Wood Pellet Standards

The European standard EN 14961, and its national predecessors (from organisations like the German DIN, Austrian ÖNorm and Swedish SIS), sets out a standard approach for assessing and describing solid biomass fuels, including wood pellets. Almost any solid biomass fuel can be described under EN 14961. That is why it is meaningless to refer to "pellets to EN 14961 standard", and why you should distrust the competence of any supposed expert who suggests such a requirement.

What the standards for wood pellets (and other solid biomass fuels) define

EN 14961 (and its predecessors) sets out ranges of parameters that are useful to judge how various types of solid biomass fuel should perform (a different set of parameters for each type of fuel, though with many parameters in common). It also indicates the tests (each with their own European standard) that should be used in order to ensure that you are comparing like with like (to avoid people cheating by using a more lenient test to achieve a misleadingly good result for a given parameter). And it refers to sampling techniques (also with their own European standards) that should be used to ensure that (so far as possible) the fuel being tested is a representative sample of the fuel to be supplied.

How wood pellets are described according to the European standard (EN 14961)

EN 14961 sets out in tabular form the parameters that are most relevant to the assessment of the suitability of wood pellets (and other fuels), and also provides a shorthand way of referring to this information. For instance, the diameter, calorific value (i.e. energy content), and moisture content are some important characteristics of wood pellets. These could be set out (along with many other parameters) as one line each in a table, showing the value achieved, the units in which that value is stated, and the testing methodology used to determine that value. Or they can be set out in a short series of letters and numbers.

So an Energy content (E) of at least 4.7 kWh/kg net calorific value (CV) calculated on an "as received" (aka "wet") basis according to the testing methodology set out in EN14918 can have that information set out fully on a line of a table, or it can be condensed into E4.7 in shorthand. If the Diameter (D) of the wood pellets is 6mm (give or take no more than 1mm), this is expressed as D06 (and carries implications for the associated acceptable length, according to EN 14961). A Moisture content (M) of no more than 10% on an "as received" basis tested according to EN14774-1 or EN14774-2 is expressed M10. And so on. Consequently, you may see a certain quality of wood pellet described as D06 M10 E4.7 etc.

Parameters within the standards describe a range, not a measurement

It is important to notice that the classification described in the previous paragraph is not attempting to describe the precise measurements, but the range within which one can be confident that the pellets' parameters will fall. An E4.7 pellet may have a net CV (wet basis) of 4.8 kWh/kg. E4.7 is simply saying that the pellets will have a net CV of at least 4.7 kWh/kg. Pellets with a higher energy-content (within reason) are assumed to be perfectly satisfactory to someone needing pellets with an energy content of 4.7 kWh/kg. Moisture works in the other direction, because dryer is assumed to be better. So M10 means no more than 10% moisture content. M10 could refer to a pellet with 6% moisture content.

This distinction between the actual content and the acceptable range is the distinction between the analysis and the specification of a particular load of wood pellets.