comparing environmental impact of conventional and high speed rail

8/8/2019 Comparing Environmental Impact of Conventional and High Speed Rail

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Comparing environmental impact of

conventional and high speed rail

Planning and Regulation

Route Planning New LinesProgramme


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Comparing the Environmental Impact of Conventional and High-Speed Rail

ii

Executive Summary

Introduction

The New Lines Programme is to test the hypothesis that in 2020, the existing rail lines from London tothe North and West will be operating at full capacity and the conventional and the next generationtools for increasing capacity will be exhausted. There will be the need for additional intervention.

The programme aims to develop and evaluate the options for building new lines; including in this is theneed to evaluate the environmental impacts of such an intervention in terms of expected energyconsumption of new rolling stock, understand any step change in energy consumption between newversus existing rolling stock including diesel versus electric and to assess localised environmentalimpact during and after construction.

As a result there is a need to better understand the environmental impact of building one or more newlines in terms of:1) Performance (energy consumption) of rolling stock, both current high-speed (electric),

conventional (diesel) rolling stock and future electric rolling stock;2) Seating occupancy levels in high-speed versus conventional services;3) Estimated direct and indirect greenhouse gas emissions from diesel and electric rolling stock (both

in current and likely future electric mix);4) Estimated emissions resulting from the construction, maintenance and decommissioning of rolling

stock;5) The potential energy consumption/emissions resulting from construction of new infrastructure in

terms of materials used in the construction of infrastructure (and the energy consumption /emissions per kg of these materials) as well as the energy use/emissions resulting frominfrastructure construction activities;

6) The role of energy consumption/emissions savings resulting from modal shift and factoring in

demand generation in the overall comparison.

This environmental study was carried out to assess the relative environmental performance ofconventional and high speed electric rail services. The purpose of this work is to provide an objectivecomparison between the different options and the key assumptions that affect the outcome of thecomparison. In doing this, the work also needs to take into account the long timeframes associatedwith planning and constructing large railway infrastructure projects including wholly new rail lines (e.g.around 20 years for both the Channel Tunnel Rail Link and Crossrail). Hence comparisons will need tobe made on the anticipated performance of future high-speed and conventional rail rolling stock likelyto be put into service in the 2025-2030 timeframe.

For the purposes of this study, high-speed rail (HSR) services are defined as services faster thantypical UK intercity limit of 200 km/hour, typically over 250 km/hour and up to 350+ km/hour.Comparisons in this report are made for similar types of electric rail services for HSR vs conventionalrail i.e. with conventional intercity service rolling stock (up to 200 km/hour), rather than rolling stockused in slower stop-start commuter services. The focus for the work for this project has been onenergy consumption and greenhouse gas emissions. Other environmental impacts will be consideredin more detail at a later phase and are not within the scope of this project.

In order to obtain as up to date and accurate information as possible the project team consulted widelywith experts in industry and academia, as well as with the Department for Transport (DfT). This wascarried out via a letter of introduction and accompanying questionnaire and follow-up by email andtelephone interviews.


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Summary of Analysis Results and Conclusions The results of the comparative analysis of conventional versus high-speed rail have been presentedsplit between three source areas:1. GHG emissions resulting from to direct energy consumption by the trains;2. GHG emissions resulting from the construction, maintenance, use and disposal of new electric rail

infrastructure;3. GHG emissions resulting from the production, disposal and maintenance of electric trains.

These results have demonstrated the following points: Per seat-km conventional rail uses less energy and produces fewer GHG emissions than high-

speed rail. High-speed rail would be expected to result in around 9.3% more GHG emissions onaverage (at 12.8 gCO 2eq/seat-km) than equivalent conventional rail (at 11.7 gCO 2eq/seat-km) in2025, according to calculations using central scenario values. This difference drops to 4.4% more over the 30-year lifetime of the trains, with HSR at 7.8 gCO 2eq/seat-km and conventional rail at7.5 gCO 2eq/seat-km. This is because the importance of emissions from direct energy consumptiondecreases due to decarbonisation of electricity generation;

Per passenger-km (pkm) HSR is anticipated to produce significantly lower GHG emissions thanconventional rail. This is the case both when assuming typical differences in European occupancylevels between conventional and HSR and for the modelled differences in occupancy levels fromthe NLP Strategic Business Case. On average HSR (at 30.3 gCO 2eq/pkm) is expected to result inaround 15% less GHG emissions on average than conventional rail (at 35.7 gCO 2eq/pkm) in2025, according to the calculations using central values. This GHG emissions for HSR reducefurther to 18.8% less (at 18.5 gCO 2eq/pkm) than conventional rail (at 22.7 gCO 2eq/pkm) whenconsidering them over the 30-year lifetime of the trains. The differential increases further whenmodal shift and demand creation are factored in to 17.4% less (26.4 gCO 2eq /pkm and 32.0gCO 2eq/pkm respectively for HSR and conventional rail) in 2025, and 23.5% less (15.1gCO 2eq/pkm and 19.7 gCO 2eq/pkm respectively) over the 30-year train lifetime;

Impact of electricity decarbonisation: When assuming current grid electricity emission factorsand electric train models the GHG emissions due to direct energy use of the train accounted forover 80% of the total emissions (with 18% due to rail infrastructure and


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Sensitivity analysis on the carbon intensity of electricity generation: The sensitivity on theelectricity decarbonisation rate shows that varying the assumption on future decarbonisation ofelectricity generation has a 30-40% impact on the total greenhouse gas emissions and over 60%on the component due to direct energy consumption by trains. Under central (rapiddecarbonisation) assumptions the range for the GHG emissions between 2025 and 2055respectively was from 30.3 to 15.0 gCO 2eq/pkm for respectively HSR and 35.7 to 19.0gCO 2eq/pkm for conventional rail (excluding the effects of modal shift and demand creation).

