A generator comprising: - a vertical supply column that can be filled with a certain quantity of liquid; - an intake valve disposed at a base of the vertical supply column ; - a leaktight tank communicating with the vertical supply column via said intake valve , which leaktight tank is capable of being filled with liquid; - an exhaust valve disposed on said leaktight tank and capable of releasing pressure generated in said leaktight tank ; - a piston-forming device disposed inside said leaktight tank so as to be immersed in the liquid contained in the leaktight tank , which piston-forming device is capable of being set in reciprocating movement between an upper position and a lower position, the piston-forming device comprising a first, float-forming portion capable of bringing the piston-forming device into the upper position and a second portion forming an output shaft ; and - a converter device coupled to the output shaft , which converter device is capable of converting the reciprocating movement of the piston-forming device into mechanical or electrical energy, said generator being configured in such a way that, in operation, the leaktight tank is filled with liquid, and in such a way as to repeat the following sequence of operating phases in order to induce the reciprocating movement of the piston-forming device , namely: - a first operating phase during which the intake valve is closed and the vertical supply column is filled with liquid so as to form a column of liquid above the leaktight tank ; - a second operating phase during which the exhaust valve is closed and the intake valve is open in order to connect the vertical supply column and the leaktight tank , generating an increase in pressure in the leaktight tank and causing a displacement of the piston-forming device to the lower position; and - a third operating phase during which the intake valve is closed and the exhaust valve is open in order to release excess pressure formed inside the leaktight tank , allowing the piston-forming device to return to the upper position under the action of the first, float-forming portion . - a vertical supply column that can be filled with a certain quantity of liquid; - an intake valve disposed at a base of the vertical supply column ; - a leaktight tank communicating with the vertical supply column via said intake valve , which leaktight tank is capable of being filled with liquid; - an exhaust valve disposed on said leaktight tank and capable of releasing pressure generated in said leaktight tank ; - a piston-forming device disposed inside said leaktight tank so as to be immersed in the liquid contained in the leaktight tank , which piston-forming device is capable of being set in reciprocating movement between an upper position and a lower position, the piston-forming device comprising a first, float-forming portion capable of bringing the piston-forming device into the upper position and a second portion forming an output shaft ; and - a converter device coupled to the output shaft , which converter device is capable of converting the reciprocating movement of the piston-forming device into mechanical or electrical energy, - a first operating phase during which the intake valve is closed and the vertical supply column is filled with liquid so as to form a column of liquid above the leaktight tank ; - a second operating phase during which the exhaust valve is closed and the intake valve is open in order to connect the vertical supply column and the leaktight tank , generating an increase in pressure in the leaktight tank and causing a displacement of the piston-forming device to the lower position; and - a third operating phase during which the intake valve is closed and the exhaust valve is open in order to release excess pressure formed inside the leaktight tank , allowing the piston-forming device to return to the upper position under the action of the first, float-forming portion . <EOS>