Comparitive LCA of Waste Tyre Managment routes

Edward Dooney BSc. In Environmental Science & Technology Final Year Project 2013
Title of Project:
Comparative Life Cycle Analysis of Management options
for Waste Tyres in Ireland
Author: Edward Dooney
Academic Year: 2012-2013
Supervisor: Steve Tonry
This project is submitted as part fulfilment of the Honours Degree (Level 8) Environmental
Science in the Institute of Technology, Sligo.

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Declaration
Declaration of Ownership: I declare that the attached work is entirely my own and that all
sources have been acknowledged:
Signed: __________________
Date: ____________________

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Abstract

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Acknowledgments
I would like to thank the following individuals who made the completion of this work
possible with their help and support throughout the year.
My project supervisor, Mr Steve Tonry, who’s mentoring and guidance throughout the project
enabled its completion.
All the staff and lecturers at IT Sligo involved in my studies to date in the Environmental
Science and Technology course I am undertaking.
Finally, I would like to thank my parents Anne and Eddie Dooney for all their support
throughout my education.

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Table of Contents:
Abstract...................................................................................................................................... II
Acknowledgments ....................................................................................................................III
1.0 Introduction......................................................................................................................1
1.1 Aims and Objectives .........................................................................................................4
2.0 Literature Review ............................................................................................................5
2.1 Similar Life Cycle Assessments .......................................................................................6
2.2 Legislation and Initiatives.................................................................................................8
2.2.1 End-of-Life Vehicle Directive....................................................................................8
2.2.2 Waste Management (Tyres and Waste Tyres) Regulations 2007 ..............................8
2.2.3 ‘TRACS’.....................................................................................................................9
2.3 Waste Tyre Circulation in Europe and Internationally ...................................................11
2.5 Illegal Stockpiling...........................................................................................................13
2.6 Current leading methods of Tyre disposal......................................................................14
2.6.1 Landfill .....................................................................................................................14
2.6.2 Mechanical Breakdown............................................................................................15
2.6.3 Re-treading ...............................................................................................................15
2.6.4 Pyrolysis ...................................................................................................................16
2.6.5 Whole Tyre Re-use...................................................................................................17
2.6.6 Use as Tyre Derived Fuel in Cement production .....................................................17
2.7 Life cycle assessment......................................................................................................20

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2.8 ISO: 14040:2006.............................................................................................................20
2.8.1 Defining goals and scope of study............................................................................20
2.8.2 Life cycle inventory assessment...............................................................................20
2.8.3 Assessment of Impacts .............................................................................................21
2.8.4 Interpretation of results.............................................................................................21
3.0 Methodology..................................................................................................................23
3.1 Definition of Goals and scoping .....................................................................................24
3.1.1 Establishing the Functional Unit ..............................................................................24
3.1.3 System boundaries: Baseline Scenario – Current management of Irish ELTs.........24
3.1.3 System boundaries: Scenario A – TDF use in Cement Kilns...................................25
3.1.4 System boundaries: Scenario B – Use of Tyre re-treading ......................................26
3.1.5 Assumptions and Limitations...................................................................................26
3.1.5 Life Cycle Impact Assessment .................................................................................27
4.0 Results.................................................................................................................................28
4.1 Results Presented ............................................................................................................29
4.2 Current scope of waste Tyre Circulation in Ireland ........................................................30
4.3 Life cycle inventory assessment .....................................................................................32
4.3.1 The Baseline Scenario ..............................................................................................32
4.3.1 Scenario A: Substitution of coal with TDF in Cement production ..........................33
4.3.3 Scenario B: Application of used tyres in Re-treading Process.................................34
4.4 Comparisons of Scenarios...............................................................................................36

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4.5 Life Cycle Impact Assessment........................................................................................40
5.0 Discussion...........................................................................................................................41
5.1 Interpretation of Results..................................................................................................42
5.2 Current Scope of Irish Waste Tyre Management............................................................42
5.3 Baseline Scenario............................................................................................................45
5.4 Scenario A.......................................................................................................................47
5.5 Scenario B.......................................................................................................................48
5.6 Comparison of Scenarios ................................................................................................50
5.7 Life Cycle Impact Assessment........................................................................................52
6.0 Conclusion..........................................................................................................................54
6.1 Recommendations...........................................................................................................55
7.0 References...........................................................................................................................57
7.1 Literature.........................................................................................................................57
7.2 Websites..........................................................................................................................59
8.0 Appendix.............................................................................................................................61

VII
List of Tables and Figures
Figure 1 shows the process of extended producer responsibility in the european union.10
Graph 1shows the estimated end of life tyre recovery rates in three contrasting markets
internationally over the last 17 years....................................................................................12
Figure 2 shows the process a typical used tyre would encounter depending on waste
criteria......................................................................................................................................14
Table 1: likely emissions from a proposed pyrolysis plant in dublin which would recieve
250,000 - 400,000 tonnes elt per year ....................................................................................16
Picture 1: tdf being stored prior to use at lagan cement, kinnegad, co. Westmeath ........19
Figure 3: flow chart of lca inventory assessment (epa, 1993) .............................................21
Figure 4: the phases of a typical lca (iso 14040, 2006).........................................................22
Table 2: share of each recovery method currently practiced in ireland ...........................25
Chart 1: distribution of elt management routes in ireland in 2010. ..................................30
Chart 2: distribution of elt management routes in ireland in 2011. ..................................31
Table 3: co2 production in the baseline scenario..................................................................33
Table 4: calculation of co2 emissions from scenario a .........................................................34
Table 5: calculation of co2 emissions from scenario b.........................................................35
Graph 2: co2 emissions arising from each scenario annually............................................36
Graph 3: co2 emissions arising from both individual recovery routes..............................37
Graph 4: co2 emissions from coal vs. Tdf use in cement kiln .............................................38
Graph 5: difference in co2 emissions between re-treading 3000 tonnes of used tyres with
the manufacture of an equivalent amount of new tyres ......................................................39
Table 6: environmental impact assessment of each scenario..............................................40
Table 7: international elt recovery rates from us, japan and europe ................................61

VIII
Table 8: calculation of energy inputs/outputs during shredding and feeding stages for tdf
use.............................................................................................................................................62

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1.0Introduction

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‘’The disposal of tyres in Ireland is a looming environmental problem considering the ever-
increasing number of vehicles on the road.’’ (EPA, 2000)
It is estimated that an average of 35,000 tonnes of waste tyres is produced in the Republic of
Ireland annually while the European Union (EU) is thought to produce around 3,339,000
tonnes of tyres annually (Department of Environment, Community and Local Government,
2007). However these figures vary greatly due to illegal stockpiling and disposal e.g. TRACS,
Irelands Tyre Recovery Activity Compliance Scheme’s website claims 25,000 tonnes was
produced in 2009.
Used tyres are classified under non-hazardous waste in the European waste catalogue (EWC).
(EPA 2002) In the past Landfill was the first port of call when discarding waste tyres even
though their chemical composition, albeit this varies depending on the type of tyre, is very
resilient to biodegradation due to its composition, particularly the hydrocarbon based material
content including synthetic rubber and carbon black. Currently there is a need for the
introduction of a reliable method of decreasing the volume of legally and illegally stockpiled
tyres in Ireland with the possibility of providing an energy source.
In 1998, the minister for the Environment and Local Government released a policy statement
entitled ‘Waste Management: Changing our ways’ which laid out the government’s plan to
bring Irish waste management techniques into the 21st century. The report highlighted the
international utilization of thermal energy recovery methods e.g., pyrolysis and gasification,
and how these methods not only dispose of waste but produce a valuable commodity in the
form of syngas. However, to date there has not been an introduction of such technologies in
Ireland even though the feasibility of such a plant was considered with ‘’Indications that
pyrolysis has reached a stage where plants in the order of 20,000tpa -80,000tpa (tonnes per

