Wood pellets are mainly used as a fuel source for stoves and heating furnaces. But they can also be used as cat litter, horse bedding, or as mulch for your garden.
So, how do they make wood pellets?
In essence, they are made by compressing sawdust and other industrial waste produced from the milling of lumber, furniture production, and construction.
It All Starts With…
A pellet mill.
Pellet mills are the place where all raw material for wood pellets is gathered for further processing. Usually, material that arrives at the mill are sawdust and wood chips, though, sometimes even entire trees are used.
Then, trees and larger parts of wood go through a wood chip. Once everything is small enough, it is sent into the hammer mill. These mills shred the chips into fibers, which is the last step before shaping them into pellets.
The next process that takes place is drying. Because some of the fibers might be highly humid due to rain and other elements, the material goes through large dryer drums, which heat the wood to dry it out much as your clothes dryer would do.
This way, the mills ensure all wood is treated equally so that the end product is uniform and consistent. This is extremely important, and manufacturers aim to keep the same standard in pellet production to burn consistently.
Further Reading: Do Wood Pellets Contain Chemicals
Shaping The Pellets
After drying, the material is processed through high pressure dies that ensure the pellets are bound together into a desired and uniform shape and size. The metal die is actually made out of small holes, and the processed wood fiber is pushed through those holes by a large rotating arm.
Thanks to the fiber’s heating, the material is bound together to create pellets as it is being pushed through the die.
The mill itself determines its pellets’ size, which greatly depends on what the pellets will be used for. As some appliances require a particular pellet size, the pellet’s consistency that leaves the die is vital for a consistent burn and heat.
Pellets shaped and bound are still hot, coming out at over 200 degrees Fahrenheit (93°C). This means they need to be cooled. A cooling tower does this part of the job, which also helps to harden the pellets.
After cooling, wood pellets are stored in a silo, where they await distribution.
Distribution Of Pellets
When pellets are sold in bulk, they are loaded from the silo directly into a truck to distribute them to bulk storage containers.
If they are not sold in bulk, they are packaged into plastic bags and stacked onto pallets or skids. One bag weighs up to 40 pounds, while the entire packed pallet can reach one to one and a half tons of wood pellets.
From there, they are transported by truck or train either to port to be shipped elsewhere for sale or directly to the sellers.
The Pellets Journey
It takes a long time for raw materials to be processed into pellets ready for sale, but it’s a journey that promises sustainable fuel that is better for the environment than coal.