Earth battery
Dissimilar electrodes in soil or sea / From Wikipedia, the free encyclopedia
An earth battery is a pair of electrodes made of two dissimilar metals, such as iron and copper, which are buried in the soil or immersed in the sea. Earth batteries act as water-activated batteries. If the plates are sufficiently far apart, they can tap telluric currents .[citation needed] Earth batteries are sometimes referred to as telluric power sources and telluric generators.