GeoCU220

Geothermal

The Star Peak site is generally acknowledged as one of the largest, undeveloped geothermal resources in the American West

The site has long been known as an area of high heat flow, with two operating, hydrothermal gold mines and widespread evidence of hot springs and vents.  Both the commercial mineralization and geothermal heat occur at the faulted transition between the Humboldt Range to the east and Humboldt River Valley to the west.  Star Peak, the Project namesake, vaults to an elevation of 9,741 feet, a full mile above the Valley pediment surface.

The geothermal resource extends for nearly eight miles along and west of the range-bounding faults. First explored by the major oil companies, the area’s large heat endowment – estimated at nearly one thousand megawatts-thermal – has been confirmed by shallow and deep wells, temperature gradient holes and numerous geophysical surveys.  To give a sense of scale, the Dixie Valley resource, supporting a flash plant with output of 62 MW, produces power from just 3 ¾ miles of faulting along the east flank of the Stillwater Range.

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Structural Profile

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Temperature Gradients

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Reference Map

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Binary & Steam Cycles


The site owner and developer has adopted a multi-phase, managed-risk approach to development of the site’s geothermal energy, beginning with the low-cost start-up of the existing binary plant and wellfield near the southern limit of the resource. Subsequent development will proceed systematically, expanding the capacity of the existing plant, and developing the high-enthalpy, “deeper, hotter” resource to the north. The new plant or plants, most likely using flash technologies, will be sited to the north of the existing facility.

Baseload geothermal power is expected to serve as the foundation for development of the site’s other resources: solar, energy storage and wind.