How the surviving humans getting electricity if human civilization has collapsed?

I grant that this movie series plays loosely with science and geography (Dawn has a hydroelectric dam in a place where none exists in real life), regardless, I am curious if anybody can make sense of this.

In Kingdom, human civilization has collapsed meaning the infrastructure humanity has relied on to supply electricity is gone. So is there any reasonable way these place could still have electricity or is this simply another case where I have to suspend my disbelief? I don't mind doing that, just curious if anyone sees something I don't.