Abstract: The buoyancy-gravity engine according to the present invention comprises buoyancy gravity rollers (1) which is constructed with specific dimensions and shape so as to perform its function effectively; a buoyancy chamber; a float regulation machine; a gravity machine with at least one wheel (3); a De-Pressure transfer box (9A); an interlinked BG roller (1) transfer mechanism; and a liquid compensator. The BG Roller (1) travels up and down through the buoyancy column and the gravity machine. When the BG roller (1) moves down in the gravity machine at least one wheel (3) of the machine is rotated due to the eccentric weight of the roller (1) in one end of the wheel (3). The roller (1) then slips down from the fingers of the wheel and rolls down to the mouth of the DP transfer box (9A). The roller is then pushed into the buoyancy column, and due to the inherent law of buoyancy, the roller (1) automatically reaches the top of the buoyancy column and again falls into the fingers of the gravity machine.