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WRAP – A CLASSIFICATION SCHEME TO DEFINE THE QUALITY OF WASTE DERIVED FUELS – October 2012
A CLASSIFICATION SCHEME TO DEFINE THE QUALITY OF WASTE DERIVED FUELS
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WRAP – A CLASSIFICATION SCHEME TO DEFINE THE QUALITY OF WASTE DERIVED FUELS – October 2012
Executive Summary
Acknowledgements
This classification scheme aims to provide unambiguous and clear classification of waste derived fuel (WDF) properties for use by energy from waste (EfW) facilities. The system is designed to help fuel users define the fuel parameters of WDF they need to power their facilities, by the use of a system of ‘Classes’. The system will also help fuel producers to classify their WDF in terms of the same Classes and therefore the potential end user is able to analyse the data to determine whether they can accept the WDF within their facility. This will enable direct and efficient trading of WDF and facilitate a good understanding between the seller and the buyer. The scheme is not intended to define end of waste criteria for waste derived fuels
We would like to express our gratitude to the TAG members for their assistance in developing this classification scheme and their assistance in the collection of industry data. The TAG played a significant role in defining the fuel parameters included within this scheme and represents the numerous industries producing and using waste derived fuel.
The system classifies the fuel properties of WDF against 3 main criteria: economic, technical and environmental, within each of which are the key factors in need of determination: Economic attributes: characteristics that will affect the economics of the fuel’s usage: || calorific value; || biomass* content; and || moisture content.
The TAG consisted of the following members: Philip Cozens, Progressive Energy Ltd; Liam Oldershaw, Systems 4 Recycling; Will Spurr, Waste Recycling Group; Claire Downey, Indaver Ireland Ltd; David Lawrence, Lawrence Recycling; and Simon Little, Powerday.
These determine the value of the fuel and any potential incentive payments. Technical attributes: characteristics that will affect the performance of the combustion facility: || chlorine (Cl) content which causes corrosion and fouling; || ash content which affects melting and sintering temperatures; and || bulk content which affects transport/space and infeed levels. The facility will need to be designed to handle WDF with these qualities. Environmental attributes: characteristics that will influence emissions to the environment: || mercury (Hg); || cadmium (Cd); and || other heavy metals. Failure to manage the environmental attributes may result in harmful emissions if not properly abated.
* For the scope of this report, the term “biomass” is used to mean ‘biogenic content of contemporary origin’, but ‘biomass’ has been used as this is the more recognised industry-wide term. The more technically correct term ‘biogenic’ refers to the proportion of carbon present within the material which can be defined as the carbon isotope C-14 (‘new’ carbon which was absorbed from the atmosphere) as opposed to the somewhat decayed over time C-12 (‘fossil’ carbon which has been stored in the earth’s crust for a minimum of 6,000 years). C-14 is sourced from wood, paper, cardboard and energy crops, and C-12 is sourced from coal, oil and gas (and their derivatives).
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WRAP – A CLASSIFICATION SCHEME TO DEFINE THE QUALITY OF WASTE DERIVED FUELS – October 2012
1.0 Developing a Classification Scheme for waste derived fuel
1.1 Background 1.2 Introduction 1.3 What is waste derived fuel? 1.4 Scope of the classification scheme
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WRAP – A CLASSIFICATION SCHEME TO DEFINE THE QUALITY OF WASTE DERIVED FUELS – October 2012
1.1 Background
1.2 Introduction
Recovering energy from waste (EfW) is playing an increasing role in generating ‘low carbon’ energy and will support achievement of the UK’s target of 15% of its energy from renewable sources by 2020. This project is part of WRAP’s EfW programme, the objective of which is to address market failures relating to a lack of information. One of the current unknowns in the sector is the quality and variability of waste derived fuels (WDF). As this is a relatively immature sector unfamiliar fuels could create a level of uncertainty and a lack of confidence amongst users, leading to limited market development and poor market confidence. This project seeks to address the barriers by defining a system of classification for WDF which clarifies the quality required for different end uses or the quality of the fuel actually produced. This system would assist in a number of ways by:
The classification scheme for WDF aims to help fuel producers and users to identify the appropriate specification to use when characterising the quality of WDF. This scheme can assist businesses and organisations operating and supplying gasification, pyrolysis, incineration and co-incineration plants in defining the minimum quality of the WDF required for their process. This classification scheme has been developed following extensive research into existing standards, specifications and quality criteria for WDF including publicly available specifications. A list of the current standards available for solid recovered fuel (SRF), refuse derived fuel (RDF) and biofuels is shown in the reference section.
