[Matumio]

But there are some pretty cool applications. Apparently the heat difference between a buried water-pipe and the surrounding earth is already enough to power a wireless sensor, which can transmit data to localize leaks, for example.

[m463]

Voyager 2 and 1 are powered by thermocouples and a chunk of plutonium.

(I ordered them that way because Voyager 2 was launched first)