Using process simulation for material flow and energy analysis gives a good insight into the possibilities of a combined ethanol and methane production. A description of the overall process, including all assumptions for simulation, serves as basis for mass and energy balances. It is shown that approximately 650 000 t a(-1) straw (90% dry matter, DM) or 870 000 t a(-1) spruce (45% DM) is needed to produce 100 000 t of ethanol per year. Straws biogas yield accounts for 84.5 . 10(6)Nm(3)a(-1), which is many times more than the 22.5 . 10(6)Nm(3)a(-1) obtained by spruce. An energetic analysis is used to calculate the respective efficiency of the two process options whereas straw results in a slightly better value than spruce.