SIST EN ISO 21644:2021

SLOVENSKI STANDARD
SIST EN ISO 21644:2021
01-marec-2021
Nadomešča:
SIST EN 15440:2011
SIST EN 15440:2011/AC:2011
Trdna alternativna goriva - Metode za določevanje biomase (ISO 21644:2021)
Solid recovered fuels - Methods for the determination of biomass content (ISO
21644:2021)
Feste Sekundärbrennstoffe - Verfahren zur Bestimmung des Gehaltes an Biomasse (ISO
21644:2021)
Combustibles solides de récupération - Méthode de détermination de la teneur en
biomasse (ISO 21644:2021)
Ta slovenski standard je istoveten z: EN ISO 21644:2021
ICS:
27.190 Biološki viri in drugi Biological sources and
alternativni viri energije alternative sources of energy
75.160.10 Trda goriva Solid fuels
SIST EN ISO 21644:2021 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 21644:2021

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SIST EN ISO 21644:2021


EN ISO 21644
EUROPEAN STANDARD

NORME EUROPÉENNE

January 2021
EUROPÄISCHE NORM
ICS 75.160.10 Supersedes EN 15440:2011
English Version

Solid recovered fuels - Methods for the determination of
biomass content (ISO 21644:2021)
Combustibles solides de récupération - Méthode de Feste Sekundärbrennstoffe - Verfahren zur
détermination de la teneur en biomasse (ISO Bestimmung des Gehaltes an Biomasse (ISO
21644:2021) 21644:2021)
This European Standard was approved by CEN on 22 November 2020.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.





EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 21644:2021 E
worldwide for CEN national Members.

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SIST EN ISO 21644:2021
EN ISO 21644:2021 (E)
Contents Page
European foreword . 3

2

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SIST EN ISO 21644:2021
EN ISO 21644:2021 (E)
European foreword
This document (EN ISO 21644:2021) has been prepared by Technical Committee ISO/TC 300 "Solid
recovered materials, including solid recovered fuels" in collaboration with Technical Committee
CEN/TC 343 “Solid Recovered Fuels” the secretariat of which is held by SFS.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by July 2021, and conflicting national standards shall be
withdrawn at the latest by July 2021.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN 15440:2011.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the
United Kingdom.
Endorsement notice
The text of ISO 21644:2021 has been approved by CEN as EN ISO 21644:2021 without any modification.

3

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SIST EN ISO 21644:2021

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SIST EN ISO 21644:2021
INTERNATIONAL ISO
STANDARD 21644
First edition
2021-01
Solid recovered fuels — Methods for
the determination of biomass content
Combustibles solides de récupération – Méthode de détermination de
la teneur en biomasse
Reference number
ISO 21644:2021(E)
©
ISO 2021

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SIST EN ISO 21644:2021
ISO 21644:2021(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved

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SIST EN ISO 21644:2021
ISO 21644:2021(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviations . 3
5 Principle . 4
6 Determination of biomass content . 4
6.1 Sampling . 4
6.2 Sample preparation . 4
6.3 Applicable methods . 4
7 Expression of results . 5
8 Performance characteristics . 5
9 Test report . 6
14
Annex A (normative) Determination of the biomass content based on the C method .7
Annex B (normative) Determination of biomass content using the selective dissolution
method (SDM) .25
Annex C (normative) Determination of biomass content using the manual sorting method
(Msort) .34
Annex D (informative) Limitations of the determination methods .39
Annex E (informative) Performance data .42
Bibliography .45
© ISO 2021 – All rights reserved iii

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SIST EN ISO 21644:2021
ISO 21644:2021(E)

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www .iso .org/ iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 300, Solid recovered fuels.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2021 – All rights reserved

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SIST EN ISO 21644:2021
ISO 21644:2021(E)

Introduction
The biomass content of solid recovered fuels is relevant for the evaluation of the impact of energy
production on greenhouse gas emission. Instrumental methods, wet chemical and manual procedures
are available for the calculation of the renewable energy fraction. Instrumental methods are based on
14
the determination of C content while manual procedures are based on separation of different fractions
by visual inspection. The wet chemical procedure differentiate biomass from non-biomass materials as
function of the acid dissolution behaviour.
The fraction of biomass is expressed:
— by mass;
— by energy content (gross or net calorific value);
— by carbon content.
This document is primarily intended for laboratories, producers, suppliers and purchasers of solid
recovered fuels, but is also useful for the authorities and inspection organizations.
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SIST EN ISO 21644:2021

