The importance of the climate change problem is recognised by the governments of the overwhelming majority of the world’s countries. To bring additional attention and enable more concrete action, in a number of countries and municipalities the issue has been declared a climate emergency. The need to solve this problem predetermines the task of replacing fossil energy sources with renewable alternatives. The process of the ongoing transformation is called energy transition. It includes transformation of all the energy-intensive sectors of economic activity: power generation, supply and consumption, heat generation and supply, electrification of transport, agriculture and households.The main goal of the energy transition is obvious – it is necessary to reduce the emissions of carbon dioxide into the atmosphere. The main sources of energy used to achieve this goal in power generation are wind and solar energy. Even though the goal is unambiguously defined and the way to achieve it seems evident, it is already clear that a number of serious problems and obstacles have arisen. They are caused by the emergence of additional objectives that must be achieved and constraints that need to be satisfied in the process of the required transformations. Indeed, the transition should be carried out taking into account power system properties describing techno-economic efficiency, reliability, stability, adequacy, etc. This list can be expanded easily. It should be noted that the additional objectives are not less important than the overarching goal. Along with reducing emissions, it is also necessary to improve energy supply reliability, its availability and affordability for all the segments of the population as well as maintain the security of the energy supply infrastructure and processes.