I would not say biokerosine will never be used in the long term. They are pricey because the production capability are small and projects are still in R&D. I would not be surprised if in 15-20 years they become widely available along with electric cars.

Moreover, about frying oil, the food industry is using a lot of it and don't know how to recycle them. That is a way to do it. And from 2012, airlines will have to pay for their CO2 emissions. The use of frying oil, garbage oil, etc... is not counted towards this tax.

It is funny to think you fly thanks to all the fries you ate. You don't have to feel guilty anymore.