Cross-border impacts of nuclear phase-out policies on the European power system: Economic and environmental insights for strategic energy planning

The European power system plays a strategic role in reducing dependence on fossil fuels while contributing to reaching Europe's CO2 emissions targets. The energy crisis triggered by Russia's war against Ukraine has revived interest in the role of nuclear energy in the European power system. We examine how postponing nuclear phaseout affects optimal dispatch and environmental performance of the interconnected European power system. We use ESMOD, a unit commitment model of the European electric system at the 2030 horizon, built with Antares Simulator, to assess the impact of nuclear phase-out policies in Germany and Belgium. The model accounts for 36 European countries and focuses on cross-border effects and country-level impacts. The model shows that not decommissioning 4 GW of nuclear capacity in these two countries would have reduced European CO2 emissions by 16 million tons in 2030. Strikingly, about 45% of such reductions would have occurred in other European countries and keeping nuclear power plants in operation would have increased the total European surplus by 3 billion euros heterogeneously affecting across countries. To interpret these heterogeneous effects, we analysed the load size, power mix, trader status and interconnections to explain cross-border sensitivities. Finally, we assessed the countries' sensitivity to weather variation across 34 climate years by classifying them using the Kmeans clustering method. The results underscore the central role of European energy policy coordination in shaping future energy strategies that prioritize climate goals and efficient system integration while challenging the economic efficiency and environmental effectiveness of solely national plans.