Depends on what long term means. But batteries are used for power grid storage. Tesla is selling huge numbers of tesla megapacks (https://en.wikipedia.org/wiki/Tesla_Megapack) often used to replace peaker plants.
Peaker plants are power plants sitting there ready to turn on during peak power usage. I think they used to be often coal, which took a while to start up and produced lots of pollution, but then more recently natural gas plants start up faster and have much lower emissions. So during an evening power usage peak, or during really cold or hot times when power demand is high, the grid can tap that power source. Now you can replace those plants with a bunch of batteries that are ready in milliseconds to provide additional power, and then you can charge them if they get used up at night when electric usage is low.
Yeah, I think my question was a bit fuzzy, what is the definition of long term? Batteries are excellent for short term storage, days or weeks but they don’t have the same storage performance as fossil fuels of where talking months and years.
Peaker plants are power plants sitting there ready to turn on during peak power usage. I think they used to be often coal, which took a while to start up and produced lots of pollution, but then more recently natural gas plants start up faster and have much lower emissions. So during an evening power usage peak, or during really cold or hot times when power demand is high, the grid can tap that power source. Now you can replace those plants with a bunch of batteries that are ready in milliseconds to provide additional power, and then you can charge them if they get used up at night when electric usage is low.