Factoid #5 — Untapped Geothermal Resources Could Provide 25,000MW of Electrical Generating Capacity

On August 29, 2005, the Geothermal Energy Association (GEA) released data showing the untapped geothermal power potential in the West. This data, extracted from publicly available reports and studies, shows almost 100 undeveloped geothermal power sites. These sites have a total production potential approaching 25,000 MW of electrical generating capacity — enough to meet more than 70% of California’s electricity needs.

GEA pulled together these estimates for the Western Governors’ Association’s (WGA) on-going assessment of the ability of geothermal and other clean energy resources to meet the substantial growth projected in the region’s electric power demand. The data demonstrates significant geothermal potential from identified but undeveloped hydrothermal sites in eleven western states: Alaska, Arizona, California, Colorado, Hawaii, Idaho, Nevada, New Mexico, Oregon, Utah, and Washington.

These estimates exclude unknown, undiscovered resources. Substantial undiscovered geothermal resources are expected to exist, and they are generally considered to be much larger. USGS Circular 790, for example, estimated that 72,000 to 127,000 megawatts could be supported by undiscovered hydrothermal resources not included in its assessment. Hydrothermal resources, which use steam or hot water to transfer the geothermal resource from the ground to the power station, are one of the four main types of geothermal resources. Hydrothermal resources are used for geothermal electricity production today, while the other three types, geopressured, hot dry rock, and magma, remain in the initial stages of development.

Sources for the GEA data are: USGS Circular 790 – Assessment of Geothermal Resources in the United States; Supply of Geothermal Power from Hydrothermal Sources: A Study of the Cost of Power in 20 and 40 Years, (Petty S., Livesay B., Long W. & Geyer J., 1992); DOE data extracted from the National Energy Modeling System (NEMS) model and EIA data used for the Annual Energy Outlook 2005 report; and New Geothermal Site Identification and Qualification prepared by GeothermEx Inc. for the California Energy Commission (CEC) and released in April 2004.

The data will be available shortly on the GEA website at: http://www.geo-energy.org. It can also be obtained in spreadsheet format by emailing your request to Alyssa Kagel, c/o GEA at research@geo-energy.org