Softwood pellets

What softwood pellets are

Softwood pellets are made from the wood of coniferous trees — in Central Europe mainly pine and spruce. The typical raw material is sawdust and shavings from sawmills processing softwood. Quality standards do not treat softwood pellets as a separate category: ENplus and the ISO standards describe the raw material by its origin (e.g. stemwood or wood-processing residues — codes according to ISO 17225-1), not by species^[1],[13]. Nor is the wood species one of the mandatory markings on an ENplus bag^[2].

“Softwood” is therefore commercial information, not a quality class. Even so, softwood has several typical characteristics worth knowing — as long as we remember how much bark, contamination and the process can change them.

Softwood properties in figures

The data below describe the wood, not a specific pellet. They do, however, show the starting point from which the producer works.

For comparison: ENplus A1 allows up to 0.70% ash, 0.3% nitrogen, 0.04% sulphur and 0.02% chlorine (dry basis)^[1]. Clean softwood falls well within these limits. VTT points out that the higher calorific value of coniferous species results from their higher content of lignin (A natural polymer in the cell walls of wood; in the pellet it acts as a natural binder.)A natural polymer in the cell walls of wood; in the pellet it acts as a natural binder. and resins^[44].

Advantages and limitations

What speaks for softwood pellets

• Low ash in clean raw material. Debarked softwood sawdust is one of the cleanest raw materials for pellet production — an example from the VTT data is 0.08% ash for pine sawdust^[44].
• A slightly higher calorific value per kilogram. The difference compared with hardwood is, however, only a few per cent: VTT gives 19.31 MJ/kg for pine and approx. 18.6–18.7 MJ/kg for birch (dry basis)^[44].
• Little nitrogen. Pine and spruce contain approx. 0.05% nitrogen, less than birch (0.08–0.1%)^[44].

What the “softwood” label does not guarantee

• Low ash when there is bark in the raw material. Softwood bark typically has approx. 4% ash^[45] — even a small admixture quickly raises the result. More in the article on raw material quality.
• A high ash melting temperature. In the VTT data, the ash deformation temperature of pine sawdust was 1150 °C^[44], whereas ENplus A1 requires at least 1200 °C^[1]. The sample preparation conditions in those studies may have differed from the ENplus procedure (ash prepared at 815 °C), so the figures should not be compared directly — but the example shows that “softwood” does not automatically mean “no clinker”. Testing according to ISO 21404 is what decides^[24].
• Durability and low fines. These parameters depend mainly on the production process — see how wood pellets are made.

Where softwood raw material comes from

In Poland, coniferous stands dominate on 68.8% of the forest area, and pine covers 59.1% of all forests^[48],[49]. In the Czech Republic, conifers make up 54.9% of forests, including spruce at 40.3%^[51]; in Austria, spruce accounts for approx. 49% of commercial forests^[58]; and in Germany, pine and spruce cover 22% and 21% of the forest area respectively^[57]. It is no surprise that softwood is the main raw material of sawmills in the region, and therefore also the source of sawdust for pellet production.

The species mix is changing, however. In Poland, since 2005–2009 the share of pine has fallen by 1.3 percentage points and that of spruce by 1.5 points, while the share of broadleaved species has grown^[48],[49]. In Germany, the area of spruce stands has decreased by 17% since the 2012 inventory^[57]. Details for individual countries are in the wood pellets by country section.

How to assess a specific product

1. Check the class and the certificate — and verify it in the register, not on a copy (see how to do it).
2. Ask for batch test results: ash, moisture content, net calorific value as received, mechanical durability and ash deformation temperature.
3. Ask about the raw material: sawmill sawdust or roundwood, with or without bark.
4. If you are torn between softwood and hardwood pellets, read our comparison and the article on combustion differences.