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SIST EN ISO 21644:2021
INTERNATIONAL STANDARD ISO 21644:2021(E)
Solid recovered fuels — Methods for the determination of
biomass content
1 Scope
This document specifies three methods for the determination of the biomass content in solid recovered
14
fuels: the C content method, the selective dissolution and the manual sorting methods.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 21637:2020, Solid recovered fuels — Terminology, definitions and descriptions
1)
ISO 21645 , Solid recovered fuels — Methods for sampling
2)
ISO 21646 , Combustibles solides de récupération — Préparation des échantillons
3)
ISO 21654 , Solid recovered fuels — Determination of calorific value
4)
ISO 21656 , Solid recovered fuels — Determination of ash content
ISO 21663, Solid recovered fuels — Methods for the determination of total carbon (C), hydrogen (H),
nitrogen (N) and sulphur (S) by the instrumental method
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 21637:2020 and the
following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
ash content on dry basis
mass of inorganic residue remaining after ignition of a fuel under specified conditions, expressed as
mass fraction in percent of the dry matter in the fuel, also includes removed ash contributors
Note 1 to entry: This is typically expressed as a percentage of the mass of dry matter in the fuel source.
Note 2 to entry: Depending on the combustion efficiency the ash may contain combustibles.
Note 3 to entry: If a complete combustion is realized, ash contains only inorganic, non-combustible components.
[SOURCE: ISO 21637:2020, 3.3]
1) Under preparation. Stage at the time of publication ISO/FDIS 21645.
2) Under preparation. Stage at the time of publication ISO/DIS 21646.
3) Under preparation. Stage at the time of publication ISO/FDIS 21654.
4) Under preparation. Stage at the time of publication ISO/FDIS 21656.
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SIST EN ISO 21644:2021
ISO 21644:2021(E)

3.2
biogenic
produced in natural processes by living organisms but not fossilized or derived from fossil resources
3.3
biomass
material of biological origin excluding material embedded in geological formations and/or fossilized
[SOURCE: ISO 16559:2014, 4.32, modified — Notes 1 and 2 to entry have been removed.]
3.4
calorific value
quantity of heat produced by the complete combustion, at a constant pressure equal to 1 013,25 mbar,
of a unit volume or mass of gas, the constituents of the combustible mixture being taken at reference
conditions and the products of combustion being brought back to the same conditions
[SOURCE: EN 437: 2018, modified — Second paragraph (the list) has been removed.]
3.5
gross calorific value
calorific value where the water produced by combustion is assumed to be condensed
[SOURCE: ISO 21637:2020, 3.34]
3.6
isotope abundance
fraction of atoms of a particular isotope of an element
3.7
laboratory sample
part of the sample (3.13) sent to or received by the laboratory
Note 1 to entry: When the laboratory sample is further prepared (reduced) by subdividing, mixing, grinding, or
by combinations of these operations, the result is the test sample. When no preparation of the laboratory sample
is required, the laboratory sample is the test sample. A test portion is removed from the test sample for the
performance of the test or for analysis.
Note 2 to entry: The laboratory sample is the final sample from the point of view of sample collection, but it is the
initial sample from the point of view of the laboratory.
Note 3 to entry: Several laboratory samples may be prepared and sent to different laboratories or to the same
laboratory for different purposes. When sent to the same laboratory, the set is generally considered as a single
laboratory sample and is documented as a single sample.
3.8
moisture
water removable under specific conditions
[SOURCE: ISO 21637:2020, 3.46]
3.9
net calorific value at constant volume
calorific value where the water produced by combustion is assumed to be in the vapour state
[SOURCE: ISO 21637:2020, 3.47]
3.10
nominal minimum particle size
aperture size of the sieve used for determining the particle size distribution of solid recovered fuels
through which no more than 5 % by mass of the material passes
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SIST EN ISO 21644:2021
ISO 21644:2021(E)

