Operating utility-scale battery storage power capacity has more than quadrupled in the U.S. from the end of 2014 (214 megawatts (MW)) through March 2019 (899 MW).

The Energy Department's Energy Information Administration (EIA) said that if currently planned additions are completed and no current operating capacity is retired, utility-scale battery storage power capacity could exceed 2,500 MW by 2023.

An energy storage site in Arizona. Source: Arizona Public ServiceAn energy storage site in Arizona. Source: Arizona Public ServiceEIA defines utility-scale battery storage units as having 1 MW or greater power capacity. It credits growth in utility-scale battery installations to supportive state-level energy storage policies and the Federal Energy Regulatory Commission’s Order 841. That order directed power system operators to allow utility-scale battery systems to take part in their wholesale energy, capacity and ancillary services markets.

Holy grail no longer?

Long considered something of the holy grail for the electric power industry, utility-scale batteries make it possible to store energy for use at times other than when it was produced. Previously, energy had to be consumed as it was produced. That characteristic caused frequent headaches for grid operators who have to balance intermittent renewable energy resources with demand and with relatively inflexible generating resources such as coal and nuclear.

Source: EIASource: EIAHeadline-grabbing events that included a natural gas storage leak in California and hurricanes in the Caribbean helped battery energy storage gain a foothold. Large-scale production — aided by growing demand for lithium-ion batteries for electric vehicles — has helped to drive down the cost of large-scale storage.

In 2017, the CEO of NextEra Energy, parent of Florida Power & Light, was quoted as saying, “Yeah. Storage is very real now."

Pairing utility-scale battery storage with intermittent renewable resources such as wind and solar has become increasingly cost-competitive compared with traditional generation options, EIA said. (Read "This utility is adding 950 MW of solar and energy storage capacity.")

EIA said that the two largest operating utility-scale battery storage sites as of March 2019 provide 40 MW of power capacity each: the Golden Valley Electric Association’s battery energy storage system in Alaska and the Vista Energy storage system in California. It said that 16 operating battery storage sites have an installed power capacity of 20 MW or greater. Of the 899 MW of installed operating battery storage reported by states as of March 2019, California, Illinois and Texas account for a little less than half of that capacity.

Source: EIASource: EIAIn the first quarter of 2019, 60 MW came online, and an additional 108 MW of installed capacity will likely become operational by the end of the year. Of these planned 2019 installations, the largest is the Top Gun Energy Storage facility in California with 30 MW of installed capacity.

(Read "California OKs big move to energy storage.")

As of March 2019, the total utility-scale battery storage power capacity planned to come online through 2023 was 1,623 MW. If these planned facilities come online, total U.S. utility-scale battery storage power capacity would nearly triple by the end of 2023. Additional capacity beyond what has already been reported may also be added as future operational dates approach.

Of the planned battery storage projects, the largest two sites account for 725 MW and are planned to start commercial operation in 2021. The largest of these planned sites is the Manatee Solar Energy Center in Parrish, Florida. With a capacity of 409 MW, this project would be one of the largest solar-powered battery systems in the world and would store energy from a nearby Florida Power & Light solar plant in Manatee County.

The second-largest planned facility is the Helix Ravenswood facility located in Queens, New York. That project would be developed in three stages and would have a total capacity of 316 MW.

Storage for peak demand

In June, the National Renewable Energy Laboratory (NREL) released a report that said roughly 28 gigawatts (GW) of practical potential exists for 4-hour storage providing capacity for times of peak energy demand, assuming current grid conditions and demand patterns. NREL said that deployment at that scale could help cut storage costs and enable still greater solar photovoltaic (PV) deployment. It said this, in turn, could extend the practical potential for 4-hour storage to 50 GW or beyond (assuming PV provides 10% of the nation’s electricity demand).

The NREL report said that the relative value of storage capable of providing system flexibility (such as time-shifting generation resources and avoided thermal plant starts) increases the value of batteries relative to gas-fueled combustion turbines and will vary by power grid mix, fuel price and energy storage size.