ABSTRACT
Energy storage is an important area of research as is one of the key issues to improve the efciency and the economic feasibility of energy systems. There are different types of energy storage1,2:
1.Mechanical energy storage that includes the gravitational energy storage, the compressed air energy storage, and the ywheels. The rst two can be used for large-scale utility energy storage, and the ywheels are appropriate for intermediate storage.
