Karlsruhe Institute of Technology; Limits of lithium extraction from geothermal energy
Pumping water from the depths, separating lithium and using it to produce batteries for electromobility – the idea of environmentally friendly and regional lithium as a by-product of geothermal energy seems promising. However, the extent to which domestic mining is really worthwhile has not yet been sufficiently clarified. A team from the Karlsruhe Institute of Technology (KIT) has now summarized the state of research, analyzed raw material markets and evaluated technologies. According to this, thousands of tons of lithium per year could theoretically be mined in Germany, but central questions still have to be clarified.
For the energy transition, Europe needs a lot of batteries and enough lithium to produce them. The European Union (EU) classifies lithium as a critical raw material – there is a risk of a lithium deficit. “We are completely dependent on imports, 80 percent of the lithium worldwide comes from Chile and Australia,” says Valentin Goldberg from the Institute for Applied Geosciences (AGW) at KIT. “At the same time, we accept significant environmental costs from conventional mining in these countries, such as negative effects on the groundwater.” In contrast, lithium production in geothermal power plants should use the existing infrastructure in Europe, with which large quantities of thermal water, some with a high lithium content, are already being pumped. After the energy production, the lithium is to be technologically separated and the water, as is usual in power plant operation, is to be returned to the subsoil. “Basically, we see the technology very positively. Land use and environmental costs would be low, as would the transport costs,” says Goldberg. In order to clarify what contribution domestic lithium can realistically make in the future, he and a team at the AGW have now compiled and analyzed the available knowledge and calculated the possible potential for Germany for the first time.
Regional lithium extraction as an ecological supplement
How much lithium can be extracted depends not only on the lithium concentrations in the water, but also on the site-dependent flow rate and the size of the reservoir. For their estimate, the researchers considered potential locations in Germany, analyzed the raw material markets and evaluated different technologies in terms of their efficiency, applicability and ability to be integrated into geothermal energy production. “On this basis, we consider an optimistic estimate of an annual production of around 2,600 to 4,700 tonnes of lithium carbonate equivalent to be possible if all relevant geothermal sites are equipped with the appropriate systems,” says Dr. Fabian Nitschke from the AGW, who was also involved in the studies. “We could cover around 2 to 13 percent of the annual requirements for the planned battery production in Germany with this.” The construction of further geothermal power plants could increase production volumes, but it would take at least five years for a newly planned power plant to go into operation. “In view of the global lithium deficit forecast and the planned battery production, the situation, especially for Germany, will quickly come to a head. The lithium from geothermal energy can only be a supplement in the medium term,” says Nitschke. “In view of the global lithium deficit forecast and the planned battery production, the situation, especially for Germany, will quickly come to a head. The lithium from geothermal energy can only be a supplement in the medium term,” says Nitschke. “In view of the global lithium deficit forecast and the planned battery production, the situation, especially for Germany, will quickly come to a head. The lithium from geothermal energy can only be a supplement in the medium term,” says Nitschke.
Different technologies in direct comparison
The forecasts are still characterized by many uncertainties: The size and origin of the lithium deposits in the geothermal systems and the reaction of the reservoirs to continuous production are currently being researched. In addition, the technologies for extraction are in an early to mid-stage of development – decisive development stages and long-term tests are still pending. “In a direct comparison, however, specific advantages and disadvantages were already apparent, which are particularly relevant for economical lithium extraction,” says Dr. Tobias Kluge from the AGW, another author of the studies. “Thus, the need for additional raw materials, damage from deposits at wells, extraction units and energy consumption have a direct impact on economics.”
A prerequisite is broad acceptance
Whether the lithium production using geothermal power plants will ultimately be realized in Germany does not only depend on further technological developments and suitable locations. Rather, social support and acceptance are also necessary, emphasizes Valentin Goldberg: “Our publications in the magazine Grundwasserare therefore not only aimed at a specialist audience. Rather, we want to give decision-makers in politics and business, but also all interested citizens, the opportunity to obtain direct and independent information about opportunities and challenges.” In addition, her work now offers a basis for future research and development on this socially relevant topic. The studies were carried out as part of the GeoEnergy Research conducted by the AGW’s Department of Geothermal Energy and Reservoir Technology as part of the Helmholtz Energy Program and the BrineMine research project of the Federal Ministry of Education and Research (BMBF).