Critical Minerals in US Geothermal Brines: Opportunities and Challenges for their Extraction

Geothermal power plants produce a large volume of brine for power generation. Since these brines are the product of long-term water-rock interactions at elevated temperatures at depth, they contain dissolved chemical components including critical and strategic mineral commodities at various concentrations. Despite the low concentrations for many of these minerals, significant quantities of select minerals could be recovered due to the large volumes of brine utilized by geothermal power plants. Over the years, the U.S. Department of Energy (DOE) Geothermal Technologies Office (GTO) has been funding research activities focusing on characterization of brine resources and development of extraction technologies for the rare earth elements, lithium, and other critical minerals from geothermal brines. The primary goal of the GTO’s efforts is to secure domestic sources for these critical materials as well as provide an additional revenue stream to the geothermal developers and make geothermal energy more competitive against other types of renewable energy. Our assessment of the US geothermal brines for their mineral contents indicates that several mineral commodities (e.g., Li, Mn, SiO2, etc.) are present in high enough concentrations and sufficient flow rates to be economically recovered from geothermal brines. In this presentation, we will provide a summary for mineral contents in geothermal brines in the US. Also we will provide a summary of past as well as current mineral extraction status, opportunities, and challenges for the commercial-scale deployment of mineral extraction technologies.