Borehole thermal energy storage (BTES). First results from the injection phase of a living lab in Torino (NW Italy)

The seasonal storage of thermal energy in the ground is a useful application able to provide H&C and DHW demand of commercial or residential buildings. Several examples in Canada and Northern Europe demonstrated the reliability and convenience of these systems in terms of both energy and economic savings, but more demonstration sites are however necessary. The surrounding litho-, hydro- and bio-sphere are influenced by the plant's activity and a trustworthy supervision of the temperature field would bring advantages to both the environment and the system's efficiency. Usually numerical modeling is used to forecast the system behavior but results of simulations can be strongly dependent from assumed material characteristics and should be strictly calibrated on real data. To better understand thermal processes in the ground related to thermal injection and thermal storage, a field scale BTES living lab was build up nearby Torino (Northern Italy) within unsaturated alluvial deposits. Results show that approximately 9.1 GJ were transferred to the ground during the first year, raising the undisturbed temperature by 2 °C, and that a correct comparison of monitoring data and numerical simulations can be obtained following a specific site characterization.