Abstract

This study analyzes the system effects of integrating surplus heat from Forsmark Nuclear Power Plant into the district heating systems of Stockholm and Uppsala. Using scenario-based modeling with a MATLAB-based simulation tool, the impact on production mix, system costs, and CO₂ emissions was examined under varying conditions.

Results show that surplus heat priced at 336-354 SEK/MWh reduces total system costs in both cities, primarily displacing biofuel-based production and oil while waste incineration remains as base load. Uppsala showed greater integration potential than Stockholm, where combined heat and power production stays highly competitive due to electricity revenues. Electricity and biofuel prices were identified as the most decisive factors for surplus heat competitiveness.

Scenarios without waste incineration yielded the largest CO₂ reductions but significantly higher costs, illustrating a tension between economic and climate optimization. However, in this scenario, the surplus heat was shown to be even more effective in reducing the total system cost. The study concludes that surplus heat from Forsmark has potential to improve both cost efficiency and climate performance, though its role remains strongly dependent on future energy prices, heat demand, and policy frameworks.