The effect of particle size and thermal pre-treatment on the methane yield of four agricultural by-products

► We analyze the methane production of four ligno-cellulosic agricultural by-products. ► We pretreated the biomasses to increase the methane yield. ► Pre-treatments employed are easily reproducible in a biogas plant. ► The pre-treatments used affected positively the methane yield of some by-products. ► The electrical energy balance resulted positive for all pre-treatments.