Electricity production from wind and other renewables technology has increased significantly to meet the renewable portfolio standards (RPS) targets imposed by 31 U.S. states and the District of Columbia. Energy storage is attracting greater interest as an enabling technology for integrating variable renewable power into the electric grid, addressing grid reliability challenges, and increasing overall infrastructure utilization. The integration of renewable energy technology into the U.S. grid is one of the key drivers for the growing interest in stationary energy storage systems. Other countries are also interested in advanced energy storage systems for accommodating the variable nature of renewable resources and the inherent uncertainty in accurately forecasting production. Internationally, significant investments in research and development for advanced energy storage systems are being made to address the perceived need that energy storage will be an important component of the future power grids worldwide