Assessment of coal phase-out in a third-generation multi-source district heating system

This paper addresses the transition toward a climate-friendly modernization path for an existing multi-source district heating system in Northern Italy, aiming for a complete coal phase-out by 2030. The primary objective is to evaluate the technical feasibility and performance of replacing a coal-fired boiler with a cogeneration gas turbine within a Third-Generation multi-source network integrated with heat pumps, thermal energy storage, a Waste-to-Energy plant, and industrial waste heat recovery. The novelty of this approach lies in the dynamic integration and macro-scale operational dispatch of multiple energy streams under real-world industrial constraints and off-design vendor performance maps, bridging the gap between theoretical optimization and practical utility execution. Quantitative results demonstrate that replacing coal with natural gas achieves a substantial CO2 emission reduction of approximately 40%. The selected gas turbine effectively covers around 10% of the annual thermal demand while simultaneously generating electricity. Comparative analysis between two candidate models indicates that the LM2500 + yields lower gas consumption and emissions, whereas the SGT-700 offers competitive advantages in terms of cogeneration value. Ultimately, this study provides a validated, replicable framework for large-scale heating network decarbonization, concluding that the proposed configuration serves as a robust transitional strategy toward long-term climate neutrality goals.