Understanding Wood Pellets
It is generally agreed that pellet stoves are less polluting than other sources of home heating. One of the reasons given is that they are made from wood shavings and chips, sawdust, shells of nuts, tree bark, corn, grain, and even recycled paper and cardboard, or any combination of these materials. These are all renewable and, as far as the wood chips and shavings are concerned, they might otherwise be thrown into the landfills.
Since, however, the composition and structure of a wood chip is different from the shell of a nut, or even from a tree bark, not to mention the differences among the different varieties of wood, logic dictates that they would also burn differently. This implies that not all wood pellets produce the same amount of heat, emit the same volume of carbon dioxide, or leave the same quantity of ash.
What, then, makes a good wood pellet? What materials should they be made of?
From the name alone, it should be easy to conclude that the best wood pellets are those that are made purely of wood –no paper, cardboard, grains, not even tree bark. Wood pellets should be made of wood. These produce the most heat and least ash. You can easily tell if pellets contain materials other than wood by smelling them. If there is any odor other than a fresh wood scent, then you have reason to believe that there are other materials in the pellet.
Recycled paper and cardboard incorporated in pellets often also include ink, glue, and even paint that reduce the pellet stove’s heating efficiency, and contribute to ash buildup. Corn pellets may, in some places at least, be cheaper than wood pellets but they leave substantially more ash.
Not even pellets made purely of softwood and hardwood will produce the same amount of heat. Sometimes you will find pellets labeled “Premium” because they are made of hardwood with a corresponding premium in price. This is an instance, however, when the higher price does not necessarily mean better performance. The premium paid is only because of the higher cost of processing hardwoods. The reality is that softwoods perform better than hardwoods, producing more heat and less ash. Indeed, a study by the wood industry reveals that white oak rates a heat output of 8,810 BTU per pound, while yellow pine rates higher at 9,610 BTU per pound.