TRANSFORMATION OF OUTDATED DISTRICT HEATING SYSTEMS

The transformation of outdated district heating (DH) systems is a pressing issue for countries with well-developed DH infrastructure, which was predominantly built in the previous century and designed for the use of fossil fuels. These systems face the simultaneous challenges of replacing obsolete equipment, improving fossil fuel efficiency, and substituting these fuels with renewable energy sources and waste energy resources. These challenges must be addressed while ensuring the stable supply of thermal energy to consumers. Solving such a complex and multifaceted task requires the development of a scientifically grounded strategy. The pace of modernization and decarbonization of DH systems varies significantly across countries. For Ukraine, which is among the countries with a developed but outdated DH infrastructure, the transformation and decarbonization of this vital energy system are being approached based on European experience, adapted to national circumstances. This study focuses on the methodological and techno-economic aspects of a transitional strategy for decarbonizing large, outdated DH systems, taking into account the specific features of the current state of such systems in Ukraine. It examines the necessity and content of transitional plans, the experience of DH system transformation in EU countries, key methodological considerations of transition planning, including temporal changes in DH systems, the current structure and condition of existing DH networks, the potential for fossil fuel substitution with renewable energy sources, criteria for comparing different decarbonization approaches, third-party access to district heating networks, and directions for further research into DH decarbonization. Natural gas is the main fuel used in existing outdated DH systems, and gas boilers are the primary source of thermal energy. These form the baseline for evaluating the economic efficiency of alternative transformation pathways. The study demonstrates the economic feasibility of replacing gas boilers with solar district heating plants equipped with seasonal thermal energy storage. Bibl. 29, Fig. 9, Tab. 3.