A thermo-electro-acoustic engine comprises a sealed body having a regenerator, hot and cold heat exchangers, an acoustic source, and an acoustic energy converter. An acoustic pressure wave is generated in a gas in the region of the regenerator. The converter converts a portion of the acoustic pressure into electrical energy. A portion of the electrical energy is used to drive the acoustic source. The acoustic source is controllably driven to produce acoustic energy which constructively adds to that of the acoustic pressure wave in the region of the regenerator. The remaining electrical energy produced by the converter is used external to the engine, such as to drive a load or for storage. The resonant frequency of the engine and the frequency of the energy output can be controlled electronically or electromechanically, and is not limited solely by the physical structure of the engine body and its elements.