Abstract
The presented topic deals with the transformation and diversification of the EU energy sector. Energy security is examined in the context of geopolitical changes and viewed through the lens of the interdependence between the EU and Russia in the import and export of fossil fuels. The topic is studied on the demand side and on the supply side. The political element plays a fundamental role in the territorial structure of energy flows. The descriptive analysis employed two case studies, which illustrated the transformation of the EU energy mix as well as the extent of the EU's import dependence on Russian gas. It is possible to observe the (a)symmetry of mutual dependence in the context of energy transformation. The key theme of the article is the assessment of EU energy security based on changes in energy resource flows through the lens of geopolitical changes. The research has demonstrated the need for a dramatic change in the EU energy mix, one which will reduce reliance on fossil fuels and increase the role of renewable energy sources. This trend is positive for the diversification of fossil fuel imports to the EU. Additionally, proposals and recommendations are put forward to help strengthen the EU's energy security in the future.