producing a common understanding between producers and buyers; providing a measure/definition of fuel quality; defining a simple language to be used when describing the fuel; and ensuring the fuel is fit for purpose for use with the technology in place or planned.
The scheme is specifically aimed to help SMEs that either produce WDF, plan to utilise it for energy production or supply it to a third party fuel user. The TAG indicated that industry recognises that a formal classification scheme is necessary for supporting the use of WDF and to establish and maintain market confidence.
The existing European standards (CEN 343) define the quality criteria for a wide range of WDF. Although these standards can be used to define the fuel quality of WDF, they do not guarantee market confidence in the use of WDF to generate energy in smaller scale facilities. For example, the European standard BS EN 15359: 2011[9] which defines the quality criteria for SRF was developed using data from large industrial WDF users such as cement kilns and coal fired power plants, therefore some of the classes are not appropriate for smaller scale EfW facilities which have tighter fuel requirements to ensure they are economically viable and to ensure permitting regulations are not breached. This was confirmed by the Technical Advisory Group TAG and the scheme as shown in Section 3.0 was developed to address that.
Classifying WDF could help businesses to assess the benefits of substituting fossil fuels in industrial plants, and will enable its quality to be compared with other WDF and virgin fuels based on a number of parameters. The development of this classification scheme was made possible by the creation of a Technical Advisory Group (TAG) which was put together to ensure all recommendations and decisions were taken in the wider interests of industry representatives. It consisted of members of WDF producers, WDF users, energy from waste (EfW) industry experts and technology providers. The project has relied upon their significant experience and knowledge of the industry and the scheme was developed with the knowledge of, and agreement from, all members of the TAG.
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WRAP – A CLASSIFICATION SCHEME TO DEFINE THE QUALITY OF WASTE DERIVED FUELS – October 2012
1.3 What is waste derived fuel?
1.4 Scope of the classification scheme
For the purpose of this project’s classification scheme, WDF is defined as ‘A heterogeneous group of non-hazardous wastes that do not cease to be such by virtue of their being used to generate energy without a greater negative environmental impact than landfill disposal’.
The wastes listed below are considered to be outside the scope of this scheme: Products from anaerobic digestion (AD) – the markets for biogas and digestate are normally readily available and accessible. Work in this area is covered by a separate programme within WRAP. Untreated municipal solid waste (MSW) -treatment of MSW increases the recovery rates of certain materials and therefore only post-treatment residual MSW is considered within the scope of this scheme. Hazardous wastes (other than waste oil) - defined in the Environment Agency document ‘Hazardous Waste: Interpretation of definition and classification of hazardous waste (2nd edition v2.3)’. Wastes that currently fall outside the scope of Waste Framework Directive (2008/98/EC): - These are: a. gaseous effluents emitted into the atmosphere; and b. where they are already covered by other legislation; i. radioactive waste; ii. animal carcasses, faecal matter and other natural, non-dangerous substances used in farming; and iii. decommissioned explosives. iv. Any waste material which is subject to an end of waste criteria under the waste protocols project. The development of this scheme is not in any way attempting to define end of waste
To improve the marketability of WDF, the industry adopted the term ‘solid recovered fuel’ (SRF) for waste fuels that meet a tighter quality specification. The term ‘refuse derived fuel’ (RDF) is generally used to define unspecified waste after basic processing to increase the calorific value (CV) of municipal solid waste (MSW), commercial or industrial waste materials.