3.11
nominal top size
smallest aperture size of the sieve used for determining the particle size distribution of solid recovered
fuels through which at least 95 % by mass of the total material passes through the sieve
[SOURCE: ISO 21637:2020, 3.48]
3.12
percentage modern Carbon
pmC
carbon mass fraction from biogenic origin
Note 1 to entry: The internationally accepted radiocarbon dating reference value is 95 percent of the activity, in
AD 1950, of this NBS oxalic acid SRM4990B.
Note 2 to entry: In 2015, the value of 100 % biogenic carbon was set at 102 pmC.
Note 3 to entry: The biogenic origin is expressed in percentage.
3.13
sample
quantity of material, from a larger amount for which the quality is to be determined
[SOURCE: ISO 21637:2020, 3.63, modified — Notes 1–3 to entry have been removed.]
3.14
sample preparation
actions taken to obtain representative laboratory samples (3.7) or test portions from the original sample
(3.13) as received
[SOURCE: ISO 21637:2020, 3.66]
4 Symbols and abbreviations
For the purposes of this document, the following symbols and abbreviations apply.
C symbol for element carbon
D diameter (mm)
14
C carbon isotope with an atomic mass of 14 u
LSC Liquid Scintillation Counter or Liquid Scintillation Counting
Msort manual sorting method
RSD relative standard deviation
SDM selective dissolution method
SRF solid recovered fuel
TC total carbon content
u atomic mass unit
w mass fraction expressed as a percentage by mass
w content expressed as a percentage of the energy content
cal
w content expressed as a percentage of the total carbon content
TC
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SIST EN ISO 21644:2021
ISO 21644:2021(E)

The different references used in this document are indicated by the following indices:
— for air dried (dried at room temperature 20–25 °C for 24 hours)
(ad)
— for as received
(ar)
— for dry
(d)
— for dry and ash free, where appropriate.
(daf)
EXAMPLE w means the fraction of energy content in the non-biomass fraction by calorific value, on
cal,NB()d
dry basis.
5 Principle
14
The determination of the biomass content is based on selective dissolution, manual sorting or C
measurement of biomass in solid recovered fuel. The choice for the method to be used is described
in Clause 6. The biomass content gives an estimation of the content of the biogenic fraction in solid
recovered fuel.
6 Determination of biomass content
6.1 Sampling
Sampling, transport, storage of the solid recovered fuel and sample preparation in the field shall be
conducted according to ISO 21645 and ISO 21646.
6.2 Sample preparation
14
Preparation of the test sample for the C or SDM shall be conducted according to ISO 21646. For the
Msort, no sample preparation is performed.
Since SRF is considered as a heterogeneous material, the minimum sample amount to be used for each
test shall be:
14
— C method: a quantity between 0,4 and 2 g of the material with a nominal top size of 1 mm or
less, depending on the device used for combustion (bomb, combustion tube furnace or elemental
analyser) or the quantity indicated by the constructor in the case of the use of a laboratory scale
combustion apparatus;
— selective dissolution method (SDM): at least 5 g of the material with a nominal top size of 1 mm or less;
— manual sorting method (Msort): at least as big as the minimum sample size according to ISO 21645
(as received), as calculated in ISO 21646.
6.3 Applicable methods
For the determination of biomass content three methods are available:
14
1) the instrumental C method shall be according to Annex A. This method is based on the
14 14
determination of the ratio of C to the total carbon content; the C is proportional to the biomass
content of the SRF. This method is suitable for samples of all types of fuel and shall be according to
14
Annex A. A value of 10 % biogenic carbon can be considered as the lower range of application of C
method by liquid scintillation counter (LSC);
2) the selective dissolution method (SDM) shall be according to Annex B. The determination of the
biomass content by the SDM is based on the property of biomass that it can be dissolved in a
sulphuric acid / hydrogen peroxide mixture. This method has limitations that makes it less suitable
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SIST EN ISO 21644:2021
ISO 21644:2021(E)

if the content of natural and/or synthetic rubber in the SRF is more than 10 %, or if the sum of the
content of hard coal, coke, brown coal, lignite, degradable plastics of fossil origin, non-degradable
plastic of biogenic origin, oil or fat present as a constituent of biomass, wool, viscose, nylon,
polyurethane or other polymers containing molecular amino groups and silicon rubber exceeds
5 %. Additional information about these limitations is found in Annex D. The selective dissolution
method (SDM) is applicable for the biomass percentage content between 10 % and 90 %;
3) the manual sorting method (Msort) shall be according to Annex C. The determination of the
biomass content by the manual sorting method is based on the visual examination of fractions and
their separation on the basis of their nature and origin. The method is suitable for samples with a
particle size >10 mm.
For the limitations of the three methods see Annex D.
7 Expression of results
Depending on the use of the results, three different dimensions are used to express the biomass content:
a) biomass in percent by mass w ;
B
b) biomass in percent by calorific value w ;
B,cal
c) biomass in percent by carbon content w .
B,TC
14
The expression of results by C method shall be according to Annex A.
The expression of results by SDS method shall be according to Annex B.
The expression of results by Msort method shall be according to Annex C.
8 Performance characteristics
External data for the calculation of the expanded uncertainty of measurements are presented in
Annex E where results of round robin and validation studies are summarized. These values should be
used in combination with individual laboratory performance characteristics and a desired coverage
factor to get the overall uncertainty.
Practical examples of use of the data from Annex E:
EXAMPLE 1
A laboratory wants to determine the expanded uncertainty of measurement of SDM method (% by mass).
The intra-laboratory reproducibility for the laboratory calculated from internal validations studies and control
charts was determined to be 2,5 % (RSD).
[3]
The round robin results from the QUOVADIS study (Table E.2) give a RSD value of 3,43 % (at 67,79 % level).
2 2
   u c,rel = √(2,5 +3,43 ) = 4,24 %
   U rel = 2 × u c,rel = 8,48 %
where u c,rel is the combined uncertainty of measurement and U rel is the expanded uncertainty of measurement
using a coverage factor of 2 (~95 % confidence interval).
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SIST EN ISO 21644:2021
ISO 21644:2021(E)