Sensitivity analysis on embedded greenhouse gas emissions: The percentage of recycling ofmaterials at the end of the life of infrastructure (and to much a lesser degree trains) has a verysignificant impact on the final results. Because of the dominating effect of embeddedinfrastructure emissions in the overall assessment this puts a high level of importance to designingrecyclability into the design of new infrastructure as far as possible. The sensitivities on % tunnelson new line infrastructure and on the type of track also underline the importance of these elementsin the overall analysis. Using ballastless track results in significantly higher GHG emissions in itsconstruction compared to conventional track, but no detailed information was available on GHGsavings due to reduced maintenance. More detailed evaluation of the GHG savings potentialthrough avoided maintenance would be beneficial to inform the comparison should this optionbecome preferred over conventional track in the future. The sensitivity on the % tunnels on newlines suggests that the alternatives to tunnelling should be investigated where possible.

Sensitivity analysis on modal shift and demand creation: The analysis using information fromthe NLP Business Case showed that the benefits of modal shift from car and air tranpsortoutweighed the counteracting demand creation element in the overall analysis. They also showedthat the net benefits due to modal shift and demand creation for high-speed rail services arenotably larger than those for conventional rail, further improving high-speed rails relativeperformance. Because of the complexity in changes to rail services and passenger numbers onexisting lines it was not possible to quantitavily factor in the impact if abstraction from existing rail.

Overall Conclusions and Recommendations for Future Work Overall, this work has provided a comprehensive review and evaluation of the elements that contributeto the overall energy consumption and net greenhouse gas emissions from electric rail. Through

detailed analysis and sensitivities this study has also explored the impacts of key assumptions onthese elements on the overall comparison of the relative performance of future conventional and high-speed rail on proposed new lines. The work has clearly demonstrated the significant net benefit ofhigh-speed rail services over equivalent conventional services in terms of energy consumption andGHG emissions per passenger-km in the context of proposed new line development. Factoring in thenet effects of modal shift and journey creation adds to this advantage. Also highlighted is theoverriding significance of the GHG emissions due to new rail infrastructure in the anticipated futurewhere the electricity system is highly decarbonised. This in turn puts significant emphasis on theimportance of minimising emissions from the construction of any new rail infrastructure, focussing onsourcing lower carbon materials and on the recyclability of end of life components. On the basis of theanalysis for this study, the development of new lines to provide high-speed rail services appears to behighly desirable in reducing GHG emissions in the long-term. However, there will be very significant upfront GHG emissions from the construction of new infrastructure in the short-term.

The results of the work also suggest a number of areas for further research to help better understandand minimise the environmental impact of rail.

More detailed analysis of specific proposals including other environmental impacts: This workhas provided a preliminary scoping level assessment of the potential impacts of thedevelopment a high-speed rail service in terms of greenhouse gas emissions. However, amore detailed assessment would be beneficial once the preliminary proposals have beenfirmed up. At this stage an assessment of the other environmental impacts would beappropriate, such as emissions of air quality pollutants, noise and land-take.

Research into ways to minimise the environmental impact of new rail infrastructure: Theresults on the relative importance of infrastructure emissions suggests a more detailed pieceof research focussing on this element would be worthwhile to include other impacts such

embedded emissions of air quality pollutants. Whilst a preliminary assessment of the impactshave been carried out here, a more in depth life cycle assessment is desirable. Research intothe potential for minimisation of the GHG emissions footprint of new rail infrastructure throughsourcing of less carbon intensively produced materials would also seem worthwhile.


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Table of Contents

Executive Summary ii

Glossary and Energy Unit Equivalencies viii

1 Introduction 1

1.1 Scope of work 1

1.2 Information collection 2

1.3 Report structure 2

2 Factors Affecting Comparisons of Energy Consumption and GHG

Emissions 3

2.1 Direct energy consumption and emissions from trains 4 2.2 Indirect energy consumption and emissions from trains 15

2.3 Energy consumption and emissions resulting from rail infrastructure 20

2.4 Other factors affecting comparisons 24

3 Results of Comparative Analysis 32

3.1 Definition of scenarios 32

3.2 Breakdown of relative impacts 35

3.3 Sensitivity analysis on key parameters 40

4 Summary and Conclusions 45

5 References 50

Appendices

Appendix 1: Consultation Questionnaire 55


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List of Figures

Figure 2.1: Typical composition of energy demand for high-speed and conventional rail services 4 Figure 2.2: Energy flow diagrams for passenger trains with and without regenerative braking 5 Figure 2.3: Energy conversion losses for a German ICE electric multiple unit 7 Figure 2.4: Comfort function demands for a train in UK winter (0 C) 7 Figure 2.5: Typical breakdown of components in electric multiple unit trains by weight 10 Figure 2.6: Typical breakdown of components contribution to drag in electric trains 10 Figure 2.7: Energy consumption of current and future rolling stock (kWh per seat-km) 13 Figure 2.8: Trend between energy use (kWh/seat-km) and speed (km/h) for European trains 13 Figure 2.9: Low and High Scenarios for Future Carbon Intensity of UK Grid Electricity 15 Figure 2.10: Proportional breakdown of materials used in electric rail rolling stock and corresponding

net emissions of greenhouse gases for production and disposal at different recycling

rates 18 Figure 2.11: Breakdown by electric rail infrastructure element of the net embedded greenhouse gas

emissions for (at a 50% recycling rate), annualised over the infrastructure lifetime 21 Figure 2.12: Proportional breakdown of materials used in electric rail infrastructure and

corresponding net emissions of greenhouse gases for production and disposal (at a50% recycling rate) 23

Figure 2.13: The core New Line only options from London considered in the New Lines ProgrammeStrategic Business Case (NEW LINES PROGRAMME, 2009) 26

Figure 2.14: Speed Assumptions for the New Lines Programme Strategic Business Case (NEWLINES PROGRAMME, 2009) 26

Figure 2.15: Detail on the full option (MB1.4.1) considered in the New Lines Programme StrategicBusiness Case (NEW LINES PROGRAMME, 2009) 27

Figure 2.16: Train Service Specification for Full Option (MB1.4.1) considered in the New LinesProgramme Strategic Business Case (NEW LINES PROGRAMME, 2009) 27

Figure 2.17: Modal share of high-speed rail services and flights by journey time 30 Figure 2.18: Assumptions on the projected improvement in the greenhouse gas emissions from cars

and domestic air transport 31 Figure 3.1: Breakdown of the total GHG emissions from conventional and high-speed rail per seat-

km for different routes (assumes current trains and carbon intensity of electricity) 35 Figure 3.2: Breakdown of the total GHG emissions from conventional and high-speed rail per seat-

km for different routes (assumes future trains and carbon intensity of electricity) 36 Figure 3.3: Breakdown of the total GHG emissions from conventional and high-speed rail per

passenger-km for different routes (assumes future trains and carbon intensity ofelectricity) 37

