Shutting off your lights is a nice thing to do, but when it come to data center usage, you're talking about 1% or 2% of the total power used, contrast that with half or more for a big box store (less if it's really hot out).
But whether or not you can oblige the utility and shut down some or all of your data center, you'd certainly like to know when a brownout is headed your way. Firing up the generators ahead of time, even if just to test them is good thing to do. And if you don't have generators, knowing that you'll likely be on batteries and possibly have to shut down is even more important to know.
Turns out that, at least in California, the California Independent System Operator has an automated e-mail service to provide just such information.
So I signed up and I'll report here what I get. One odd thing -- in the registration process I was never asked my ZIP code or anything else that would tell the CAISO where I was. I guess that means getting notification just of issues in your area is beyond the CAISO capability.