Development of future-proof supply concepts for sector-coupled district heating systems based on scenario-analysis

Existing districts pose a particular challenge within the transition into a renewable energy system. Especially the heat supply requires innovative concepts. In many districts, renewable energy resources are limited, and district heat supply relies on energy imports from the upstream energy infrastructures, especially the gas and electricity grid. These upstream infrastructures are in an ongoing process of transformation into a renewable energy system with uncertain speed and depth. To design future-proof heat supply concepts, this work presents a scenario-based design approach considering different scenario paths for the upstream energy infrastructures as well as the development of the existing building stock. Therefore, a mixed-integer linear programming model is set up to optimize the energy converter and storage capacities of a generic district heat supply with respect to costs and emission. Additionally, three different refurbishment scenarios are considered for the existing buildings stock. From the results of the different scenarios, future-proof heat supply concepts are derived. The analysis shows that heat-pump capacities in combination with a thermal storage is of great importance for a future carbon-neutral heat supply. A combined heat and power unit helps to reduce emissions in short term. However, only if the gas network has a high share of renewable energies, this technology will compete with electricity based heating via heat-pumps. The results show that electrolysis is at least in short term not a viable option for designing a cost-efficient carbon-neutral district heat supply.