Energy mapping and district heating as effective tools to decarbonize a city: Analysis of a case study in Northern Italy

The process of achieving decarbonization and greenhouse emissions’ reduction goals is facilitated and accelerated by the implementation of renewable-based DH rather than multiple individual renewables systems. This work presents an application case that demonstrates how an energy system based on conventional and carbon-emitting heat supply sources can be converted in a fully renewable network. In its current configuration, the city under study, located in Northern Italy, gets 40% of the total 160GWh of heat demand of the DH from a waste-to-energy plant, 9% from a biomass-fuelled ORC, 33% from natural gas cogeneration and 18% from natural gas boilers. In order to support the city’s municipality in developing decarbonization measures through the modernization of the current district heating network, the aim of this work is to investigate in detail the possibility to integrate local renewable and excess heat sources, whose availability and synergy with the heat demand has been highlighted by a recent mapping-based project developed with the Italian DH Association, AIRU, on the whole Italian territory. The present work can be therefore seen as a validation case study of the methodology developed at large-scale level in the latter project. The results of that analysis show that there are the conditions to meet 90% of the heating needs of the DH with renewables and waste heat recovery from two already existing plants, namely a wastewater treatment plant (WWTP) and a steelwork. The approach used in this work, in which different scenarios of integration are simulated in energyPRO, brought to the definition of the energy mix which evidenced a favourable cost–benefits ratio: 59% of thermal energy from the steelwork, 31% from the WWTP, 5% from the natural gas CHP and 5% from the boilers.