A simple experiment that to prove the potential energy is unlimited.

[Zhang Yalin]

It's not so easy.

[sm0ky2]

Suppose we have a rigid container filled with water at the bottom of a tank.
the walls of the container cannot compress, and so inside the container
the pressure is not exerted from the volume of water.


If then two valves and hoses lead outside the tank
1 to drain the water
1 to let air in
(this happens simultaneously as one step)


We avoid the problem of having to fight the water pressure


In this format, the math becomes favorable to the bouyant force.


This may achieve the same goal, and avoid the feasibility issues of
"consuming the contents".


A latch can then release the container, to extract the bouyant energy.


mgh applies to the volume in the container (vdgh)
This is input at the upper height of the water
To sink the container


Bouyancy applies to the volume of the entire tank
(vdgh)


If the tank is large and container relatively small
There is (mathematically) a net energy
The outlet hose has to be slightly lower than the tank
So we lose some negligible h, the volume of the container
But we empty the container and fill it with air for free.
Thus creating v(tank)dgh= v(container)dgh
This is an inequality. (in most cases)
Therefore net E is not =0


unless of course I am missing some detail....