I thought the idea was to make ethanol from the cellulose, not from the oil? (In corn, it's the sugar you use.) Plants have a lot more cellulose than sugar, so if you can utilize it for making ethanol, you tap a much larger potential source.
Cellulose is a horribly difficult material to do anything at all with. After drying it can be burned to produce heat, and that's pretty much all that's ever been done to it.