Upscaling experimental data to model the impact of high-temperature underground thermal energy storage

Integrating high-temperature underground thermal energy storage (HT-UTES) into dense urban areas requires a precise understanding of how heat plumes evolve in groundwater, including potential implications for drinking-water resources and compliance with regulatory temperature criteria. Here, laboratory experiments at mock-up scale are combined with numerical heat-transport modelling using MODFLOW 6–GWE to assess the thermal footprint of HT-UTES on groundwater. The modelling accounts for temperature-dependent density effects to capture buoyancy-driven flow that can influence plume geometry, which is particularly pronounced at high temperatures.

The numerical model is calibrated against a controlled setup using distributed thermal fibre-optic sensing. Observations of transient temperature fields and plume geometry are used to constrain key transport processes and parameters. The laboratory-constrained thermal transport parameters are subsequently applied in an urban-scale model to simulate HT-UTES operation under representative hydrogeological conditions.

We analyse the thermal plume behaviour across a range of hydraulic gradients and compare two operational strategies: (i) cyclic heating/cooling operation and (ii) active plume management using downstream abstraction wells to limit plume migration. The proposed upscaling workflow provides an experimentally constrained basis to evaluate UTES-induced temperature anomalies and thermal interference in groundwater, supporting impact assessment and permitting in urban settings.