Hydrogen Production Using Solid Oxide Electrolysis as a Flexibility Option for Nuclear Power Plants

In the context of decarbonization, it is crucial to integrate low-carbon sources effectively. Among these, nuclear power can offer a significant and stable contribution to the electricity balance, but its integration is hindered by the limited flexibility. A promising option is coupling with high-temperature electrolysis, which utilizes both thermal and electric power from the nuclear plant to obtain hydrogen, which is a high-value and storable product. In this work, a hybrid system combining a solid oxide electrolyser (SOE) with a small modular reactor nuclear power plant (SMR-NPP) is investigated, to assess potential and performance. In the SMR-NPP, thermal energy is transferred to water/steam that then drives a steam turbine. In the hybrid configuration, a fraction of the high-pressure steam is diverted towards the SOE section, where it provides heat for the evaporation of the water stream that is fed to the stack. Due to the higher operating temperature of SOE (700 °C) than that of the steam cycle (317 °C), exothermic operation of the electrolysis stack is considered, enabling regenerative heat exchange. The model allows to observe the SOE section operation in different configurations to assess the effects on components sizing and operating parameters. Results show promising performances in the analysed scenarios, with an important role played by the SOE modularity.