I'll answer my own question: This is not a MWh of installed capacity, this is a MWh of discharge. That is, over the expected lifetime of a storage installation,

I'll answer my own question: This is not a MWh of installed capacity, this is a MWh of discharge. That is, over the expected lifetime of a storage installation, consuming one MWh from such an installation would cost $187. Still much more expensive than alternatives (about 4x the cost of nuclear) but arriving in the realm of feasibility.