Ok, just a misunderstanding.

I agree, the market of used frying oil is small and will never be big enough for the airline industry!
One of the problem with biofuel is when it uses crops "not to feed the poor but to let rich people fly, drive their car, etc."
The good point here is that KL will use used oil. I don't know what LH will use.

Moreover, this kind of annoucement is always in a PR plan to improve the company's image