Tank sloshing energy recovery system

A hydrodynamic energy recovery system for a liquid-containment vessel to effect movement of gases in a headspace above a liquid in the vessel, the system comprising:

• a hydro-driven actuator mountable with respect to the vessel so as to be movably driven by a movement force of moving liquid fuel in the vessel;
• a mixing device drivable by the hydro-driven actuator, the mixing device being mountable with respect to the vessel, at least partially in a ullage-space of the vessel above the fuel, such that motion of the mixing device effects mixing of gases contained in the headspace above the liquid in the vessel;
• and
• a motion converter for converting motion of the hydro-driven actuator into motion for driving the mixing device, and wherein the motion converter is connectable between the hydro-driven actuator and the mixing device.

A method of mixing gases in an ullage-space above fuel contained in a fuel tank, the method comprising the steps of:

• moving a hydroturbine device by a movement force of the fuel moving within the fuel tank;
• mixing gases in the ullage-space of the fuel tank via motion of a mixer located in the ullage-space;
• and
• converting motion of the hydroturbine device into motion for driving the mixer wherein motion of the hydroturbine device is converted into motion of the mixer via a motion converter connected between the hydroturbine device and the mixer.