District Heating and Cooling Networks Supplied by Renewable Energy Sources for Local Energy Communities: A Simulation-Based Approach for the Early Design and Operation

The new generation of district heating and cooling networks enables higher penetrations of renewable energy sources in the energy system by harnessing low-temperature sources of renewable energy and waste heat. They also maximize self-consumption and self-sufficiency of shared renewable energy production. These networks offer vital options for decarbonizing the thermal energy needs of the building sector, promoting carbon neutrality in urban areas, and enhancing energy security. In this context, this study aims to assess the potential synergies arising from the implementation of renewable energy communities (RECs) in fifth-generation district heating and cooling systems (DHCs) from both energy and regulatory perspectives. To achieve this goal, a dynamic energy simulation approach is utilized to evaluate the transient energy behaviour of a unified thermal network or water loop serving as a source and sink for multiple heat pumps meeting the heating and cooling needs of various buildings. The developed dynamic simulation tool facilitates the calculation of thermal and electrical energies provided by intermittent renewable energy sources deployed within a district, thereby exploiting the energy and economic advantages of shared renewable energy. A case study analysis of an REC based on a DHC plant serving a cluster of buildings in Sorrento, Italy, is appropriately conducted as a proof of concept. This case study enables the exploration of how the concept of RECs associated with DHCs can enhance overall energy-economic performance. The study focuses on i) assessing the potential of excess solar energy and adopting different strategies to maximize self-consumption and self-sufficiency within the investigated RECs based on DHC, and ii) evaluating the most efficient investment in economic terms by exploiting the incentive tariff on shared energy provided to RECs. A comprehensive sensitivity analysis is performed to identify the design and operating parameters influencing the energy and economic performance of the studied cluster of users, considering the Italian regulatory context. The study findings reveal significant primary energy savings, up to 30%, compared to the reference scenario where utilities operate independently. Finally, obtained results suggest that renewable energy communities can play a leading role in the energy transition and represent an effective opportunity for the decarbonization of district heating networks and for supporting the implementation of renewable energy technologies.