Knowledge base
Everything worth knowing about wood pellets — from raw material to ash
Articles written so that any boiler owner can follow them, yet rigorous enough for installers, boiler-house managers and producers. Every figure has a source.
The basics
What wood pellets are, how they are made, what raw material they come from and why its quality matters.
- 01
What are wood pellets?
Wood pellets are a wood fuel, but they are not simply “bits of wood”. They are an industrial product with standardised dimensions and properties — which is exactly why they can be measured and compared.
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How wood pellets are made
The same sawdust can make very good or very poor wood pellets. The difference lies in the process — drying, milling, pressing, cooling and screening — and, at the end, in the quality control that confirms it.
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Raw material for wood pellet production
Wood pellets are only as good as the wood they are made from. The standards do not specify the species, but they describe very precisely which part of the tree and which source the raw material in each class may come from.
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Raw material quality and wood pellet quality
Even the best production line cannot remove from wood pellets what the raw material brought in. Bark, sand and leaves stay in the fuel and come back as ash — sometimes in the form of hard clinker.
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Types of pellets
Softwood, hardwood and mixed — without the myths, with the parameters.
- 05
Softwood pellets
Pine and spruce dominate the forests of Poland and its neighbours, so softwood is the natural raw material for local sawmills and pellet producers. It has some real advantages, but the “softwood” label on its own guarantees nothing.
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Hardwood pellets
Hardwood pellets have gathered quite a few beliefs — that they are “premium”, that they burn longer, or that they leave too much ash. The data paint a less clear-cut picture: there are differences compared with softwood, but they are smaller than the influence of the raw material and the process.
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Mixed wood pellets
Mixed wood pellets are sometimes seen as a compromise or a “lower grade”. Yet their quality is decided not by the fact of mixing, but by whether the proportions and the quality of the components are consistent.
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Wood species
Spruce, pine, beech, oak and birch as raw materials for pellet production.
- 08
Spruce pellets
Spruce is one of the main species in Central European forests and a common raw material for pellets from the Czech Republic, Austria and Germany. Its wood has good fuel properties — but the quality of a specific pellet is decided by something other than the name of the species.
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Pine pellets
Pine covers more than half of Poland’s forests, so for many buyers pine pellets are a fuel “from next door”. Pine wood has very good fuel properties — with one caveat that is rarely mentioned.
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Beech pellets
Beech pellets are often sold as a “premium” fuel. Beech is a good raw material — but the name of the species on its own says nothing about the ash, moisture content or durability of a particular bag.
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Oak pellets
Oak is associated with hard, heavy, high-quality timber, so “oak pellets” sounds solid. But the hardness of solid wood does not carry over directly into pellet quality — and there are fewer data on oak as a fuel than the marketing suggests.
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Birch pellets
Birch is the best-documented hardwood species in the sources this site relies on — with measurements of calorific value, nitrogen and bark ash. This makes it possible to show honestly how hardwood differs from softwood — and how small those differences are.
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Combustion and properties
How wood pellets behave in the boiler and what determines their durability.
- 13
Differences in how wood pellets burn
Same boiler, same settings, different pellets — and suddenly there is more ash, unburnt fuel or clinker. We explain where the differences come from and how to read the symptoms in the burner.
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The role of natural resins and lignin in wood pellets
Lignin is the natural binder in wood pellets, and resins and other extractives are one of the reasons why softwood has a slightly higher calorific value. We separate the facts from popular opinion.
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Pellet hardness and mechanical durability
“Hard pellets” is an everyday expression. The standards speak of mechanical durability — and that is what decides how much dust you will find at the bottom of the bag after transport.
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Next
Knowledge is the foundation. Figures are the proof.
See how to read quality parameters and compare them with the requirements of the ENplus classes.