Standards & Technical Specifications

Over the last 20 years a comprehensive suite of standards relating to solid biofuels has been developed at first by the CEN Technical Committee TC335 Solid Biofuels, then by ISO TC238. These standards include many aspects of solid biomass, from terminology to physical and chemical properties. They also include quality requirements for fuel for smaller boilers as well as for quality assurance.

Copyright on standards is strictly enforced, so standards are available only from an official standardization body, which in Ireland is NSAI).

The ISO standards have been produced under the so-called Vienna Agreement, so they become automatically European standards, so they get the designation EN ISO. As such these standards then replace eventual existing European standards, so for example the EN 16964 Solid Biofuels, Requirements and classes has been replaced by the EN ISO 17225.

The development of a standard goes through several steps to ensure that the contents are alright and that a majority of the participating countries in ISO accept the standard. The development follows a strict time schedule. In general, it takes 3 to 4 years to produce a standard.


The steps are called:

  • Working Document (WD). A document which is being prepared by experts within a particular working group. This document is discussed in the working group until consensus is reached. The document is restricted to members of the working group
  • Committee Draft (CD): this is the final version of the working document that goes for ballot to the countries participating in the drafting. The document is not available to the general public.
  • Draft International Standard (DIS): this version goes for ballot to a much wider circle. Comments may be given on the technical content as well as editorial comments. The document is not available to the general public
  • Final Draft International Standard (FDIS). This is a document with the widest circulation in ISO member states. Only editorial comments can be made. It is not available to the general public.
  • EN ISO standard, the published version of standard, available to the general public. It is published in English, French and German and may be translated into the national language by the national standardization body. Where there are disputes; the English version takes precedence.
  • Below is a list of published and upcoming standards within TC335 and TC238 Solid Biofuels. Check the homepage of NSAI if the particular standard you are interested in has already been published.
  • Many of the standards in the EN ISO suite of solid biofuels have been published 5 years ago, which means that they come up for automatic revision. A revision is carried out if the majority of members of the TC vote for that in a ballot.
  • Besides standards there can also be Technical Reports (TR) or Technical Specifications (TS)
  • In the case that a measuring method is not entirely scientifically based, or the method is not used widespread, a Technical Report can be written. Such a TR explains the state of the art and the experiences gained with the method.
  • A Technical Specification is used when the method is more widely accepted, but there is insufficient data or experience with the method. A TS must be revised within 3 to 5 years and either it is then promoted to a standard or the subject is dropped altogether.

ISO and CEN solid biofuel standards status 01-2021

The first list shows all the current standards with the year of publication. The second list shows all the standards that are under development or revision. These will be published within the next few years (the lists were updated in January 2021). For the most recent lists search for ISO TC 238 and CEN TC 335.

Explanation of abbreviations:

EN – European standard; EN ISO – combined world and European standard; TR – Technical report; TS – Technical specification.

Current solid biofuel standards

EN 15234-1:2011 Solid biofuels

Fuel quality assurance – Part 1: General requirements

EN 15234-2:2012 Solid biofuels

Fuel quality assurance – Part 2: Wood pellets for non-industrial use

EN 15234-3:2012 Solid biofuels

Fuel quality assurance – Part 3: Wood briquettes for non-industrial use

EN 15234-4:2012 Solid biofuels

Fuel quality assurance – Part 4: Woodchips for non-industrial use

EN 15234-5:2012 Solid biofuels

Fuel quality assurance – Part 5: Firewood for non-industrial use

EN 15234-6:2012 Solid biofuels

Fuel quality assurance – Part 6: Non-woody pellets for non-industrial use CEN/TR 15569:2009 Solid biofuels – A guide for a quality assurance system

EN ISO 14780:2017 Solid biofuels

Sample preparation

EN ISO 14780:2017/AMD 1:2019 Solid biofuels

Sample preparation – Amendment 1

EN ISO 16559:2014 Solid biofuels

Terminology, definitions and descriptions

EN ISO 16948:2015 Solid biofuels

Determination of total content of carbon, hydrogen and nitrogen

EN ISO 16967:2015 Solid biofuels

Determination of major elements – Al, Ca, Fe, Mg, P, K, Si, Na and Ti

EN ISO 16968:2015 Solid biofuels

Determination of minor elements

EN ISO 16993:2016 Solid biofuels

Conversion of analytical results from one basis to another

EN ISO 16994:2016 Solid biofuels

Determination of total content of sulfur and chlorine

EN ISO 16995:2015 Solid biofuels

Determination of the water-soluble chloride, sodium and potassium content

EN ISO/TS 16996:2015 Solid biofuels

Determination of elemental composition by X-ray fluorescence

EN ISO 17225-1:2014 Solid biofuels[1]

Fuel specifications and classes – Part 1: General requirements

EN ISO 17225-2:2014 Solid biofuels

Fuel specifications and classes – Part 2: Graded wood pellets

EN ISO 17225-3:2014 Solid biofuels

Fuel specifications and classes – Part 3: Graded wood briquettes

EN ISO 17225-4:2014 Solid biofuels

Fuel specifications and classes – Part 4: Graded woodchips

EN ISO 17225-5:2014 Solid biofuels

Fuel specifications and classes – Part 5: Graded firewood

EN ISO 17225-6:2014 Solid biofuels

Fuel specifications and classes – Part 6: Graded non-woody pellets

EN ISO 17225-7:2014 Solid biofuels

Fuel specifications and classes – Part 7: Graded non-woody briquettes

EN ISO/TS 17225-8:2016 Solid biofuels

Fuel specifications and classes – Part 8: Graded thermally treated and densified biomass fuels

