Geothermal energy is energy generated by heat stored beneath a planet's surface or from the collection of absorbed heat in the atmosphere and oceans. Such energy was utilized extensively by the Ancients: in the Taranis outpost on Taranis, and the mobile drilling platform on Lantea. (ATL: "Inferno", "Submersion", "First Strike")

The people on P3X-289 used geothermal energy from geothermal vents to power their dome and protect them from their planet's harmful atmosphere. Because of the movement of tectonic plates the hotspot powering the vents moved and the vents started to cool down. Thus their dome started to shrink according to the drop in power.(SG1: "Revisions")

The fallout bunker on the planet Novus used geothermal power, in addition to solar and wind, to power the fallout bunker. (SGU: "Epilogue")