Earth Day 2016: Moving Toward Green Energy

What is Geothermal Energy?

Schematic representation of an ideal geothermal system

Geothermal energy is thermal energy generated and stored in the earth. When most people think of geothermal they think of hot springs, fumaroles, and geysers. These are surface features that are linked (through faults and fractures) to the subsurface hydrothermal reservoir. Geothermal energy can be harnessed by drilling into hydrothermal reservoirs and extracting the hot fluids and/or steam.

Check out this Geothermal 101 video or this one on geothermal heat pumps to learn more.

Geologists and engineers can tap deep into a hydrothermal reservoirs to generate electricity, or use the shallow heat beneath the surface to heat and cool homes through geothermal heat pumps.

How is it used?

Geothermal power plant, USGS photo

Geothermal energy is a renewable, environmentally friendly, baseload power source that has potential to be successful in Washington State.  It has many uses, which are dependent upon the temperature of the resource. Low (<194 degrees F) and moderate temperature (194–302 degrees F) geothermal resources can be used for residential and commercial heating/cooling, or for agriculture. Moderate to high-temperature (>302 degrees F) resources can be used to generate electricity. For more information, see the USGS Fact Sheet.

Geothermal Potential of Washington

Washington is home to five major active volcanoes and numerous hot springs and fumaroles (check out DGER’s geothermal portal to see where they are all located).


Most of the high-temperature wells and hot springs in Washington are associated with active volcanism and recent faulting. Faults provide pathways for heated fluids to travel from their source to the surface. There is also a large, yet poorly understood area of warm water in the Columbia Basin in eastern Washington.

2014 geothermal resource assessment results

We conducted a statewide geothermal resource assessment in 2014  which revealed three areas in the Cascade Range with elevated geothermal potential within developable land: the Mount St. Helens seismic zone, Mount Baker, and the Wind River valley (outlined in the map above). These three sites are currently being studied in detail by DGER, Seattle based geothermal company AltaRock Energy Inc., USGS, and a number of other talented partners. This study is funded by the U.S. Department of Energy Geothermal Technologies Office and is in the second phase of exploration now.

Please check back soon for project updates from this year’s field season.