In this final paper, electrical energy storage systems are described. The power system has the task of ensuring high-quality and reliable delivery of electricity at all times. The condition for fulfilling this task is to equalize the consumption and production of electricity. Electrical energy storage systems play an essential role in the implementation of this task. Electric energy storage tanks are increasingly used, and the main reason for this increase is the intensified use of renewable energy sources. Electrical energy storage systems can be divided into: mechanical, electrochemical, chemical, electrical and thermal electrical energy storage systems. For each listed electrical energy storage system, the principle of operation is explained, and the advantages and disadvantages of the described systems are outlined. After specifying the characteristics of individual electrical energy storage systems in the following text, their application is also specified. Throughout the work, the textual descriptions are accompanied by images that help to understand the topic of this final work.