Assessment of size reduction as a preliminary step in the production of ethanol from lignocellulosic wastes

Abstract Comminution, an energy-intensive operation, is required in order to obtain adequate yields of ethanol from lignocellulosics. Energy consumption was quantified for size reduction of hardwoods and agricultural wastes as a function of final particle size and ratio of comminution. Main conclusions include better qualifications for knife mills, and variations of the non-linear relationship between energy input and final particle size, depending on each combination of raw material and equipment. It is proposed that energy input for comminution, in a multiple feedstock process plant, can be kept below 30 kWh per tonne of wastes, provided final particle size is held in the range 3–6 mm.