Potential of Small Modular Reactors for Decarbonizing District Heating Systems: A Case Study of the Helsinki Metropolitan Area

This study examines the potential of small modular reactors (SMRs) for decarbonizing the district heating and cooling (DHC) system of the Helsinki Metropolitan area, which relies heavily on fossil fuel power plants. Two SMR technologies are studied: E-SMR, which produces both heat and electricity, and VTT developed LDR-50, which is designed exclusively for heat production. A single reactor unit of E-SMR can produce 155 MWe/50 MWth with a heat recovery rate of 10%, and the much smaller LDR-50 can produce 50 MWth. The study was conducted with VTT developed adaptable energy systems modelling framework Backbone which is an open-source tool for operational and investment planning of energy systems. The studied SMR technologies along with existing capacity and planned future investments based on the year 2030 were implemented in the Backbone city-level model of the studied area. The model is studied from the perspective of a district heating (DH) operator, the model includes heat demand, but electricity price is modelled instead of electricity demand. An investment analysis was conducted on the modelled scenarios to evaluate the new capacity, costs, and emissions along with sensitivity analysis of assumptions used in the model. The results show interest in integrating SMRs to supply district heat networks in the Helsinki Metropolitan area. From the perspective of a DH operator whose priority is to produce heat as a baseline, small LDR-50 units were profitable. Both of the SMR designs were successful in reducing carbon dioxide emissions effectively, but E-SMR was not a profitable DH production technology. The high summer-to-winter variability of the heat demand in the area and additionally, the seasonal variation of electricity prices in the Finnish electricity market creates challenges for the bigger E-SMRs. However, as E-SMR generates mainly electricity, its potential is not thoroughly studied in this work. Sensitivity analysis indicates the economic factors such as investment cost, discount rate and operating costs as the most influential factors for profitability of the SMRs.