This study investigates the technical potential of shallow low-temperature Aquifer Thermal Energy Storage (ATES) systems in Freiburg, Germany, to reduce greenhouse gas emissions from space heating and cooling. Using 3D numerical modeling, the authors determine heating and cooling power densities for different ATES configurations in an unconsolidated gravel aquifer with varying hydrogeological characteristics. High groundwater flow velocities (up to 13 m/d) cause significant energy loss, limiting power densities to 3.2 W/m². However, compared to existing thermal energy demands, ATES systems can achieve substantial heating and cooling supply rates. Specifically, ATES can fully supply cooling needs for 92% of residential buildings, while potential greenhouse gas emission savings from ATES heating alone are estimated at 70,000 tCO₂eq/a, equivalent to 40% of current emissions from space and water heating in the study area. The study's modeling approach can be applied to other regions with similar hydrogeological conditions to estimate local ATES supply rates and support city-scale energy planning.This study investigates the technical potential of shallow low-temperature Aquifer Thermal Energy Storage (ATES) systems in Freiburg, Germany, to reduce greenhouse gas emissions from space heating and cooling. Using 3D numerical modeling, the authors determine heating and cooling power densities for different ATES configurations in an unconsolidated gravel aquifer with varying hydrogeological characteristics. High groundwater flow velocities (up to 13 m/d) cause significant energy loss, limiting power densities to 3.2 W/m². However, compared to existing thermal energy demands, ATES systems can achieve substantial heating and cooling supply rates. Specifically, ATES can fully supply cooling needs for 92% of residential buildings, while potential greenhouse gas emission savings from ATES heating alone are estimated at 70,000 tCO₂eq/a, equivalent to 40% of current emissions from space and water heating in the study area. The study's modeling approach can be applied to other regions with similar hydrogeological conditions to estimate local ATES supply rates and support city-scale energy planning.