A system for supplementing a fixed fuel source for an engine includes a motor-generator set connected to a mechanical load device and a controller. The motor-generator set includes a motor and a generator. The engine is configured to provide a first torque from a fixed fuel source from an independent variable flow input. The fixed fuel source is independent of the engine and set external to the engine. The mechanical load device is driven by the engine and configured to require a second torque defined by an independent flow device. The controller is configured to compare the first torque and the second torque, provide a first control signal to the motor to provide power to the engine when the second torque exceeds the first torque and provide a second control signal to the generator to draw power from the engine when the first torque exceeds the second torque.