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By svfoster
#3379
Here is my idea in very rough form! Go out to the ocean where it is approx 1 mile deep (but this might work also in a deep lake where it is only 500 feet deep) and put down a metal pipe maybe 30 ft in diameter (also consider only 5' diameter). Pump the water out of it and every 300 to 500 feet have a turbine in the pipe which generates electricity. Let water fall down through the pipe until it gets to the bottom where (and this is either the strength or weakness of my idea)...

1- it has heated up so much because of friction that has turned into steam and will automatically rise in an adjoining pipe and with fans and some of the generated electricity blown up and out back into the sky or...

2- if it has not heated up enough to form steam it should be close to it so that a little bit of electricity can turn it into steam and again get rid of it,

3- how much electricity would it take to force the water out into the ocean at that lower depth? (probably too much), and...

4- what does the increased atmospheric pressure at the bottom of the 1 mile pipe do to the whole situation? Or perhaps drill a hole further down into the ocean bottom where the heat increases and pump the water into that so it again turns into steam. I realize that this whole thing probably does not make any sense, but it might stimulate your thinking in some other area.

One question would be what is the minimum distance that water has to fall to heat up 212 degrees due to friction? (as the pipe probably shouldn't be any longer than that. Good luck with it.

Reward: cheaper source of non-polluting energy for all
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By Steve
#3391
Definitely a creative and stimulating idea! ;-) What makes you think that the water will heat up due to friction on such a relatively short strech, especially in a pipe that is - well, water-cooled? If I'd get asked in a quiz show, I would guess it stays about the same temperature, but then again I know nothing about this stuff... :-?
By mtd28student
#3395
Possible a better idea is to use the temparature difference between the top of the ocean and the top of the ocean to drive some sort of heat engine. If the liquid used had a boiling point of around 15 degrees celceuis then the tubines could be driven, if water was used then a striling engine would prob be best.

Coming back to your question about how much a fluid heats up in a pipe. The pressure loss in a pipe along a lenght L, and diamter D is equal to:

P loss = 4L/D x cf x 1/2 x p U^2

where cf = the friction factor of the pipe (around .004 for a typical pipe), p equals the density of the fluid and U equals the velocity of the fluid. This pressure loss, i believe, is proportinal to the energy lost in the pipe, which is turned into heat.

The pipe would have to be very well insulated in order for the heat to be transfered into the fluid.

hope this helps in some way.
By MissPlayful
#3396
It’s certainly a stimulating idea but there are, how can I put this, certain problems. As Steve has intimated I’m sure the water would only warm slightly when it fell, and even if it boiled it wouldn’t allow you to circumvent the principle of the conservation of energy. Methinks the perpetual motion machine has once again risen in new guise from the ashes of its last cremation. Even if by some magical means you could extract all of the energy generated by the falling water, you would need to use all of that energy to remove the water from the bottom of the pipe as fast as it fell. You would have to pump it out against the immense pressure at the bottom of the ocean. And using geothermal energy to help your cause would be a very inefficient way to convert geothermal heat into useful energy.

mtd28student says: “Possible a better idea is to use the temperature difference between the top of the ocean and the bottom of the ocean to drive some sort of heat engine.” Now that idea I like. The climate cools the oceans in the polar regions, and that cold water flows along the bottom of the oceans towards the tropics (it is heavier than the warmer water above it so it stays near the bottom), the sun near the tropics heats the surface waters, and we make use of that substantial temperature difference to extract large quantities of useful energy. Whether it is a practical proposition I have no idea.
By WreckingBall
#3399
svfoster wrote:Here is my idea in very rough form! Go out to the ocean where it is approx 1 mile deep (but this might work also in a deep lake where it is only 500 feet deep) and put down a metal pipe maybe 30 ft in diameter (also consider only 5' diameter). Pump the water out of it and every 300 to 500 feet have a turbine in the pipe which generates electricity. Let water fall down through the pipe until it gets to the bottom where (and this is either the strength or weakness of my idea)...

1- it has heated up so much because of friction that has turned into steam and will automatically rise in an adjoining pipe and with fans and some of the generated electricity blown up and out back into the sky or...

2- if it has not heated up enough to form steam it should be close to it so that a little bit of electricity can turn it into steam and again get rid of it,

3- how much electricity would it take to force the water out into the ocean at that lower depth? (probably too much), and...

4- what does the increased atmospheric pressure at the bottom of the 1 mile pipe do to the whole situation? Or perhaps drill a hole further down into the ocean bottom where the heat increases and pump the water into that so it again turns into steam. I realize that this whole thing probably does not make any sense, but it might stimulate your thinking in some other area.

