Master's thesis and Internship : Modeling and Optimization of a District Heating Network: Case Study of Sart-Tilman, Liège

Abstract

District heating networks can play a major role in the decarbonization of large heat consumers such as university campuses. This thesis investigates the modernization of the Sart-Tilman district heating network at the University of Liège, which currently relies on a high-temperature system supplied mainly by biomass cogeneration and natural gas boilers. The objective is to identify technically and economically credible pathways to reduce carbon emissions while maintaining reliable heat supply.

The analysis is based on a set of energy-system scenarios developed in NPro. These scenarios assess the effects of lowering the network temperature, increasing biomass-based heat production, integrating geothermal heat pumps with regeneration strategies, adding solar thermal energy, and introducing short-term thermal storage. The scenarios are compared in terms of energy performance, CO$_2$ emissions, primary energy use, investment requirements, and heat cost indicators.

The results show that reducing the network temperature is a key enabling step, as it significantly lowers distribution losses and prepares the system for low-temperature heat sources. Biomass expansion can strongly reduce direct fossil-fuel use, but it also raises important questions regarding fuel demand and operational flexibility. Geothermal heat-pump pathways offer a more structural long-term decarbonization option, although their feasibility depends on drilling conditions, land availability, electricity use, and regeneration needs. Thermal storage appears mainly as a flexibility measure rather than a stand-alone decarbonization solution.

Overall, the study concludes that the decarbonization of the Sart-Tilman heating network should be approached as a progressive transition combining building-side adaptation, network-temperature reduction, and the phased integration of low-carbon heat supply technologies.