EN ISO/TS 17225-9:2020 Solid biofuels[2]

Fuel specification and classes, Technical specification – Part 9: Graded hog fuel and woodchips for industrial use

EN ISO 17827-1:2016 Solid biofuels

Determination of particle size distribution for uncompressed fuels – Part 1: Oscillating screen method using sieves with apertures of 3,15 mm and above

EN ISO 17827-2:2016 Solid biofuels

Determination of particle size distribution for uncompressed fuels – Part 2: Vibrating screen method using sieves with aperture of 3,15 mm and below

EN ISO 17828:2015 Solid biofuels

Determination of bulk density

EN ISO 17829:2015 Solid Biofuels

Determination of length and diameter of pellets

EN ISO 17830:2016 Solid biofuels

Particle size distribution of disintegrated pellets

EN ISO 17831-1:2015 Solid biofuels

Determination of mechanical durability of pellets and briquettes – Part 1: Pellets

EN ISO 17831-2:2015 Solid biofuels

Determination of mechanical durability of pellets and briquettes – Part 2: Briquettes

EN ISO 18122:2015 Solid biofuels

Determination of ash content

EN ISO 18123:2015 Solid biofuels

Determination of the content of volatile matter

EN ISO 18125:2017 Solid biofuels

Determination of calorific value 

EN ISO 18134-1:2015 Solid biofuels

Determination of moisture content – Oven dry method – Part 1: Total moisture – Reference method 

EN ISO 18134-2:2017 Solid biofuels

Determination of moisture content – Oven dry method – Part 2: Total moisture – Simplified method

EN ISO 18134-3:2015 Solid biofuels

Determination of moisture content – Oven dry method – Part 3: Moisture in general analysis sample

EN ISO 18135:2017 Solid biofuels

Sampling 

EN ISO 18846:2016 Solid biofuels[3]

Determination of fines content in quantities of pellets

EN ISO 18847:2016 Solid biofuels

Determination of particle density of pellets and briquettes

EN ISO 19743:2017 Solid biofuels

Determination of content of heavy extraneous materials larger than 3,15 mm

EN ISO 20023:2018 Solid biofuels

Safety of solid biofuel pellets – Safe handling and storage of wood pellets in residential and other small-scale applications

EN ISO 20024:2020

Solid biofuels – Safe handling and storage of solid biofuel pellets in commercial and industrial applications      

EN ISO/TS 20048-1:2020

Solid biofuels – Determination of off-gassing and oxygen depletion characteristics – Part 1: Laboratory method for the determination of off-gassing and oxygen depletion using closed containers

EN ISO 20049-1:2020

Solid biofuels – Determination of self-heating of pelletized biofuels – Part 1: Isothermal calorimetry

EN ISO/TS 20049-2:2020

Solid biofuels – Determination of self-heating of pelletized biofuels – Part 2: Basket heating tests 

EN ISO 21404:2020

Solid biofuels – Determination of ash melting behaviour

EN ISO 21945:2020

Solid biofuels – Simplified sampling method for small scale applications

EN ISO/TR 23437:2020

Solid biofuels – Bridging behaviour of bulk biofuels


[1]
  EN ISO 17225 parts 1,  2, 3, 4, 5, 6 and 7 will come out in 2021 in a revised version some with substantial changes.

[2]  EN ISO/TS 17225 part 9, will become a full standard with substantial changes in 2021 or early 2022.

[3] EN ISO 18846 will be replaced by EN ISO 5370, which still is in an early stage of development, meaning it will take a year or two to be completed.

Solid biofuel standards under development or revision

These standards are not publicly available at this time (January 2021), but are in the process of development. Standards that appear in both lists are under revision.

Explanation of abbreviations:

CD – Committee Draft; DIS – draft international standard; FDIS – final draft international standard; AWI – approved new work item

EN ISO/AWI 5370

Solid biofuels – Determination of fines content in pellets

EN ISO/DIS 16559

Solid biofuels – Terminology, definitions and descriptions

EN ISO/FDIS 17225-1

Solid biofuels – Fuel specifications and classes – Part 1: General requirements

EN ISO/FDIS 17225-2

Solid biofuels – Fuel specifications and classes – Part 2: Graded wood pellets

EN ISO 17225-3

Solid biofuels – Fuel specifications and classes – Part 3: Graded wood briquettes

EN ISO 17225-4

Solid biofuels – Fuel specifications and classes – Part 4: Graded wood chips

EN ISO/DIS 17225-5

Solid biofuels – Fuel specifications and classes – Part 5: Graded firewood

EN ISO/DIS 17225-6

Solid biofuels – Fuel specifications and classes – Part 6: Graded non-woody pellets

EN ISO/DIS 17225-7

Solid biofuels – Fuel specifications and classes – Part 7: Graded non-woody briquettes

EN ISO/DIS 17225-9

Solid biofuels – Fuel specifications and classes – Part 9: Graded hog fuel and wood chips for industrial use

EN ISO 18135:2017/AWI AMD 1

Solid Biofuels – Sampling – Amendment

EN ISO/CD 20048-2

Solid biofuels – Determination of off-gassing and oxygen depletion characteristics –

Part 2: Operational method for screening of carbon monoxide off-gassing

EN ISO/AWI TS 21596

Solid biofuels – Determination of grindability – Hardgrove type method for thermally treated biomass fuels         

EN ISO/FDIS 23343-1

Solid biofuels – Determination of water sorption and its effect on durability of thermally treated biomass fuels – Part 1: Pellets

Copyright COFORD 2006.