Engineered Geothermal Systems (EGS)
The Energy Under Our Feet

Geothermal energy provides clean, renewable baseload electricity available 24 hours a day, seven days a week, and emits little or no CO2.

EGS projects produce electricity using heat extracted with engineered fluid-flow paths in hot rocks. These pathways are developed by stimulating them with cold water injected into a well at high pressure.

In the EGS power generation cycle, water is continuously injected down a well into the enhanced fractures, where it heats up as it flows through the rocks. The water is then brought to the surface in multiple production wells, and its heat is extracted to generate electricity in power plants. Finally, the water, depleted of its heat, is re-injected to be heated again in the fractures.

The EGS concept provides the potential to remove the "dry hole" risk associated with conventional hydrothermal geothermal, which requires finding existing fractures that contain high flows of hot water.

EGS would also allow the placement of geothermal development in sites without conventional geothermal resources.

A 2007 study led by the Massachusetts Institute of Technology estimated that with suitable investments and improvements to existing technology, EGS could supply up to 10 percent of the country's electricity needs within 50 years at prices competitive with fossil-fuel fired generation. The report, "The Future of Geothermal Energy--Impact of Enhanced Geothermal Systems (EGS) on the United States in the 21st Century," may be found online at:
http://www1.eere.energy.gov/geothermal/future_geothermal.html.