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annum), to suit less urbanised areas, may be viable and merit consideration.’’ (Waste
Management: Changing our ways, 1998)
Some methods to deal with tyres have been introduced in Ireland and this can be seen in the
EPA’s ‘National Waste Report 2010’ which states that in 2009 there was no import of tyres
for the purpose of energy recovery however in 2010 8 tonnes of waste tyres was imported to
Ireland (National Waste Report, 2010). A number of methods already exist in Ireland to
dispose, re-use or recycle tyres however it is unknown which of these techniques are the best
environmentally, economically and socially.
Internationally used methods Include:
 Landfill
 Mechanical Breakdown
 Re-treading
 Pyrolysis
 Whole Tyre Re-use
 Tyre Derived Fuel

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1.1 Aims and Objectives
The aim of this assessment is to prepare a comprehensive, factual and relevant report on the
current state of waste tyres in Ireland using the most up to date material available and
compare two viable scenarios for the treatment of waste tyres arising in Ireland.
The objectives of this study are:
 Determine the amount of Waste tyres produced in Ireland to create a baseline Scenario
to be used in the Life Cycle assessment (LCA)
 Research available treatment technologies for waste tyres management and propose
two viable scenarios in the Irish context.
 Carry out an LCA on the baseline and proposed Scenarios based on their resultant CO2
emissions.
 Compare the LCA results of each Scenario and provide recommendations.

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2.0Literature Review

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2.1 Similar Life Cycle Assessments
A number of studies have been carried out by means of LCA on both recovery methods of
End-of life tyres and on the production and life-span of tyre.
One study carried out at the University of Florence titled ‘End life tyres: Alternative final
disposal processes compared by LCA’ compares the waste to energy (WtE) process of
combustion in a cement clinker furnace with two forms of tyre re-use i.e. filling material
created by the ‘’cryogenic pulverisation process (CPP) and filling material created by the
mechanical pulverisation process.’’ (Corti, A. 2004) This study concluded that the
combustion of waste tyres in the WtE process proved to have less environmental impacts
mainly due to the avoided combustion of conventional fossil fuels. High energy use in the
CPP and MPP process was also a major factor in the findings.
Another study, conducted by ‘PricewaterhouseCoopers’ Advisory’s Sustainable Development
Department upon request by ‘Aliapur’ (the organisation responsible for the recovery of used
tyres in France) titled ‘Life Cycle Assessment of nine recovery methods for End of Life Tyres
(ELT)’ looks at some of the most common methods of re-use, disposal and waste to energy
(WtE) recovery. The nine recovery methods are as follows: Cement production, specialist
metal forges steel production plants, urban heating systems, and synthetic surfaces,
production of moulded objects, infiltration basins and retention basins. This study followed
the methodology laid out in the internationally recognised LCA standard ‘ISO 14040’. The
main conclusions drawn from this study was that all nine methods showed ‘’net
environmental benefits’’, however investment in the initial stages of End of Life Tyre (ELT)
recovery is critical ‘’as the environmental benefits are currently secondary in the collection,
sorting and shredding phase.’’ (PWC, 2010)

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A more recent study carried out in Sweden by ‘IVL’ a Swedish research institute titled ‘Life
cycle of recycled tires: Comparisons between deck materials and alternative materials in
artificial turf, drainage layers and equestrians uses’ which looked mainly at construction of
artificial surfaces from ELT was conducted in 2012. This study concluded that the use of tyre
granulate as opposed to alternative materials in football fields had a positive impact on the
environment as did the selection of tyre cuts in drainage layers as opposed to conventional
gravel. However, the study found that the use of sand in equestrian platforms had a reduced
impact on the environment when compared to the used tyre alternative surface which resulted
in a retrograde impact on the environment. (Alongi Skenhall. S, et al, 2010)
The conclusions from these studies, with the exception of the equestrian surface LCA in the
IVL study, prove that the re-use or energy recovery of used tyres is fundamentally positive
when compared with conventional methods and baseline scenarios which use non ELT
materials and methods.

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2.2 Legislation and Initiatives
The waste tyre generation and circulation is governed by the legislation imposed on the region
in question. Irish tyre circulation is governed by the following National and European
legislation and Initiatives:
2.2.1 End-of-Life Vehicle Directive
In 2000 the European commission introduced the ‘’End-of-life Vehicle Directive’’ which
states that 80% of an end life vehicle be reused or recycled by 2006 with this jumping to 95%
by the 1st of January 2015 with the management of used tyres playing an important role in
achieving this target (EC, 2000). Due to this the Irish government decided it was imperative
that a financially viable, energy efficient and dependable method of dealing with this difficult
and large waste stream was adopted on a national level to ensure Ireland complies with EU
legislation which banned the landfilling of whole tyres from 2003 and shredded tyres from
2006 in the Landfill Directive (EC, 1999). However the European commission’s directives
did not stipulate how these targets were to be achieved and left this to the member states.
2.2.2 Waste Management (Tyres and Waste Tyres) Regulations 2007
In response to the EU landfill directive and the End-of-life Vehicle Directive, Ireland
implemented the ‘Waste Management (Tyres and Waste Tyres) Regulations 2007’ on the 1st
of January 2008 in an effort to monitor the waste stream of used tyres under more scrutiny
and impose more responsibility on the suppliers of Tyres in Ireland (S.I. No 664, 2007).
These regulations require producers of new tyres to provide details by the 28th of February
each year on the amount of tyres sold to suppliers in tonnes and the category of tyres sold
ranging from 1-7 e.g. HGV, Motorcycles, re-treaded etc. Regulations enforcing waste tyre
collectors were also installed requiring them to produce information regarding the category,
location and weight in tonnes of waste tyres collected. This allowed the Department of

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Environment, Community and local government to trace the movement of new and used tyres
in Ireland and ensure greater responsibility for the disposal of these tyres was put on
producers and suppliers.
2.2.3 ‘TRACS’
An exemption from these obligations is granted to those who participate in TRACS (Tyre
Recovery Activity Compliance Scheme) the voluntary compliance scheme that has been
developed by the department and the tyre industry. TRACS main aim is to ‘’promote
legitimate reuse and recycling of waste tyres’’ (TRACS, 2012). It works like many of its
European counterparts producer responsibility systems e.g. ‘Signus’ in Spain or ‘SDAP’ in
Sweden, even though it operates on the free market. Ireland administrated this free market
system in 2008, which assumes that profitability could be achieved through the recovery and
recycling of tyres. This model assumes that used tyres are a source of valuable raw materials,
the management of which is profitable to the firms involved however this has posed quite a
challenge (Sienkiewicz M, 2012).
The European tyre and rubber manufacturers association state that the widely used producers
responsibility initiatives introduced in 16 of the 27 European countries, of which Ireland is
not one of, ‘’ appears to be the most suitable and robust for addressing and resolving end of
life tyre arising’s, in a sustainable manner for the long term, and to achieve a 100% recovery
rate, in the most economical way.’’ There are currently 26 organisations registered with
TRACS permitted to collect waste tyres in Ireland. (TRACS, 2013) The diagram below shows
how this system works.

