Requirements of load following by nuclear power plant as a function of variable renewable energies's development

Nuclear energy's low variable cost makes it a base load technology. It is expected to be among the last ones te see its working hours reduced. Nevertheless, with higher VRE penetration, nuclear energy should adapt to changes in demand and variable energy production, in particular in regions with high nuclear energy shares such as France. We will present some results of a benchmark of technology dispatching tools: MAEL from CEA/ITESE, OPTIMIX from CEA/IRSN, EUCAD from CNRS/ University Grenoble Alpes and EcoNUK from CNRS/University of Nantes. The models aimed at reproducing the hourly production of France during year 2012. The total demand as well as the actual productions of wind and solar energies are known and common assumptions for variable and ramping costs as well as technology efficiencies are taken. The compared outputs are agreggated costs, CO2 emissions, average load factors for the different technologies. Then we will present some simulation results for the 2030 horizon. Assumptions of demand and installed capacities are taken whether from energy prospective tools (Prospective Outlook for Long Term Energy Supply, POLES), or extrapolated from the French Transport System Operator RTE. Variations in the average load factors as well as distribution of daily load reductions are computed. These results allow complementary studies, such as those presented by R. Loisel et al. at the same workshop which are assessing the evolution of the business model of nuclear energy as well as the technical requirement in term of load following capacity of future nuclear reactors.