Hot dry rock (HDR) geothermal energy technology is unique in many aspects. HDR resources are much more widely distributed than hydrothermal resources, the production temperatures of fluids extracted from fully-engineered HDR reservoirs can be selected at will, and other important characteristics of HDR reservoirs can be controlled and even deliberately varied over time. Because HDR reservoirs can be rapidly discharged and recharged, a wide variety of operating scenarios can be envisioned that are not normally feasible for hydrothermal systems. Flow testing over the past few years has shown that HDR systems can be operated in a routine, automated manner that should make them rapidly adaptable to industrial applications. An industry-led HDR project now being formulated will lead to the development and operation of a practical facility to produce and market energy from an HDR resource by the turn of the century
