I followed a mate’s Landcruiser Diesel into the tennis club the other day, to be greeted by the overwhelming smell of fish oil coming from the exhaust.
He told me that he was running it on recovered cooking oil from the local restaurants and clubs- he works at the municipal refuse dump, so it’s free (at present).
There’s a thriving collection industry springing up to collect this oil, he tells me.
Now those clever Americans are marketing a lubricating engine oil made from rendering down beef tallow- an animal fat, not vegetable nor mineral from the ground,
Each cow contributes 90 kg of tallow fat to the process. I wonder where the energy to render it down (by boiling) comes from -oil, coal, natural gas or animal fat?