Figure 3.4: Breakdown of the total GHG emissions from conventional and high-speed rail perpassenger-km by impact area 38

Figure 3.5: Summary comparison of the relative performance of conventional and high-speed rail atdifferent timeframe assumptions (NLP-SBC Total) 39

Figure 3.6: Sensitivity analysis breakdown on the impact of varying occupancy levels andpassenger numbers on the comparison of total GHG emissions from conventional andhigh-speed rail 40

Figure 3.7: Sensitivity analysis on the impact of the assumptions on the future decarbonisationelectricity generation to the comparison of conventional and high-speed rail 41

Figure 3.8: Sensitivity analysis on the impact of the assumptions on the % recycling of end of lifeinfrastructure and trains to the comparison of conventional and high-speed rail 43

Figure 3.9: Sensitivity analysis on the impact of the infrastructure assumptions on the % tunnelsand type of rail track to the comparison of conventional and high-speed rail 43


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Figure 3.10: Sensitivity analysis on the impact of the assumptions on modal shift and demandcreation to the comparison of conventional and high-speed rail 44

List of Tables

Table 2.1: Principal contributors and example values for the three Davis formula coefficients 6 Table 2.2 Elasticities for efficiency measures on total energy consumption for current electric

trains 8 Table 2.3 Modelled impacts of efficiency measures on energy consumption for Japanese

Shinkansen HSR 8 Table 2.4: Summary of measures to reduce energy consumption from trains 9 Table 2.5: Characteristics of current and future rolling stock used for conventional and high-speed

rail 12 Table 2.6: Total greenhouse gas emissions (in kgCO 2eq per tonne material) resulting from

different stages of the material lifecycle (production, recycling, other disposal) 16 Table 2.7: Material breakdown for typical electric rail rolling stock and corresponding net emissions

of greenhouse gases for production and disposal at different recycling rates 18 Table 2.8: Characteristics of current and future rolling stock used for conventional and high-speed

rail and the net greenhouse gas emissions under the central recycling scenario 19 Table 2.9: Estimated energy and water consumption per train-drive km for train maintenance and

refitting 19 Table 2.10: Estimated embedded emissions for electric rail infrastructure based on ballasted or

ballastless track, breakdown by element 22 Table 2.11: Estimated annual in-use activity elements for electric rail infrastructure and equivalent

2007 emissions factors 23 Table 2.12: Typical load factors for European high-speed rail services 25 Table 2.13: Modelled average load factors for conventional and high-speed services from the New

Lines Programme Strategic Business Case (NEW LINES PROGRAMME, 2009) 28 Table 2.14: Modelled average modal switch and journey creation for conventional and high-speed

services from the New Lines Programme Strategic Business Case (NEW LINESPROGRAMME, 2009) 30

Table 3.1: Summary definition of the Central, Low and High scenario assumptions used in theanalysis 32

Table 3.2: Assumtions for scenarios on the projected greenhouse gas emission factors forelectricity, passenger cars and domestic flights 32

Table 3.3: Detailed definition of the Central, Low and High scenario assumptions for passengernumbers, occupancy and the proportion of tunnels on new lines for different services 33

Table 3.4: Comparison of services in the New Lines Programme Strategic Business Case withtypical European high-speed rail services 34 Table 3.5: Definition of the Central, Low and High scenario assumptions for modal shift and

demand creation on new lines for different services 34 Table 3.6: Sensitivity analysis on the impact of the assumptions on modal shift and demand

creation to the comparison of conventional and high-speed rail (NLP-SBC Total) 44


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GlossaryTerm/Abbreviation Definition/Explanation

Carbon footprint A measure of the impact human activities have on the environment in terms ofthe amount of greenhouse gases producedCatenary The system of overhead wires suspended above the track that deliver power

to electric trains.CH 4 MethaneCO 2 Carbon dioxideeq CO 2 or CO 2eq Carbon dioxide equivalent: a quantity that describes, for a given mixture and

amount of greenhouse gas, the amount of CO 2 that would have the sameglobal warming potential (GWP), when measured over a specified timescale(usually 100 years).

EMUs Electric Multiple Units a type of electric train that has powered vehiclesacross the train formation, rather than a single power vehicle/locomotive ateither end with unpowered carriages.

GHG Greenhouse gasGWP Global Warming PotentialIPCC Intergovernmental Panel on Climate ChangeLCA Life cycle assessmentLoad Factor The fractional or percentage occupancy of a trainN2O Nitrous oxidePantograph A pantograph is a device fitted to the roof of the train that collects current from

the overhead wires.passenger-km or pkm Passenger kilometre = Unit of measure representing the transport of one

passenger over one kilometre.RE Renewable energyseat-km or skm Seat kilometre = Unit of measure representing the movement over one

kilometre of one seat available in a train (or other mode of transport)Tare mass The technical term for the total unlaiden mass of a trainTOC Train Operating Company

Energy Unit Equivalencies

From /To - multiply by GJ kWh Toe Gigajoule, GJ 1 277.78 0.023885Kilowatthour, kWh 0.00360 1 8.5985E-05Tonne oil equivalent, toe 41.868 11630 1


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1 Introduction

The New Lines Programme is to test the hypothesis that in 2020, the existing rail lines from London tothe North and West will be operating at full capacity and the conventional and the next generationtools for increasing capacity will be exhausted. There will be the need for additional intervention.

The programme aims to develop and evaluate the options for building new lines; including in this is theneed to evaluate the environmental impacts of such an intervention in terms of expected energyconsumption of new rolling stock, understand any step change in energy consumption between newversus existing rolling stock including diesel versus electric and to assess localised environmentalimpact during and after construction.

