Aquion Energy and its partners will demonstrate a low cost, grid-scale, ambient temperature sodium-ion energy storage device. The energy storage chemistry in this device uses an electrochemical couple that combines a high capacity carbon anode with a sodium intercalation cathode capable of thousands of deep discharge cycles over extended periods of time. The proposed aqueous sodium-ion technology includes the use of thicker electrodes, less expensive separator and current collector materials, and the use of benign materials for electrodes and electrolyte salts. This project will progress the work from bench-scale to pilot-scale, enabling multiple ampere-hour cells to be manufactured and assembled into test batteries. Aquion plans to site units between 10 kWh and 100 kWh capacity that have the ability to perform medium to long duration (more than 2 hours) charge and discharge functions with greater than 95 percent DC-DC efficiency. The units will be safe and environmentally benign. Testing will characterize the energy storage capacity of the units, the response to various signals, compliance with utility interconnection standards, battery and power conversion system efficiency, and effectiveness under various cycles typical of the applications being validated. Utility application-level testing will test the functionality of the unit with respect to its ability to respond to external control signals and properly interact with electric grid in carrying out relevant sequences. The pilot line will be commissioned for production at the end of the project.