The growing lithium demand and the dependence on poorly diversified oversea sources point towards a high strategic importance of domestic resources. Furthermore, potentially lower CO₂ emissions and reduced areal use during production favor local co-production of geothermal energy and lithium.

Based on a technology comparison for direct lithium extraction from geothermal fluids and the current state of geothermal energy production in Germany, different scenarios for the extractable amount of lithium carbonate were considered. In the most optimistic scenario, taking into account all currently active wells, a maximum production of 4700 t/a of lithium carbonate equivalent is expected. This could cover 2 – 13% of the annual demand of the planned German battery cell production.

Uncertainties in the resource assessment regarding its size, and the sustainability of its management, are still considerable. Yet a full-scale Li extraction from geothermal brines is missing and thus long-time behavior is not clear. For this purpose, a generical model, based on Upper Rhine Graben geothermal settings was developed, and a Li extraction over a 30-year operation time was simulated. Despite a significant Li depletion, a mean Li production of 231 t/a (1230 t/a LCE) is achieved, for a current state-of-the-art geothermal power plant.

This could significantly increase the economics of a geothermal power plant as well as, if transferred to several plants, a partly independency from global imports. The strongest influence on productivity is the achievable flow rate, which provides access to the raw material, highlighting the importance of good geological reservoir exploration and development.

Highly saline lithium-rich hydrothermal fluids occur in the deep calcareous Muschelkalk aquifer of the northern Alpine foreland basin. We have combined geologic, hydraulic, hydrochemical, and stress field data of the Triassic Muschelkalk aquifer beneath sediments of the Molasse basin of SW-Germany for a synthesis to constrain the origin and development of these brines. In contrast to the regional southeast plunge of Mesozoic and Cenozoic strata, low gradient groundwater flow in the Upper Muschelkalk aquifer is to the north, induced by regional recharge from west, south, and east. North trending maximum horizontal stress axes might provide development of fracture permeability in the competent carbonates of the Upper Muschelkalk aquifer for northward flow. The highest lithium concentrations and total dissolved solids (TDS) can be found in the southeastern parts of the Muschelkalk aquifer, close to the Vindelician High, whereas during northward transport TDS and lithium concentrations are increasingly diluted. We argue that the highly saline lithium-rich fluids originate from fluid-rock interaction of meteoric water with Variscan crystalline basement rocks and entered the Muschelkalk aquifer by permeable faults and fractures. The marginal calcareous sand-rich facies of the Muschelkalk enables the inflow of brines from crystalline basement faults and fractures into the aquifer. We thus argue for an external origin of these brines into the aquifer. Potentials are considered as 100±25 t Li/yr per well.

Lithium mining operations based on direct lithium extraction from brines often use groundwater models such as FEFLOW or MODFLOW for their resource estimation, especially as the amount of extractable lithium (or LCE) depends on how much water can be extracted by pumping wells. At the same time the environmental impact of the pumping (e.g., drawdown) and in some cases the injection (e.g., dilution) needs to be assessed, also using groundwater models.

To effectively use the groundwater models for the mining operation, they should directly be connected to measured data, such as water level data, pumping rates, lithium concentration, to constantly reconcile the measured data with the predictive models. Furthermore, the groundwater model should not be a “black box” that can only be used by specialists, but be interactive and accessible by the mine operators, to run and analyze different mine plan scenarios themselves.

Therefore, an interactive web-based platform was developed based on FEFLOW and MIKE Operations. With the platform the user can, in a simple way, create new groundwater model scenarios by changing pumping rates or adding additional pumping wells, without having to open the software GUI. The model will then run automatically in the Cloud and the results are shown in an interactive map view and dashboard. At the same time the system includes all relevant monitoring and operational data, to easily compare the model data with the monitoring data.

This way the lithium mining operator has the necessary tools and data in one place to make effective decisions.