This lecture introduces the case of the electricity sector, focusing on the integrated planning and modeling of energy systems for medium-term (2030) and long-term (2040) evolutions. The instructor discusses the current situation, main challenges, and the particular case of renewable energies, emphasizing the technological and geographic structure of consumption. Various scenarios are presented, including the sustainable scenarios for 2030 and 2040, highlighting the global energy mix and the production of electrical energy. The lecture also covers the regional shares of electricity generation, final consumption of electrical energy, and perspectives for total final consumption by sector in 2040.