Wood pellet is a solid fuel that is produced by crushing and densifying waste timber like sawdust, forestry residues, industrial byproducts like old paper and forestry wastes. The length is 1-2 cm and the diameter is generally 6, 8, 10, or 12mm. It is possible to produce 25mm wood pellet at maximum. In Sweden, 6mm wood pellet is encouraged to use in house as it can realize the best condition of combustion. Wood pellet production doesn’t need to add binder as lignin, an element of wood, plays a role of binder and helps to pelletize when it is melted by heat.