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Figure 1 shows the process of extended producer responsibility in the European Union.
(ETRMA, 2010a)

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2.3 Waste Tyre Circulation in Europe and Internationally
Annually, global production is estimated to be 1.5 billion tyres which at one stage will
become ELTs (End-of-life tyres) (IRSG, The World Rubber Industry Review and Prospects to
2020, 2010). In Europe alone the cost of managing these tyres is thought to be about €600
million. (IRSG, 2010)
Three of the world’s biggest tyre consumers Europe, the US and Japan have made a
significant increment towards complete waste tyre recovery. Since 1994, Europe has
increased its tyre recovery from 21% of the market share to 96% ELT recovery(2010), while
the US has made a more modest increase from 50% waste tyre recovery in 1994 to 82% in
2010.
Since 1996, Japan has had a recovery rate which has never dropped below 80%, as of 2010
the total amount of waste tyres in the country being subjected to some form of energy
recovery; re-use or recycling is just below 90% (ETRMA, End of Life tyres, 2011). See graph
1 below. This huge leap over a relatively short period of time is thought to be down to a
reduced cost of recycling to consumers because of factors like the streamlining in
management structures and the increase in variation of waste tyre management options.

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Graph 1: Estimated end oflife tyre recovery rates in three contrasting markets internationally
over the last 17 years.
Graph generated from figures taken from ETRMA End of life tyres 2011
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010
Historical recovery rates for ELTs inmajor international
markets
Japan
US
Europe

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2.5 Illegal Stockpiling
The RTE current affairs program ‘Primetime’ investigated illegal tyre dumping in Ireland and
found that the blanket ban on all forms of waste tyres, shredded or otherwise caused major
stockpiling above ground of tyres to avoid costs associated with the disposal of tyres. This not
only exasperates the problem but leads to issues of health and safety. (Primetime Investigates
–Illegal Tyre Dumping, 2010) This implies Ireland still has a problem regarding the disposal
of waste tyres with such illegal activity risking both government imposed fines on those
partaking in dumping and European fines against the state if the problem is identified and
persists.

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2.6 Current leading methods of Tyre disposal
When tyres have been used and disposed of there are a limited number of options which can
be utilised to ensure they are not illegally stockpiled or burned. In Ireland the process
typically follows the diagram below with the exception of pyrolysis and gasification.
Figure 2: Process a typical used tyre would encounter depending on waste criteria
(ETMRA, 2009)
2.6.1 Landfill
Tyres are undesired at landfill because of their 75% void space and the difficulty in breaking
down the highly stable carbon black composition it is composed of. The most recent figures
on Ireland’s annual production of used tyres indicate that in 2010 35,000 tonnes of Waste
Tyres was created with 3,000 tonnes of this assumed to have found its way to Landfill
(ERTMA, 2010b). On a European level the amount of used tyres going to landfill has dropped
from over 60% of total produced waste tyres in 1994 to under 5% in 2010 (Sienkiewicz M,
2012).

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2.6.2 Mechanical Breakdown
Material recycling by means of mechanical breakdown without energy recovery is thought to
be currently the most common form of tyre recycling in use today. ‘’ It is realized as
mechanical grinding of tyres, which yields rubber materials of different degrees of
comminution, or as devulcanization, which produces rubber regenerates ‘’ (De S.K et al,
2005) This process begins with the shredding of tyres prior to the removal of any steel wire or
reinforcing fibre. The resulting rubber granules or ‘crumb’ natural and synthetic rubber is
ready for devulcanization which is the breaking down of the rubbers sulphur cross-linkages.
This process is necessary prior to used tyres use as TDF in the cement kiln.
2.6.3 Re-treading
Re-treading is a process for extending the lifetime of tyres. It is based on the preliminary
preparation of a tyre for regeneration, by stripping it of its tread and then applying a new one.
Only tyres that have passed a wear and tear inspection, and have been certified to have no
damage to the tyre carcass, may be re-treaded. (Glijer, Lipinska. 2002) In 2010, 2,000 tonnes
of waste tyres was re-treaded in Ireland (ERTMA, 2010b).
Re-treading of tyres is seen as innovative way to re-use waste tyres and provide a cheaper
alternative to buying newly produced tyres but there is a public perception that the products of
re-treading are unsafe compared to new tyres (G, Ferrer, 1997). However this has been proved
to be erroneous by a number of studies conducted relatively recently, including one carried
out by Northern Irelands Assembly’s committee for the environment who published ‘An
Interim Report on the Committee's Inquiry into Used Tyre Disposal’ that stated ‘’re-treading
used tyres has become highly specialised and improved technology ensures a safe product’’
(NIA: CE, 2012). In addition, the multinational tyre producer Bridgestone claims that the re-
treading of a tyre uses only 32% of the petroleum resources needed to create a new tyre.
(Bridgestone, 2012)

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The process is considered a viable business enterprise with a number of companies in Ireland
already partaking in re-treading and new companies are currently being set up including ‘Eco
tire tread solutions’, Belturbet, Co. Cavan. An LCA was carried out later in this study
comparing the CO2 production of re-treading with the use of TDF in cement kilns.
2.6.4 Pyrolysis
The use of Pyrolysis in Ireland is currently considered a future technology. The management
of used tyres by means of pyrolysis is based on the decomposition of the elastomers contained
in the rubber as a result of heating them to temperatures of 400–700 °C, in the absence of
oxygen (Solid Waste Engineering, 2002). Products include solid residue (char) and a synthetic
gas (syngas). Char is a combination of non-combustible materials and carbon. Because of the
absence of oxygen in the initial process less dioxins and furans are released however if the
char and gas is combusted later on these will be released. One method being adopted is to
deep bury the char in designated sites of landfills.
A report published by MCOS, a Kilkenny based architect working for ‘Dublin Corporation’
produced a ‘Report on Residues from Thermal treatment’ for a Dublin waste to energy project
which deals with the emissions an energy recovery plant in the Dublin area could release.
Table 1: Emissions from a proposed pyrolysis plant in Dublin
Waste Generated Percentage (w/w) Amount (tonnes per year)
Gas/Liquids 50 – 60% 125,000 - 240,000
Char 30 – 40% 75,000 - 160,000
Residues 10% 25,000 - 40,000
(Figures taken from ‘Report on residues from thermal treatment, 2007)

