How closed-loop geothermal works

Two vertical wells joined deep underground by sealed horizontal branches make a giant radiator. Water never touches the rock; it just picks up heat by conduction and rises on its own. Pick a part to isolate it, see through the rock, or go down to the laterals.

Sources: ThinkGeoEnergy, “Eavor set to begin start-up of closed-loop geothermal pilot” (Nov 2025); ZfK, Geretsried status report (Oct 2026: loop 1 operating with six lateral pairs, first power December 2025, rigs withdrawn, loop 2 unscheduled). Rock temperature, flow, the per-loop share of 8.2 MW and the timeline's pacing are illustrative. Others on this approach: XGS Energy, GreenFire Energy.