According to data from the Energy Information Administration (EIA), more than 20 gigawatts (GW) of battery capacity have been added to the US electric grid in the last four years. This rapid expansion is equivalent to the production of 20 nuclear reactors and is crucial for averting power disruptions, especially in states that rely significantly on intermittent renewable energy sources such as wind and solar.
Welcome to the rabbit hole of energy storage.
Turns out nobody cares about the capacity but about the discharge rate. Which is why you’ll often hear about how many Gigawatts a certain energy storage project has, and nothing about GWh.
If you think about it for a bit, it does make sense. A lot of solutions would take days to fully discharge, so you might think “oh we have an entire city’s energy consumption for a week in some storage”, but in reality you could maybe power one neighborhood with that cuz of the discharge rate.
So, capacity refers to the “output capacity”.