The production of biofuels also involves fossil fuels in multiple ways. It starts with nitrogen fertilizers made from fossil gas. Refinery processes like hydrogenation use Hydrogen, and that is, these days, by and large also made from fossil gas. (Hydrogenated Vegetable Oil, or HVO, a common type of biofuel, even has this in its name.)
oh wow, i had never thought where the hydrogen comes from til this para