Well, I’m not sure what this context is but let’s have a discussion.
In a prolonged power outage, you can expect that all of your computer systems will need to be powered by something substantial like a generator or a very large UPS (Uninterruptible Power Supply) in order for your organization to remain in operation. In the time while you know main power is offline, you should save all information and power down any non critical systems until main power can be restored. This will allow your primary computers/services to use that power for any extra bit of time saved.
So I guess you would say that this statement given is true.
Cheers.