Quantification of the torrefaction effects on the grindability and the hygroscopicity of wood chips

•Beech wood chips are torrefied in a continuous pilot-scale rotary kiln.•A minimum of hygroscopicity is obtained for a mass loss between 1.7 and 7.4%.•A method is developed to determine accurately the grinding energy requirement.•The surfacic grinding energy is divided by 6.3 between wet and dry chips.•Torrefaction can divide surfacic grinding energy by 8.1 for a mass loss of 25%.