Enhanced geothermal systems (EGS)
Enhanced geothermal systems (EGS), also sometimes called engineered geothermal systems, offer great potential for dramatically expanding the use of geothermal energy. Present geothermal power generation comes from hydrothermal reservoirs, and is somewhat limited in geographic application to specific ideal places in the western U.S. This represents the ‘low-hanging fruit’ of geothermal energy potential.
EGS offers the chance to extend use of geothermal resources to larger areas of the western U.S., as well as into new geographic areas of the entire U.S. More than 100,000 MWe of economically viable capacity may be available in the continental United States, representing a 40-fold increase over present geothermal power generating capacity. This potential is about 10% of the overall U.S. electric capacity today, and represents a domestic energy source that is clean, reliable, and proven.
Injection Well
A production-injection well is drilled into hot basement rock that has limited permeability and fluid content. This type of geothermal resource is sometimes referred to as “hot, dry rock” and represents an enormous potential energy resource.
Injecting Water
Water is injected at sufficient pressure to ensure fracturing, or open existing fractures within the developing reservoir and hot basement rock.
Hydro-fracture
Pumping of water is continued to extend fractures some distance from the injection wellbore and throughout the developing reservoir and hot basement rock. This is a crucial step in the EGS process.
Doublet
A second production well is drilled with the intent to intersect the stimulated fracture system created in the previous step, and circulate water to extract the heat from the previously “dry” rock mass.
Multiple Wells
Additional production-injection wells are drilled to extract heat from large volumes of rock mass to meet power generation requirements. Now a previously unused but large energy resource is available for clean, geothermal power generation.
Source: eere.energy.gov No tag for this post.
