There is no need for storage technology to "progress". It just needs to be built out. It would be stupid to build out storage before you have built enough rene

There is no need for storage technology to "progress". It just needs to be built out. It would be stupid to build out storage before you have built enough renewable generating capacity to charge it from: when renewables are not producing enough, you fill in with gas turbines, as now. As renewable generating capacity rises, and storage is built to take up the surplus, you rarely need to run the turbines. The turbines will eventually be converted to burn ammonia or hydrogen cracked from ammonia, when that becomes cheaper. There is never a time when you have enough storage for all possible scenarios. Instead, you plan to fill in with other methods when storage runs low. Storage is a cost-cutting measure. Importing ammonia from tropical solar farms is always on the table.