GHC BULLETIN, JUNE 2004 - EMPIRE ENERGY LLC, A Case Study

http://www.energy.wsu.edu/documents/renewables/2GeoHeat%20Bulletin_July04.pdf

www.energy.wsu.edu/documents/renewables/2GeoHeat%20Bulletin_July04.pdf

EMPIRE ENERGY, LLC

- A CASE STUDY -

R. Gordon Bloomquist

Washington State University Energy Program

Olympia, WA

Empire Energy, LLC

LOCATION

Empire Energy, LLC is part of the Empire Group of companies including Empire Research and Empire Farms. Facilities owned by or to which Empire Energy supplies energy include an approximately 3.6-MWe net geothermal binary power plant and an onion/garlic dehydration plant operated by Empire Farms (Figure 1). Both facilities are located in the San Emidio Desert in northern Washoe County, Nevada. The site is located just south of Empire and Gerlach, and approximately 100 miles (161 km) north of Reno, Nevada. The power plant was constructed by ORMAT Energy Systems and went online in mid-1988. The plant consists of four 1.2- MWe ORMAT energy converters (OEC) designed to produce 3.6 MWe of net power at a design temperature of 285oF (141oC). The dehydration plant, originally built by Integrated Ingredients, was dedicated in May of 1994. The dehydration unit uses approximately 800-1200 gpm (50.47- 75.71 L/s) of 298oF (148oC) geothermal water for the four- stage dryer. Present, capacity of the dehydration plant is 75,000 pounds (34,019 kg) of onions per day or 85,000 pounds (38,555 kg) of garlic (Stewart and Trexler, 2003).

RESOURCE

The San Emidio geothermal area is located within the Basin and Range Physiographic Province. The distinctive features of the province are isolated, longitudinal fault-block mountain ranges separated by long, alluvial-filled basins. It is adjacent to the northern end of the Lake Range. The geology is dominated by a thick sequence of Tertiary lava flows, ash flow tuffs and volcaniclastic sedimentary rocks that accumu-lated on an irregular surface of Mesozoic metamorphic base-ment (Stewart and Trexler, 2003). Within the San Emidio Desert, the Tertiary rocks are covered by a layer of lake beds. A discontinuous line of hydrothermally altered rocks marks the boundary of the desert on the east (Mackelprang, et al, 1980). The northern portions of this zone show intense silificants and calcium carbonate deposits which, to the south of the zone, is marked by fumaroles, acid leaching and some deposits of native sulfur (Mackelprang, et al., 1980). Mapping has identified four north-south striking faults and one southwest-northeast striking fault in the area of geothermal development. The faults appear to have between 1,000 and 2,000 ft (305-610 m) of vertical offset (Stewart and Trexler, 2003).

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