Electrical energy storage applications for power systems are surveyed and presented. Energy storage for electrical energy has been the focus of attention due to improved technology, increased use of intermittent renewable sources, constrained transmission and distribution infrastructure and improved market rules. Though many applications exist, a detailed cost benefit analysis is required before large scale integration of energy storage devices in the power grid is possible. Many technical and non-technical challenges remain. Due to multiple benefits and costs associated with storage systems, detailed optimization studies are required to understand the electrical and financial impact of connecting energy storage to the grid.