NOVELTY - A heat of fusion thermoelectric generator comprises a phase change material in thermal contact with a hot side heat sink; an electric heat source in thermal contact with the phase change material; and thermoelectric module(s) between and in thermal contact with hot side heat sink and cold side heat sink. Electric power is generated by the thermoelectric module from a temperature difference between the hot and cold sides.    USE - Used as e.g. a back-up power source to provide electricity to illuminate the gun sight mechanism of a military weapons system.    ADVANTAGE - The generator has a virtually infinite shelf life. It can be recharged more times compared to a chemical rechargeable battery. It is unaffected by normal storage conditions. It can be charged rapidly. With an electric source providing 500 watts to heating coil, 150 grams of sodium nitrite inside heat source capsule should take 4-5 minutes to melt and be ready for full power operations. There is only a slight loss in peak power under high normal ambient operating temperatures (e.g. 120degreesF) and there is a slight increase in peak power at low ambient operating temperatures (e.g. -40degreesF).    DETAILED DESCRIPTION - A heat of fusion thermoelectric generator comprises a hot side heat sink; a phase change material in thermal contact with the hot side heat sink; an electric heat source (4) in thermal contact with the phase change material to provide heat to melt the phase change material; a cold side heat sink; and thermoelectric module(s) (8) between and in thermal contact with the hot side and cold side heat sinks. Electric power is generated by the thermoelectric module from a temperature difference between the hot side heat sink and cold side heat sink.    DESCRIPTION OF DRAWING(S) - The figure shows a heat of fusion thermoelectric generator.    Pressure shell (2)    Electric heat source (4)    Heating coil (6)    Thermoelectric module (8)    Thermocouple (9)    Tie wires (10)    Belleville spring stack and nut assembly (12)    Cylinder of aluminized polyimide foil (14)    Aluminized polyimide disks (16, 18)    Pinch off tube (20)    Protective cap (22)    Electric leads (30, 31)    Switch (39)    Output power wire (42)