Birch pellets

Birch as a raw material

Birch is a common broadleaved tree, particularly important in the forests of the Baltic states. Its wood is light-coloured and relatively uniform. Both by-products of birch processing and stemwood can be used for pellet production. Both raw-material groups — chemically untreated wood-processing residues and stemwood — are allowed in class ENplus A1^[1].

Birch may be the sole raw material or one component of a blend. The species is not a mandatory marking on an ENplus bag^[2], so the raw-material composition has to be established with the producer or the seller.

Birch, pine and spruce in figures

The Finnish VTT study contains measurements for downy birch, pine and spruce, which makes it possible to compare a hardwood species with softwoods on the same basis.

The values as received — even for birch — are above the ENplus minimum of 16.5 MJ/kg^[1], although with a smaller margin. VTT attributes the advantage of coniferous species to their higher lignin and resin content^[44]. The bark is an interesting detail: in these measurements, birch bark had the least ash of the three species. This does not change VTT’s general conclusion that hardwood species contain more ash than softwoods^[44], nor the fact that bark always contains many times more ash than wood.

What this means in practice

Calorific value: there is a difference, but it is small

The difference between birch and pine on a dry basis is approx. 0.6–0.7 MJ/kg, or 3–4%. For comparison: if the same pellets have a moisture content of 6% instead of 9%, their net calorific value as received rises by approx. 0.6 MJ/kg — an editorial calculation using the VTT formula^[44]. The moisture content of a specific batch can therefore matter as much as the species. See the article on moisture content and the calculator in the calculators section.

Nitrogen: higher, but with a margin

Birch contains roughly twice as much nitrogen as pine and spruce (0.08–0.1% versus approx. 0.05%)^[44]. Nitrogen translates into nitrogen oxide emissions, which is why ENplus limits it to 0.3% in class A1^[1] — clean birch wood falls well within this limit. More on the chlorine, sulphur, nitrogen page.

Where birch wood comes from

Birch is one of the main species in the Baltic states. In Latvia it is dominant on 30% of the forest area^[54], in Estonia on 29.9% of the stand area — slightly more than pine^[55], and in Lithuania it accounts for approx. 16% of the growing stock^[56]. Birch also grows in the forests of Poland and other countries of the region. More on the Baltic market on the Baltic states page.

FAO notes that the typical values for hardwood as a group are approx. 0.3% ash and 19.0 MJ/kg on a dry, ash-free basis^[45] — the VTT birch measurements fit this picture well.

How to check birch pellets