Nuclear cogeneration in district heating systems: optimal pathways to decarbonization

Nuclear cogeneration—the use of nuclear plants in cogeneration mode to produce both heat and electricity—is a proven technology for decarbonized electricity generation and has already been employed in a number of district heating (DH) networks worldwide. However, despite its promises as an option for low-carbon residential and commercial space heating, expanding the use of nuclear technology requires substantial investment, whereas more established conventional low-carbon heat energy sources such as biomass and large-scale heat pumps are already available. At this juncture, the potential role of nuclear cogeneration demands thoughtful assessment. This paper aims to identify key factors influencing the optimal transition pathways to low-carbon DH systems with the potential to include nuclear cogeneration plants. We explore how nuclear cogeneration can fit into an optimized heat production mix at local scale alongside conventional low-carbon technologies. We develop scenarios to quantify the benefits of nuclear cogeneration in optimal multi-year DH network decarbonization pathways in various local-scale configurations and exogenous economic and policy conditions. Transport of heat produced is a pivotal factor in both the modeling and the economic evaluation. Our results suggest that integrating a nuclear cogeneration plant (NCP) into the set of technologies available to the DH planner could significantly reduce overall DH system costs, with larger and closer networks benefiting more from NCP availability. The economic competitiveness of nuclear cogeneration depends primarily on NCP-to-DH network distance, annual consumption of the DH network, and discount rate, rather than on carbon emissions caps or the prices of conventional fuel sources. We find that when it is cost-competitive to include nuclear cogeneration in the production mix, the NCP can largely replace conventional low-carbon heat generators and cover the bulk of district heat demand.