A method is invented for converting heat in a liquid to power and generating thermal difference of the heat source liquid between the inlet and the outlet of a machine. The heat source liquid (8) is drawn to the lower right side of the cylinder (1) through the inlet (5). The heat in the heat source liquid (8) boils the working liquid (2) at the right side of the cylinder (1). The vapor from the boiling creates pressure to push working liquid (2) to the left of the cylinder (1) and to compress the vapor at the left side back to working liquid. The buoyant force on the right and the gravitational force on the left of the cylinder (1) rotate the cylinder (1) to produce power. As heat is transferring to the cylinder (1), the temperature of the heat source liquid (8) is lower at the outlet (4).