People often wonder which kind of raw materials to choose when buying the wood pellets. Usually they think that hardwood pellets are better than the softwood pellets.
Hard wood is wood from angiosperm trees which includes many different species of trees. According their density, hardwoods can be divided into medium heavy, heavy and very heavy. Woods like birch, beech, poplar, yew, hard maple, elm, cottonwood are all belongs to hardwoods. Commonly, hardwoods are with a lower moisture content, denser than softwood and can burns longer. While softwood is wood from gymnosperm, featured with easy lighting and more ashes. Pine, redwood, cedar, firs, spruce are all softwoods. So the thought hardwood is better than softwood when used as firewood is true when it comes to cordwood, but when it comes to wood pellets, things are all different.
The truth is that wood pellet mill quality is more important than the species.
Hardwood logs generally are drier, denser and longer burning than softwood logs. However, when making a pellet, the sawdust or wood chips are dried to a consisted moisture level about 10 to15%. And also in the pelletizing process, the heat and the pressure has changed the structure and density of the wood logs, so with same weight , the wood pellets can burn equal time whether the raw materials are hardwood or softwood.
While some people still think that hardwood pellet is superior to softwood pellets for hardwood burns cleaner. But the fact is that the ash content determines the cleanness of the wood pellet not the species. According statistics, some hardwoods have more ash content. And in addition, the cleanliness of the raw materials and the quality of the wood pellet mill will also affect the ash content. The raw materials with no barks and impurities will be with less ash content and burns cleaner. And the quality of the wood pellet mill decides how well the wood pellet be made, high quality raw materials with poor pelletizing process will generate low quality wood pellets.
In a word, what really matters is the quality of the wood pellet not the specifies of wood. High quality wood pellets can be made from both the hardwood and the softwood.