Geothermal Energy - How an Enhanced Geothermal System Works
Enhanced Geothermal Systems (EGS), also sometimes called engineered geothermal systems, offer a 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 such as the western U.S. This represents a 'low-hanging fruit' of the geothermal energy potential.
EGS offers a chance to significantly extend the use of geothermal resources in larger areas such as the western U.S. and in new geographic areas of the entire world. More than 100,000 MWe of economically viable capacity may be available in the continental United States, representing a 40-fold increase over the present geothermal power generating capacity. This potential is about 10% of the total U.S. electric capacity today, and represents a domestic energy source that is clean, reliable, and proven.
The EGS concept is extraction of heat by creating a sub-surface fracture system to which water can be added through injection wells. Creating an enhanced, or engineered, geothermal system requires improving the natural permeability of rock. Rocks are permeable due to minute fractures and pore spaces between mineral grains. Injected water is heated by contact with the rock and returns to the surface through production wells as in naturally occurring hydrothermal systems. The EGS are reservoirs created to improve the economy of resources without adequate water and/or permeability.
Geothermal Anywhere Enhanced Geothermal Systems (EGS) can effectively produce energy from previously unusable sites. Unlike traditional geothermal systems, which rely on locating anomalies and heated water, this technology uses hot dry rock to heat water in artificially created reservoirs anywhere. Traditional geothermal energy systems for effective electricity production can be potentially used only on less than 10 percent of Earth’s surface. The potential of the EGS is massively larger than the traditional geothermal systems.
Other geothermal sources of information:
- Wikipedia - Hot dry rock geothermal energy
en.wikipedia.org/wiki/Enhanced_Geothermal_System - MIT Study "The Future of Geothermal Energy"
www1.eere.energy.gov/geothermal/future_geothermal.html - U.S. Department of Energy (How an Enhanced Geothermal System Works)
www1.eere.energy.gov/geothermal/egs_animation.html - International Geothermal Association – What is Geothermal Energy?
iga.igg.cnr.it/geo/geoenergy.php - Geothermal Resources Council (Geothermal Virtual Tour)
www.geothermal.org/virtualgeo.html