Pellets are produced by extruding raw sawdust through a dye. The energy produced in the process causes the natural lignin in the wood to melt forming a solid shiny outer coating. Some manufacturers also add starch or other lingo-based materials. To manufacture pellets successfully, the raw sawdust has to have the correct particle size distribution, usually 3-5mm. This is achieved by passing the raw material through a hammer mill and recycling the heavier fractions. Pellets can be manufactured from a number of wood sources, generally however most pellets are manufactured direct from sawdust produced as a by-product of the saw milling industry. Pellets mills are very large and are usually financed and operated by large companies and energy utilities.
Find out more about pellet Quality Standards and why they are important (hyperlink to Wood fuel quality standards and certification
Pellets contain more energy per cubic metre than chips; and this means they can be used in sites where there are space constraints in terms of fuel storage. Typically this means smaller and domestic applications are well suited to pellets.
When using pellets the design of the silo and the method of bulk blown delivery should be carefully considered to reduce the accumulation of dust and reduce the scope for pellets to breakdown in transport, handling or storage.