Pine pellets

Pine as a raw material

Scots pine is Poland’s number one species — by a wide margin: it covers 59.1% of the forest area^[48],[49]. It is no surprise that large volumes of pine wood go to domestic sawmills, and that pine sawdust and shavings are a natural raw material for wood pellets. From the standards’ point of view, pine pellets are not a separate category: they are classified by the origin of the raw material (e.g. stemwood or chemically untreated wood-processing residues), and both these groups are allowed in class ENplus A1^[1].

The species is not a mandatory marking on an ENplus bag^[2], so “pine” is the producer’s declaration. In practice, softwood pellets made from a mix of pine and spruce are also common.

What the data say

In terms of energy, pine comes out best among the species described by VTT — 19.31 MJ/kg on a dry basis, compared with 19.05 MJ/kg for spruce and approx. 18.6–18.7 MJ/kg for birch. VTT links the higher calorific value of coniferous species to their lignin and resin content^[44]. For comparison, FAO gives a typical value for softwood of 19.2 MJ/kg on a dry, ash-free basis^[45].

In terms of chemical purity, debarked pine sawdust is practically a textbook example: very little ash, trace chlorine, little nitrogen^[44]. That is good news for boiler users — less ash to remove and little chlorine, which is one of the fuel components relevant to boiler corrosion^[46].

Ash and ash melting temperature

The caveat mentioned in the introduction concerns how the ash behaves at high temperature. In the VTT data, the ash deformation temperature (DT, in an oxidising atmosphere) was 1150 °C for pine sawdust, 1210 °C for chips from whole pine trees and 1340 °C for pine bark^[44]. ENplus A1 requires at least 1200 °C, with the ash for testing prepared at 815 °C^[1].

The practical conclusion: with pine pellets, as with any others, it is worth asking for the ash deformation temperature result. A small amount of ash eases the problem — there is less material that can fuse — but does not rule it out, especially in burners operating at high temperatures.

Where pine wood comes from

In Poland, pine covers 59.1% of all forests — 61.1% in the State Forests and 55.9% in private forests — and coniferous stands dominate on 68.8% of the forest area^[48],[49]. The share of pine is slowly falling: since 2005–2009 it has dropped by 1.3 percentage points^[49].

Pine is also important in other countries of the region. In Germany, it covers 22% of the forest area and, after the latest inventory, overtook spruce as the most common species^[57]. In Latvia it is dominant on 33% of the forest area^[54], in Estonia on 29.8% of the stand area^[55], and in Lithuania it accounts for approx. 36% of the growing stock^[56].

More on the pages wood pellets from Poland, Germany and Austria and the Baltic states.

How to check pine pellets

Pine pellets have a good starting point but — like any pellets — they are only as good as the specific producer’s raw material and process. A comparison with other types is available in the softwood or hardwood overview.