Battery Storage in lieu of emergency generator

[Yikes]

I'm looking at designing a new senior housing development in California. Our state energy codes and utility incentives strongly push us towards solar PV and/or battery storage to assist the grid overall. At 5 stories, our building would normally be equipped with a a backup generator for the elevator, and it may also power emergency lighting, alarm systems, fire pump etc.
Have any of you heard of using this same grid battery storage to provide backup power in lieu of generator? If so, would there need to be some minimum requirement that the batteries not be discharged lower than the capacity necessary to sustain for 2 hours of elevator / fire pump operation, etc.?

 

[Yankee Chronicler]

I haven't heard of any such alternatives. For starters, I would be asking how much power the elevator(s) and -- especially -- a fire pump will require. I've seen diesel fire pumps running at initial start-up. They are not small. I suspect the power required to run a fire pump for the required time will be substantial.

 

[bill1952]

While it seems technically feasible, I'd think overcoming the listing requirements for use for back up power would be difficult.