The course introduces students to energy sources used in traditional and innovative energy systems. The energy sources that make up the global energy mix will be introduced and the constraints and challenges associated with their use will be presented. In the form of working diagrams, students will be introduced to the principle of technologies used for energy transformation. The scope of the course will provide a comprehensive overview ranging from the use of fossil fuels, to renewable sources, to the future possibilities of hydrogen energy. Furthermore, the technologies used for the storage of thermal, mechanical and electrical energy and the possibilities of subsequent use of the stored energy will be presented. In the field of chemical energy storage, power-to-gas technology based on the generation of hydrogen and other synthesis gases will be presented. Current trends in the Czech and world energy sector will be commented during the course.