Hot Dry Rock Geothermal Energy

Hot dry rock, or HDR, is a method for extracting geothermal energy from hot but naturally dry crystalline basement rock that has no natural fluid pathways, by circulating pressurized fluid through the rock in a closed loop rather than drawing on an existing hydrothermal reservoir. The technology was developed starting in 1970 at Los Alamos National Laboratory, using engineered reservoirs that are totally confined and sealed. Although the term is often used loosely alongside Enhanced Geothermal Systems, the source describes hot dry rock as a technically distinct approach, since HDR reservoirs are sealed and closed while EGS reservoirs are deliberately left open, with correspondingly higher water loss. Because hot dry rock, once developed at sufficient depth, could tap an enormous and widely distributed store of thermal energy that is otherwise uneconomical to reach, it is regarded as an extremely abundant but still difficult to access geothermal resource.