As the energy transition advances and demand for lithium increases, geothermal lithium is attracting attention as a strategic resource. To date, there has been no large-scale lithium mining in Europe. Europe's lithium reserves are about 5 million tons, accounting for 6.9% of the world total. However, France has another source of lithium: the abundance of soluble lithium ions in natural geothermal water - a lithium reserve that has not been industrially mined.

Geothermal power plants extract natural hot water from the ground to generate heat and electricity, and the cold water used up is injected back into the ground. Large quantities of lithium have been found in geothermal water in some parts of France: the brine used in the Soultz-sous-Forêts power plant in the east contains 200 milligrams of lithium per liter.

There are several new technologies for lithium extraction from geothermal heat. In the last decade, the French mining group Eramet and the French Institute for Petroleum Research (IFP), through the EuGeli joint research project, have developed the Direct Lithium Extraction (DLE) technology, which allows for a significant increase in the efficiency of lithium extraction from brines, and optimizes the process for the characteristics of underground hot water. Still another process is ion exchange: allowing lithium-rich water to circulate through a filter. French company Geolith is testing this on a semi-industrial scale in Cornwall, UK.

Geothermal lithium extraction not only has the advantage of being environmentally friendly, but can also directly utilize existing geothermal power plant equipment, reducing costs and energy consumption. However, the current geothermal lithium extraction technology still faces some challenges, such as the time to re-dissolve the lithium after the tailings are reinjected. Solving these problems requires an in-depth study of the specific mechanisms of lithium recharge from geothermal water in order to realize sustainable geothermal lithium extraction.