Demand and potential for seasonal heat storage in urban district heating systems in aquifer thermal energy storages

District heating is becoming increasingly important in the decarbonisation of the heat supply for buildings throughout Europe. District heating networks must therefore be expanded and decarbonised at the same time. Seasonal heat storage is important to increase the utilisation of renewable and waste heat. The paper assesses the need for seasonal heat storage in three urban district heating systems in Germany and the potential role of aquifer thermal energy storage (ATES) as an option for seasonal heat storage. The three district heating systems analysed are located in the geothermal regions of the Upper Rhine Graben, the South German Molasse Basin and the North German Basin. The networks differ in terms of flow temperatures and the available renewable and waste heat potential in summer.