Enhanced Geothermal Systems
Enhanced Geothermal Systems (EGS) “enhance” and/or create underground geothermal heat systems through hydraulic stimulation of subsurface rock to create a reservoir of superheated water. This is called hydrofracing. When natural cracks and pores will not allow for economic flow rates, the permeability of the rock can be “enhanced” or stimulated by pumping cold water into the rock under pressure. These artificially created or expanded geothermal systems are called Enhanced Geothermal Systems (EGS). In EGS water is injected into hot rock through an “injection well” that travels through fractures in the rock capturing the heat of the rock until it is forced out of a second borehole (the “production well”) as hot water which is converted into electricity using either a steam turbine or a binary generation system. All of the water, now cooled, is then injected back into the ground to heat up again.
Source: U.S. Department of Energy
Like Dry and Flash geothermal systems, EGS is a base load resource which produces electric power 24 hours a day at operation efficiencies greater than fossil fueled power plants, but without any of the CO² emissions. Unlike Dry and Flash geothermal systems that completely depend upon natural geothermal resources, EGS and other forms of geothermal energy production are scalable technologies.