A system and method for providing a constant output from a variable flow input comprises a liquid flow energy input, for example, air or water for driving a constant speed generator. An inner and outer cam assembly is controlled by a control input to achieve varying eccentricity and control the output speed at an output shaft to be constant despite a varying rotational velocity input at an input shaft. A feedback control may be provided between one of the input shaft and the output shaft and the inner and outer cam assembly to maintain constant output by varying the eccentricity. The constant output may drive a constant speed generator having an infinitely variable torque generator. In this manner, a power grid may be provided with constant frequency alternating current at, for example, 50 Hz (Europe) or 60 Hz (USA). Also, a pair of non-circular gears, for example, a square gear and a cloverleaf gear may be used to reduce ripples in rotational velocity measured at the output shaft for a four OWCB constant output, variable flow input system.