Given that the deeper you go into the ocean the higher the pressure, could this pressure difference between atmospheric (above water) and a certain depth in the ocean be used to run a stirling engine?

The piston would have to have an open facing to both or either the water at a certain depth (high pressure side) or the atmospheric end (low pressure side.)

In typical stirling designs the high pressure end uses heat in a fixed area which increases the pressure and moves the piston. What if the heat were the same and constant? Would that still work? The ocean depth would be a fixed pressure and that is why I ask.

Instead of heat difference we would be using pressure difference between two areas to drive the stirling engine.

Just a thot


I appreciate the responses so I came up with a possible workaround for the high pressure side (in the ocean.)

Let’s say for the high pressure side there is a open ended cylinder that is facing upward. In this cylinder, when the piston is fully extended upwards it goes halfway the distance of the cylinder length. On the downstroke it goes the opposite direction which would be towards the bottom of the ocean floor.

So as some commenters have pointed out, when the high pressure piston has the upstroke, it is pushing against the depth of the ocean.

A possible workaround may be to introduce air right before the upstroke on top the high pressure piston so the piston is pushing a bubble of air out the end of the cylinder instead of the pressure of the water. The bubble would rise and be like a buffer until the piston reaches its furthest extension from which point the water fills the cylinder and the pressure difference from the atmosphere and the depth of the ocean drives the piston downwards again.

I imagine a lot of cavitation would happen in such a setup so you would need very strong materials.

  • 1
    $\begingroup$ This looks like a 'Novel Idea' question. Such questions tend to become moving targets and lead to discussions, neither of which are a good fit for our format. See if you can edit your question to make it specific and answerable. $\endgroup$ – Wasabi Jul 21 '19 at 17:18
  • $\begingroup$ It looks for me like a first-class perpetuum mobile. $\endgroup$ – peterh - Reinstate Monica Jul 21 '19 at 19:36

No. It will take work to push the apparatus down into the water far enough to perform compression work on the contents of the cylinder, meaning that you will not get that compression work "for free" and hence this scheme can't be used to drive the engine.

| improve this answer | |

Not the answer you're looking for? Browse other questions tagged or ask your own question.