I'm not the person you've been replying to, but I note that your replies in this chain are getting more and more acrimonious. If you're going to repeatedly accuse the other commenter of bad faith, it's probably best to stop replying.
I'm not a civil engineer, nor any kind of expert in grid-scale energy storage, so I can only note that in my amateur readings I've seen many different people (alleged experts) say the same things that Manuel_D is saying. That doesn't mean it's true, that's not my point. My point is that if you know something that all these other commentators don't, I and others would greatly appreciate it if you would explain that. But you'd need to actually explain it, not just accuse others of bad faith.
Literally no one with any expertise says that energy storage is an unsolved problem.
All do acknowledge that building out storage will be a project of a scale similar to that of building out renewables. Only the most dishonest would insist that the relatively small amount of storage already built demonstrates anything other than that capital is overwhelmingly better used, today, to build out new generating capacity. It would be obviously stupid to spend on building storage you have not generating capacity to charge up.
I'm not a civil engineer, nor any kind of expert in grid-scale energy storage, so I can only note that in my amateur readings I've seen many different people (alleged experts) say the same things that Manuel_D is saying. That doesn't mean it's true, that's not my point. My point is that if you know something that all these other commentators don't, I and others would greatly appreciate it if you would explain that. But you'd need to actually explain it, not just accuse others of bad faith.