Environmental radiation in space (from the Sun, etc.) and operational thermal loads result in heat flows inside the structure of satellites. Today these heat flows remain unused and are collected, transported to a radiator and emitted to space to prevent the satellite from overheating, but they hold a huge potential to generate electrical power independently of solar panels. Thermoelectric generators are a promising approach for such applications because of their solid state characteristics. As they do not have any moving parts, they do not cause any vibrations in the satellite. They are said to be maintenance-free and highly reliable. Due to the expected small heat flows modern devices based on BiTe have to be considered, but these devices have no flight heritage. Furthermore, energy harvesting on space systems is a new approach for increasing the efficiency and reliability. In this paper, different systems studies and applications are discussed based some experimental characterisation of the electrical behaviour and their dependence on thermal cycles and vibration. 

2. Secondly, a flight-proven capable source of power is the Radioisotope Thermoelectric Generator (RTG)—essentially a nuclear battery that reliably converts heat into electricity. 

 

When an atom undergoes radioactive decay the kinetic energy of the emitted particles is converted into thermal energy. This thermal energy is then applied to the “hot side” of a thermocouple and the “cool side” is kept as cool as possible (with the use of a heat sink). The result is the generation of an EMF across the thermocouple which can be directly used as an electrical source.