Integration of distributed storages in district heating systems for supply temperature reduction = Integration of distributed storages in district heating systems for supply temperature reduction

Distributed Storage Modeling in District Heating Networks District heating networks are an essential component of a low-carbon ecosystem for energy in the residential sector. In particular, they enable efficient heat supply in urban areas, with very low CO2 emissions. In order to improve the efficiency of these networks and to be able to integrate low carbon production assets (heat pumps, solar thermal...), an effort has to be made for lowering the network operation temperature levels. This kind of transformation requires often intervention on the network design in order to upgrade part of the existing installation (pipes, substations, pumps). The integration of thermal storage solutions, strategically located on the distribution network and adequately piloted, is particularly promising. This research focuses on the utilization of liquid water tanks as a thermal storage solution and seeks to assess the extent to which they can contribute to the adaptability of real-world district heating networks. The aim of the present work is to analyze the behaviour of the storage integrated in district heating networks and to demonstrate the benefits that a distributed storage can bring to them. With the objective of studying the operation of the network with and without storage, a one dimensional model of the storage has been applied to a real case-study. More specifically, a set of distributed heat storages has been integrated into a detailed model of the district heating network of the city of Metz (France), with the aim of uncoupling demand from supply. As DH network evolves toward lower temperatures, the design of such systems is more complex and it is crucial to maintain a high thermal and economic performance. Several simulations have been run in order to obtain an optimal design of the network at different temperature levels, considering an economic perspective.