Lazard uses current commercial cost figures. If people actually tri d to deploy grid storage on a wide scale, prices would skyrocket as supply fails to match demand.
While scaling up the industry isn't trivial, it's absurd to claim it's impossible or that demand outpacing supply will somehow reduce investment in greater supply.
You haven't actually given a plan to provision this much storage - or even specified how much storage we'll need for that matter - so yeah I'm still very comfortable in claiming it is not possible. At least not without some massive breakthrough in storage technology, which doesn't yet exist.
While it's unlikely to reach this value, it's such a high figure that actually can solve the energy storage problem altogether.
Again, the answer is point to an unproven form of storage and assume it'll be a silver bullet.
I'll come back at you: what technological component involved in underground storage of hydrogen is not already demonstrated?
It's pretty well-established tech at this point.