Dad tried that and since hatching eggs wasn't his business, but a hobby, they wouldn't help.
However, you can hire generators, and it might well be worth it for just that day. I'd get in quick though, since there'll be quite a demand for them! Or Aldi/Argos etc sell them - I've got an Aldi one which does the job, as we get plenty of power cuts and I'm always worried it will be when I've got some small creatures under a heat lamp.