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The main concern with the method of pyrolysis is the remaining ash or char. It can be used as
a fuel onsite along with the gas and liquids produced however it has a low calorific value and
an expensive flue gas scrubbing system would be required. Another option is too use it as a
low grade form of activated carbon for wastewater and flue gas scrubbing however the MCOS
reports that such a market for char would be difficult to attain in Ireland with the current
providers available e.g. ‘Acorn Water’. The remaining option for the disposal of this char is to
send it to landfill however this is not ideal as there is a risk that heavy metals will find their
way into the groundwater.
The construction and operation of a pyrolysis plant as a waste management solution for used
tyres in Ireland is highly unlikely due to the start-up costs of such a plant, the absence of a
large enough waste stream and the availability of already established options in Ireland
2.6.5 Whole Tyre Re-use
There are a number of common practices which can utilise the complete waste tyre, and
provided the need for such a re-use does exist it can be a very useful method of tyre disposal.
The most common needs arising for whole waste tyre re-use in Ireland are for the capping of
silage pits on farms and for the protection of small vessels hulls in Irish marinas but other
small scale needs exist. ‘’Many garages pay a nominal cost to have their used tyres
periodically collected by a contractor who then sells the tyres on to farmers for use on their
silage pits however other reuse options for tyres include landfill engineering, dock-fenders,
playgrounds, artificial reefs and several other small-scale applications.’’(EPA, 2000) 8% of
Irish tyres were reused in some way in 2011 which amounts to 3000 tonnes.
2.6.6 Use as Tyre Derived Fuel in Cement production
In the European ‘Waste management hierarchy’ there are 5 different classifications of waste
management which, based on their environmental impacts range from most favourable option

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to least favourable option, which includes prevention, minimisation, re-use, recycling and
disposal. (EC, 1998) The method of using shredded tyre as combustible fuel to replace
conventional fuels in cement kilns is a form of energy ‘recycling’.
It is widely practiced in mainland Europe (for example Hanson-Heidelberg cement groups
plant in Stamford, Lincolnshire, UK uses 9,000 tonnes of tyre derived fuel (TDF) which
negates ‘’approximately an equal volume of coal use’’ and is thought to be quite
environmentally advantageous due to the avoidance of tyres going to landfill and fossil fuel
use in kilns. (Hanson-Heidelberg, 2013) The use of TDF is known to reduce greenhouse gas
emissions from cement works. (Schmidt, et al. 2009)
There are four cement plants in Ireland which have received approval to burn alternative fuels
(400,000 tonnes of Alternative fuel per annum in total) including Lagan cement, Co.
Westmeath, Irish Cement facilities in Co. Louth and Co. Limerick and Quinn cement, Co.
Cavan. (CMI, 2013) The 400,000 tonnes allowance dwarfs Ireland’s current used tyre
production which ranges between 30,000 and 40,000 legally collected tonnes per annum.
Lagan Cement was granted its first Integrated Pollution Prevention and Control (IPPC)
Licence by the EPA in November 2001 and most recent in March 2012. In January 2009 the
EPA reviewed Lagan Cements IPPC licence and granted permission for the use of Solid
recovered fuel (SRF) and TDF. (EPA, 2012)
Companies involved in the mechanical breakdown of used tyres in Ireland are currently
lobbying for the co-combustion of ground tyres in the cement production process e.g. ‘Crumb
Rubber’ Ltd, one of Irelands largest mechanical tyre shredding companies submitted an
objection in 2010 to the EPA licencing office with regards to the use of tyres for WtE.
(Kerley, L. 2010)

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It is currently a widely used and internationally applauded method with great potential in
Ireland and has formed the basis of Scenario A in this LCA.
Picture 1: TDF being stored prior to use at Lagan cement, Kinnegad, Co. Westmeath

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2.7 Life cycle assessment
A life cycle assessment is a set of ‘’systematic procedures for compiling’’ and examining the
inputs and outputs and energy involved in a product, process or service (ISO 14040.2 Draft:
Life Cycle Assessment - Principles and Guidelines, 1999. It is a common way of determining
which product, practice or process has a greater impact on the environment by providing the
results of a comparative study. (Welford, Gouldson, 1993)
2.8 ISO: 14040:2006
The international standard of LCA is laid out in ISO: 14040:2006 or ‘Environmental
management - Life cycle assessment: Principles and framework’ which will form the basis of
the study. This method of assessment has been used in a number of similar studies including
‘End life tyres: Alternative final disposal processes’ by Andrea Corti and the ‘Alipur’ study
‘Life Cycle Assessment of nine recovery methods for ELT’. The LCA, according to ISO
14040 is generally considered to be composed of four major phases. (ISO 14040, 2006)
2.8.1 Defining goals and scope of study
The first phase of carrying out an LCA using ISO 14040 entails stating the objectives of the
study and creating the boundaries to which the study will be confined. The creation of a
‘functional unit’ is a key part of this phase as it allows the achievement of comparison with
regards to each methods use of inputs and the environmental impacts of their outputs
(Rebitzer, G, et al, 2004).
2.8.2 Life cycle inventory assessment
This phase of the LCA compiles each interlinked processes inputs and outputs associated with
the methods being studied and typically involves the creation of a materials and energy inputs
flow from nature to the processes outputs. (ISO 14041, 1998)

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Figure 3: Flow chart of LCA inventory assessment (EPA, 1993)
2.8.3 Assessment of Impacts
From a successful inventory analysis which comprehensively comprises inputs and outputs,
ideally the main environmental strains and impacts from each process can be identified under
well-defined and specifically chosen categories which depend on the aims of the study. (Corti,
A, 2004) In this LCA, the production of CO2 from each Scenario will be assessed based on
the gases potential as a greenhouse gas.
2.8.4 Interpretation of results
This involves the generation of a summary from all the previous phases of the LCA (see
Diagram No. 3 below) and the creation of unbiased conclusions and recommendations from
the study. It is critically important that the interpretation phase is carried out with due
consideration to the accuracy and potential failings of the study up to that point.

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Figure 4: The Phases of a typical LCA (ISO 14040, 2006)

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3.0Methodology

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3.1 Definition of Goals and scoping
The goal of this LCA study is to compare two accessible methods of tyre disposal in the Irish
context. They are: the use of shredded tyre in the cement production kilns e.g. practiced at
Lagan Cement, Co. Westmeath and the tyre re-treading process an example of which is ‘Eco
tyre tread solutions’, Bellturbet Co. Cavan.
The study will use data from previous LCA studies on TDF use in cement kilns and the re-
treading process to deduce the amounts of CO2 released for every functional unit managed.
These results will be applied to the results from the study which assessed the latest volumes of
waste tyres produced in Ireland using the figures for problematic tyre streams which need to
be addressed i.e. those being exported and going to landfill. This will form the Baseline
Scenario.
The LCA will take environmental considerations into account however the study will not look
at the economics of each method unless relevant to the process’s function, inputs and outputs
with the aim of garnishing comparisons based on CO2 release from each Scenario.
3.1.1 Establishing the Functional Unit
For the purposes of comparison between the information gathered on the Baseline Scenario,
Scenario A - the TDF combustion in cement kilns and Scenario B - the re-treading of tyres in
Ireland the functional unit that will be the problematic waste stream of 3000 tonnes of whole
waste tyres.
3.1.3 System boundaries: Baseline Scenario – Current management of Irish ELTs
The LCA will use the Baseline Scenario, generated from the figures attained in the first part
of the study, 3000 tonnes of tyres from problematic waste streams managed inadequately or
through an avoidable environmentally harmful method i.e. Landfill and Export (Shown in red
in Table No.2 below).

