35 Years of Geothermal Power Generation in Nevada, USA: A Review of Field Development, Generation and Production Histories

Abstract

Geothermal electricity generation began in Nevada in 1984, with the commissioning of the ~ 1.2 MWe plant at Wabuska. Since then, 26 geothermal power plants have been built, with a total installed nameplate capacity of ~770 MWe (~520 MWe gross) in 2018. The share of geothermal electricity generation in the state increased from less than 4% in 1990 to 8.7% in 2018. Average fluid production temperatures at the wellhead for Nevada’s geothermal plants range from ~97 – 187 °C (207 – 369 °F) for electricity generation, and three reported direct-use applications use geothermal fluids ranging between 78 – 95 °C (172 – 203 °F). Due to the moderate to low resource temperatures of most geothermal systems in the Great Basin, and the groundwater resource challenges in its arid environment, most power plants are using closed-loop, binary-cycle systems, with only three operating flash plant systems. Production flow rates for an individual well average 130 liters/second (l/s; ~2,060 gallons/minute (gpm)) for electricity generation, with the highest average production flowrates measured at the Don A. Campbell geothermal field (315 l/s; 4,993 gpm). Reviewing trends in electricity generation over time, it is apparent that some fields have experienced periods of production decline (e.g. San Emidio, Brady Hot Springs, Stillwater, Soda Lake and Salt Wells), whereas others demonstrate relatively stable generation, including Dixie Valley, Wabuska, Steamboat Hills, Jersey Valley, and Beowawe. In the last decade, three geothermal sites have installed combined solar-geothermal systems to offset the effects of diurnal and seasonal changes in climate that reduce overall binary plant efficiency. Such efforts have proven successful and may become more common for future plant installations.