Broodies that have mind farts are why I have an incubator in the first place. Unfortunately broodies are pea-brained, simple critters and they up and decide to abandon nests, break eggs or do something else dumb that means a human has to take over or lose the hatch.
And while a good broody is a great thing, you can't make them broody when you want to hatch eggs.
So I can totally see the use for alternative fuel bators.
Yes. I have used hot water bottles before I had a bator. That can sometimes last long enough. Heated rocks and towels, even. (Never heat a wet or creek rock. BANG when the water expands.)
I've had broodies that can handle 10-12 eggs at a time. I've had them also QUIT without warning on the same number.
I was using my incubator to "rescue" badly brooded eggs long before I used it to hatch as a primary source.
So yeah Kerosene or alternative fuels make a lot of sense. I've lost chicks and eggs to power outtages before.