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(ETRMA. 2010, 2011)
Table 2: Share of each recovery method currently practiced in Ireland
(ETRMA. 2010, 2011)
The Baseline Scenario will calculate the CO2 production from 2000 tonnes of tyres being sent
to landfill and 1,000 tonnes being exported for treatment annually. The CO2 production of the
combustion of 3000 tonnes of coal and creation of 3750 tonnes of new tyres (as the re-
treading of 3000 tonnes of used tyres, each weighing 7.2 kg would result in the creation of
3750 tonnes of re-treads with an individual weight of 9 kg) will also be factored in as these
processes are commercial and participation by cement producers and new tyre manufacturers
would be fulfilled regardless.
By assessing the CO2 emissions from each of these activities and combining the results the
Baseline Scenario will be created using the latest figures on Irish waste tyre management
provided by ETRMA.
3.1.3 System boundaries: Scenario A – TDF use in Cement Kilns
The LCA will take the entire flow of one functional unit of whole tyres through the TDF
combustion process in a typical cement kiln using the Lagan Cement facility in Kinnegad, Co.
Westmeath as an Irish reference facility, in place of an equal volume of Coal. The study will
Year Reuse Re-tread Export Civil Engineering Recycling Landfill Total
2010 3,000 2,000 2,000 8,000 17,000 3,000 38,000
2011 3,000 2,000 1,000 6,000 14,000 2,000 28,000

26
look at the energy requirements during the shredding stage, tyre loading or feeding stage and
the combustion requirements of the functional unit through the kiln system itself. This
Scenario will however still take into account the CO2 production of 3750 tonnes of new tyres
which will be produced in place of the avoided re-treaded alternative possiblity. The LCA will
garnish the resultant emissions of CO2 and any solid waste generated from these processes to
identify any long and short term affects which may lead to environmental degradation and
apply the results to the current arising Irish waste tyre situation.
3.1.4 System boundaries: Scenario B – Use of Tyre re-treading
The energy requirements of the 3000 tonnes of used tyres will be traced through the tyre re-
treading process using figures generated from a similar comparative study that assessed the
CO2 emissions from the production of new tyres and the re-treading of used tyres. The study
will use the ‘Eco tyre treads solutions’ facility in Belturbet, Co. Cavan as an Irish reference
facility that could possibly carry out this management technique. This part of the LCA will
also identify any short and long term environmental impacts related to the re-treading process.
In this Scenario however the CO2 emissions of the 3,000 tonnes of coal used in place of the
avoided TDF option will also be factored in.
3.1.5 Assumptions and Limitations
This study assumes that 100% of the functional unit is suitable for re-treading to ensure
comparisons can be made between each Scenario.
For the purpose of this study it has been assumed that the transportation emissions are equal
between both facilities in question and therefore will not be factored in.
It will be assume that the energy used for the manufacture of re-treads and the shredding and
feeding of waste tyres into the WtE system is generated by power generation coal fired
stations.

27
The CO2 ‘Emission factor’ for the creation of electricity in Ireland is 135.7 t CO2/TJ. (SEAI,
2011)
According to a report by Jim Rushworth, the National energy manager of one of the United
Kingdom’s largest Cement producers ‘Lafarge’, the combustion of 1 tonne of used tyres or
the combustion of 1 tonne of coal in a Cement kiln would each produce 2,400 Kg of CO2.
(Rushworth, 2002)
A study by environmental consultants ‘Best foot forward’ commissioned by the ‘Centre for
Remanufacturing & Re-use’ titled ‘The Carbon footprint of re-treaded vs. new vehicle tyres’
the re-treading of each individual tyre produces 60.7 Kg CO2 while the production of a new
tyre is equivalent to 87.2 kg CO2. (CRR, 2008)
The study assumes that the average weight of one new car tyre is 9kg and that there is a 20%
mass decrease during use (Ravindra, K. 2001) therefore the weight of an average used tyre is
taken as 7.2 kg.
According to the US EPA’s report on ‘Landfilling’, there are no Net greenhouse gas
emissions from the decomposition of tyres in Landfill due to the materials stable composition.
(US EPA, 2012)
For the purpose of this study it will be assumed that any used tyres being exported are subject
to Landfilling.
3.1.5 Life Cycle Impact Assessment
The Impact assessment will distinguish if a Scenario has a Positive or Negative impact on the
Environment based on whether it produces less or more CO2 then the Baseline Scenario. The
Baseline Scenario will be classed as neutral as it represents current practices up to 2011.

28
4.0 Results

29
4.1 Results Presented
The results obtained in this study vary from information gathered on national, European and
international organisations and databases and results from the calculation of CO2 emission
factors for each Scenario. The results are presented as follows:
 Current scope of waste Tyre Circulation in Ireland
 Life cycle inventory assessment
1. Baseline Scenario: Based on current Irish ELT management trends
2. Scenario A: Substitution of coal with TDF in Cement production
3. Scenario B: Application of used tyres in Re-treading Process
 Comparison of Scenarios

30
4.2 Current scope of waste Tyre Circulation in Ireland
Chart No.1 shows the distribution of waste tyre management routes in Ireland in 2010 using
figures attained from the ‘European tyre and rubber manufacturers association’
Chart 1: Distribution of ELT management routes in Ireland in 2010.
In 2010, 15% of Irelands used tyres were either sent to landfill or exported. Recycling of used
tyres e.g. Use as TDF, was by far the largest method of ELT management in Ireland.
This means in 2010 Ireland subjected 85% of its waste tyres to some form of energy recovery,
re-use or recycling.
Chart No.2 Shows the distribution of Irelands ELTs management routes in 2011 generated
using the latest figures from ‘European tyre and rubber manufacturers association’
8%
6%
6%
23%
48%
9%
Distribution of used tyres between recovery
/disposal options in Ireland 2010
Reuse Re-treaded Export
Use in Civil Engineering Recycling Landfill/Unknown

31
Chart 2: Distribution of ELT management routes in Ireland in 2011.
According to the European tyre and rubber manufacturers association, of the 28,000 tonnes of
used tyres generated in Ireland in 2011 about 3000 tonnes were reused. 2000 tonnes of used
tyres were also subjected to the re-treading process in Ireland today however the same amount
was exported for treatment abroad. While use in civil engineering and recycling accounts to
8,000 tonnes and 17,000 tonnes used tyres respectively.
In 2011, Irelands managed 89% of the waste tyres produced with some form of energy
recovery, re-use or recycling.
11%
7%
4%
21%50%
7%
Distribution of Used tyres between
recovery/disposal options in Ireland 2011
Reuse Re-treaded Export
Use in Civil Engineering Recycing Landfill/Unknown

32
4.3 Life cycle inventory assessment
This section contains the calculations and CO2 production results from the
occurrence/implementation of each Scenario using data gathered from various sources laid out
in the Assumptions and Limitations section.
4.3.1 The Baseline Scenario
The functional unit of 3000 tonnes of used tyres is divided between 2000 tonnes going to
Landfill and 1000 tonnes being exported for landfilling abroad. The average feeding system
energy requirements for 1 tonne of coal into a cement kiln is 0.413MJ. (Corti, A. 2004) This
means that the feeding of 3000 tonnes of coal into the combustion process at a cement plant
would be result in the use of 1239 MJ of electricity generated by a coal fired plant. (3000 X
0.413 = 1239). This is equal to 1.239 X 10-3 TJ. When this is multiplied by the emission factor
for coal fired power stations a CO2 production of 0.1681 tonnes of CO2 is obtained.
The combustion of the 3000 tonnes of coal itself is equal to the emission of 7200 tonnes of
CO2 (2.4 X 3000 = 7200).
The production of 3750 tonnes of new tyres, which was explained in the System Boundaries
of the Baseline Scenario, at 9kg per tyre, would mean the manufacture of 416666.6 new
individual tyres. The creation of each new tyre produces 87.2 kg/CO2. This means a total
emission of 36333.3t/CO2 per functional unit. (416666.6 X 87.2 = 36333333.33)
The total CO2 emission from the Baseline Scenario is 43533.5.835 tonnes of CO2.
Table No. Shows the CO2 emissions related to each impacting process from under the current
methods of waste tyre management in Ireland.

