I Googled around for this some time ago and found quite a few grid-storage projects in the US and Europe (both public and private), but I don’t have links handy

I Googled around for this some time ago and found quite a few grid-storage projects in the US and Europe (both public and private), but I don’t have links handy at the moment. They all seem to be pretty early-days IIRC. But yes, mostly you have to sift through a lot of results related to transportation fuel cells.