
« Reply #18 on: 19/01/2010 06:43:45 »
I guess all the answers are on wikipedia regarding the diving bell.
http://en.wikipedia.org/wiki/Diving_bell
It seems that the air needs to be pressurized to keep the external water pressure outside
 

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Why can't we use water weight to create energy?
« Reply #18 on: 19/01/2010 06:43:45 »

 

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