This study quantifies the technical potential of shallow low-temperature aquifer thermal energy storage (LT-ATES) systems in Freiburg, Germany, for city-scale heating and cooling. Using 3D heat transport modeling, heating and cooling power densities are determined for different ATES configurations in an unconsolidated gravel aquifer with varying hydrogeological characteristics. High groundwater flow velocities (up to 13 m d⁻¹) lead to significant storage energy loss, limiting power densities to a maximum of 3.2 W m⁻². However, comparisons with existing thermal energy demands show that ATES systems can achieve substantial heating and cooling supply rates. For cooling, ATES can fully supply 92% of residential buildings. For heating, potential greenhouse gas emission savings of up to 70,000 tCO₂eq a⁻¹ are calculated, equivalent to 40% of current emissions from space and water heating. The modeling approach can be applied in similar regions to estimate local ATES supply rates and support city-scale energy planning. The study highlights the importance of power density in assessing renewable energy potential, comparing it to conventional technologies. The results show that ATES systems in the Breisgau Formation have higher thermal recovery and power densities, making them more feasible for heating and cooling. The study also demonstrates that ATES can significantly reduce greenhouse gas emissions, with potential savings of up to 70,000 tCO₂eq a⁻¹. The findings suggest that integrating ATES into existing district heating networks could help realize its full potential. The study also notes that while ATES systems have lower power densities than some conventional technologies, they offer significant emission savings and efficient operation. The results indicate that ATES can supply up to 92% of cooling demand and 80% of heating demand in residential buildings. The study concludes that ATES systems have the potential to significantly reduce greenhouse gas emissions and support sustainable energy planning in cities.This study quantifies the technical potential of shallow low-temperature aquifer thermal energy storage (LT-ATES) systems in Freiburg, Germany, for city-scale heating and cooling. Using 3D heat transport modeling, heating and cooling power densities are determined for different ATES configurations in an unconsolidated gravel aquifer with varying hydrogeological characteristics. High groundwater flow velocities (up to 13 m d⁻¹) lead to significant storage energy loss, limiting power densities to a maximum of 3.2 W m⁻². However, comparisons with existing thermal energy demands show that ATES systems can achieve substantial heating and cooling supply rates. For cooling, ATES can fully supply 92% of residential buildings. For heating, potential greenhouse gas emission savings of up to 70,000 tCO₂eq a⁻¹ are calculated, equivalent to 40% of current emissions from space and water heating. The modeling approach can be applied in similar regions to estimate local ATES supply rates and support city-scale energy planning. The study highlights the importance of power density in assessing renewable energy potential, comparing it to conventional technologies. The results show that ATES systems in the Breisgau Formation have higher thermal recovery and power densities, making them more feasible for heating and cooling. The study also demonstrates that ATES can significantly reduce greenhouse gas emissions, with potential savings of up to 70,000 tCO₂eq a⁻¹. The findings suggest that integrating ATES into existing district heating networks could help realize its full potential. The study also notes that while ATES systems have lower power densities than some conventional technologies, they offer significant emission savings and efficient operation. The results indicate that ATES can supply up to 92% of cooling demand and 80% of heating demand in residential buildings. The study concludes that ATES systems have the potential to significantly reduce greenhouse gas emissions and support sustainable energy planning in cities.