At the end of 2021, the United States had 4,605 megawatts (MW) of operational utility-scale battery storage capacity, according to our latest Preliminary monthly inventory of electric generators. Power capacity refers to the greatest amount of energy a battery can discharge at any given time. Batteries used for network services have relatively short average durations. Average battery life is the time a battery can supply electricity at its rated capacity until it is depleted. Batteries used for electric charge transfer have relatively long durations.
We calculate battery life using the ratio of energy capacity (measured in megawatt-hours [MWh]) to the electrical capacity (in MW). Energy capacity refers to the total amount of energy these batteries can store. Our energy capacity data comes from our latest Electric Generators Annual Reportwhich contains data through the end of 2020. When fully charged, battery units built through 2020 can produce their rated power capacity for approximately 3.0 hours on average before recharging.
Our Electric Generators Annual Report also contains information on how energy storage is used by utilities. Utility-scale battery storage can be used primarily in two ways: serving grid applications and enabling electrical load transfer. Our Battery Storage in the United States: An Update on Market Trends The report contains a full description and breakdown of all Grid Service and Electric Load Transfer applications reported to us.
Battery operators report that more than 40% of battery storage energy capacity operated in the United States in 2020 could provide both grid services and electrical load transfer applications. About 40% only performed electrical load transfer and about 20% only performed network services.
Battery less than two hours in duration are considered short-lived batteries, and almost all of them can provide network services that help maintain network stability. Batteries providing grid services discharge power for short periods of time, sometimes even for seconds or minutes only, so it can be economical to deploy short-lived batteries. Most of the battery capacity installed in the late 2010s consisted of short-lived batteries used for grid services, but this trend has changed over time.
Batteries lasting between four and eight hours are typically cycled once a day and are used to move electricity from periods of relatively low demand to periods of high demand. In a region with relatively high solar power capacity, daily-cycling batteries can store solar electricity at noon and discharge this electricity during peak hours of electricity consumption in the evening when solar power decreases. .
According to the planned installations compiled in our Preliminary monthly inventory of electric generatorswe expect battery storage increase by 10 gigawatts (GW) by the end of 2023. More than 60% of this battery capacity is intended for twinned with solar power plants. As of 2020, most collocated storage batteries installed in solar installations operate to move electrical loads and have average durations of four hours or more.
First published on “Today in energy.” Main contributor: Vikram Linga
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