Executive Summary

Sierra Geothermal Power Corporation’s (SGP) Alum prospect is one of several promising geothermal properties located in the middle to upper Miocene (~11-5 Ma, or million years BP) Silver Peak-Lone Mountain metamorphic core complex (SPCC) of the Walker Lane structural belt in Esmeralda County, west-central Nevada. The geothermal system at Alum is wholly concealed; its upper reaches discovered in the late 1970s during a regional thermal-gradient drilling campaign. The prospect boasts several shallow thermal-gradient (TG) boreholes with TG >75C/km (and as high as 440C/km) over 200-m intervals in the depth range 0-600 m. Possibly boiling water encountered at 239 m depth in one of these boreholes returned chemicalgeothermometry values in the range 150-230C. GeothermEx (2008) has estimated the electricalgeneration capacity of the current Alum leasehold at 33 megawatts for 20 years; and the corresponding value for the broader thermal anomaly extending beyond the property at 73 megawatts for the same duration.