Again, this is only for very short term storage. We are comparing apples and oranges.
As an example, for most of Aus, 5 hrs storage will only work for <80% renewables [0]. It's only practical on smaller scales which doesn't mean it isn't useful now but just means that the ~$100/MWh systems will not be practical everywhere, especially when renewables become more ubiquitous.
Edit: I had a deeper look at the NREL paper and most of their costs seem to be in the $100s/kWh rather than MWh. E.g ~$300/ kWh for 6 hour systems on Fig. 6.
