Overview of energy storage in renewable energy systems

This paper presents an overview of energy storage in renewable energy systems. In fact, energy storage is a dominant factor in the integration of renewable sources, playing a significant role in maintaining a robust and reliable modern electricity system. It can reduce power fluctuations, enhances the electric system flexibility, and enables the storage and dispatching of the electricity generated by variable renewable energy sources such as wind and solar. Different storage technologies are used in electric power systems. They can be chemical, electrochemical, mechanical, electrical or thermal. Energy storage facility is comprised of a storage medium, a power conversion system and a balance of plant. This work focuses on hydrogen, batteries and flywheel storage used in renewable energy systems such as photovoltaic and wind power plants, it includes the study of some economic aspects of different storage technologies. Finally, the behavior of battery and flywheel storage systems in photovoltaic and wind energy applications is studied under Matlab/Simulink and some obtained results are presented. •The state of art of chemical, electrochemical, mechanical, electric or thermal storage is presented in this work.•Storage technologies can be applied for energy management and power quality in electric power systems.•Storage mitigates power variations, enhances system flexibility, and enables storage and dispatching of renewable energy.•The advantages and drawbacks of different storage technologies in renewable energy are examined.•Major obstacles to market entry of storage systems are the actual costs, material stability and safety.•Relatively low costs can be obtained by using PHES and CAES systems. The battery is less competitive than PHES, but can be considered as a relatively cost efficient solution.•Heat storage system costs depend on the size and the technology.