Low- to moderate-temperature geothermal resource assessment for Nevada: area specific studies, Pumpernickel Valley, Carlin and Moana. Final report June 1, 1981-July 31, 1982

Abstract

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Techno-Economic Analysis of Integration of Low-Temperature Geothermal Resources for Coal-Fired Power Plants

“…During this time, the hot springs were reported to flow to the surface at 70 gpm with recorded temperatures up to 58°C. 4,7,8 However, by the 1980s extensive groundwater withdrawal from the Valmy power plant and dewatering activities associated with local mine operations contributed to lowering the water table and cutting off the surface flow at the hot springs. 5 The current surface expressions of the dried up hot springs are defined by four travertine mounds that are large enough to be seen in the satellite image presented in Figure 1.…”

“…During the 1980s, Trexler et al 4 drilled a temperature gradient borehole (PVHT-5), located near the Hot Pot hot springs. The PVHT-5 boring encountered a shallow basalt flow at 120 ft and reached a total depth in basalt of 140 ft.…”

Pumpernickel Valley Geothermal Project Thermal Gradient Wells

“…In [1981][1982], the University of Nevada System (UNS), under contract to the U.S. Department of Energy (DE-AC08-NV10220), completed a regional assessment of the Pumpernickel Valley area (Trexler et al, 1982;Flynn and Trexler, 1982). The UNS fieldwork included geologic reconnaissance, geochemical sampling, satellite imagery, air photo interpretation, 2-meter depth temperature probe survey, gravity survey, seismic survey, soil mercury survey, and temperature gradient drilling.…”

“…The thermal gradient wells were drilled to map the aerial distribution of the thermal anomaly. The sites, as well as the access routes, were optimally distributed and selected based on the findings of the recent geophysical survey (Shore, 2005) combined with the results of the previous drilling programs (Magma well; Trexler et al, 1982), and geological data (Szybinski, 2005). Additional aspects taken under consideration were: access to existing dirt roads minimizing surface disturbance and the ease of permitting.…”

“…All four wells drilled by Nevada Geothermal Power Company were successful in encountering geothermal fluids. The temperatures from the new temperature gradient holes ( Figures 29-32 and Appendix B) and old exploration boreholes (Trexler, 1982) were obtained using calibrated thermistor probes having an accuracy of approximately 0.1°C. This data was used to calculate the shallow thermal gradients (Sadlier-Brown, 2004; and this work), which are in the range of less than 100 o C/km to over 280 o C/km (Table 1).…”