Characteristics: Pellets are fibrous materials compressed at high pressures either bound by its own material or a binding agent added to it. Material bars ranging from a few millimetres to several centimetres are extruded from the raw material, depending on the applied pelletising technology. As energy carriers, mostly plane chips and sawdust generated in the wood processing industry are used for pelletising. Wood pellet is of high calorific value, easy to store and to transport, it is a clean fuel in comparison to fossil fuels and also of a more favourable price.
- calorific value: approximately 18.5 MJ/kg
- ash content: 0.5-1%
- approximately 650 kg/cubic metre
Heating using pellets are more environmentally friendly than burning wood as it uses recycled material. The moisture content of the pellet is about 10% in comparison to the wood’s 40%, its efficiency is therefore better. Their combustion takes place in so-called pellet boilers; each system is fitted with a fuel tank, a burner and a purpose-designed heat exchanger. Their fuel forwarding system mostly resembles that of carborobots. The flame leaving the burner of a wood pellet boiler is of a temperature around 800-1000 °C. Therefore it can be established, that the system’s efficiency is 90%. A household pellet tank’s capacity is around 1 cubic metre. After combustion, about 0,5 – 1 kg cinder substance is generated, depending on the quality, which falls on the cinder tray of the boiler.