Are they? Why haven’t they already? It looks like they are supplementing peak capacity right now with gas plants dynamically reacting to varying demand with storage being oders of magnitude too small.
Do you understand the difference between already built-out storage, and preparing to build out storage? If you want to compare like against like, the number of ThorCon reactors deployed is exactly zero (0).
Storage is not already built out because it is still obviously better to spend the money building out generating capacity, and will be until its share is much larger. In particular, before storage can be useful, you need enough spare generating capacity to top up your storage while also driving customer load.
The business model for storage is leveraging the difference in prices at different times (of the day mostly). There is already quite a price difference on energy markets and negative prices happen regularly around the world.
You seem to be talking about storage as a separate business. But the major market for storage will be public utilities that also own generating capacity, and sell power principally to end users. After their storage is full, maybe they sell any extra to the grid, or use it to synthesize liquid fuel for sale.
Negative prices are a very, very temporary phenomenon. Very soon, all surplus generating capacity will be absorbed producing hydrogen and ammonia for sale into an unlimited market.
