Fuel pellets are a relatively new form of energy. Pellets have traditionally mainly being used for animal feed. Both fuel pellets and feed pellets have similar properties. Both fuel pellet and feed pellets are made from a compressed milled raw material. Fuel pellets can be made from different raw materials; collectively these materials are referred to as biomass. There are many different types of biomass pellets, for example biomass pellets could be made from straw, such as barley straw and wheat straw. Many grasses are also being considered for biomass fuel pellets, this includes reed canary grass and switchgrass. Hemp also has a huge potential in the future for biomass fuel pellets, went burnt hemp pellets produce very little ash similar to premium wood pellets.
Wood pellets of a certain standard are referred to as premium wood pellets. Premium wood pellets are the most popular type of wood pellet used in the US and Europe. Both hardwoods and softwoods are used in the production of premium wood pellets. Usually the pellets are made from the waste of wood processing. So it is common for wood pellet plants to be setup next to sawmills. For example Canada has very little premium wood pellet consumption, however their premium wood pellet production is as high as Sweden, the worlds largest user and producer of premium wood pellets. For a wood pellet to be called a premium wood pellet it must have certain qualities. It must have very low ash content; in many cases this can be as low as 0.5%. For a premium wood pellet to produce so little ash the raw material must contain very little or no bark. The moisture content of a premium wood pellet must also be very low, this generally means below 10%, however many premium wood pellets are much lower. The density of a premium wood pellet is also very important. It must hold together well, and break cleanly producing few fines. Fines, which are pellet dust, must also be kept below a certain level. Excessive fines can cause issues with the auger system in the pellet stove or boiler, and also combustion efficiency is reduced meaning less heat and more ash is produced.
Premium wood pellets have benefits with efficient burning and low maintenance. The high density and very low moisture content of the premium wood pellet means a very high efficiency burn. Some wood pellet stoves are rated a being 99% efficient. This means as much heat as possible is extracted from the premium wood pellets and very little if any smoke can be seen exiting the chimney. The low ash content means the user will only have to clean the stove and empty the ashbin at most every few days. Some pellet stoves and boilers have very large ashbins and some have ash compression systems. Large ashbins and ash compression means stoves and boilers can operate from tens to hundreds of hours without attention.
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