Wood pellet standards

Standards are commercially important in that they establish a common ground of expectation for producers, suppliers, installers and consumers. Many commercial and domestic wood pellet boilers currently installed in the UK have been sold with warranties which stipulate that only fuel of a specified standard can be used to fire them. In practice this often means that only pellets made from virgin sawdust, with no bark and without any form of chemical treatment, can be used in these boilers without a risk of the warranty being invalidated.

Legacy standards (now obsolete in the EU)

Historically, a range of individual national technical standards have been developed or adopted within countries and regions where wood fuel is used significantly. Examples include the Austrian ÖNORM M1735 and German DIN 51731 standards, among others. These legacy standards have been refined over many years, with the object of ensuring that a consistent fuel quality is produced which both burns efficiently and does not produce harmful residues and emissions which could damage appliances and affect environmental air quality.

Replacement European standards

For some years the European Committee for Standardisation, CEN, has developed and refined a weighty suite of interrelated technical standards (TS) for solid biomass – including wood pellets - to define the terminology, specification, fuel quality assurance framework, sampling methods and test procedures associated with wood pellet production. Whilst in development these have been referred to as CEN/TS; from 2010 they have been adopted and published and upgraded to Euro Norms (EN), replacing all other national standards across the EU. Since the publication of the UK Biomass Strategy by DEFRA in 2007 the CEN standards have been accepted as the UK standards for wood fuel. It is expected that BSI will publish a mirrored version of the EN standards, designated as BS EN. They are also expected to form the basis for new international standards, under the aegis of the ISO.

Standards in the context of fuel quality assurance

In the UK’s nascent wood fuel pellet market much of the early focus was centred on the draft CEN/TS 14961 fuel specification as an indicator of pellet quality. But this specification alone is not enough: for specified parameters to be relevant it is important that there is a standard way of measuring them to ensure they can be reproduced without ambiguity. There is currently a list of over twenty additional CEN technical standards that define terminology, fuel quality assurance, sampling and measurement of parameters. In short, pellet production is expected to be undertaken within the framework of a fuel quality assurance process (EN 15234) and pellets sampled and analysed on a regular basis (EN 14780 etc.) to ensure conformance with technical specifications (EN 14961). Moves are currently underway in the industry to establish a common wood pellet quality assurance certification scheme, complete with a distinct brand identity, which will serve to reassure users that the pellets they buy meet the required standards.

What EN 14961 indicates

The latest version of EN 14961 has been split into multiple parts, to address different aspects of solid bio-fuel production, these include: -

EN 14961-1, covering all solid bio-fuels and aimed at all user groups (but will probably be used mainly for industrial applications)
EN 14961-2 covering wood pellets for non industrial use (i.e. fuel for smaller appliances for domestic, small commercial and public sector building installation)

Additionally the EN14961-2 specification is sub-divided into three quality classes: -

A1 - covering pellets manufactured from virgin timber and chemically untreated wood residues low in ash, nitrogen and chlorine
A2 - as for A1 but with slightly higher ash, nitrogen and chlorine levels allowed
B - covering pellets containing some proportion of chemically treated and used wood with heavy metal content below specified threshold levels

These three classes can be expected to roughly correspond to wood pellets originating from: -

Virgin sawdust from the stemwood (bark removed) or untreated timber (EN 14961-2 A1)
Whole tree chippings, including bark (EN 14961-2 A2)
Recycled wood (EN 14961-2 B)

Duffield wood pellets are manufactured from virgin timber, with no additives, to conform to EN 14961-2 (A1) grade pellets.

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.

Quality assurance schemes:

Schemes such as EN Plus, DIN++, SBAS and Woodsure differ from standards in that they are generally commercially driven accreditation schemes, often adopted by industry bodies with the aim of achieving 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 control activities in preparation for accreditation assessment.

EN 14961 standard specifications

EN 14961 specifies a list of testable parameters which, in conjunction with a framework of quality assurance procedures and regular sampling and analysis, can be used to indicate the suitability of pellets for their intended use... read more

Your local regional supplier...

...for biomass fuel: -