The Green Deal program promoted by the European Commission sets new challenging decarbonization objectives to be achieved by 2030. In July 2021, the Fit For 55 package was proposed, which contains the legislative proposals needed to achieve these objectives.
Starting from a scenario of evolution of the Italian energy system to 2030, based on the achievement of these new objectives, the possible role of fourth generation district heating networks (DHNs) in the decarbonization path was studied.
The fourth generation of DHNs features an integration between the electrical and thermal systems. District heating networks are in fact evolving towards systems that distribute heat at lower temperatures and using different types of technologies for heat production.
In networks based mainly on co-generators powered by fossil fuels, the use of Power-to-X solutions, such as heat pumps, allow greater exploitation of renewable energy sources (RESs). This flexibility becomes even more significant in energy systems characterized by a high penetration of random renewable sources such as PV and wind.
Heat pumps are essential for developing IV generation DHNs, but they are also useful for improving and transforming III generation systems in cases where low temperature heat resources are available, which must be raised to allow the heat distribution in III generation networks.
In this way, district heating evolves from a system for heat distribution to a solution for increasing the integration of RESs in the electricity system. The advantages are even more if thermal storage systems are also introduced into the DHNs to manage the production and distribution of heat in the networks more flexibly.