Abstract: Systems and methods providing modular and scalable flow batteries are disclosed. The modular design can utilize the ability of flow batteries to separate power, provided by a battery stack, from energy, provided by a stored electrolyte. Power of the system can be determined by a number of battery cell stacks, while stored energy capacity of the system can be determined by how much electrolyte is available for use by the battery cell stacks. Catholyte and anolyte solutions can be stored in pipes having an adjustable length. Electrolyte storage capacity can be increased by increasing the length of the pipes by an amount sufficient to provide a desired increase in electrolyte storage. Alternatively, electrolyte storage capacity can be decreased by decreasing the length of the pipes.

Abstract: A flow battery system is provided that has at least one cell stack and at least a pair of storage containers or tanks connected to the at least one cell stack. Each of the storage containers is formed from a rigid (e.g., metal) shell and includes a liner directly bonded to inner walls of the rigid shell and forming an enclosure configured to retain a liquid electrolyte. The electrolyte can be an anolyte or catholyte. In the assembled configuration, the metal shell of the storage container provides secondary containment whereas the liner directly bonded thereto provides primary containment. The flow battery system includes a fault detection system configured to detect a presence of a fault or leak and further to determine a location of that leak in the flow battery system, such as a storage container or a specific portion of the storage container.

Abstract: Methods and systems for removing impurities from electrolyte solutions having three or more valence states. In some embodiments, a method includes electrochemically reducing an electrolyte solution to lower its valence state to a level that causes impurities to precipitate out of the electrolyte solution and then filtering the precipitate(s) out of the electrolyte solution. In embodiments in which the electrolyte solution is desired to be at a valence state higher than the precipitation valence state, a method of the disclosure includes oxidizing the purified electrolyte solution to the target valence.

Abstract: The invention provides in various embodiments methods and systems relating to controlling energy storage units in flowing electrolyte batteries.

Abstract: Flowing electrolyte batteries capable of being selectively neutralized chemically; processes of selectively neutralizing flowing electrolyte batteries chemically; and processes of selectively restoring the electrical potential of flowing electrolyte batteries are disclosed herein.

Abstract: A method for responding to a change in electric power demand includes (1) charging an energy storage subsystem from an electric power grid, (2) discharging the energy storage subsystem into the electric power grid at a discharge rate that is less than a maximum rate of discharge of the energy storage subsystem, and (3) adjusting the discharge rate in response to a signal selected from the group consisting of a signal to provide a regulation up service and a signal to provide a regulation down service. An energy storage system includes an energy storage subsystem for storing electric power, an interface for interfacing the energy storage subsystem with an electric power grid, and a controller configured to control operation of the interface in response to a signal to provide a regulation up service and a signal to provide a regulation down service.