Ace: We are not producing anywhere near enough cooking oil to fuel the entire United States. Yes Diesel engines can run on it, but it is less efficient than using actual diesel fuel. And if everyone did so, I know that I alone would need 10 to 15 gallons of it a week, just to go to and from work. Now multiply that by 300,000,000 and you need one huge supply. (There are 300 million people in the USA) That oil has to come from somewhere, and we are not producing that much of it now. No where near that much.
What I posted about people starving really did happen in Africa and a few other countries. This is a problem with a lot of new technologies, sometimes people don't think about the side effects.
I do agree that some people should do this, so that we don't just throw that oil away, but not all of us can. It just won't work.