Pellets are divided into three main categories. Woodpellets are made of 100% wood, Biopellets are made of energy plants and Agropellets are made of agricultural residues. Besides the basic types, there are pellets made of various mixtures in the market.
The top quality pellets are Woodpellets and their price depends on the tree species. The top quality trees are: Beech, Oak, Fir, Pine etc.
According to the specifications of the new standard ENplus A1 the wood pellets should contain a maximum of 1% powder.
The new European standard for solid biomass fuels came into force in 2011. This standard, following the general standard EN14961-1, is EN14961-2 "Solid biofuels - Fuel and classes specifications".
Pellet recycling table
They are are used in stoves and pellet boilers as fuel for heating.
Be aware that in a stove or a pellet boiler, which consumes brown pellets, 12-20% more scale is generated in the exhaust gas pipes. This disadvantage is particularly visible in pellet stoves because the front glass blackens within a very short time. Regarding the boilers, you will see the problem in the operation and cleaning. A boiler with the white pellets will operate without interruption and the ashes will be clean. In case of using brown pellets, the boiler will be damaged very often and while cleaning it from the ash you will find pieces like hard caramel crust. This crust is silicon and is formed from trash that have pellets of very poor quality.
Important quality criteria, such as e.g. low ash and powder content (chips), the high point of ash melting etc., are crucial fuel characteristics for the efficient combustion of the boiler.
All pellet boiler manufacturers indicate that, when the pellets are of poor quality, the boiler`s life is shortened, it has a problem in the smooth operation with frequent failures and, most importantly, no warranty applies when there is damage caused by poor quality of the pellets.