EXAMPLE 2
14
A laboratory measures the biomass content by C method – LSC B (% by TC).
The intra-laboratory reproducibility for the laboratory calculated from internal validations studies and control
charts was determined to be 2,4 % (RSD).
[3]
The round robin results from the QUOVADIS study (Table E.6) give a RSD value of 2,5 % (at 55,5 % level).
2 2
   u c,rel = √(2,4 +2,5 ) = 3,5 %
   U rel = 2 × u c,rel = 7,0 %
where u c,rel is the combined uncertainty of measurement and U rel is the expanded uncertainty of measurement
using a coverage factor of 2 (~ 95 % confidence interval).
9 Test report
The test report shall contain at least the following information:
a) identification of the laboratory performing the test;
b) date of the test;
c) identification of product (sample) tested;
d) sample preparation (e.g. method of size reduction, drying, subdivision);
e) storage conditions;
f) date of receipt of laboratory sample and dates of the test (beginning and end);
g) a reference to this document (ISO 21644:2020) and the method used;
14
h) in case of C-method, the results of the test including the basis on which they are expressed and
application of the isotope correction;
i) the biomass content expressed as a percentage by mass, calorific value and/or carbon content,
rounded to the nearest 0,1 %;
j) any operation not included in this document, or regarded as optional;
k) any unusual features noted during the test procedure.
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SIST EN ISO 21644:2021
ISO 21644:2021(E)

Annex A
(normative)

14
Determination of the biomass content based on the C method
A.1 General
14
The two proposed methods for C measurement, Proportional Scintillation Method (PSM) or
Accelerated Mass Spectrometry (AMS), require specialised personnel and instrumentation. However,
the preparation step for instrumental analysis can be completed as normal routine laboratory activity.
14
For the collection from the sample of the C fraction, generally accepted methods for the conversion of
the carbon present in the sample to CO are described.
2
A.2 Principle
The methods for the determination of the biomass content specified in this annex are based on the
14
determination of the C content. The amount of biomass carbon in solid recovered fuel is proportional
14
to this C content.
The carbon present in the sample is converted to CO by combustion. The combustion is carried out
2
14
in a way to comply with the requirements of the subsequent measurement of the C content. This
measurement is carried out according to one of the two following methods, Proportional Scintillation
Method (PSM) or Accelerated Mass Spectrometry (AMS). These methods are considered equivalent,
giving the same results within the scope of this document. The results are expressed as the percentage
biomass carbon of the total carbon content. The fraction of biomass content by mass and the fraction of
biomass by energy content are calculated from the carbon content of biomass, using the carbon content
of biomass and the energy content of the biomass fraction that is present in the sample.
A.3 Limitations
For the limitation of this method see Annex D.
A.4 Symbols
For the purposes of this annex, the following symbols apply.
C symbol for element carbon
14
C carbon isotope with an atomic mass of 14
AMS Accelerator Mass Spectrometry
β beta particle, electron emitted during radioactive decay
Bq Bequerel, disintegrations per second
d on dry base
DPM disintegrations per minute
CPM counts per minute
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SIST EN ISO 21644:2021
ISO 21644:2021(E)

CV coefficient of variation
GM Geiger Müller
LCV Low calorific value
LLD Lower Limit of Detection
m mass expressed as a percentage by mass
M moisture expressed as a percentage by mass
MOP 3-Methoxy 1-propyl amine
NCV Net Calorific Value
LSC Liquid Scintillation Counter or Liquid Scintillation Counting
REF reference value of 100 % biogenic carbon
pmC percentage
...

