| Abstract |
Heat demand varies significantly across seasons, being high in winter and minimal in summer, while renewable heat sources like geothermal wells provide a consistent year-round supply. Additionally, residual heat from data centers and industries often results in excess heat during the warmer months. To manage this seasonal mismatch, underground thermal energy storage (UTES) can be used to store excess heat generated in summer for use in winter. This strategy reduces energy waste and optimizes resource use, lowers costs, and enhances the reliability of heating systems. The EU-funded PUSH-IT project aims to overcome the seasonal mismatch between heat demand and generation from sustainable sources using high-temperature (HT) UTES through three different storage technologies: in aquifers - ATES, in borehole - BTES, and in abandoned mines - MTES. This study aims to evaluate the utilization of the HT-ATES system on the TU Delft campus, which serves as one of the project's pilot demonstration sites, and assess its storage efficiency. The reservoir modeling study was conducted using the open-source simulator Delft Advanced Research Terra Simulator (DARTS) to evaluate the impact of different injection strategies. Three operational scenarios were analyzed: a moderate and stable injection rate (742 m³/day), a higher injection rate with intermittent rest periods (1254 m³/day), and a sinusoidal flow pattern based on heat demand. The results indicate that a stable injection rate yields the highest storage efficiency, minimizing heat losses while maintaining effective heat recovery. In contrast, higher injection rates lead to increased thermal dispersion, whereas a variable injection pattern provides operational flexibility but requires careful management to sustain efficiency. As part of the pilot demonstration, new wells will be drilled on-site, providing additional subsurface data to refine the geological model and improve reservoir predictions. Moreover, future modeling efforts will integrate the reservoir model with surface facility components, such as heat exchangers and heat pumps, to develop a fully coupled system. These advancements will enable more representative simulations, ensuring that model predictions better reflect real-world HT-ATES operation. |