Smart Reutilisation of Data Centres' Waste Heat into DHN: The Role of Heat Pumps and Thermal Storage

This study investigates the integration of waste heat from a data centre (DC) into a third-generation district heating network (DHN) situated in Calenzano, with the objective of reducing the network’s environmental footprint, currently dominated by natural gas-fired combined heat and power (CHP) units. The low-grade thermal energy rejected by the DC is upgraded to the DHN supply temperature through high-temperature heat pumps (HPs). Hourly energy simulations were performed over a full year, based on real DHN load profiles and varying DC thermal capacities (100–500 kW). Results indicate that, in the non-integrated configuration, a 100 kW DC rejects approximately 926 MWh/year of thermal energy into the ambient environment, thereby contributing to the urban heat island effect. Under integration, the recovered waste heat contributes between 12% and 59% of the annual DHN demand, leading to a reduction in natural gas consumption of 11–58%. These findings confirm that DC waste heat recovery, when combined with high-temperature HPs, represents a technically viable strategy for reducing fossil fuel dependency and enabling the progressive decarbonisation of third-generation DHNs.