it serves as a medium for the buoyancy effect produced on the inverted cups 21 by the circulating gas 29 gas 29 is injected into column 11 from a pair of nozzles 31 located just below a juxtapositioned pair of cups 21 at a point near the lower left of wheel 24 where the cups 21 are achieving their inverted position during their travel along the endless path beginning at the point of discharge from nozzle 31 a quantity of gas 29 is discharged into each passing pair of cups 21 as they assume their inverted position the gas producing a buoyant upward force on cups 21 and driving them upwardly until they reach the top surface 32 of fluid 28 then as the cups rotate to an upright position the gas is spilled into the open space above the surface 32 of fluid 28 where it flows around a baffle plate 33 and upward through a pipe 34 which carries it down into condenser 15 condenser 15 is similar to a truck radiator where the gas flows through finned tubes around which cool air is blown to remove excess heat that was not converted to mechanical energy as it drove the cups upward inside column 11 in one embodiment of the closed cycle system of the invention gas 29 may be but is not limited to hexane c 6 h 14 formed from its liquid hydrocarbon state which.