Proser said
I'd guess anyone who can reliably get fuel for them would be able to use generators for electrical stuff, too. Cool, I was just trying to get a good idea of what people are working with since it's not like all of humanity's been knocked back to the Paleolithic by the looks of things.
The havens we've visited have largely been fortunate and had time to establish themselves. It's sort of the blessing of a haven, these luxuries, and the potential to create wind-farms or gather solar energy using naturally heating water and the like. These places also have governance that may restrict or commodify such resources too, though. You start getting into the curses of havens in this area and, of course, there's more too that may make the living situation less enticing.
Out of havens, power is probably way less likely in force. Groups like the 1007th and Legion probably have solutions for this, likely using alternates like oil collected from animals or otherwise. A big thing to consider is that this is a world where all the past discoveries were at peoples' fingertips just 5 years ago. You might not remember the exact recipe for something you got off google, but you probably remember enough to give you a quick head start. Plus, you know it exists, unlike the original creators who were likely dabbling and hoping.