Can a Vacuum Generate Energy?

[CuriouslyDumb]

I recently thought about using capillary action to power a generator (capillary action lifts water, right?) then researched it and learned that 1) I'm not the first one to think of it and 2) it wouldn't work anyways. Then I thought, why can't you use a vacuum to lift the water through a tube, like siphoning gas (though maybe I'm just missing something, and siphoning doesn't actually work or something). Any ideas? Could you use a vacuum to siphon water up a tube, let it fall and turn a generator?

 

[JaredJames]

1) You need to produce a vacuum - that takes more energy than you'd get back.

2) You'd have to apply the vacuum in a on / off pattern (lift / drop) which would mean a control system = losses.

3) Siphoning works using gravity so the reservoir has to be lower than the source.

 

[CuriouslyDumb]

ok so I agree with #1, it would take a lot of energy to make a vacuum, and I know nothing about siphoning so I'll take your word for #3, but for #2 I was thinking that water is drawn up through the tube, the tube curves down at the top and deposits the water into a resevoir, and the water in the resevoir then falls to a source pool which feeds the tubes, like a loop. Giving up any ideas of power production, if you have a vacuum would it work? No control system is needed from what I can tell.

 

[JaredJames]

ok so I agree with #1, it would take a lot of energy to make a vacuum, and I know nothing about siphoning so I'll take your word for #3, but for #2 I was thinking that water is drawn up through the tube, the tube curves down at the top and deposits the water into a resevoir, and the water in the resevoir then falls to a source pool which feeds the tubes, like a loop. Giving up any ideas of power production, if you have a vacuum would it work? No control system is needed from what I can tell.

No, it wouldn't work.

The "tube curves down at the top"? So the whole reservoir is under vacuum? If that's the case, how would water flow out?

The water will be drawn into the vacuum and remain there, unless you 'release' the vacuum to allow it to drop. (Think about the vacuum system they use for internal mail in some companies).

For siphoning, take a piece of tube and try it out. Simple experiment. Once the output is higher than the input the flow will stop / reverse.