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Why quality matters
You cannot run a car that is designed for gasoline with diesel. If you do so the car will most likely stop working. The same is true for many energy generating devices – if the fuel you feed them does not comply with the design specifications of the device it may stop to work. Of course different appliances can vary in their fuel flexibility – some may accept a wide range of fuel properties, other may need very specific properties.
What applies for conventional fuel also applies for pellets: for a fuel to be successful in the market it needs to have clearly specified properties. For this reason ISO-standards have been introduced and are used worldwide to specify pellet properties. Particularly when international trade of pellets is involved, the compliance of pellet quality with specific standards is indispensable.
At the moment most traded pellets are based on wood as raw material. For this reason at present clearly specified quality classes only exist for wood pellets. These quality classes are defined in the ISO-standard 17225. This standard specifies 3 quality classes for wood pellets that are used in domestic applications (A1, A2, B) – and 3 pellet quality classes that are used in mainly in power plants (I1, I2, I3), . The quality classes differ with respect to the type of woody raw material that is used, with respect to the physical properties of pellets and with respect to the chemical properties.