SLOVENSKI STANDARD
oSIST prEN ISO 21644:2020
01-marec-2020
Trdna alternativna goriva - Metoda za določevanje biomase (ISO/DIS 21644:2019)
Solid recovered fuels - Methods for the determination of biomass content (ISO/DIS
21644:2019)
Feste Sekundärbrennstoffe - Verfahren zur Bestimmung des Gehaltes an Biomasse
(ISO/DIS 21644:2019)
Combustibles solides de récupération - Méthode de détermination de la teneur en
biomasse (ISO/DIS 21644:2019)
Ta slovenski standard je istoveten z: prEN ISO 21644
ICS:
27.190 Biološki viri in drugi Biological sources and
alternativni viri energije alternative sources of energy
75.160.10 Trda goriva Solid fuels
oSIST prEN ISO 21644:2020 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN ISO 21644:2020

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oSIST prEN ISO 21644:2020
DRAFT INTERNATIONAL STANDARD
ISO/DIS 21644
ISO/TC 300 Secretariat: SFS
Voting begins on: Voting terminates on:
2019-12-31 2020-03-24
Solid recovered fuels — Methods for the determination of
biomass content
ICS: 75.160.10
THIS DOCUMENT IS A DRAFT CIRCULATED
This document is circulated as received from the committee secretariat.
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
ISO/CEN PARALLEL PROCESSING
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 21644:2019(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
©
PROVIDE SUPPORTING DOCUMENTATION. ISO 2019

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oSIST prEN ISO 21644:2020
ISO/DIS 21644:2019(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2019
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved

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oSIST prEN ISO 21644:2020
ISO/DIS 21644:2019(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviations . 3
5 Principle . 4
6 Determination of biomass content . 4
6.1 Sampling . 4
6.2 Sample preparation . 4
6.3 Applicable methods . 4
6.4 Selection of methods for the determination of the biomass content . 5
7 Expression of results . 7
8 Performance characteristics . 7
9 Test report . 8
14
Annex A (normative) Determination of the biomass content based on the C method .9
Annex B (normative) Determination of biomass content using the selective dissolution method .25
Annex C (normative) Determination of biomass content using the manual sorting method .34
Annex D (informative) Limitations of the determination methods .39
Annex E (informative) Performance data .42
Bibliography .44
© ISO 2019 – All rights reserved iii

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oSIST prEN ISO 21644:2020
ISO/DIS 21644:2019(E)