One question would be what is the minimum distance that water has to fall to heat up 212 degrees due to friction? (as the pipe probably shouldn't be any longer than that. Good luck with it.

Reward: cheaper source of non-polluting energy for all


___________
Dude...perpetual motion machine Water will never heat up to 212 as all the heat generated will flow through the pipe into the ocean. If you insulated it a mile in diameter, you might get the heat...but as you know hot water rises to the top.

It won't work. But, at least you are concerned with the environment.
By MissPlayful
#3404
This idea “Energy from a hole in the ocean” reminds me of a cartoon I vaguely recall seing once. It went something like this. Two divers are exploring the sea floor when they come across a giant rubber bath-plug fitted into a hole in the sea bed. One of the divers is about to give the plug a tug to see what would happen and the other says “I would be inclined to leave that thing alone if I were you Smithers”.

Now if we could find that plug, pull it out and fit the bottom of svfoster’s pipe over the hole, we could let seawater pour in at the top of the pipe, generate electricity as it fell, and the water would disappear down the plughole at the bottom. Problem solved! We would of course have to lower the top of the pipe progressively as the level of the oceans fell. Assuming the hole in the ocean floor was sufficiently large for us to generate enough electricity to power the whole planet, I wonder how long it would be before we would drain the oceans dry. On that final day there would be a dramatic and awesome gurgling sound as the last of the world’s ocean water disappeared down the hole, and we would stand around on the dry ocean bed and say “Well that’s that then”.
By Rishi
#4388
The idea is really a perpetual motion machine. If a pump and a turbine are used together it is not possible to generate more than about 80% of the energy that went into pumping because of mechanical losses.

The second law of thermodynamics indicates that all systems are tending to reach an equilibrium. From this it follows that the best chance of getting energy out of the ocean is to use the difference of temperature between the top and bottom. (It will not need 500 feet perhaps). A suitable low boiling liquid has to be used, which condenses at the lower temperature but develops sufficient pressure at the higher. This high pressure vapour can run a turbine. What is really being achieved is that ultimately the temperature at different levels of the ocean are equalised.

Well the oceans are large enough and can stand it I suppose. There could be melting of the ice caps though.

This has already been demonstrated but is uneconomical at present.

Rishi
By Bubba
#5397
Just one problem here. Falling water actually cools, by about one degree in 78 feet of fall.

Sorry to burst your bubble, but this is bad science.
#5401
Bubba are you sure about this? What physical process would cool water by this amount as it fell? Evaporation? If you are right it would mean that water at 10 degrees that enters the top of a waterfall 780 feet high would be at freezing point when it reached the bottom.
By Rishi
#5407
Water will get cooler, whether it falls or not, if there is evaporation. For this to happen, the surrounding atmosphere should have a humidity less than saturation. Also, the lowest temperature that can be attained by water (Or any other liquid for that matter) is the Dew Point. A shallow pan of water left on a table will gradually cool to the dew point. This is the temperature at which water comes out of the air as dew. At dew point the air will be saturated with water vapour.

In any case, the air around a water fall is likely to be saturated with water vapour and will not allow any evaporation. There is negligible risk of your being hit by falling ice if you are bathing in a waterfall unless the ice was already in the water at the top.

Rishi
By law
#9099
Scrap the heat generation. Tidal pull alone would generate a significant amount of energy given the amount of turbines involved. Just switch the generators polarity appropriately with the rotation of the moon. I would crunch some numbers though... get a general idea of feasibility. Note, due to the corrosive nature of salt water, many organizations stray away from the energy generational power of the ocean.
GL
By Rishi
#9135
law wrote:Scrap the heat generation. Tidal pull alone would generate a significant amount of energy given the amount of turbines involved. Just switch the generators polarity appropriately with the rotation of the moon. I would crunch some numbers though... get a general idea of feasibility. Note, due to the corrosive nature of salt water, many organizations stray away from the energy generational power of the ocean.
GL


Tidal power generation is very much an ongoing R&D activity at various federal and private labs. But that is going away from the original suggestion

rishi
By law
#9136
yes, tidal pull is a very researched subject at various federal and private labs. However the focus in those labs is the utilization of horizontal, not vertical energy. The key to the original posters idea.
By Rishi
#9137
law wrote:yes, tidal pull is a very researched subject at various federal and private labs. However the focus in those labs is the utilization of horizontal, not vertical energy. The key to the original posters idea.


I was myself involved in one of those projects. The motive force always is the height difference between the high tide and the low tide zones. It is true that the turbines are horizantal and the flow of water across causes the power generation. BUt ultimately it is the vertical force that is the driver.

rishi
By law
#9138
yeah that whole mass/gravity thing...
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