A circuit which extends the operational life of a main energy source coupled to a load, said circuit comprising a power generator having a heat source and a cooler thermally coupled to a thermoelectric generator (TEG) for converting thermal energy into electrical energy; and a first capacitor coupled to the TEG for receiving and storing the electrical energy from the TEG. The circuit further comprising at least one switching element coupled between the first capacitor and the load, a converter coupled between the capacitor and the at least one switching element for generating a regulated output, and a controller for activating the at least one switching element when the charge stored on the first capacitor reaches a predetermined level, thereby delivering power from the first capacitor to the load, via the converter, and reducing the amount of power drawn from the main energy source, thereby extending the operational life of the main energy source.