Posted: 11/06/2012 at 14:20
My Husband makes biodiesel from used cooking fat. We get the fat free from a local school my sister-in-law works in. A basic biodiesel machine will cost around £500, plus there's the extra chemicals you need (and some of them are pretty nasty). It does take time, but it's in half-hour chunks, you start one stage of the reaction and then leave the machine to get on with it.
My 'gas-guzzling' land rover runs on this stuff, it costs around 15p a litre to make, my car is over voting age so hasn't gone to landfill, and we're stopping LOTS of oil going to land fill too. Yet my car is still targeted by hippy types that quite happily drive Priuses which run on COAL (well, the leccy has to come from somewhere), and the batteries are made of all sorts of bad stuff. Sorry, went a bit off topic there, but it's a bit of a thing with us, we're a land rover mad family.
So it's possible to make biodiesel, but the outlay is a bit steep, and you need to know someone that already makes homebrew biodiesel, as it's a steep learning curve. You also need an oldish car, as some of the things that are left in biodiesel (even after washing) can corrode the pipes an electronic fuel pumps don't like it. If like me you've got an old, beloved car, it's fantastic!
You can already buy heaters that run on used engine oil, have you looked into these, as I suspect they would also run on veg oil, or if you've a local garage, they might be able to give you a supply, as it costs them a lot to dispose of it at the council.
Hope this helps!