Numerical Modeling to Investigate Geothermal Power Production and Lithium Co-Extraction in the Great Salt Lake Desert

Abstract

Wendover Graben in the Great Salt Lake Desert (GSLD), Utah, has been identified as a potential resource of both geothermal energy and lithium (Li+) extraction. Facilities capable of Li+ removal constructed as part of a geothermal power plant could increase Li+ availability and improve costs associated with both geothermal and Li+ extraction. Previous work on Wendover Graben has suggested a high geothermal gradient and reservoir temperature greater than 200°C, facilitated by circulation of hot water through faults from deeper, carbonate and sandstone aquifers (~7000 m thick), through a thin volcanic and tuff layer (100-400 m thick) up to shallower aquifers (~200-1,200 m thick) in the uppermost basin fill. Well data suggests aqueous Li+ concentration below 10 m depth in the basin fill aquifer approximately 17 ppm, and up to 41 ppm in the shallow brine (above 10 m depth). To investigate the potential for combining geothermal energy and Li+ extraction, a series of reactive transport models of Wendover Graben, parameterized using available data in the literature, were constructed in the reactive-transport code PFLOTRAN. Simulation results indicate that Li+ from dissolution of Li-bearing igneous minerals can be transported along with deep, hot water via faults to the basin fill aquifer, facilitating both increased Li+ concentration and precipitation of Li+ bearing clays at shallower depths. These results suggest a potential mechanism by which both increased Li+ concentration and hot ( greater than 200°C) water can be found at depths reasonable for well construction and geothermal power production. This supports the need for additional work to investigate Wendover Graben hydrogeology and mineralogy to improve model parameterization and further determine the location’s suitability for geothermal power production and potential co-extraction of dissolved Li+.