There are already many energy storage systems in place and many more being installed even now. The problem is that energy storage and recovery is a hard problem. Anyone who solves it will be rich overnight.
Texas is like Germany. No hills (unless you count the waste disposal hills, where you cannot pump up water)
I live in the hill country in Texas, so I would disagree there.
I’m from the hill country… but that’s just a small area near Austin. Houston, SA, DFW, etc. are all very flat.