Re: Powering the grid and providing backup?
I respect Mr. Sod's input, and yes, it will happen.
My point is that it will happen infrequently. Moreover, it will happen anyway, even if you never deplete your reserve. You need 2nd-level strategies, like load-shedding, controlled shutdown, which is a thing datacentres can do pretty well.
Just to run the numbers, the batteries will hold-up for 2-4 hours if fully charged. This only drops 20% if you allow depletion. I'm saying that the probability of a 2.4 hour outage (assuming this is the figure with no depletion) is very close indeed to the probability of a 2.0 hour outage (with depletion).
So, all you need to do, in the worst case, is to run your load-reduction (which you have to do at some point regardless) a little bit earlier.
Taking this observation to its limit, a datacentre only really needs enough battery power to divest itself of [most of] its workload - which might be just a few minutes. It would then run at maybe 5% till power returns - just so that it doesn't drop off the network altogether.
I'm assuming of course that there are other datacentres that do have power, and spare capacity - isn't this the original raison d'etre for DARPANET and the internet in the first place?
Biting the hand that feeds IT
