I know someone who makes biodiesel to sell, he's on a farm somewhere in North Wales.
There's arguments for and against. You still get emissions of toxic by-products but it's recycled fuel. I am very much in favour of biodiesel but only on a small scale. If it becomes popular enough that people start growing crops just to produce the vegetable oil, it will become unsustainable.
Of course, you can only use it in a diesel engine, and then you need to convert the engine a little I think, but the best kids drive diesels anyway cos it's generally better fuel economy.
What I want to know is, can you convert sound system generators to run on biodiesel?