A hydro pneumatic engine, providing rotational energy at very low RPM, proper to drive an electric generator directly coupled, using as power supply atmospheric pressure variations, originated by vacuum coming from an oscillating wave chamber. With dynamic variable resonance for marine working environment, low internal friction, few mechanical internal reactions and low level noise, this devise operates with potential/kinetic energy multiple conversions and uses as torsion converter a similar unbalanced turbine mechanism, with modified movement, of external zero flow and outstanding minimum head pressure with non corrosive recycling liquid; works offshore or shore line, including also indoor or basement locations, even works with some lakes and with some rivers also without any dam requirement, being as such an environmentally low impact design.