As a result there is a need to better understand the environmental impact of building one or more newlines in terms of: Performance (energy consumption) of rolling stock, both current high-speed (electric),

conventional (diesel) rolling stock and future electric rolling stock; Seating occupancy levels in high-speed versus conventional services; Estimated direct and indirect greenhouse gas emissions from diesel and electric rolling stock (both

in current and likely future electric mix); Estimated emissions resulting from the construction, maintenance and decommissioning of rolling

stock; The potential energy consumption/emissions resulting from construction of new infrastructure in

terms of materials used in the construction of infrastructure (and the energyconsumption/emissions per kg of these materials) as well as the energy use/emissions resultingfrom infrastructure construction activities;

The role of energy consumption/emissions savings resulting from modal shift and factoring indemand generation in the overall comparison.

This environmental study was carried out to assess the relative environmental performance ofconventional and high speed electric rail services. The purpose of this work is to provide an objectivecomparison between the different options and the key assumptions that affect the outcome of thecomparison. In doing this, the work also needs to take into account the long timeframes associatedwith planning and constructing large railway infrastructure projects including wholly new rail lines (e.g.around 20 years for both the Channel Tunnel Rail Link and Crossrail). Hence comparisons will need tobe made on the anticipated performance of future high-speed and conventional rail rolling stock likelyto be put into service in the 2025-2030 timeframe.

1.1 Scope of work

1.1.1 Definition of High-Speed Rail and Evaluation of Environmental Impacts

For the purposes of this study, high-speed rail (HSR) services are defined as services faster thantypical UK intercity limit of 200 km/hour, typically over 250 km/hour and up to 350+ km/hour.Comparisons in this report are made for similar types of electric rail services for HSR and conventionalrail i.e. with conventional intercity service rolling stock (up to 200 km/hour), rather than rolling stockused in slower stop-start commuter services.

Although there are a wide range of environmental impacts resulting from rail, the focus for the work at

this stage is primarily on energy consumption/ greenhouse gas emissions. Other environmentalimpacts (e.g. air quality, noise and land-take) will be considered in more detail at a later phase and arenot within the scope of this project.


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1.2 Information collectionIn order to obtain as up to date and accurate information as possible the project team needed toconsult widely with experts in industry and academia. This was to enable the collection of moredetailed information and develop of a more nuanced understanding of the issues than could be

achieved from a simple review of the available literature. As part of this consultation an introductoryletter was sent out in March 2009 requesting cooperation. A questionnaire (provided in Appendix 1)was also provided alongside this request to help identify key information for the analysis. The letterand questionnaire was subsequently followed up in email and telephone conversations and interviews.Advice and information was gratefully received by the project team from the following organisationsand individuals which has informed the work: Alstom; Association of Train Operating Companies

(ATOC); DeltaRail; Department for Transport (DfT); Forum for the Future (FFF); Greengauge 21; Hitachi; Professor Roger Kemp (University of Lancaster);

Rail Industry Association (RIA); Rail Industry Forum; Rail Research UK (RRUK); Rail Safety and Standards Board (RSSB); Siemens; Steer Davies Gleave; International Union of Railways (UIC).

1.3 Report structureThe aim of this report is to provide a preliminary assessement of the relative environmental impact ofconventional and high-speed rail to help inform the wider business case being developed for the NewLines Programme. The report provides a summary of the results from this project, including the reviewof literature and consultation with stakeholders, results from comparative analyses, sensitivities andconclusions. This report is structured as follows:

The theoretical background to train energy consumption, measures available to reduce thisand, discussion of the different elements affecting the comparison of high-speed andconventional rail are provided in Section 2.

A summary and discussion of the comparative analysis is presented in Section 3; The summary and conclusions for the work are presented in Section 4, together with

recommendations for future work; References for source material are provided in Section 5.


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2 Factors Affecting Comparisons of EnergyConsumption and GHG Emissions

This chapter provides a discussion of the major elements that influence the overall energyconsumption comparison of conventional and high-speed rail. For the purposes of this work, thecomparison is restricted to energy use and greenhouse gas emissions. To properly consider therelative impacts a range of factors need to be evaluated. These can be loosely grouped into thefollowing major categories:

1) Direct performance (energy consumption) of the rail rolling stock: In making comparisons itis important to understand both the current situation and the anticipated performance of trains thatwould be supplied to service new lines (i.e. most likely not going into service before 2025).Comparisons between different trains are most usefully made in terms of the average energy usedper seat-kilometre (i.e. total energy used per kilometre for the whole train divided by the totalnumber of seats).

2) Seating occupancy levels and service frequency for high-speed versus conventional rail: Seating occupancy levels (also known as the load factor) directly influence the net energy use / emissions per passenger. There are significant differences between different types of services,with high-speed services typically having higher occupancy levels. Together, average seatingoccupancy and service frequency provide a measure of the intensity of the use of the railinfrastructure. This is important to enable the embedded emissions from infrastructure to beallocated on a per passenger-km basis.

3) Direct and indirect greenhouse gas emissions from electricity production (current and likely future electricity mix): Assumptions on the projected carbon intensity of electricity in thefuture will significantly impact on the relative importance of the components of direct energyconsumption by rail vehicles versus other elements such as the indirect/embedded energyconsumption/emissions from rolling stock and infrastructure production and disposal;

4) Indirect emissions resulting from the construction, maintenance and decommissioning of rolling stock: A complete assessment of the impact or rail rolling stock needs to factor in theenergy consumption and emissions resulting from the production, disposal and maintenancephases, as well as the direct energy consumption considered in earlier sections. There may bedifferences between the types or volumes of different materials used for conventional and HSRrolling stock that will affect their relative impacts;

5) Energy consumption/emissions resulting from construction and use of new rail infrastructure: These can be very significant in size and could potentially significantly alter thepicture if there are significant differences between conventional rail and HSR in the totalpassengers carried on rail new infrastructure. Elements include:a) Materials used in the construction of infrastructure (and the energy consumption /emissions

per tonne of these materials);

b) Energy use/emissions resulting from infrastructure construction activities;c) Annual variable energy use/emissions from infrastructure use and maintenance.

6) Energy consumption/emissions savings resulting from modal shift and factoring in demand generation: Modal shift (e.g. from car and air transport to rail) and journey creation haveeffectively opposing impacts on the overall evaluation. Whilst modal shift from other modes oftransport will provide additional benefits, demand creation effectively reduces the benefits of thehigher occupancy rates (and total passenger numbers) typically achieved by high-speed rail. It istherefore important to provide a quantitative estimate of their respective impacts in the overallevaluation. Abstraction from existing rail services is much more complex to quantify due tochanges in the type and frequency of service provision affecting the total energy consumption andpassenger-km.

