The energy security of the European Union is still a concept, rather than the actual action. It was confirmed by legal regulations that give Member States the possibility of individual control of energy security. Furthermore, EU Member States can perform unilateral energy policy, which is often in the interest of the most powerful countries. The concept of energy solidarity, solidarity mechanisms of energy flows directly from the Treaty of Maastricht. This was intended to help to increase energy security, and above all, its construction at the EU level. The functioning of the European Communities and the European Union is showing that the goal of building energy security of the European Union is still in the process of creation and still remain a certain course of action. Following th energy crisis of 2009 we can observe discussion about the concept of energy union, as a way to build energy security of the European Union. Currently, its energy security is limited to the definition adopted by the European Commission and activities aimed at the development of energy infrastructure of Community interest, which contributes to improving EU energy security. The aim of this article is analyze the concept of energy union and attempt to answer the question whether it has a real chance of success, and whether the concept of the proposed shape will be effective and necessary. These questions are important because of we can observe discrepancies between the regulations, promotion of building a common energy security and the practical action of individual Member States of the European Union.