Pellets can be made from a variety of organic materials, including industrial waste. The most common type of pellets is wood. Typically, wood pellets are made from a combination of sawdust and waste from production or construction. Sawdust, wood chips, and waste are heated and compressed to form pellets. Besides wood pellets, there are alternative heating pellets made from paper or grass.
Since wood pellets remain the most popular option, you can purchase various types. Wood pellets are divided into two categories:
- Softwood Pellets: these pellets produce from 10% to 20% more BTU when burned, meaning they usually have a higher heat output. Softwood pellets also have a lower ash content.
- Hardwood Pellets: due to their higher density, hardwood pellets typically burn longer than softwood pellets. Hardwood pellets from most manufacturers have a much higher ash content than softwood pellets.
Overall, the most significant difference between softwood and hardwood pellets is the rate at which they burn. Besides the type of pellets, the most crucial factor to consider when choosing wood pellets is the quality.
You want to use high-quality pellets to prevent ash buildup in your stove. Premium pellets use higher quality materials, making them a better option. These pellets have an ash content of less than 1%, while standard grade pellets can contain up to 3% ash.
When looking at pellets, it’s very important to see the composition and amount of ash they produce to ensure you get the best pellets for your stove.
How Are Heating Pellets Made for Consumers?
The production of heating pellets can be a lengthy and technical process. Here are the stages of heating pellet production:
- Material Collection: as mentioned earlier, pellets contain a combination of substances. To start producing a renewable energy source, manufacturers obtain large quantities of raw materials and bring them to their facility. The manufacturer then processes the raw materials so that they have consistent moisture content, calorific value, and combustion characteristics.
- Creating Uniform Sizes: pellet mills process materials of various shapes and sizes. However, machines must break down the materials into uniform sizes to ensure consistent calorific value. Large materials, such as wood, are placed in a wood splitter to turn pieces into smaller, uniformly sized pieces. Smaller materials, such as sawdust, are ground to create uniformity.
- Drying Materials: raw materials exposed to moisture may have excess moisture. Excess moisture can lead to poor pellet consolidation, resulting in dust in the final product. Ground materials are passed through large drying drums to align the moisture content of different materials and remove excess water. Ultimately, most wood heating pellets have a moisture content of 5% to 10%. Any moisture level above 10% will result in a poor product.
- Pressing and Forming Wood Fragments: after drying, materials pass through high-pressure dies. This process allows sawdust and other materials to bind through heating. This is a critical step as it determines numerous product characteristics, including density, size, and durability. The manufacturer sets specific settings on their pellet mill to determine what the product will look like after passing through the mill.
- Cooling Pellets: hot pellets can break apart. To preserve them, heating pellets are placed in a cooling tower, like a silo, to harden. The pellets will remain in the hopper to maintain their integrity until they are ready to be unloaded into bags and distributed.
- Bagging Pellets: the manufacturer bags the pellets when they are ready for distribution. Pellets are typically shipped in 40-pound bags. Once bagged, the manufacturer must store the pellets in a temperature-controlled area to ensure the pellets do not acquire moisture and spoil the quality of the product.