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 300, Solid recovered fuels.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
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Introduction
The biomass content of solid recovered fuels is relevant for the evaluation of the impact of energy
production on greenhouse gas emission. Instrumental methods, wet chemical and manual procedures
are available for the calculation of the renewable energy fraction. Instrumental methods are based on
14
the determination of C content while manual procedures are based on separation of different fractions
by visual inspection. The wet chemical procedure differentiate biomass from non-biomass materials as
function of the acid dissolution behaviour.
The fraction of biomass is expressed:
— by weight;
— by energy content (gross or net calorific value);
— by carbon content.
This document is primarily intended for laboratories, producers, suppliers and purchasers of solid
recovered fuels, but is also useful for the authorities and inspection organizations.
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oSIST prEN ISO 21644:2020
DRAFT INTERNATIONAL STANDARD ISO/DIS 21644:2019(E)
Solid recovered fuels — Methods for the determination of
biomass content
1 Scope
This document specifies three methods for the determination of the biomass content in solid recovered
14
fuels: the C content method, the selective dissolution and the manual sorting methods.
14
A value of 10 % biogenic carbon can be considered as the lower range of application of C method by LSC.
The SDM method is applicable for the biomass percentage content between 10 % and 90 %.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO/DIS 21637, Solid recovered fuels — Terminology, definitions and descriptions
1)
ISO/CD 21645, Solid recovered fuels — Methods for sampling
2)
ISO/CD 21646, Solid recovered fuels — Sample preparation
ISO/DIS 21654, Solid recovered fuels — Determination of calorific value
ISO/DIS 21656, Solid recovered fuels — Determination of ash content
ISO/DIS 21663, Solid recovered fuels — Methods for the determination of total carbon (C), hydrogen (H),
nitrogen (N) and sulphur (S) by the instrumental method
ISO/IEC 17025:2017, General requirements for the competence of testing and calibration laboratories
CEN/TS 15414-1:2010, Solid recovered fuels — Determination of moisture content using the oven dry
method — Part 1: Determination of total moisture by a reference method
EN 15413:2011, Solid recovered fuels — Methods for the preparation of the test sample from the
laboratory sample
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/DIS 21637 and the
following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
1) ISO/DIS 21645 is expected 03/2020.
2) ISO/DIS 21646 is expected 03/2020.
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3.1
ash content
inorganic mass remaining after complete combustion of a solid recovered fuel under specified
conditions expressed as a percentage of the mass of the dry matter in the solid recovered fuel
3.2
biogenic
produced in natural processes by living organisms but not fossilized or derived from fossil resources
3.3
biomass
material of biological origin excluding material embedded in geological formations and/or fossilized
[SOURCE: ISO 16559:2014, 4.32]
3.4
calorific value
energy amount per unit mass or volume released on complete combustion
3.5
gross calorific value
measured value of the specific combustion energy per mass unit of a solid recovered fuel burned in
oxygen in calorimetric bomb under the conditions specified
Note 1 to entry: The results of combustion are assumed to consist of gaseous oxygen, nitrogen, carbon dioxide and
sulphur dioxide, of liquid water (in equilibrium with its vapour) saturated with carbon dioxide under conditions
of the bomb reaction, and of solid ash, all at the reference temperature and at constant volume.
3.6
isotope abundance
fraction of atoms of a particular isotope of an element
3.7
laboratory sample
sample sent to or received by the laboratory
Note 1 to entry: When the laboratory sample is further prepared (reduced) by subdividing, mixing, grinding, or
by combinations of these operations, the result is the test sample. When no preparation of the laboratory sample
is required, the laboratory sample is the test sample. A test portion is removed from the test sample for the
performance of the test or for analysis.
Note 2 to entry: The laboratory sample is the final sample from the point of view of sample collection, but it is the
initial sample from the point of view of the laboratory.
Note 3 to entry: Several laboratory samples may be prepared and sent to different laboratories or to the same
laboratory for different purposes. When sent to the same laboratory, the set is generally considered as a single
laboratory sample and is documented as a single sample.
3.8
moisture
water removable under specific conditions
3.9
net calorific value
calculated value of the specific energy of combustion for unit mass of a solid recovered fuel burned in
oxygen in calorimetric bomb under such conditions that all the water remains as water vapor at 0,1 MPa
Note 1 to entry: The old term for net calorific value is lower heating value.
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3.10
nominal minimum particle size
aperture size of the sieve used for determining the particle size distribution of solid recovered fuels
through which no more than 5 % by mass of the material passes
3.11
nominal maximum particle size
aperture size of the sieve used for determining the particle size distribution of solid recovered fuels
through which at least 95 % by mass of the material passes
3.12
percentage modern Carbon (pmC)
carbon mass fraction from biogenic origin (express in percentage)
Note 1 to entry: The internationally accepted radiocarbon dating reference value is 95 percent of the activity, in
AD 1950, of this NBS oxalic acid SRM4990B.
Note 2 to entry: In 2015, the value of 100 % biogenic carbon was set at 102 pmC.
3.13
sample
quantity of material, representative of a larger quantity for which the property is to be determined
3.14
sample preparation
all actions taken to obtain representative analyses samples or test portions from the original sample
4 Symbols and abbreviations
For the purposes of this document, the following symbols and abbreviations apply.
C symbol for element carbon
D diameter (mm)
14
C carbon isotope with an atomic mass of 14
Msort manual sorting method
RES-E directive 2001/77/EC of the European Parliament and of the Council of 27 September 2001
RSD relative standard deviation
SDM selective dissolution method
SRF solid recovered fuel
TC total carbon content
X mass fraction expressed as a percentage by weight
cal
X content expressed as a percentage of the energy content
TC
X content expressed as a percentage of the total carbon content
The different references used in this document are indicated by the following indices:
— for air dried
(ad)
— for as received
(ar)
— for dry
(d)
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— for dry and ash free, where appropriate.
(daf)
cal
EXAMPLE x means the fraction of energy content in the non-biomass fraction by calorific value, on
NB d
()
dry basis.
5 Principle
14
The determination of the biomass content is based on selective dissolution, manual sorting or C
measurement of biomass in solid recovered fuel. The choice for the method to be used is described in
the next clause. The biomass content gives an estimation of the content of the biodegradable/biogenic
fraction in solid recovered fuel.
6 Determination of biomass content
6.1 Sampling
Sampling, transport, storage of the solid recovered fuel and sample preparation in the field shall be
conducted according to ISO/CD 21645 and ISO/CD 21646.
6.2 Sample preparation
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Preparation of the test sample for the C or selective dissolution method shall be conducted according
to EN 15413:2011. For the manual sorting method, no sample preparation is performed.
Since SRF is considered as a heterogeneous material, the minimum sample amount to be used for each
test shall be:
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— C method: a quantity between 0,4 and 2 g of the material with a nominal maximum particle size
of 1 mm or less, depending on the device used for combustion (bomb, combustion tube furnace or
elemental analyser) or the quantity indicated by the constructor in the case of the use of a laboratory
scale combustion apparatus;
— selective dissolution method: at least 5 g of the material with a nominal maximum particle size of
1 mm or less;
— manual sorting method: at least as big as the minimum sample size according to ISO/CD 21645 (as
received), as calculated in EN 15413:2011.
6.3 Applicable methods
For the determination of biomass content three methods are available:
1) the instrumental 14C method. This method is based on the determination of the fraction of 14C to
the total carbon content; the 14C is proportional to the biomass content of the SRF. This method is
suitable for samples of all types of fuel and shall be according to Annex A;
2) the selective dissolution method (SDM) shall be according to Annex B. The determination of the
biomass content by the selective dissolution method is based on the property of biomass that it can
be dissolved in a sulphuric acid / hydrogen peroxide mixture;
3) the manual sorting method (Msort) shall be according to Annex C. The determination of the
biomass content by the manual sorting method is based on the visual examination of fractions and
their separation on the basis of their nature and origin. The method is suitable for samples with a
particle size > 10 mm.
The selective dissolution method can give false results which may be caused by the following
components in SRF. In case that these components are present in an amount defined below, the selective
dissolution method is not applicable.
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List of components giving false results:
— solid fossil fuels like hard coal, coke, brown coal, lignite and peat;
— charcoal;
— degradable plastics of fossil origin;
— non-degradable plastics of biogenic origin;
— oil or fat present as a constituent of biomass;
— natural and/or synthetic rubber residues;
— wool;
— viscose;
— nylon, polyurethane or other polymers containing molecular amino groups;
— silicon rubber.
If components in this list are expected to be present with an amount of less than 10 % by weight (for
natural and/or synthetic rubber residues) or 5 % by weight (for the other mentioned components), an
assessment is not necessary. If the components in this list are expected to be present in the sample
with a higher amount, an assessment shall be made of the estimated influence of the presence of these
components and the results of that assessment shall be mutually agreed between the parties involved.
14
In case of conflicts the C method shall be used to confirm the results of that assessment.
NOTE In typical residual and similar waste, the content of nylon, polyurethane, biodegradable plastics of
fossil origin, wool, viscose, non-biodegradable plastics of biogenic origin and oil/fat is fairly low and the defect is
negligible.
For the limitations of the three methods see Annex D.
6.4 Selection of methods for the determination of the biomass content
For the selection of the method the following aspects shall be considered:
1) What is the purpose of the biomass content determination? If the results are used according to
renewable energy sources, then biomass content by weight and/or calorific value needs to be
determined. If the results are used for greenhouse gas reduction related issues (CO trading), then
2
the biomass content by carbon and/or calorific value has to be determined;
2) Are the measurements parts of a regular routine control check for RES-E issues? In that case the
SDM/Msort shall be used, provided that there is no restriction due to false results as described
in 6.2. The SDM and Msort measurements are regarded as preferred methods as they can be
performed in a typical laboratory by proficient analysis using simple standard equipment. Results
can be available within 1 to 2 days and if the nature of the SRF is well known and constant, the SRF
and Msort measurements are the most efficient options;
3) Are the measurements intended for CO trading matters or accounting biomass content in CO
2 2
14
emissions? In that case the C method or the SDM may be used. Validation studies show that there
14
is a good agreement in the determination of the biomass content by carbon between the C method
and the SDM/Msort method in SRF materials.
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Table 1 — Method selection
[RES-E] [CO trading]
2
SDM / Msort Msort
x
B
14
cal
SDM / Msort C / SDM/ Msort
x
B
14
TC C / SDM
x
B
14
NOTE 1 The determination of the biomass fraction with C expressed by energy content has not been
validated.
NOTE 2 The Msort combined with the calorific value determination or the TC determination of the biomass
and the non-biomass fraction could be used for internal analyses.
In Table 1, [RES-E] refers to renewable energy sources and [CO trading] refers to greenhouse gas
2
reduction related issues.
Figure 1 a) and b) gives a decision tree for selection of the appropriate method for the determination.
a)
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b)
Key
Msort manual sorting
SDM selective dissolution method
14
C radiocarbon method
D nominal minimum particle size
05
Figure 1 — Decision tree for the selection of determination method
7 Expression of results
Depending on the use of the results, three different dimensions are used to express the biomass content:
a) biomass in percent by weight x ;
B
cal
b) biomass in percent by calorific value x ;
B
TC
c) biomass in percent by carbon content x .
B
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The expression of results by C method shall be according to Annex A.
The expression of results by SDS method shall be according to Annex B.
The expression of results by Msort method shall be according to Annex C.
8 Performance characteristics
External data for the calculation of the expanded uncertainty of measurements are presented in
Annex E where results of round robin and validation studies are summarized. These values should be
used in combination with individual laboratory performance characteristics and a desired coverage
factor to get the overall uncertainty that is demanded by the customer.
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Practical examples of use of the data from Annex E:
EXAMPLE 1
A laboratory wants to determine the expanded uncertainty of measurement of SDM method (% by mass).
The intra-laboratory reproducibility for the laboratory calculated from internal validations studies and
control charts was determined to be 2,5 % (RSD).
The round robin results from the QUOVADIS study (Table E.2) give a RSD value of 3,43 % (at 67.79 % level).
2 2
u c,rel = (2,5 +3,43 ) = 4,24 %
U rel = 2 × u c,rel = 8,48 %
where u c,rel is the combined uncertainty of measurement and U rel is the expanded uncertainty of
measurement using a coverage factor of 2 (~ 95 % confidence interval).

