The Crucial Role of Geothermal Fluids in Reducing the Water and Carbon Footprints of Lithium Mining in Salt Flats Worldwide

ABSTRACT Thermal waters, which often have a high Li concentration, can influence the formation of Li-rich brines in the salt flats. Several studies suggest that geothermal activity accelerates the leaching of Li-rich volcanic rocks in the catchment areas of the closed basins, contributing to higher Li concentrations in brines. Considering that there is no salt flat in Chile or other parts of the world that does not have a present-day (active) or palaeo-geothermal system, there is a need for a holistic geoscientific study of the salt flats to investigate the association between lithium enrichment of brine in the salt flats and geothermal systems present in the host closed basins. The expected results of such studies in different salt flats will help understand the role of geothermal systems in forming economic Li deposits that could be selectively mined sustainably. This is because thermal waters can also concentrate Li in specific horizons, allowing for selective extraction with minimal impact on freshwater aquifers. This would be possible because conductive heating by underlying thermal water could induce circulation (convective overturn) of basin brines within hydrologically connected horizons. Accordingly, this geothermally induced brine circulation may develop a heterogeneous subsurface Li distribution, where thermal waters could be instrumental in forming Li-enriched horizons in subsurface brine. Deciphering and modeling the latter will form a strong and tangible basis for developing environmentfriendly methods for Li mining that will have negligible influence on the groundwater and wetland ecosystems using drilling technologies prevalent in the hydrocarbon industry for extracting particular sedimentary horizons. Further, geothermal systems present in the closed hydrologcal basins could aid in reducing the environmental footprint of Li mining by providing thermal energy for extraction processes and electricity generation using low-enthalpy binary power plants. Considering the focus on direct extraction of Li (DLE) in Chile and neighboring countries, it is necesary to integrate it with geothermal following holistic geoscientific studies involving geological, geochemical and geophysical investigations, validated by exploratory drilling. This will help mitigate environmental challenges associated with current DLE technologies by using geothermal water in the extraction process and expertise from the geothermal industry in brine recharge.