NOVELTY - The mass displacement drive (1) includes a chamber (6a) located at distal end of a primary arm (4a) while second chamber (6b) is located at distal end of second arm (4b). The primary chamber has a primary piston (10a) while second chamber has the second piston (10b). Movement of the primary piston draws fluid into the primary chamber to increase buoyancy of primary chamber while movement of second piston forces fluid from the second chamber to decrease buoyancy of second chamber. Change in mass of the primary chamber relative to second chamber generates a mass displacement torque to move arms.    USE - Mass displacement drive for rotating a shaft to generate energy and electric power for e.g. commercial installation and to augment or replace base load power supply to an existing electricity network. Uses include but are not limited to e.g. farms, rural, industrial properties, resorts, residential complex, aluminum production plant, metals refining facility, chemicals plant, surface and submerged vessels, trucks, cars, train, airplanes.    ADVANTAGE - The low cost and efficient renewable power generation device makes use of constantly available forces which are sustainable and is not location dependent. The drive can be scaled to fit a particular system. The device can be installed in remote locations and can be operated independently in array or grid connected. The device harnesses the effect of varying the mass of mass displacement chambers relative to their effective center of rotation axis to allow descent and ascent characteristics of buoyancy and negative buoyancy, positive and negative states of gravity to be used as a drive method. The device is not dependent upon its location and orientation to operate efficiently and can be mounted on a moving platform, vehicle, vessel, train, airplane or other transport. The device does not require unique materials like solar films to operate effectively and can be manufactured from metal, minerals, plastic, composite or natural materials or a combination to achieve the operating properties of the device. The device has the ability to function subsea in varying depths of water and to function in a manufactured or constructed environment such as the vertical installation and vary the cycle to suit the environment and power generation needs.    DESCRIPTION OF DRAWING(S) - The drawing shows a side view of the mass placement drive.    Mass displacement drive (1)    Primary arm (4a)    Second arm (4b)    Chamber (6a)    Second chamber (6b)    Primary piston (10a)    Second piston (10b)