Simulation Study on Operating Modes of Seasonal Underground Thermal Energy Storage

A simulation was performed, which concerns the feasibility of great-scale seasonal underground thermal energy storage in Tianjin, China. The investigated system consists of a 1000m2 flat plate solar collector (FPSC) and a underground storage. In summer, solar thermal energy is collected and emitted into the soil surrounding borehole heat exchangers, through which the stored heat is extracted in winter with a GSHP to provide a proper heating temperature. According to the experimental data about a GSHP system in Tianjin and local meteorological conditions and soil properties, a simulation study was performed for the influence of system operation modes on heat emitting and extracting. Results indicate different features of temperature distribution in the storage field under different running modes. For a more share provided by clean and free energy, an operation mode was presented based on both less loss and better thermal recovery in the soil storage.