The primary focus of the project work was initially on the first three categories. However, it wasimportant to consider the other areas where they may influence the relative comparison between HSRand conventional rail. The analysis presented in Section 3 has shown the importance of including the


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other elements in the comparison, particularly the embedded emissions from construction of new railinfrastructure.

The following sub-sections provide a more detailed discussion of the different elements and asummary of the default and sensitivity data used for the analysis in Section 3.

2.1 Direct energy consumption and emissions from trains

2.1.1 Theoretical background to energy consumption

The direct energy consumption of electric train systems from electric substation to wheel-rail interfacecan be broken down into four main areas:

Energy required to overcome the trains resistance to movement; Energy lost due to inefficiencies in the traction system between pantograph and wheel; Energy used for on-board passenger comfort functions; and

Losses in the electrical supply system between the substation and pantograph.Figure 2.1 shows the breakdown of energy demand for power taken from the catenary for high-speedand conventional electric trains; it can be seen that the majority of demand for energy is to providemotive power to overcome running and inertial \ grade resistance. Figure 2.2 shows the energy flowfor trains with and without regenerative braking (which feeds power back into the catenary that wouldotherwise be dissipated as heat in friction brakes).

Figure 2.1: Typical composition of energy demand for high-speed and conventional rail services

17%

9%

19%

10%

53%

35%

63%

69%

61%

68%

27%

37%

20%

22%

20%

22%

20%

28%

0% 20% 40% 60% 80% 100%

High Speed (withoutregeneration)

High Speed (withregeneration)

Intercity (withoutregeneration)

Intercity (withregeneration)

Regional (withoutregeneration)

Regional (withregeneration)

Inertia and grade resistance Running resistance Comfort functions

Notes: Reproduced from UIC EVENT (2003) Project report p27


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Figure 2.2: Energy flow diagrams for passenger trains with and without regenerative braking

Energy fed in at electric substation

Catenarylosses

Losses intractionsystem

Comfortfunctions

Train

Mechanical energy at the wheels (train motion)

Inertia and graderesistance

Eventually dissipated inbrakes

Air resistance andfriction

Net energy intake


Catenarylosses


Comfortfunctions

Train




Net energy intake

Regenerativebraking

D i s

s i p

a t e d i n

b r ak

e s

L o s s e s i n

t r a c t i on

s y s t em

E n

er g

y r e

t ur n

e d t o

c a t en

ar y

a) Energy flow diagram for a passenger train without regenerative braking

b) Energy flow diagram for a passenger train with regenerative braking


Catenarylosses


Comfortfunctions

Train



Eventually dissipated inbrakes


Net energy intake


Catenarylosses


Comfortfunctions

Train




Net energy intake

Regenerativebraking

D i s

s i p

a t e d i n

b r ak

e s

L o s s e s i n

t r a c t i on

s y s t em

E n

er g

y r e

t ur n

e d t o

c a t en

ar y

a) Energy flow diagram for a passenger train without regenerative braking

b) Energy flow diagram for a passenger train with regenerative braking

Notes: Reproduced from UIC EVENT (2003) Project report, Figures 2 and 3.


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2.1.1.1 Energy required to move the train

The energy required by the traction system accounts for around three-quarters of a trains directenergy use in service (UIC EVENT 2003), as indicated earlier in Figure 2.1. Traction energy demandfalls into two main categories: energy required to overcome inertial (ie accelerating the train) andgrade resistance, and energy needed to overcome running resistance (friction and drag).

The energy needed to overcome inertial and grade resistance is caused by and hence directlyproportional to train mass. Energy used is not dissipated but stored as kinetic and gravitationalpotential energy respectively, and thus is theoretically fully recoverable. Regenerative braking aims torecover as much of this energy as possible, but inefficiencies and operational restrictions mean thatinevitably a proportion is lost. The acceleration profile of the train (eg number of stop/start cycles,driving style) affects the amount of energy needed to overcome inertia; topography of the line affectsthe energy input needed due to grade resistance.

All energy needed to overcome running resistance is due to friction and is disspiated, mostly as heat.An empirical expression for train resistance R on a straight level track is given by the Davis formula(UIC EVENT 2003, RSSB 2007a) as:

2CvBvAR ++=

Where A, B and C are constants for a given train-track system: A is the rolling resistance component independent of train speed v; B is the train resistance component dependant on train speed v; C is a coefficient dependent on train aerodynamic properties, proportional to the square of

train speed.

Table 2.1: Principal contributors and example values for the three Davis formula coefficients

Principal contributors Example values 1 A Journal resistance; rolling rotational resistance; track resistance 2240

BFlange friction; flange impact; wave action of rail; wheel to railrolling resistance 43.53

C Head end wind pressure; skin air friction on train sides; rear airdrag; air turbulence between vehicles; yaw angle of constant wind 4.41

Sources: Based on information from RSSB (2007a) and UIC EVENT (2003)

Notes: 1

Figures for the Swedish X2 high-speed train in a 6-car configuration running at 200km/h (v = 55.56m/s) calculatedfrom p20 of the EVENT final report.

It can be seen from the example values given in Table 2.1 that for a train travelling at 200 km/h (55.56m/s) the aerodynamic term (Cv 2) is around an order of magnitude greater than the other two terms,which are similar to each other in magnitude. From this it can be concluded that:

For modern high-speed rail travel, aerodynamic resistance dominates, and; For a given train, the resistance to motion increases approximately with the square of train

speed.

2.1.1.2 Losses in traction systems

Inefficiencies in various electrical and mechanical components in the train traction system lead toenergy being dissipated as heat, which in turn leads to a demand for ancillary energy for cooling.Modern electric trains draw power from overhead lines, transform to DC (if necessary) before using atraction inverter to provide 3-phase AC power to synchronous motors. State-of-the-art 16.7Hz 15kVAC systems are around 85% power efficient at full load, with 50Hz AC or DC systems reporting higherefficiencies (UIC EVENT, 2003). However it should be noted that overall power efficiency is lower atlower loads, meaning that energy efficiency over a typical load cycle will be much lower than at peakload. The inverse power train (used in regenerative braking) has approximately the same efficiency asthe forward power train (Kemp 2009, Hitachi 2009).