33
Table 3: CO2
production in the Baseline Scenario
Process Quantity (t) CO2 Emission (t)
Landfilling of used tyre 2000 -
Export of used tyres 1000 -
Coal Feeding 3000 0.1681
Coal Combustion 3000 7200
New tyre manufacture 3000 36333.3
Total 43533.5835 tonnes/ CO2
4.3.1 Scenario A: Substitution of coal with TDF in Cement production
To assess the amount of CO2 produced from the replacement of Coal in a cement kiln with
TDF, figures from previous LCA’s were obtained. There are three phases in the Tyre Derived
Fuel process which includes tyre shredding, system feeding or loading and finally
combustion. The first two phase’s uses power generated from coal fired electricity while the
final phase is carried out using energy generated by TDF. The use of TDF does not produce
any solid waste as whatever resultant ash is created during combustion ends up in the cement
product itself. (Portland cement association, 2008)
The CO2 ‘Emission factor’ for the creation of electricity in Ireland is 135.7 t CO2/TJ. (SEAI,
2011) 170,413KJ of energy is used during the tyre shredding and feeding system processes
per tonne of TDF. When multiplied by the functional unit and converted to TJ (170413 X
3000 = 511239000 KJ which equates to 0.51123 TJ) the conversion factor for CO2 emissions
of electricity generated can be applied and the amount of CO2 released per functional unit can
be identified. The resultant CO2 emission is 69.3751t/CO2 per functional unit fed into the
system. (135.7 X 0.51123 = 69.3751)

34
This means that the estimated production of CO2, when added with the 7200kg/CO2 per
functional unit produced from the combustion of the total shredded TDF in the cement Kiln
equates to 7269.375t/CO2.
However, the manufacture of 3750 tonnes of new car tyres in place of the avoided re-tread
option would mean a further 36333.3 t/CO2 generated.
In total, Scenario A would produce 43602.67t/CO2 per annum.
Table 4: Calculation of CO2
emissions from Scenario A
Landfilling of used tyres 0 -
TDF Shredding/Feeding 3000 69.3751
TDF Combustion 3000 7200
New tyre manufacture 3000 36333.3
Total 43602.67 t/CO2 per annum
4.3.3 Scenario B: Application of used tyres in Re-treading Process
This Scenario involves the re-treading of the 3000 tonnes of waste tyres that are currently
going to landfill and subject to landfill. This would offset any emissions created by the
manufacture of 3000 new tyres for the Irish market but would result in the use of coal as fuel
in a cement plant as opposed to TDF.
The weight of each individual used tyre is equal to 7.2Kg; therefore the functional unit would
contain 41666.6 used tyres (3000000 ÷ 7.2 = 416666.6). This means the re-treading of the

35
entire functional unit would result in the production of 25291.6t/CO2. (416666.6 X 60.7 =
8355.76 kg/CO2/t)
Using the CO2 emissions released from coal feeding and combustion in the cement production
system identified in the Baseline Scenario this would result in the generation of a further
0.1681t/CO2 and 7200t/CO2.
In total, Scenario B would produce 32491.7t/CO2 annually to deal with Irelands problematic
waste tyres.
Table 5: Calculation of CO2
emissions from Scenario B
Landfilling of used tyres 0 -
Coal Feeding 3000 0.1681
Coal Combustion 3000 7200
Used tyre re-treading 3000 25291.6
Total 32491.7 t/CO2 per annum

36
4.4 Comparisons of Scenarios
Graph 2 shows the total annual CO2 production from the event of each Scenario.
Graph 2: CO2 emissions arising from each Scenario annually
Graph 3 shows the CO2 emissions arising from the use of 3000 tonnes of waste tyres as TDF
or and an equal volume being subjected to re-treaded.
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
Baseline Scenario Scenario A Scenario B
tonnes/CO2perfunctionalunit
CO2 emissions of eachScenarioannually

37
Graph 3: CO2 emissions arising from both individual recovery routes
The upper phases of the TDF use in the cement kiln i.e. Shredding and feeding, are combined
with the CO2 emissions from the wastes combustion itself and compared with the emissions
of the re-treading process.
Graph 4 Shows the amounts of CO2 in tonnes released from the feeding and combustion of
one functional unit of coal compared the functional unit being utilised as TDF in the cement
kiln.
0
2500
5000
7500
10000
12500
15000
17500
20000
22500
25000
27500
Use as TDF Re-treading
tonnes/CO2perfunctioalunit
CO2 Emissonfrom the waste managment routes alone

38
Graph 4: CO2
emissions from Coal vs. TDF use in cement kiln
Graph 5 shows the amounts of CO2 produced from both the manufacture of 3750 tonnes of
new tyres at 9kg per tyre and the re-treading of the equivalent 3000 tonnes of used tyres at 7.2
kg individually.
5000
5200
5400
5600
5800
6000
6200
6400
6600
6800
7000
7200
7400
Use of Coal Use of TDF
tonnesofCO2perfuntionalunit
CO2
productionfromCoal and TDF use incement kilnper
functioal unit

39
Graph 5: Difference in CO2 emissions between re-treading 3000 tonnes of used tyres with the
manufacture of an equivalent amount of new tyres
0
5000
10000
15000
20000
25000
30000
35000
40000
New tyre manufacture Used tyre re-treading
tonnes/CO2perfunctionalunit
CO2
producedby re-treading 3000 tonnes of usedtyres or
manufacturing the equivalant amount of new tyres

40
4.5 Life Cycle Impact Assessment
Table 6 Shows the impact each Scenario would have on the environment in relation to its CO2
production compared to the Baseline Scenario.
Table 6: Environmental Impact assessment of each Scenario
Scenario Baseline Scenario Scenario A Scenario B
Impact Assessment Neutral Negative Positive

41
5.0 Discussion

42
5.1 Interpretation of Results
The areas that will be discussed include:
 The results obtained on Ireland’s generation of ELTs and the adequacy of its current
treatment.
 The development and Inventory assessment of each Scenario will then be discussed.
 The comparison of Results from all Scenarios and the limitations of the study.
 The impact of the results environmentally and in Irish context looking forward.
5.2 Current Scope of Irish Waste Tyre Management
Acquiring information on the volumes of waste tyres generated in Ireland proved difficult
with little information provided by TRACS or on the EPA’s National Waste Reports for 2010
or 2011. Much of the information gathered to assess the current scope of Irelands waste tyre
management and generate results was gathered through the European tyre and rubber
manufacturer’s publications. This meant that comparisons could not be made between various
sources of information and unfortunately results from an Irish organisation or agency could
not be used. One of the objectives of this study was to create a comprehensive and factual
report on the state of Ireland’s waste tyre generation and management proved to be quite
difficult due to the lack of information provided from reputable Irish sources.
One major facet of Irelands ELT generation which could not be assessed was the volume of
tyres currently being stockpiled or illegally managed. The Irish EPA had no information
regarding the practice of illegal tyre management and a number of other Irish stakeholders in
Irish waste tyre management including TRACS and the Mayo County council could not
provide any information on the extent of this practice for the purpose of this study.