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WRAP – A CLASSIFICATION SCHEME TO DEFINE THE QUALITY OF WASTE DERIVED FUELS – October 2012
2.0 The development and nature of the classification sCHEME
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2.1 Introduction 2.2 End users considered within this classification scheme
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Guide page 6
WRAP – A CLASSIFICATION SCHEME TO DEFINE THE QUALITY OF WASTE DERIVED FUELS – October 2012
2.1 Introduction This system has been designed to assist WDF producers and users to define the variables which will classify their WDF. This system identifies existing European Quality Standards and defines a classification system for WDF that can be applied to fuel for smaller scale EfW facilities. Where appropriate the existing European Standards should be applied (see Figure 1 for decision tree to help highlight which system to use). In addition to this classification system, the British Standards and specifications also considered are: British Standard for SRF - BS EN 15359: 2011; and British Standard for solid biofuels - BS EN 14961-1: 2010. Further detail on each of the standards is included in Appendix 1 The specification and classes for defining the quality of WDF are determined by the appropriate quality standard. The ‘quality’ of a fuel can be defined by a number of variables. Key parameters include: calorific value (CV); moisture content; ash content; levels of undesirable material contamination; physical properties; and chemical properties.
2.2 E nd users considered within this classification scheme The main end users considered as appropriate to use this scheme are: fluidised bed and moving grate combustion plants; advanced thermal treatment users (mostly, but not exclusively, gasification and pyrolysis) cement kilns; and coal-fired power plants. More detail is available on these technologies in Appendix 2 To identify the quality standard that is applicable for each type of WDF, it is necessary to understand the nature of the WDF, the proposed end use of the fuel and the scope of each quality standard included within this framework. The decision tree illustrated in Figure 1 contains a series of questions on the nature of WDF and its end use. Depending on the answers for each question, the appropriate quality standard which should be followed to define the quality of a particular fuel can be determined. Once the usage of the classification scheme has been confirmed, the producer/ supplier can follow the guidance supplied to specify the relevant Classes of WDF as detailed in Section 3 and summarised in Appendix 3.
These parameters are required by the EfW operators to define the minimum quality of WDF that can be accepted within their process. The parameters required for defining the quality of WDF and the limit value of each parameter for their particular application will vary according to the operating parameters of the end user of the fuel. Within this classification scheme the end users shown in Section 2.2 are considered.
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WRAP – A CLASSIFICATION SCHEME TO DEFINE THE QUALITY OF WASTE DERIVED FUELS – October 2012
Figure1: Decision tree to determine the most suitable classification scheme - footnote - Please note the usage of any classification scheme is non-obligatory.
Is the waste hazardous in nature? (as defined in the ‘Environment Agency’s Guidance document?’ 1
YES
NO Is the waste excluded from the Waste Framework Directive (2008/98/EC)2?
YES
NO YES
Is the waste a product from AD?
NO YES
Is the waste untreated MSW?
NO Is the waste going to be thermally treated or used as fuel?
NO
The standards identified in this document do not apply.
YES Is the fuel classified as a solid biofuel according to BS EN YES 14961-1:2010? (Refer to Section 2.3.2 for further detail)
Follow BS EN 14961-1:2010, ‘Solid biofuel – specifications and classes’ if it is for a non-industrial use3.
NO
1 A guide to the Hazardous Waste Regulations and the List of Waste Regulations in England and Wales, Environment Agency 2008 (http://publications.environment-agency.gov.uk/PDF/GEHO0506BKTR-E-E.pdf) 2 http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2008:312:0003:0030:EN:PDF 3 http://shop.bsigroup.com/ProductDetail/?pid=000000000030200086 4 http://shop.bsigroup.com/ProductDetail/?pid=000000000030202007
Developing a scheme
Development and nature of the scheme Development and nature of the scheme
Is the WDF primarily going to be used for energy recovery in a facility processing less than 100,000 tonnes?
YES
NO Follow BS EN 15359: 2011 ‘Solid recovered fuel – specifications and classes’4.
