What is an energy storage system?

An energy storage system (ESS) for electricity generation uses electricity (or some other energy source, such as solar-thermal energy) to charge an energy storage system or device, which is discharged to supply (generate) electricity when needed at desired levels and quality. ESSs provide a variety of services to support electric power grids.

What is the power capacity of a battery energy storage system?

As of the end of 2022, the total nameplate power capacity of operational utility-scale battery energy storage systems (BESSs) in the United States was 8,842 MW and the total energy capacity was 11,105 MWh. Most of the BESS power capacity that was operational in 2022 was installed after 2014, and about 4,807 MW was installed in 2022 alone.

Why do we need energy storage systems?

As a consequence, the electrical grid sees much higher power variability than in the past, challenging its frequency and voltage regulation. Energy storage systems will be fundamental for ensuring the energy supply and the voltage power quality to customers.

What is a battery energy storage system?

A battery energy storage system (BESS) is an electrochemical device that charges (or collects energy) from the grid or a power plant and then discharges that energy at a later time to provide electricity or other grid services when needed.

What is the difference between rated power capacity and storage duration?

Rated power capacity is the total possible instantaneous discharge capability (in kilowatts [kW] or megawatts [MW]) of the BESS, or the maximum rate of discharge that the BESS can achieve, starting from a fully charged state. Storage duration is the amount of time storage can discharge at its power capacity before depleting its energy capacity.

How many MW of battery storage are there in the US?

By December 2017, there was approximately 708 MW of large-scale battery storage operational in the U.S. energy grid. Most of this storage is operated by organizations charged with balancing the power grid, such as Independent System Operators (ISOs) and Regional Transmission Organizations (RTOs).