Yes, I know it's not technically just methane, but methane is its primary constituent.
"Fossil gas" is also probably a suitable term, but I like "fossil methane" because it gets that spooky chemical name benefit.
Commercial kitchens want to flambe and all that stuff that normal people don't do. This was about "wild fluctuations" that you claim. There are no "wild fluctuations". They are so minor that I have to be informed academically that they even exist.
Ah you're emotionally invested in this, that explains it. Cheers.