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In some cases (e.g. transformers), the most efficient components are also the heaviest, and so thereis a trade-off between reducing weight and reducing traction system losses when optimising tractioncomponents.

Figure 2.3: Energy conversion losses for a German ICE electric multiple unit

6%

26%

1%5%

12%

10%

40%

Gear

Motor

Traction inverter

DC link

Rectifier

Transformer

Auxiliaries

Sources: Based on information from UIC EVENT (2003) Project report, p36

2.1.1.3 Comfort functions

Comfort functions include lighting, heating and ventilating coaches for passenger comfort. Whilst thisis mainly required during operation there is demand during stabled hours for cleaning andmaintenance and to ensure a comfortable temperature when the train begins operation. Comfortfunction energy demand depends strongly on ambient temperature. The UIC EVENT (2003) studyestimated that comfort functions account for around 20% of the energy consumption of a train onaverage. Since comfort function energy use is independent of train speed, a train that travels at higher

speeds or spends less time idling between stations will have a lower comfort function energy use per seat-km than the same train taking more time to cover a given distance.

Figure 2.4: Comfort function demands for a train in UK winter (0 C)

10%

8%

26% 56%

Passenger areaclimate control

Heating of secondaryspaces

Coach ventilation

Lighting etc

Sources: Based on information from UIC EVENT (2003) Project report, p43

2.1.1.4 Losses in supply system

Losses occur in the electrical supply system due to resistance in catenary lines and inefficiencies atsubstations. However, such losses will be constant for an electrical system supplying power at a given

voltage, regardless of the characteristics of the trains in the system. For this reason supply systemlosses are not discussed further in this section.


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2.1.2 Principal measures to reduce energy consumption in electric rail

Measures to reduce energy consumption in electric rail can be grouped into two categories: technicalmeasures where hardware is modified to reduce its consumption in given operating conditions, andoperational measures where the operating conditions are modified to reduce the energy consumptionof hardware. These measures are summarised in Table 2.4, and the most significant are discussed inmore detail below.

None of the studies reviewed or interviews conducted as part of this research pointed to anymeasures, technical or operational, which only applied to one of high-speed or conventional railservices. The rolling stock manufacturers interviewed affirmed that the main technical measuresplanned to reduce energy consumption in new rolling stock are common to both high-speed andconventional rail, and the magnitude of benefit achieved by each measure was broadly similar.

Table 2.2 shows the elasticities 1 for three key efficiency measures on overall train energyconsumption: improving the efficiency of the traction system, reducing train mass and reducing trainrunning resistance (friction and drag). The effect of regenerative braking on the elasticities is alsoshown. It can be seen that the elasticities are very similar for high speed and intercity trains; the likelydifferences for elasticities with regard to train mass and running resistance are discussed in 2.1.2.1and 2.1.2.2 respectively. Similar levels of significance for the different types of measure can also beseen in the simulated impacts for the Japanese high-speed Shinkansen trains in Table 2.3 (WCHSR,2008). It is important to note that considering elasticities alone can be deceptive. In considering howto target effort, the relative ease (and cost) of making improvements and the total remaining potentialfor improvements also needs to be taken into account. For example, it may be that it is easier or morecost effective to make significant reductions in train mass than to improve traction efficiency.Furthermore, it is important to also take account of potentially counter-balancing effects of differentoptions. For example, high-efficiency transformers tend to be heavier, offsetting electrical efficienciesgained.

The consensus amongst the rolling stock manufacturers interviewed was that high-speed trains willalways consume more energy per seat-km than conventional trains with the same technologicalrefinements, and that the current proportional difference in direct energy consumption is unlikely tochange significantly in the next 20-30 years.

Table 2.2 Elasticities for efficiency measures on total energy consumption for current electric trains

Elasticities with regard to:Train type Traction

EfficiencyTrainMass

RunningResistance

High speed without regenerative braking 1.00 0.17 0.63High speed with regenerative braking 1.11 0.12 0.66Intercity without regenerative braking 1.00 0.19 0.61Intercity with regenerative traking 1.12 0.14 0.65

Notes: Reproduced from UIC EVENT Project report, Table 2.

Table 2.3 Modelled impacts of efficiency measures on energy consumption for Japanese ShinkansenHSR

Measures Level of measure Impact on energyconsumption

Impact for1% change

Reducing vehicle weight 1 ton/car decrease -1% -0.4%Reducing air friction 10% decrease -6% -0.6%Efficiency of main electrical circuit 1% increase -4.0% -4.0%

Notes : Based on figures on effects estimated by simulation for Shinkansen vehicles with regenerating brake, 515 km fromTokyo to Osaka (WCHSR, 2008)

1 Elasticity is defined as the level of influence an energy efficiency measure has on total energy consumption; for example, if for a certain train theelasticity with regard to reducing train mass is 0.17, reducing the train mass by 10% will reduce overall energy consumption by 0.1 x 0.17 = 1.7%.


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braking, meaning additional dissipative braking is used, further reducing the cycle efficiency. Reducingthe train mass reduces the use of the comparitively inefficient regenerative braking cycle. Additionally,mass reduction will reduce frictional running resistance.

Mass reduction is typically achieved through reducing the weight of specific components (e.g.carbodies, bodies, bogies etc.) or through a system-based approach to lightweighting (e.g. thearticulated train design favoured by Alstom, which reduced the number of bogies by around 20% byplacing them between cars). Mass reduction will benefit services with less homogenous velocityprofiles (more accellerating and decelerating) most (i.e. those that accelerate and decelerate moreoften).

