This lecture covers the analysis of energy systems with a focus on electricity strategy, using Switzerland as a case study. It discusses the country's electricity production, consumption, import-export balance, renewable energy sources, and strategic options for the future. The instructor, Prof. Edgard Gnansounou, explores the challenges and constraints in the Swiss energy policy context, emphasizing the need for a sustainable and secure electricity supply. Various energy generation technologies such as hydropower, thermal power plants, geothermal power, and photovoltaics are also examined, along with energy storage solutions and interconnections with neighboring countries.