What are wood pellets? What are the benefits? Are they renewable? How are they delivered?

EN 14961-2 specification

Under EN 14961-1 a list of testable parameters are specified which are divided into normative (declaration required) and informative (declaration optional) types. However, under EN 14961-2 all specified parameters are normative. These include: -

Origin and source:

EN 14961 offers a hierarchical classification structure of codes to identify the origin of wood pellets. For A1 class wood pellets, only stemwood with bark removed (1.1.3) and chemically untreated wood residues (1.2.1) can be specified. Inclusion of bark, other parts of the tree and logging residues would designate the pellets as A2 class and inclusion of chemically treated and recycled wood would result in a B classification.

Dimensions:

Diameter can be 6mm (D06) or 8mm (D08) ±1mm with a length from 3.15 mm to a maximum of 40mm for each of the classes A1, A2 and B.

Moisture:

The moisture content of pellets should be 10% or less (M10) by weight for each of the classes A1, A2 and B. (Ref. EN 14774-2)

Ash:

For A1 class wood pellets, ash should be no more than 0.7% (A0.7) by dry weight. Ash levels of up to 1.5% (A1.5) would designate the pellets as A2 class and ash levels of up to 3.5% (A3.5) would result in a B classification. (Ref. EN 14775)

Mechanical durability:

Pellets should have a mechanical durability greater than 97.5% (DU97.5) by weight for each of the classes A1, A2 and greater than 96.5% (DU96.5) for class B. (Ref. EN 15210-1)

Fines:

The proportion of fines associated with pellets should be 1% or less (M1.0) by weight for each of the classes A1, A2 and B. (Ref. EN 15149-1)

Additives:

The proportion of additives in pellets should be less than 2% by weight for each of the classes A1, A2 and B.

Bulk density:

Pellets should have a bulk density of 600kg/m3 or above (DB600) by weight for each of the classes A1, A2 and B. (Ref. EN 15103)

Net calorific value:

For A1 class pellets, net calorific value should be 4.6kWh/kg or greater (Q4.6). For class A2 this should be 4.5kWh/kg or greater (Q4.5) and for class B this should be 4.4kWh/kg or greater (Q4.4). (Ref. EN 14918)

Nitrogen:

For A1 class pellets, nitrogen content should be 0.3% or less (N0.3) by weight. For class A2 this should be 0.5% or less by weight (N0.5) and for class B this should be 1% or less by weight. (Ref. prEN 15104)

Sulphur:

Pellets should have a sulphur content no greater than 0.03mg/kg (S0.03) by weight for each of the classes A1, A2 and no greater than 0.04mg/kg (S0.04) for class B. (Ref. prEN 15289)

Chlorine:

Pellets should have a chlorine content no greater than 0.02mg/kg (Cl0.02) by weight for each of the classes A1, A2 and no greater than 0.03mg/kg (Cl0.03) for class B. (Ref. prEN 15289)

Arsenic:

Pellets should have an arsenic content no greater than 1mg/kg by weight for each of the classes A1, A2 and B. (Ref. prEN 15297)

Cadmium:

Pellets should have a cadmium content no greater than 0.5mg/kg by weight for each of the classes A1, A2 and B. (Ref. prEN 15297)

Chromium:

Pellets should have a chromium content no greater than 10mg/kg by weight for each of the classes A1, A2 and B. (Ref. prEN 15297)

Copper:

Pellets should have a copper content no greater than 10mg/kg by weight for each of the classes A1, A2 and B. (Ref. prEN 15297)

Lead:

Pellets should have a lead content no greater than 10mg/kg by weight for each of the classes A1, A2 and B. (Ref. prEN 15297)

Mercury:

Pellets should have a mercury content no greater than 0.11mg/kg by weight for each of the classes A1, A2 and B. (Ref. prEN 15297)

Nickel:

Pellets should have a nickel content no greater than 10mg/kg by weight for each of the classes A1, A2 and B. (Ref. prEN 15297)

Zinc:

Pellets should have a zinc content no greater than 100mg/kg by weight for each of the classes A1, A2 and B. (Ref. prEN 15297)

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Standardisation and quality assurance schemes

There can be a level of confusion caused by the comparison of defined technical standards with industry adopted quality assurance schemes.

Technical Standards:

Standards such as the ISO, CEN, ÖNorm and DIN suites, are defined by stardardisation bodies. These are generally international, governmental or government sponsored organisations whose aim is to define a range of technical criteria by which the characteristics of a particular product or service can be legislatively determined.

For an overview of wood pellet standards ... read more

Quality assurance schemes:

Schemes such as EN PLus, DIN++, SBAS and Woodsure differ from standards in that they are generally commercially driven certification schemes, usually promoted by industry bodies whose aim is to achieve a common level of market accepted quality in the delivery of a product or service. It may be that, by weight of industry or market pressure, such schemes effectively become de facto standards within an industry.

At present Duffield Wood Pellets are reviewing the relevant documentation relating to our production and quality assurance activities in preparation for accreditation assessment.

However, customers should be assured that we continue to manufacture our pellets to meet the published European technical specification standard for premium quality wood pellets - the EN 14961-2 A1 grade.

Essentially this indicates that pellets meeting this specification are manufactured from virgin timber and chemically untreated wood residues low in ash, nitrogen and chlorine. Our pellets are analysed on a regular basis to ensure that we continue to deliver the highest quality product to or customers.

image: wood pellets