Modelling Aquifer Thermal Energy Storage (ATES) System with Buoyancy Flow

Abstract

Aquifer Thermal Energy Storages (ATES) as long-termstorages have a strong potential to address the seasonaldiscrepancy of supply and demand of thermal energy. Theoperation of high-temperature ATES (HT-ATES) and theirintegration into district heating systems are the subjectof current research projects. Buoyancy plays an importantrole in determining how HT-ATES performs. The target ofthis paper is to present a system model in Modelica thattakes these buoyancy effects into account. The validationwith experimental data and numerical simulations shows thatthe system model represents the buoyancy effects well. Asensitivity analysis underlines the importance ofoptimizing the grid structure and shows that a highresolution in the aquifer is necessary, especially in thevertical direction. Finally, a 10-year simulation shows thedeviation of the heat recovery factor, i.e. the ratio of theamount of heat extracted to the amount of heat injected,between a model with and without buoyancy effects.