content: The main advantage of the Hornsdale Power Reserve (Tesla battery), is its ability to provide power in milliseconds, before other backup power comes on.  First, the power plant responded to the grid frequency challenge before the offending coal plant actually finished tripping itself from the power grid. That’s not like telling the future, but it’s so fast you’d start questioning things. And secondly, it finished its work of stabilizing the grid and shut back down before the regular backup plant even started its work. Because of the slower nature of fossil fuels generator, literally spinning up a massive turbine, they’re designed to deliver far more energy than is needed to the power grid. As a form of insurance.  That said, hydroelectric storage is a great conventional means to store large amounts of energy, especially in off-peak times. Recently a wind power station of this type was built near here that combines hydroelectric storage with the notoriously unreliable wind power. It's supposed to be able to switch from storage to 16 MW generation within 30 seconds and have a storage coefficient of efficiency of 80%.