Could A Hydroelectric Power Station Be Created Out At Sea?

[crankfwd]

Okay, I've got another idea about hydroelectric power that I could use some help with. Imagine you have an enormous funnel that is 1km in diameter at the top. This enormous funnel is held in place by four hollow towers (that are open at the top), that are cemented into the sea bed. The top of the funnel is just below sea level so that it is always half full of seawater. The spout of the tunnel goes about 250m down, where it splits four ways into tubes that feed the four hollow towers. Where the water feeds into the tower there is a hydroelectric turbine. The water keeps on falling after going through the turbine and falls into the hollow tower

[crankfwd]

Peter P-yes everything is nice and balanced but then I add two more turbines or a marine engineer invents a more efficient pump and suddenly I have excess electricity. Remember I am using gravity to create electricity and I'm not using that to pump the water up to the same level, which would be an instant fail. I am using a tower which has at least three turbines, two of which are used to create electricity to power the pump. The blades on the pump could even be constructed so that they aerate the water as it hits the bottom of the tower. I think it would be easier to pump aerated water but not sure. If fact I don't even need a giant funnel (I just thought it would be better to see what was going on and control the reservoir of water), I could just have a water intake 250m below the surface, which then travels down a tube another 250m before it enters the tower.

[New Judge]

//because it can be moved up and down and tilted slightly.//

Have you calculated the weight of your funnel and its contents? I have. Ignoring the weight of the contraption itself (which will be considerable) the water it contains will come in at around 66 million tonnes. (volume of a cone is πr2*h/3. Seawater weights around 1.02 tonnes per cu. metre). So you're going to juggle upwards of 70m tonnes around, to do what? What you've got to do is ensure the level in the funnel is higher than the level of the sea surrounding it. Let's assume you can manage a difference of two metres (that is, you must lift 70m tonnes 2metres). How much energy do you think that will take (I can't be bothered to do the sums) and how much will you get in return when the level in the funnel falls back to sea level?

I think I'd better dip out of this because it's obviously beyond my comprehension. Meantime I look forward to the coast being surrounded by funnels a kilometre across!

[crankfwd]

New Judge- sorry, I think you missed the part where I said I probably don't even need a funnel, just a water intake below the surface of the sea. But hey, the towers are still good, so look at for those and avoid the large man-made whirlpool nearby.

[New Judge]

Where will it take the water in from? And why should it (the water) move downwards? I'm still struggling (as I suspect so are you but for different reasons).

[crankfwd]

Hey Judge, don't worry, not a struggle. The inlet would be below the surface of the sea, so a constant supply of water. The inlet tube would go down 250m and merge with the empty, air filled tower. The water would fall down the tower, go through three turbines and fall onto the expelling pump. So at no time does the falling water hit any other water, it falls through the air and hits the pump.

[beso]

A word of advice. Find something else to contemplate because you don't have a clue about engineering and mechanics. You are wasting your time dreaming of extracting energy from perpetual motion nonsense.

[beso]

The water at the bottom of your empty tower can only be pumped back into the ocean against the massive pressure of the depth.

It takes more energy to pump the water out than you could generate with a turbine operating on that falling water.

[ToraToraTora]

spoil sport beso! PMSL!

[New Judge]

//The inlet tube would go down 250m and merge with the empty, air filled tower. The water would fall down the tower, go through three turbines and fall onto the expelling pump. So at no time does the falling water hit any other water, it falls through the air and hits the pump.//

And what happens when the tube/tower/funnel (I've lost track of which it is) fills with water (which it will)? What happens when you add more water from your endless supply?

This is a wind-up, right? It's been amusing though.

[ToraToraTora]

your name isn't Heath Robinson is it?

[crankfwd]

beso- two words of advice. Pay attention! I'm not some Karen who believes in free energy or perpetual motion. I suggest you go hunting in a much shallower stream if you want such easy prey. Try the Cummings debate. Yes, well copy and pasted, it takes more energy to pump the water into the deep ocean than could be created by a turbine. I've already stated that! That's why I'm suggesting adding two more turbines to the tower. That's why I'm asking about underwater pumps. If you don't know enough about mechanics or engineering to give a serious or even, light hearted answer, then feel free to save yourself the energy.

[crankfwd]

Triple T- no, I'm not Heath Robinson. In much the same way that you are no Oscar Wilde, sir.

[crankfwd]

new judge- more of a wind-out than a wind-up. But if the only energy created was in the form of a chuckle, I'll settle for that.

[nescio]

crankfwd,
where do you think the energy to drive the additional turbines and pumps is coming from?

[crankfwd]

Nescio- Gravity. After the first turbine, the water would fall another 250m, picking up speed, before it hit the second turbine. Then another 250m between turbines two and three. I use 250m gaps as that's roughly the height used in the hoover dam.

[Atheist]

Crank, I'm not sure I understand your 'device'. Is it a fair question to ask why not forget the sea and the funnel, and simply use a pump to raise the water to a height then allow it to fall and drive a turbine which then produces electricity which is then used to power the pump? If so, then it obviously wouldn't work. I am deeply suspicious of your idea, but without diagrams I can't judge it with any confidence.

[New Judge]

//After the first turbine, the water would fall another 250m, picking up speed, before it hit the second turbine. Then another 250m between turbines two and three. I use 250m gaps as that's roughly the height used in the hoover dam.//

So basically you'll get a third of the potential energy of the water from each turbine (roughly). The same as you would get with one turbine at the bottom (very roughly, let's not get too complicated). What are you going to do when the tube that the turbines are in fills with water (which it will as soon as you introduce into it water equivalent to its volume)? You'd have to evacuate the tube with a pump - which - er…. would take quite a bit of energy.

[crankfwd]

Atheist- I agree with you, but I am not trying to pump water upwards, that is just a waste of energy, and as you state, obviously wouldn't work. In my device, gravity is our friend and even after going through three turbines the water would still have some downward momentum when it reaches the pump. And yes, in this case, a picture is definitely worth a thousand words.

[crankfwd]

New Judge- no, think about it, if I add further turbines underneath the first one, would they reduce the output of the first turbine? You are assuming (perhaps rightly) that a turbine placed way down the bottom of the tower produces the same energy as the three turbines. But surely the water has a terminal velocity? So placing a turbine where the water is at it's fastest, harnessing that energy and then letting the water speed up again and placing another turbine as it reaches that speed again, is what I'm trying to do.

[New Judge]

Assuming your three turbine arrangement does triple the output (and I don't believe it will but can't be bothered to go through the mechanics) the question remains - what are you going to do once the tube is full of water. If you are thinking of evacuating it into the surrounding ocean this will almost certainly take most, if not all of or more than the energy provided by the turbines. In fact, all you will be doing is powering a pump to move water through the turbines so that they (the turbines) can produce energy to drive the pump.