Hot Dry Rock
Hot Dry Rock (HDR) is a special case of Enhanced Geothermal Systems (EGS). HDR refers to extraction of energy from hot dry rock or Geothermal Deep Heat resources. This involves drilling deep into the Earth's crust to reach the hot rocks, injecting water into the rocks to create a geothermal reservoir by hydraulic fracturing in a monolith, and then circulating the water to absorb the heat before bringing it back to the surface. The heat can then be used to generate electricity or for direct heating purposes.