An electric generator system for producing electric power from the environmental
temperature changes such as occur during a normal summer day on Earth or Mars.
In a preferred embodiment a phase-change mass is provided which partially or completely
freezes during the relatively cold part of a cycle and partially or completely
melts during the relatively hot part of the cycle. A thermoelectric module is positioned
between the phase-change mass and the environment. The temperature of the phase-change
mass remains relatively constant throughout the cycle. During the hot part of the
cycle heat flows from the environment through the thermoelectric module into the
phase change mass generating electric power which is stored in an electric power
storage device such as a capacitor or battery. During the cold part of the cycle
heat flows from the phase change mass back through the module and out to the environment
also generating electric power that also is similarly stored. An electric circuit
is provided with appropriate diodes to switch the direction of the current between
the hot and cold parts of the cycle. A preferred phase change mass is a solution
of water and ammonia that has freeze points between about 270 K to about 145 K
depending on the water ammonia ratio. Preferably, a finned unit is provided to
efficiently transfer heat from a module surface to the environment.