EXAMPLE 2
14
A laboratory measures the biomass content by C method – LSC B (% by TC).
The intra-laboratory reproducibility for the laboratory calculated from internal validations studies and
control charts was determined to be 8.2 % (RSD).
The round robin results from the QUOVADIS study (Table E.6) give a RSD value of 2,5 % (at 55,5 % level).
2 2
u c,rel = (8.2 +2,5 ) = 8,6 %
U rel = 2 × u c,rel = 17,2 %
where u c,rel is the combined uncertainty of measurement and U rel is the expanded uncertainty of
measurement using a coverage factor of 2 (~ 95 % confidence interval).
9 Test report
The test report shall contain at least the following information:
a) identification of the laboratory performing the test;
b) date of the test;
c) identification of product (sample) tested;
d) sample preparation (e.g. method of size reduction, drying, subdivision);
e) storage conditions;
f) date of receipt of laboratory sample and dates of the test (beginning and end);
g) a reference to this document (ISO 21644) and the method used;
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h) in case of C-method, the results of the test including the basis on which they are expressed and
application of the isotope correction;
i) the biomass content expressed as a percentage by mass, calorific value and/or carbon content,
rounded to the nearest 0,1 %;
j) any operation not included in this document, or regarded as optional;
k) any unusual features noted during the test procedure.
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Annex A
(normative)

