US has vast geothermal resources, study shows

Posted by Kate Taylor

The US has the geothermal resources to produce ten times as much power as the current installed capacity of coal plants, Google-sponsored research shows.

In the past, geothermal production in the US has been restricted largely to the western third of the country, in tectonically active locations such as the Geysers Field north of San Francisco.

But Southern Methodist University says it's confirmed that the country has vast geothermal reserves that are realistically accessible using current technology, particularly in the eastern two-thirds of the country.

Newer technologies and drilling methods can now be used to develop resources in a wider range of geologic conditions, allowing reliable production of clean energy at temperatures as low as 100˚C (212˚F) – and in regions not previously considered suitable for geothermal energy production.

For example, there's a geothermal capacity under the state of West Virginia that's equivalent to the state’s existing, primarily coal-based, power supply.

"This assessment of geothermal potential will only improve with time," says professor of Geophysics David Blackwell. 

"Our study assumes that we tap only a small fraction of the available stored heat in the Earth’s crust, and our capabilities to capture that heat are expected to grow substantially as we improve upon the energy conversion and exploitation factors through technological advances and improved techniques."
 
The SMU researchers used temperature data and in-depth geological analysis to create their updated temperature-at-depth maps from 11,500 to 31,000 feet. They found that some areas in the eastern two-thirds of the US are actually hotter than those in the western portion of the country, an area long-recognized for heat-producing tectonic activity.

Areas of particular interest include the Appalachian trend  - Western Pennsylvania, West Virginia and northern Louisiana - the aquifer heated area of South Dakota, and areas of radioactive basement granites beneath sediments such as those found in northern Illinois and northern Louisiana.

The Gulf Coast, too, is a huge resource area, says SMU.