A thermal engine includes a cylinder and piston and an insulated thermal battery including at least a thermal mass such as the engine block itself for storing and retaining heat to enhance or cause fluid expansion within the cylinder and drive the piston, the thermal battery optionally including an electrolyte chamber containing a thermal electrolyte for functioning as an electric thermal battery. Heat is stored in the thermal battery such as by activating electric resistance heating elements in the thermal mass. The stored heat either causes expansion of a non-combustible expansion fluid such as water or enhances the expansion of a combustible expansion fluid such as gasoline. Where the thermal battery is an electric thermal battery containing an electrolyte, the storage of heat also stores electricity which can be used to power an electric motor.