43
However Environmental enforcement officer, Sean Scott from the Leitrim County Council
claimed that the number of illegally stockpiled tyres is difficult to access because much of the
information regarding charges and size of seizures related to this criminal activity is currently
subject to court judgments and therefore is withheld. However he claims that a seizure of
1,000,000 individual tyres was made in the West of Ireland in the last two years. This, if
correct, would represent 9,071 tonnes of tyres at an average weight of 9.07185kg. (EPA,
2000) This may indicate why the volumes of Irish waste tyres fluctuated between various
sources and publications. Due to this lack of sourced information, the tyres illegally stored or
dumped in Ireland could not be represented in the findings of this study.
The publication of the latest results from ETRMA indicates Ireland had a collective waste tyre
recovery rate of 89% in 2011, up 4% from the Associations corresponding publication in
2010 (See chart No. 1 and Chart No.2). These results correspond with the continuous pattern
of growth shown in the US, Europe and Japan in Graph No.1. Between 2010 and 2011, the
results show any changes in Irelands waste tyre management was unanimously positive. There
was a 2% drop in both the amount of tyres going to landfill and the amount being exported for
treatment. This dramatic change in recovery rates of end of life tyres in one year can be seen
as evidence that products and energy derived from waste tyres is becoming a more important
secondary commodity financially to countries all over the world including Ireland. However
Ireland’s recovery rate of 89% is still considerably below the European average of 96%
shown in Graph No.1.
On January 1st 2015 the European ’End-of-life Vehicle Directive 2000’ will increase the
requirement that 80% of a scrap vehicle must be recycled or re-used to 95%. This means that
Ireland must implement a strategy to ensure all its waste tyres avoid disposal in landfill, with
2000 tonnes still being managed through this route. The formation of TRACS was based on
the assumption that used tyres are a valuable resource and this assumption has been proved to

44
be true in a number of studies. (Sienkiewicz M, 2012) However 1000 tonnes of Waste tyres in
Ireland are being exported at a direct cost to the people exporting the ELT’s and to the
business’s established in Ireland capable of treating this waste stream adequately like both the
TDF use capable cement facility at Lagan cement and the re-treading operation in Co. Cavan.
This volume of untreated Irish waste tyres indicates that there is a need for the
implementation of a strategy by the Irish government to ensure it doesn’t lag behind its
European counterparts. The results show that no one method of waste tyre treatment
dominates Irish waste tyre management (See Chart No.1 and Chart No.2) and this may
indicate that much of the needed infrastructure and technologies are already in place to negate
poor management of ELTs.

45
5.3 Baseline Scenario
From the assessment of Ireland waste management strategies the Baseline Scenario was
generated to calculate a representative figure through which the utilisation of the re-treading
and TDF technologies could be compared. One of the most important aspects of creating the
Baseline Scenario was to ensure the results were representative of the management routes the
waste tyres were subjected to in Ireland in 2011. However to ensure time constraints were met
only the ELT routes considered to be disposal methods were assessed.
The figures of 2000 and 1000 tonnes of tyres going to Landfill and exported respectively were
employed as waste generated and disposed of without any CO2 emissions using a publication
by the Ohio EPA on Landfill emissions in 2000. This does conflict with another study by the
tyre manufacturer ‘Pirelli’ titled ‘Existing plants, waste-to-energy and CO2 reduction: a
sustainable equation’ that states that WtE technologies using TDF do negate some CO2
produced by waste tyres in Landfill however no detailed information has been gathered on
such emissions. (Pirelli, 2005) The unabated coal use in the cement facility and new tyre
manufacture was also factored in to create total CO2 emissions from the path that was, as of
2011, used (See table No.2).
The total CO2 emissions from the Baseline Scenario were 43533.5.835 tonnes of CO2 (See
Table No.2) The main contribution to this figure, which was 36333.3 tonnes of CO2, came
from the manufacture of new tyres which uses energy in the manufacture phase along with
considerable petroleum resources in the tyres composition. This figure was generated using
‘The Carbon footprint of re-treaded vs. new vehicle tyres’ publication by the ‘Best Foot
Forward’ environmental consultancy which stated that the production of one new tyre resulted
in 87.2kg/CO2 emitted while the re-treading of one new tyre produced 60.7kg/CO2. This

46
meant a reduction of 23.1% in CO2 emissions. However the review of the re-treading
literature and practices identified a study by the tyre manufacturer ‘Bridgestone’ which
concluded that re-treading one tyre used 32% less petroleum resources. This may have been
due to the energy requirements of the inspection and moulding phases and therefore the ‘Best
Foot Forward’ study was used in the inventory assessment.

47
5.4 Scenario A
This Scenario was created to attain the representative CO2 emissions from using the entire
problematic waste stream in TDF. To ensure that this Scenario could be used for comparative
purposes all factors which resulted from its use in one process or no non-utilisation in another
had to be identified and assessed. Coal use was therefore omitted while the creation of new
tyres included.
The emission factor for coal combustion matched that of TDF combustion in Cement Kilns at
2.4 tonnes CO2 per tonne of TDF. This figure was attained from a study by Jim Rushworth,
the National energy manager with ‘Lafarge’, one of the United Kingdom’s largest producers
of cement. This figure was used because of the likely similarities between practices and
technologies used in the UK and those used in Ireland. Another study, ‘Carbon Dioxide
Emission Factors for Coal’ by B.D Hong colluded that one tonne of coal would generally emit
2.86 short tons of CO2 which equates to 2.55 metric tonnes of CO2. (Hong, B.D, 2009)
This meant that the difference between the Baseline Scenario’s and Scenario A’s CO2
emissions had were relatively close however the results may have been altered if further data
on both the Baseline Scenarios Landfill and Export CO2 emissions and Scenario A’s coal
extraction related emissions could have been identified and factored into the calculations.
The major contributor to the total CO2 emissions of 43602.67t/CO2 per functional unit was
again in this Scenario the manufacture of new tyres with 36333.3t/CO2 attributed to this
process (See Table No.3). However the shredding phase required for the feeding and
combustion of the TDF also added to the Carbon dioxide emissions which resulted in the
management route proposed in Scenario A being 69.0865tonnes more CO2 emitting than the
Baseline Scenario. However Scenario A did ultimately provide a management route for the
waste tyres in question and ensured this was done with environmental responsibility.

