Potential of Solar Powered Underground Waste Heat Utilisation in Total Site Heat Integration

This work presents the integration of Photovoltaic-Thermal (PVT) waste heat with Underground Thermal Energy Storage (UTES) systems and studies the potential of the system in an urban-industrial site Heat Integration. The waste heat from PVT can be used to charge the UTES unit in the summertime, where the waste heat sources/sinks from the PVT can be up-cycled to fulfil the cooling or heating demands of various systems, ranging from domestic to industrial processes. This work studies the energy requirements and temperature ranges for heat pumps via Total Site Composite Curves, evaluating the energy coverage based on the current temperature of the waste heat and potential coverage via heat pumps technologies. This tool serves as a benchmark for practitioners to evaluate the heat pump duties for the system, and the coefficient of performance (COP) of a heat pump can be identified. The obtained results indicate that the electricity generation efficiency of the PV panels is increased by up to 10 % as a result of the water cooling, and the system is capable of covering up to 90 % of the building's energy needs. When applied in the context of a Total Site Heat Integration, the RESHeat system allows substantial savings in cooling water (94 %) and low-pressure steam (23 %).