A few years back, I met a young guy, in passing, who said that his band travelled in a grease powered van. As they travelled from city to city they would go to fast food places to ask for their discarded grease. (Maybe they were also inspired by Willie. But I sensed that they really needed the free fuel.)
I can’t figure out why this idea hasn’t caught on yet. There’s money to be made in simply buying up the gallons of discarded cooking oil to be converted into fuel. Think of the implications, no more dependence on fossil fuel.