Many people are not as familiar with geothermal energy as they are with other forms of renewables. Even fewer know about Enhanced Geothermal Systems (EGS). In fact, in a recent poll of 1000 people in the western U.S. only 16% said they were well informed about EGS.
To help provide people with a basic understanding of EGS, Utah FORGE has developed a high-level Frequently Ask Questions (FAQ) available to students, the media, and anyone else interested in learning more about geothermal and EGS. It explains what EGS is, dispels some myths and discusses EGS usage. The FAQs include:
What are Enhanced Geothermal Systems?
Enhanced geothermal systems (EGS), also sometimes called engineered geothermal systems, offer great potential to significantly expand the production of geothermal energy. Currently, geothermal power is generated from hydrothermal reservoirs. In the U.S., they are found mostly in the West. This restricts the locations of current geothermal energy developments. EGS technology will greatly expand the availability of geothermal energy resources.
The idea behind EGS is to apply methods and tools to extract heat from hot rocks below the surface which lack the same natural permeability that is required for productive hydrothermal reservoirs. This is achieved by enhancing existing fracture systems – the minute fractures and pore spaces between mineral grains so that water can be injected, heated, and produced to very hot temperatures to generate electricity in power plants on the surface.
Will EGS development result in the earthquakes like those occurring in oil and gas operations?
It is important to understand the differences between EGS development and oil and gas operations. All geothermal systems naturally experience some seismic activity, but it is generally too small to be felt by humans. When oil and gas are produced, water naturally present in these reservoirs is co-produced with the hydrocarbons. In many places, the produced water is re-injected into deep dedicated disposal wells. If the disposal wells are not appropriately engineered, the large, injected volumes can lead to earthquakes. In EGS development, two or more wells are drilled into the same volume of rock and water circulated through the hot fractured rock heats up. The volume of water injected into an EGS reservoir is very similar to the volume produced. This is different from oil and gas development where the fluids are extracted from one area of the subsurface and injected into another. The balance of water put into and removed from the ground in an EGS system minimizes the environmental impact and reduces the potential of large earthquakes resulting from human activities.
Is EGS currently used?
Although EGS research has been conducted since the 1970s, it is currently still being developed. The Utah Frontier Observatory for Research in Geothermal Energy (FORGE) is a dedicated underground field laboratory for developing, testing, and accelerating breakthroughs in enhanced geothermal systems (EGS) technologies to advance the production of geothermal resources around the world.
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