The main objective of GEO.KW was to improve the efficiency of thermal groundwater use in urban areas. The management of this resource could in the future be improved by the development of flexible tools for planning and optimization. With such tools, the urban-specific demand for heating and cooling could better benefit from the dynamics and the storage capacity of the thermal resource groundwater. This will make it possible to cover an increased share of heating and cooling with renewable energies and to reduce primary energy consumption. In particular, the substitution of conventional cooling applications by free cooling with groundwater will contribute to the reduction of greenhouse gas emissions. The project aimed at combining detailed transient simulations of groundwater flow and heat transport with an optimization tool for energy systems. Through this integrated approach, synergies will be highlighted and energy savings will be maximized. The developed tools were applied in a case study of Munich, but could also be available for similar urban areas after modification. The project GEO.KW (2019 - 2021) was financed by the German Federal Ministry of Economics and Technology (BMWi).