Wood pellets are the most common form of pellet fuel, created usually from compacted sawdust or related industrial waste from lumber milling, forestry operations or manufacturing furniture or other wood products. Under proper management, wood pellet fuels can be carbon-neutral, which makes it a popular alternative to coal and other fossil fuels in generating energy.
There are two main uses for wood pellets: for heating and for thermal power generation. While the former is currently the more popular use for wood pellets, due to its benefits to the environment compared to other types of fuels like heating oils, the latter is steadily growing into one of the biggest markets for renewable energy across the world. As these two types of wood pellets serve very different purposes, they have very different characteristics as listed below:
Heating pellets: While sharing the same manufacturing process as pellet biofuel, the very delicate nature of pellet stoves and boilers means that the technical requirements for heating pellets are much more stringent. This includes low ash content, high ash melting temperature, precise size and moisture contents, etc. This means that the manufacturing processes will be limited in terms of raw materials, and has very strict requirements in terms of equipment in order to fulfill the said pellet standard. The general certification body is ENplus, with A1 certified wood pellets being widely accepted as pellet boiler fuel.
Pellet biofuel: Wood pellets used in thermal power generation don’t share the same stringent requirements that heating fuels have since they are used in industrial size power generators, which does not need pellets to be perfected to generate energy. With that being said, quality control is still needed for pellet biofuel, as it could affect the amount of energy released per unit mass of the pellets.
Another matter for consideration is how the raw materials for pellets are harvested, as manufacturers will most likely be cutting down trees in a large scale in order to satisfy its demands. This means that hundreds and thousands of hectares of forests may be lost if not managed carefully, which defeats the purpose of wood pellets being a renewable source of energy, both for heating and for being used as a source of biofuel. Many countries around the world have started adopting sustainability requirements for imported pellets, in which the most commonly used certification is FSC (Forest Stewardship Certification) which proves that forest products came from responsibly managed forest areas.