the name 'cetane' for that molecule is a nod to the whaling industry, the original source of those lovely biological oils. palmitic acid is the corresponding 16-carbon acid ... they are not merely from whales and palm nuts, these oils are widespread in nature.
the biggest objection to using e.g. olive oil to power your car is that bio-oils contain other gunk that clogs pumps and plumbing, and encourages the growth of oil-loving bacteria and fungi. diesel injectors squirt the oil thru near-microscopic holes into the combustion chamber, can be fouled by small particles, and are hard to clean.
(and of course, that is why used cooking oil is transesterified to make biodiesel, even though it would sort-of work without modification)