48
5.5 Scenario B
Scenario B was based around the allocation of the functional unit of used tyres to the re-
treading process. By creating this Scenario, comparisons could not only be made in CO2
emissions between the re-treading process and the use of TDF in WtE practices but by also
factoring in the abated or resultant processes the overall CO2 implications could be
determined.
The processes calculated in this Scenario was the feeding and combustion of 3000 tonnes of
coal in the cement Kiln and the re-treading of 3000 tonnes of used tyres. The total CO2
emissions from this Scenarios implementation were 32491.7t/CO2 (See Table No.4) per
functional unit which was considerably less than the CO2 emissions from Scenario A and
Scenario B. The main contributor to this result was the re-treading of the waste tyres however
it was 23.1% less than the creation of the equivalent amount of new tyres identified in Table
No.2 and Table No.3.
One major problem encountered in this part of the study was the fact that 3000 tonnes used
tyres for re-treading did not equate to 3000 tonnes of newly manufactured tyres. This was due
to the weight difference in used tyres (one used tyre weighs about 7.2kg) and the weight of a
new tyre (9kg). (Ravindra, K. 2001) This meant that this part of the study had to be carried
out by calculating the number of used tyres at 7.2kg in 3000 tonne and multiplying this by the
weight of a new tyre.
Another limitation in this study was the assumption that 100% of the used tyres would be
acceptable for the re-treading process. This was assumed to ensure comparisons between each
ELT management method could be gauged and results could be generated. However it is
widely accepted that a comprehensive study on re-treading is a difficult undertaking due to
variances in treatment methods and materials. The Michael Wischhusen director of

49
‘Goodyear’ the tyre manufacturer stated ‘’What makes quantitative assessment of re-treaded
tires daunting is the fact that there are 1000s of different casings, with dozens of tread
material, with dozens to hundreds of different re-treading processes’’. (Wischhusen, M.
2009)

50
5.6 Comparison of Scenarios
One of the aims of this study was to create, calculate and present each Scenario to ultimately
comparatively assess the methods and practices involved using the generation of CO2 as an
indicator of environmental suitability in terms of Irish waste tyre management. Graph No.2
shows that the least CO2 was produced from the hypothetical implementation of Scenario B.
There were a number of factors which contributed to this result.
The major contribution to this relatively low CO2 production was the avoidance of new tyre
manufacture which throughout the study proved to be a CO2 intensive operation. The 23.1%
reduction in CO2 production from the re-treading process was also aided by the CO2
emissions generated from the shredding phase of Scenario A which increased the emissions of
TDF use by 69.3791t/CO2.
Contrary to the results shown in Graph No.2, Graph No. 3 shows that the passage of one
functional unit through each recovery method alone results in 18022.2249t/CO2 less
emissions being generated from the use of TDF. This shows that this recovery method does
need consideration, however the manufacture of new tyres in Scenario A meant it ultimately
had a negative effect on the Environment. Although the results for Scenario B was overall
positive, TDF may be a more viable option for a region that imports new tyres and is without
a market for re-treads. Some literature encountered on Re-treading, stated that its products are
often associated with being of a lower quality and an unsafe alternative to new tyres and this
perception still persists among many consumers.
Graph No.4 highlights the fact that the use of TDF generates more CO2 per functional unit
than the equivalent amount of coal use, mainly due to the requirement of shredding whole
tyres to allow feeding of TDF into the system. As coal combustion does not require this
phase, this increase in emissions concurs with the study by ‘PricewaterhouseCoopers’s’ study

51
‘Life Cycle Assessment of nine recovery methods for End of Life Tyres (ELT)’ which
concluded that investment in the upper stages of the WtE process needs investment to
compete with conventional fuels. (PWC, 2010) However, this study does not account for the
mining operations involved in coal extraction which is equivalent in nature to the shredding
phase in TDF use. The inclusion of this would give a better understanding of the CO2
generation differences between types of fuel in the cement kiln and may change the results of
both the Baseline Scenario and Scenario B.
In this study the major difference in CO2 emissions from current practices and waste tyre
management methods is between the production of new tyres and the alternative option of re-
treading used tyres. This is highlighted in Graph No.5 with 11041.7t/CO2 less being produced
in the re-treading phase than new tyre manufacture of an equivalent number. New tyre
manufacture was by far the most CO2 emitting process in this study and this had a major
impact on the results.
The study did not account for the transport distances between routes and any further CO2
emissions which may have resulted from this. This was done to ensure that the study focused
on the management practices particularly. It was assumed that all distances in each process
were equal and not calculated as cement plants capable of executing Scenario A and re-
treading facilities exist across the country.

52
5.7 Life Cycle Impact Assessment
Both Scenario A and Scenario B provide environmentally conscious methods of disposing of
Irelands landfilled and exported waste tyres. However the impact of Scenario A ultimately
proved to have a negative impact on the environment when compared with the Baseline
Scenario. The results in Table No.5 show that Scenario B had a resounding positive impact in
relation to CO2 emissions when compared with the Baseline Scenario. This study shows that
considerable negation of CO2 emissions can be obtained by increasing the volume of waste
tyres being subjected to re-treading however limitations such as the amount of tyres suitable
for re-treading may reduce the efficiency of Scenario B highlighted in Graph No.2.

53

54
6.0 Conclusion
Two methods of waste tyre management were incorporated into two Scenarios based on their
possible viability of use in Ireland and compared with a Baseline Scenario developed using
the latest figures of waste tyre management and generation in Ireland. The two methods were
the waste to energy process of TDF use in cement kilns and the method of re-treading waste
tyres to produce products capable of re-use. By use of LCA methodology it was determined
that Scenario B, which was based on the waste tyres being re-treaded, produced considerably
less CO2 emissions than Scenario A, that used the waste tyres identified in the Baseline
Scenario as fuel in a cement facility. However this was only the case due to the avoided CO2
production from the manufacture of an equivalent amount of new tyres as the amount re-

55
treaded. The study showed that in fact the use of TDF in cement kilns emits less CO2 than the
re-treading process when avoided processes are not accounted for.
In relation to the Baseline Scenario, overall Scenario A had a negative effect on the
environment while Scenario B had a positive effect on the environment. Looking to the
future, if Ireland is to avoid financial penalties from the European Union in relation to the
‘Landfill Directive’ and reduce money spent on waste tyre exporting it must strive to create an
operational, viable and environmental solution to it waste tyre management. The change in the
direction of Ireland’s management methods may lie in the intensification of the re-treading
industry
6.1 Recommendations

56

57
7.0 References
7.1 Literature
 Curry, R, Powell, JC, Gribble, N Waite, S (2011), A streamlined LCA and decision
tool for used tyres recycling. Journal of Waste and Resource Management, accessed
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61
8.0 Appendix
Table 7: International ELT recovery rates from US, Japan and Europe
Year Japan US Europe
1994 No Data 50% 21%
1995 No Data 57% 25%
1996 No Data 61% 35%
1997 89% 63% 42%
1998 86% 67% 46%
1999 84% 70% 50%
2000 85% 75% 51%
2001 85% 77% 55%
2002 84% 79% 63%
2003 82% 82% 70%
2004 81% 86% 74%
2005 83% 84% 78%

62
2006 84% 85% 82%
2007 85% 85% 87%
2008 87% 84% 91%
2009 87% 82% 95%
2010 89% 80% 96%
Table 8: Calculation of energy inputs/outputs during shredding and feeding stages for TDF use
Phase Energy generated / 1t ELT Energy used / 1t ELT
Tyre shredding - 170MJ*
Feeding into system - 0.413MJ*
*Data obtained from ‘ELTs: Alternative final disposal processes compared by LCA’ (Corti, A. et al. 2004)

Comparitive LCA of Waste Tyre Managment routes

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