Advanced Geothermal Systems (AGS) are next-generation geothermal technologies that use closed-loop wellbore heat exchangers to extract heat from hot rock formations without requiring natural permeability or hydraulic stimulation. AGS designs feature one or more deep wells with sealed bottom sections where working fluid circulates through the wellbore to extract heat from surrounding hot rock, returning to surface to drive power generation or provide direct heating without ever contacting formation fluids.

Unlike traditional geothermal systems that depend on permeable fracture networks for fluid circulation, AGS wells function as giant U-tube heat exchangers. A working fluid (water, CO2, or specialized heat transfer fluid) is pumped down one leg of the wellbore, heated by conduction from surrounding hot rock as it traverses the closed-loop section at depth, and returns up the second leg to transfer heat at surface. This closed-loop approach eliminates concerns about induced seismicity from hydraulic stimulation, eliminates scaling and corrosion from formation fluids, and enables geothermal development in basement rocks regardless of natural permeability.

AGS technology offers significant advantages for geothermal deployment: reduced exploration risk since permeability is unnecessary, elimination of water management challenges, and simpler regulatory pathways without induced seismicity concerns. However, heat extraction rates from closed-loop systems are inherently lower than fracture-based systems, requiring multiple wells for commercial power generation. Drilling technology improvements that reduce well costs become critical for AGS economics—advanced systems enabling faster, deeper drilling at lower cost directly determine whether AGS can compete with other baseload energy sources.