Material use of geothermal waters

The production of geothermal energy requires the circulation of large volumes of thermal brines reaching up to several 100 L/s. These brines are the product of long-time water-rock interactions at a high temperature and depth leading to various water compositions. The contained ions have been used for the chemical characterization of a reservoir and are further a challenge for the power plant operator due to the possibility of uncontrolled mineral formation. The chemical analysis of the waters and the related precipitates have shown that the waters can contain critical and strategic mineral commodities at various concentrations. According to known standards of raw material extraction, these are not classic deposits due to their low concentrations. However, in consideration of the high annual volumes circulating in geothermal systems, relevant amounts of different raw materials are in theory extractable. An advantage of the geothermal brines is that the elements of interest are already dissolved in the water and do not have to be extracted from the rock first. Furthermore, a geothermal power plant provides decentralized heat and energy for further refinement of the raw materials. The implementation of a cost-effective and deployable mineral recovery in the geothermal cycle can thus improve the economics of geothermal energy and open up a new raw material market.