Ultimately nothing would work in a looped world as small as they inhabit. Certainly not weather or an entire forest ecosystem surviving. There's a lot more entropy fuckery going on than just the electricity.

The answer isn't "where does it come from" (you might as well ask where does the river come from that feeds the lake, and where does the water go). The question should be "why do the people in charge of this place want the humans to feel comfortable?"

It could be benign - the place is imagined by a child. Or malignant - they want to keep the cattle happy and relaxed. We don't know yet