Um, I assumed the sawdust would be the waste product from, say, a sawmill. And, that there might be some opportunity cost (assuming that sawdust is already being used for something else, and not simply discarded).
Why not just grow that crack grass or whatever that one kind of grass is that is grown for burning?
Switch grass. Someone also mentioned hemp.
Do we boil it, no no noooo no, Do we bake it, no no nooo no, do we smoke it, ya ya yaaa ya.