Follow the ‘A classification system to define the quality of Waste Derived Fuels’ provided in Section 3.0
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Guide page 8
WRAP – A CLASSIFICATION SCHEME TO DEFINE THE QUALITY OF WASTE DERIVED FUELS – October 2012
3.0 Classification of waste derived fuels for usage in small scale energy from waste facilities
3.1 Introduction 3.2 Economic attributes 3.3 Technical attributes 3.4 Environmental attributes 3.5 Summary of all WDF Classes and characteristics 3.6 Worked example 3.7 Summary
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WRAP – A CLASSIFICATION SCHEME TO DEFINE THE QUALITY OF WASTE DERIVED FUELS – October 2012
3.1 Introduction
Failure to manage the environmental attributes may result in harmful emissions if not properly abated.
This classification scheme aims to provide unambiguous and clear classification of waste derived fuel (WDF) properties for use by small scale EfW facilities. The system is designed to help fuel users define the fuel parameters of WDF they need to power their facilities, by the use of a system of ‘Classes’. The system will also help fuel producers to classify their WDF in terms of the same Classes and therefore the potential end user is able to analyse the data to determine whether they can accept the WDF within their facility. This will enable direct and efficient trading of WDF and facilitate a good understanding between the seller and the buyer. The system classifies the fuel properties of WDF against 3 main criteria: Economic, Technical and Environmental, within each of which are the key factors in need of determination: Economic attributes: characteristics that will affect the economics of the fuel’s usage: {{ biomass content; {{ calorific value; and {{ moisture content.
3.2 Economic attributes The economic attributes of the WDF are those variables which will affect the financial value of the fuel (in terms of energy generation, gate fees and the ability to claim revenue from Government incentive schemes such as Renewable Obligation Certificates - ROCs). The economic attributes covered by the scheme are: biomass content (wt% as received basis); net calorific value (MJ/kg as received basis); moisture content (wt% total). The reasons for the inclusion of each of these parameters within the economic characteristics of the classification scheme and the limit values for each class are explained in the following sections.
These determine the value of the fuel and any potential incentive payments. Technical attributes: characteristics that will affect the performance of the combustion facility: {{ chlorine (Cl) content which causes corrosion and fouling; {{ ash content which affects melting and sintering temperatures; and {{ bulk content which affects transport/space and infeed levels. The facility will need to be designed to handle WDF with these qualities. Environmental attributes: characteristics that will influence emissions to the environment: {{ mercury (Hg); {{ cadmium (Cd); and {{ other heavy metals.
Classification Developing a scheme
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WRAP – A CLASSIFICATION SCHEME TO DEFINE THE QUALITY OF WASTE DERIVED FUELS – October 2012
3.2.1
3.2.2 Net calorific value ‘as received’ (ar)
Biomass content ‘as received’ (ar)
The biomass content of WDF consists of its biodegradable fraction and is usually represented by the percentage of biogenic carbon (C-14) in comparison to the total carbon present in WDF. Biomass content is considered within the economic characteristic because: The electricity and/or heat generated from the biodegradable fraction of waste is characterised as renewable energy and may be eligible for receiving ROC or RHI payments from the government. Knowing the biomass/biodegradable content of waste could help operators and end users quantify the landfill cost saved as a result of diversion of these wastes from landfill. Classification
The calorific value of any fuel describes the amount of heat or energy generated when it is completely combusted. It is expressed as a gross calorific value (GCV) and net calorific value (NCV). NCV is determined by calculation and is equal to the GCV minus any heat lost due to moisture present in the fuel and various chemical processes. The NCV is more representative of the heat available in practice when fuels are combusted in boilers and furnaces. The NCV (ar) ensures that the calorific value takes account of the moisture content as received at the laboratory before any processing or conditioning takes place, giving a more representative result.
Classification Table 2 sets out the classification categories for the NCV content of WDF expressed as MJ/kg as received.
Table 1 sets out the classification categories for the biomass content of WDF expressed as wt/wt% as received.
Table 2: Net calorific (as received) value classification
Table 1: Biomass content classification Classification property Biomass content (as received)
Unit
Class 1
Class 2
Class 3
Class 4
Class 5
wt/wt% (mean)
≥90
≥80
≥60
≥50