And they have been used where? Everything I can find suggests they are theoretical, not in use even on micro grids yet, and many have huge concerns about them being able to support a grid on their own.

Also the technology required has been around for decades it’s not new and no one’s done it yet.

So again what’s changed because it seems like for now there is no “I have a grid and need something now” solution it’s a “maybe one day”