Yes, the fact that such a strong incentive exists, and yet it hasn't been done, shows that cost is so much that even a 10x price difference isn't enough to pay for it.
I'm pretty sure it's done quite frequently. It's a pretty simple battery system with--apparently--an 80+% round-trip efficiency to it.
The biggest problem is getting permission to move that much water around. I live next to a lake and shudder at the regulatory hurdles I'd encounter building something like this. There'd be at least 4 government agencies before I even negotiated to sell to the public utility.
It would be obviously stupid to build storage that there is not enough renewable power to charge up from, yet. So, its not having been built yet only proves money is better spent on generating capacity.
Makes no difference what generates it. OP said that power prices vary by 10x from peak to trough. If you charge from the grid when cheap you can make 10x per cycle selling it back.
The biggest problem is getting permission to move that much water around. I live next to a lake and shudder at the regulatory hurdles I'd encounter building something like this. There'd be at least 4 government agencies before I even negotiated to sell to the public utility.
https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricit...