Explain why this wouldnt work...

I came accross a topic on this site that made me register, it was a perpetual motion machine. The topic was about siphoning water from the ocean to run a turbine for energy... Why could you not siphon water from the ocean into a huge tank of water above the ocean, make it air tight and pressurized, and have a small hole at the bottom of the tank that allows water out of the tank at the exact same rate that water is let into the tank.

If you have a large amount of water in the tank, there should be enough weight to siphon water from below the tank. If the amount of water leaving the tank due to gravity is replaced by a siphon, and the siphon is assisted by the pull of the weight of the water in the tank, there will always be the same amount of pressure/water in the tank. Correct?

 

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If you've ever syphoned water you'll know that the place you are syphoning to has to be lower than the place you are syphoning from. This is because the forces of water being sucked up a pipe and water coming out of a pipe are balanced and the only way to generate a flow is to create the unbalancing of the equation by lowering the place you intend to empty into (thus causing the direction of flow)

No matter how large the volume of the tank, the actual suction effect applied is "bottlenecked" by the diameter of the pipework. This "bottlenecking" is where the "balancing" occurs, so no matter how big the tank is it won't unbalance the pipe the favour of your design.

Instead the tank would empty and so would the pipe leaving a vacuum until the last amount of water allows it to suck air back in (possibly the tank would be drawn in during this and end up dented)

 

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