Lithium is one of the key elements for the energy transition due to its application in Li-ion batteries as used in electric vehicles. The market analysis shows, that Germany will require in the future large quantities of global lithium production for supplying the transition of its automotive sector and planned battery cell production. At the same time, it becomes apparent that in whole Europe only 1 % of the global lithium production is mined. Geothermal brines in Germany can contain elevated concentrations of lithium and have recently moved into focus for local raw material production. The simplified consideration of the concentrations and the high flow rates prevailing in geothermal plants suggest great potential, opening the perspective of local, independent lithium production. Yet a full-scale Li extraction from geothermal brines is missing 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. The results show a Li depletion of 40 % over 30 years while constant heat production. Still, a mean Li production of 231 t/a (1230 t/a LCE) is achieved, which 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 reservoir exploration and development.