Before revision: Electrical energy storage is considered essential for the future energy system to solve the intermittency problems caused by renewable energy sources such as wind and solar power . Among all the energy storage technologies, battery systems may provide flexibility  in a more distributed and decentralized way.
After revision: Electrical energy storage is considered essential for the future energy system to solve the intermittency problems caused by renewable energy sources such as wind and solar power . Among all the energy storage technologies, battery systems may provide flexibility to the power grid in a more distributed and decentralized way.