Worldwide geothermal systems as potential sources for critical metals like lithium, rare earth elements, and others

Geothermal brines have the potential to revolutionize our energy system by supplementing renewable energy and also providing significant amounts of lithiumfor our energy needs. Geothermal brines are also a potential source of other critical metals, such as rare earth elements (REE), zinc, and several other metals, in addition to lithium. This comprehensive review addresses the latest developments in the potential of lithium, REE, and other critical metals in worldwide geothermal brines, their extraction, analytical, environmental, and related aspects. Lithium concentrations up to 480 µg/mL were reported from the Mofete Geothermal Field, Southern Italy, and a maximum ∑REE concentration of 29.7 ng/mL was reported from hot springs in Chinese Taipei. Out of all the metals present in geothermal brines, the recovery of lithium has gained prominence due to its high abundance, relatively low recovery cost, minimal beneficiation challenges, and its importance in current energy transition efforts. Although the extraction of REE from geothermal sources is technically feasible, it is neither economically viable nor strategically significant at this point, despite its huge scope and potential, which is marred by limitations. This review also examines the relevant literature on lithium concentrations in geothermal brines worldwide,including in India, as well as current developments in lithium extraction technology from these sources. Popular extraction methods, such as direct lithium extraction (DLE), are being used to recover lithium from these geothermal waters.