Figure 2.5: Typical breakdown of components in electric multiple unit trains by weight

21%

15%

10%

15%

22%

17%

Carbodies

Powered bogies,motors and drives

Trailer bogies

Propulsion equipment

Interior

Miscellaneous(heating, batteries etc)

Sources: Based on information from UIC EVENT (2003)

2.1.2.2 Aerodynamics and friction

As previously mentioned, at speeds above 200km/h aerodynamic drag dominates resistance to trainmotion. Figure 2.6 shows a breakdown of a trains drag by component; it shows that for a long train(as high-speed and intercity train sets typically are), surface friction and drag around the bogiesdominate aerodynamic drag. The main strategies to reduce drag are streamlining the nose and tailprofile of the train, reducing flow separation around the bogies, pantograph and train body bystreamlining, and reducing the skin friction on the train roof and sides. More effort has gone intoreducing the drag of high-speed trains as at higher speeds aerodynamic drag is more significant, butthe same principles apply to conventional trains. Interviewees suggested that improvements tomedium and high speed train aerodynamics are incremental and that developments in the next 20-30years are unlikely to radically alter the contribution of drag to energy demand, particularly in the UKwhere regulation prevents some radical aerodynamic train shapes (Hitachi 2009, Kemp 2009).

Figure 2.6: Typical breakdown of components contribution to drag in electric trains

45.5%

8.0%

7.5%

3.5%4.5%

4.0%

27.0%

Front

Tail

Bogies and wheels

Pantographs

Ventilation etc

Underfloor equipment

Surface friction on s ideand roof

Sources: Based on information from UIC EVENT (2003)


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2.1.2.3 Reducing traction system losses

New model specifications from the major rolling stock manufacturers report improved efficiency in thetraction system, both by improvements in the major components (for example permanent magnetmotors, medium frequency transformers) and improvements in the energy management controlsoftware for the system as a whole. The fundamental technologies are the same for both high-speed

and conventional rail rolling stock and consequently forecast percentage energy savings are alsosimilar.

2.1.2.4 Reducing energy consumption for comfort functions

The principal component of comfort function energy use is air heating and cooling (UIC EVENT 2003).Energy demand in air temperature control can be reduced either by reducing heat transmissionthrough improved coach insulation, or reducing fresh air intake through CO 2 monitoring (fresh airintake dependant on number of passengers rather than number of seats). In addition, energy can besupplied from waste heat rejected from traction equipment (particularly in electric multiple units,EMUs) if the requirement is for heat. It is thought that there is significant scope for energy savings inthis area (Kemp, 2009), but there is no anticipated difference in reduction of comfort function energyuse between high-speed and conventional trains.

2.1.3 Energy consumption of current and future rolling stock

In making comparisons between conventional and high-speed rail the previous sections havediscussed the theoretical background to energy consumption and the potential impacts of differentenergy saving measures that might be applied. However, it is important not only to factor in theseconsiderations, but also the more practical market limitations on what new train types will actually beavailable to be put into service at the 2025 timeframe. Compared to the road transport sector, the railindustry is relatively small and trains have much longer service lives. As such, there are relatively fewtrain manufacturing companies and train model platforms available. Also as a result of this there arerelatively much longer development cycles for new platforms and much lower frequencies of platformreplacement. This makes it easier to foresee with greater certainty the likely characteristics andperformance of different types of electric trains in the timeframe we are interested in. The trainmanufacturers consulted as part of this work have confirmed that the conventional and high-speed railplatforms they are currently marketing will essentially be the ones that would be supplied for the 2025timeframe. Although it is likely there will be some smaller incremental improvements in the efficiencyof the currently available platforms, major improvements are unlikely.

The following Table 2.5 provides a summary of the characteristics of different conventional and high-speed rail rolling stock, based on information from ATOC (2009) and DfT (2009a). The data onenergy consumption presented in this table and in Figure 2.7 are approximate figures based on acombination of in-service measurements and modelled data. In real applications the actual achievedenergy consumption will vary significantly depending on the particular characteristics of a givenservice. Factors that can significantly affect the actual performance will include elements such as:

Service distance and number of intermediate stops; Line gradients; Service speeds; Variations in service speed along the route (e.g. due to major curves, junctions, etc.),

It can be seen from the table and figure that similar levels of improvements (15-20% reduction inkWh/seat-km) have been achieved for conventional and high-speed rail rolling stock between the 1990timeframe and the most recent models (excluding the Japanese Shinkansen). In addition, in Figure2.8 shows a much less pronounced increase in energy consumption than has previously beensuggested. For the purposes of comparisons in this study we have taken the proposed Hitachi SuperExpress (HSE) for the UK Intercity Express Programme (IEP) and Alstom AGV as representative ofthe likely performance of rolling stock in the 2025 timeframe for conventional and high-speed railrespectively. In this case, the relative increase in the energy consumption per seat-km of the AGVand the HSE compared to equivalent current designs is around 18%, which is also consistent with thetrend line in Figure 2.8.


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The AGV is a train prototype rolling stock design from Alstom intended as the successor to Francescurrent TGV high-speed trains, with a commercial service speed up to 360 km/h (220 mph). The AGVwill have distributed traction with motors under the floors of the passenger carriages, instead of thecurrent TGV configuration with separate power cars at either end of the train. This arrangement isused on many regular-speed multiple-unit trains and also high-speed trains such as the SiemensVelaro and Japan's Shinkansen trains (Wikipedia, 2009) built by Hitachi. Not having separate,dedicated power cars creates additional space that enables the AGV to provide higher seating densitycompared to current models. This design feature is also employed in the Hitachi Super Express (HSE)trains. Alstom offer the AGV in configurations from seven to fourteen carriages, with a total of 250-650seats (depending on internal layout and number of carriages). The AGV weighs less than its rivalswhich reduces its power consumption, and it consumes significantly less energy than previous TGVdesigns. Other design elements implemented to reduce the energy consumption of the AGV includearticulation and permanent magnet motors. Both of these elements contributed to a reduction in thenumber of bogies, leading to further weight and aerodynamic benefits. It can be seen from Table 2.5that both the HSE and the AGV have similar seating capacities at similar train lengths. However, theAGV has shorter vehicles and therefore a larger number in each train unit for a similar capacity.

