This document discusses renewable energy integration into smart grids and the role of energy storage technologies. It begins by outlining the benefits of renewable energy and smart grids, including facilitating high shares of variable renewable energy sources. Energy storage is useful for adding flexibility to electric grids to deal with the variability of renewables. The document then discusses various energy storage technologies and their applications for integrating renewable energy at different levels of the electric grid system. Key benefits of energy storage include supporting renewable energy integration, improving grid reliability and efficiency, and facilitating demand-side management.