Feasible decarbonization of district heating systems requires a methodology for evaluating and optimizing the integration of diverse heat sources, such as biomass and gas boilers, heat-only small modular reactors (SMRs), heat recovery, and heat storage, which is proposed in this study. The method simultaneously identifies optimal source selection and sizing, including hourly energy management, and determines the sizes of the necessary heat transmission pipelines. The methodology is examined for a typical heat demand profile with a peak of 400 MWt, and several sensitivity analyses are conducted based on variations in key factors, including electricity prices, demand scales, and fuel prices. The results indicate that the optimal mix of heat sources depends on multiple trade-offs, including demand scale, SMR capacity, alternative energy prices, and source distance. However, heat-only SMRs demonstrated strong feasibility compared to other sources in many scenarios, e.g., outperforming gas boilers at a natural gas price of €20/MW t h. The biomass boiler represents a competitive alternative to gas boilers for base-load operation. Waste heat recovery using absorption heat pumps is among the most economical options, while compression heat pumps and CHP are more suitable for markets with low electricity prices. • An optimization method for optimum mixed heat source selection is proposed. • The effect of heat transmission distance on heat source selection is included. • The economics of heat-only SMRs for district heating is confirmed. • Waste heat recovery by absorption heat pump is highly competitive.
Saleh et al. (2026) studied this question.