Geothermal Potential Could be Hot in the Western US

Abstract

Exploring for good geothermal development sites in the Western US is not simple, even though a lot of the region is in the Pacific “Ring of Fire” where most of the world’s geothermal potential is located. The Ring of Fire is really more nearly horseshoe in shape and is the 25,000 mile area that extends from New Zealand, Indonesia, the Philippines, and Japan, turns east through the Aleutian Islands, and then heads south along the coasts of North, Central, and South America. The Ring is home to over 75% of the world’s active and dormant volcanoes. There are six Western States that are in or near the Ring, namely Alaska, California, Idaho, Nevada, Oregon, and Washington. These States may have significant geothermal potential due to the active and dormant volcanoes, which can provide the necessary heat sources to form geothermal reservoirs. These reservoirs have porosity and – with good meteorological conditions – can bring heat to the surface and form what geologists call “surface manifestations”. The manifestations include mud pots, fumaroles, and hot springs. However, the six States have significant groundwater at 50 to 2000 feet below the surface that is fed by late winter, spring, and early summer snowmelt. This groundwater is cold and can block potential surface manifestations from occurring. The Utility Geothermal Working Group, a non-profit organization formed by the Geothermal Resources Council to promote cost-effective geothermal development, plans to work with the US Department of Energy to identify potential sites and geothermal mapping techniques, including Vertical Electric Sounding and Audio Magnetotellurics, to be used in exploration of the sites. This paper describes the plan and the suggested mapping techniques to analyze the formations below the groundwater mask and approximate the location and size of geothermal reservoirs.