[en] After a discussion of the characterization of the security of supply (match between supply and demand on the long and medium terms), and having shown that the planned closure of steerable capacities in Europe should be better taken into account in order to guarantee the security of supply before 2030, this note comments the rate of development of intermittent renewable energies. It notices that these energies have a smaller guaranteed power, outlines that France, Germany and Belgium display the highest deficits of steerable power, that a high share of intermittent renewable energy within the energy mix increases the probability of grid destabilization, and increases the steering complexity, and that it is necessary to adapt grids and to develop demand flexibility. The authors outline that energy transition is poorly coordinated at the European level, which increases this weakening. Some recommendations are finally stated. An appendix presents the main hypotheses, uncertainties and observations related to this study.