Assessment of renewable and waste heat recovery for DH through GIS mapping: the national potential in Italy

This work aims at showing the potential of waste and renewable heat recovery in Italy through detailed mapping of these sources. The ambition of this analysis is to highlight the areas with important heat recovery potential and to show how the matching with suitable heat demand would allow its exploitation through district heating expansion. The importance of waste heat and renewable heat potentially recoverable to reduce primary energy consumption in the civil sector is widely recognized. Nevertheless, these potential is widely unexploited in Italy. The processes and energy sources have been analysed in terms of geographical location, quantification of available heat and recovery costs with a special focus on temperature levels. The main distinction between low temperature and high temperature heat sources has been applied in order to identify the heat recovery characteristics and the consequent additional costs for temperature upgrades. The inputs of the analysis performed in this work come from national database, which has allowed obtaining more detailed and wider results with respect to international existing studies on the same subject. Two different approaches have been used to map potential heat: one to identify and quantify existing waste heat recovery and one to assess and estimate energy coming from potential new plants. The analysed sources belonging to the first category are industrial processes, waste to energy plants, waste water treatment plants and datacentres, while biomass, geothermal energy and electrolysis plants estimation belong to the second one. Results shows that the national available waste and renewable heat amount to 270 TWh which is an important outcome in comparison with a national heat demand for the residential and tertiary sector of 400 TWh. Out of this results, according to a nuts 3 regional aggregation of heat demand, 95 TWh could be recovered in DH. The reduction from theoretical potential of 270 TWh to 95 TWh is due to geographical matching of heat demand and available waste heat and on some hypothesis related to the diffusion of DH. This work shows the huge unexpressed potential of waste heat reutilisation in Italy and how the mapping of recoverable heat and not only its quantification is essential to properly estimate the utilization potential.