Working principle of thermoelectric generator.

A device without moving parts that converts a temperature difference into electrical energy using the Seebeck effect. A thermoelectric generator consists of a pair of semiconductors in which a thermal gradient causes electrons to move. It is often used as a power source for space probes where the heat source is a radioisotope such as plutonium. The low thermal efficiency (5—8 percent) is balanced by the absence of moving parts or working fluid, which makes the thermoelectric generator a reliable and durable device.