14
Determination of the biomass content based on the C method
A.1 Introduction
14
The two proposed methods for C measurement, Proportional Scintillation Method (PSM) or
Accelerated Mass Spectrometry (AMS), require specialised personnel and instrumentation. However,
the preparation step for instrumental analysis can be completed as normal routine laboratory activity.
14
For the collection from the sample of the C fraction, generally accepted methods for the conversion of
the carbon present in the sample to CO are described.
2
A.2 Principle
The methods for the determination of the biomass content specified in this annex are based on the
14
determination of the C content. The amount of biomass carbon in solid recovered fuel is proportional
14
to this C content.
The combustion is carried out in a way to comply with the requirements of the subsequent measurement
14
of the C content. This measurement is carried out according to one of the two following methods,
Proportional Scintillation Method (PSM) or Accelerated Mass Spectrometry (AMS). These methods
are considered equivalent, giving the same results within the scope of this document. The results
are expressed as the percentage biomass carbon of the total carbon content. The fraction of biomass
content by weight and the fraction of biomass by energy content are calculated from the carbon content
of biomass, using the carbon content of biomass and the energy content of the biomass fraction that is
present in the sample.
A.3 Symbols
For the purposes of this annex, the following symbols apply.
C symbol for element carbon
14
C carbon isotope with an atomic mass of 14
AMS Accelerator Mass Spectrometry
β beta particle, electron emitted during radioactive decay
Bq Bequerel, disintegrations per second
d on dry base
DPM disintegrations per minute
CPM counts per minute
CV coefficient of variation
GM Geiger Müller
LLD Lower Limit of Detection
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m mass expressed as a percentage by weight
M moisture expressed as a percentage by weight
MOP 3-Methoxy 1-propyl amine
NCV Net Calorific Value
LSC Liquid Scintillation Counter or Liquid Scintillation Counting
REF reference value of 100 % biogenic carbon
pmC percentage modern Carbon
PSM Proportional Scintillation-counter Method
X fraction expressed as a percentage by weight
RSD Relative Standard Deviation
SRF Solid recovered fuel
TC Total carbon content
A.4 Reagents and materials
Carbon dioxide absorber for LSC (methoxypropylamine or equivalent)
Universal LSC cocktail for
...