To get into the alternate fuel source argument I'd like to make two points.

1. The article assumes the use of virgin vegetable oil. When used oil is factored in the production cost of the oil drops because the oil would have been produced anyway. Its sorta like recycling aluminum cans, it keeps the price af aluminum down.

2. There is an even more attractive and proven source of diesel fuel. Some time ago the South Africans developed a process for turning methane (natural gas) into diesel.
The end product is free of contaminants and thus significantly less polluting. With Oil at $25 per barrel this process could not compete but with oil at current prices it may become a very viable source. The USA has proven reserves of natural gas to last 200 years.