The impurities and all of that could be sorted out - but if you are making bio-diesel from soy and corn and stuff, you are still using a ton of fertilizer and the economics are similar to ethanol. It just does not work on a large scale.

Also, as for using fry oil and rendered fat - sure it can be made into "bio diesel", but it never be more than a drop in the bucket of our energy needs.

Besides, most of that was never thrown away anyway. It was re-refined and used in chicken feed and chemical feed stocks. If we use it for fuel, it only will be replaced by other oils and fats.. Kind of a zero-sum game. But hey, Ford F-250s and old Benzes that smell like Chinese take-out are fun - and I guess get people thinking...

Yeah, all that you write has me thinking -- of becoming vegetarian. :eek:

guess the new bio-fuel will have to be Soylent Green

Yea! Less humans! Always a good thing! SmileWavy