That's only one way that you would do hydro-storage these days though. Think, for example, if you drill a hole deep into the ground, lower a cylinder into it,

That's only one way that you would do hydro-storage these days though. Think, for example, if you drill a hole deep into the ground, lower a cylinder into it, poke a hole in the bottom of the cylinder, then fill that cylinder with water. If I put a platform with a giant weight on top of it, the platform will press all of the water in the cylinder down through the hole in the bottom. That water will travel through a tube to the top of the cylinder and pour back into the cylinder on top of the weighted platform. In that tube, is where you capture the stored energy with turbines. Then, when the wind picks back up, or the sun comes out, or power is just cheap even from the coal plant, you use that power to lift the platform back up and suck all the water back into the bottom of the cylinder. Benefits of this are, as the HN User "beat" implied below, it's so cheap and simple to build that even a single, say, shopping mall might invest in it to lower their power draw from the grid. They would build one that only serves their mall for instance. You start to build out a truly distributed power storage infrastructure.