Table 2.5: Characteristics of current and future rolling stock used for conventional and high-speed rail

Conventional Rail High Speed Rail

TrainClass

91IC225

Class 390Pendolino

HitachiSuper

Express

Class373

Eurostar

TGVReseau

TGVDuplex

AVES103

Velaro

Shinkan-sen 700

Series

AlstomAGV

Year 1989 2003 Future 1993 1992-6 1995-7 2004 1998 FutureMax Speed,km/h 200 225 200 300 300 300 350 300 360

ServiceSpeed,km/h * 200 200 200 300 300 300 300 270 300

Seating Capacity 536 439 649 750 377 545 404 1323 650Length (m) 247 215 260 394 200 200 200 400 250Vehicles per unit 11 9 10 20 10 10 8 16 14Tare mass(tonnes) 498 460 412 723 386 384 425 634 510Mass per vehicle(tonnes) 45.3 51.1 41.2 36.2 38.6 38.4 53.1 39.6 36.4

Mass per trainmetre (tonnes) 2.02 2.14 1.58 1.84 1.93 1.92 2.13 1.59 2.04

Mass per seat(tonnes) 0.93 1.05 0.63 0.96 1.02 0.70 1.05 0.48 0.78

Energyconsumption *(kWh/seat-km)

0.035 0.033 0.028 0.041 0.039 0.037 0.039 0.029 0.033

Sources: Figures for the Class 91 IC225 and Hitachi Super Express were supplied by DfT (2009a) based on public informationon the IEP. All other figures are based on figures from ATOC (2009), produced for Greengauge 21.

Notes: * The energy consumption figures are based on the service speed. Here the service speed represents the typicalmaximum speed of the train in service, usually dictated by the limits of the line infrastructure.


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Figure 2.7: Energy consumption of current and future rolling stock (kWh per seat-km)

0.00 0.01 0.01 0.02 0.02 0.03 0.03 0.04 0.04 0.05

Class 91 IC225 (1989)

Class 390 Pendolino (2003)

Hitachi Supe r Express (Future)

Class 373 Eurostar (1993)

TGV Reseau (1992-6)

TGV Duplex (1995-7)

AVE S103 Velaro (2004)

Shinkansen 700 Series (1998)

AGV (Future)

C o n v e n

t i o n a l

H i g h S p e e

d

Energy Consumption, kWh/seat-km

Figure 2.8: Trend between energy use (kWh/seat-km) and speed (km/h) for European trains

0.025

0.030

0.035

0.040

0.045

0.050

0.055

0.060

0.065

150 200 250 300 350Speed km/h

E n e r g y u s e ,

k W h / s e a

t - k m

Notes: This plot the trend-line of speed versus energy consumption has been updated from the original presented in the

RSSB (2007) traction energy metrics report using data from the more recent ATOC (2009) work and information fromthe IEP (DfT, 2009a).

Although the anticipated AGV performance is taken as representative for future UK HSR, the high-speed Japanese Shinkansen 700 trains already achieve lower energy consumption than the AGV, asshown in Table 2.5. In fact the newest model, the N700, has reportedly even lower energyconsumption per seat-km an improvement of up to 19% over the 700 series (WCHSR, 2008).However, there are a number of important barriers to trains with the energy performance of such trains

being used in the UK. The main barriers3

are linked to standards and interoperability: the wide body ofthe Shinkansen (which allows for 3+2 seats across the carriage as opposed to 2+2 in the EU) and

3 Cited by both Hitach and by ATOC in discussions as part of the consulation for this project, and in the RSSB (2007) report.


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long nose section are incompatible with UK infrastructure. Furthermore, crashworthiness regulationsin the EU mean that European trains are heavier and cannot utilise certain parts of the train forpassenger seating when compared to their Japanese counterparts.

Other measures used to improve the performance per seat-km of rail in Europe include the double-deck configuration used by the TGV Duplex. However, as for the wide-body configuration, the needfor future cross-compatibility of future rolling stock with the wider UK electricited network is asignificant limiting factor. Long-distance direct services are favoured for a number of reasons in theUK (including minimising cost and maximising stock utilisation). It is therefore likely that any high-speed rolling stock procured for new high-speed lines would also need to be compatible to run onconventional speed electrified infrastructure. This would preclude new rollingstock utilising either thewide-body or double-deck designs to reduce energy consumption per seat.

2.1.4 Emissions from electricity generation

In establishing the lifetime emissions impacts resulting from direct rail energy consumption of differentoptions it is important to factor in the likely change in the carbon intensity of the future electricitygeneration mix over time. Taking into account that services on any new lines would not be in placebefore 2025 at the earliest, and the typical 30 year lifetime of rail rolling stock this means developingsuitable electricity carbon intensity scenarios to at least 2055.

Two legislative proposals will drive the decarbonisation of the UK electricity generation mix in the shortand long term:1. The EUs commitment to a 20% reduction in GHGs by 2020 (rising to 30% if an international

agreement can be reached beyond 2012) together with the EU Renewable Energy Directive targetof 20% of EU energy consumption to come from renewable sources by 2020. As a result of effort-sharing between Member States, the UK-specific target is 15% reduction by 2020;

2. The UKs domestic Climate Change Act target of an 80% reduction in GHGs by 2050 on a 1990baseline.

In the short term the UK renewables share for electricity generation will need to be increased fromaround 5% currently to between 30-37% by 2020. This is because it is assumed the bulk of the 15%UK renewables target will need to come from electricity rather than other energy carriers (e.g. oilbased transport fuels).

In the long term the UKs statutory target to reduce greenhouse gas emissions by 80% by 2050 istaken as given, giving an approximate upper bound to the likely generation mix in this timeframe.However, detailed energy system modelling and analysis has shown that decarbonising electricitygeneration is one of the most cost-effective ways of making significant reductions in national carbonemissions. The Committee on Climate Changes (CCC) analysis has shown the greater potential andcost-effectiveness of carbon emissions reductions in electricity generation in the short to medium term.CCC has therefore recommended much faster decarbonisation of the electricity sector and a moresignificant net contribution in the long term as essential to achieve the 2050 80% reduction goal (CCC

2008, ATOC 2009). This accelerated decarbonisation would require substantial measures to stimulaterenewables, nuclear and carbon capture and storage in the short-medium term.

For the analysis carried out in this study we have therefore constructed two scenarios for the futurecarbon intensity of electricity, similar to those suggested by ATOC (2009) in their analysis forGreengauge 21, presented in Figure 2.9. In the high scenario a 4% year-on-year reduction in carbonintensity is assumed from 2010. The low scenario is more aggressive than the high scenario in termsof the rate at which the carbon intensity of electricity generation decreases and follows the rapiddecarbonisation pathway proposed by CCC (2008) 4. In both cases we have assumed the downwardtrend continues after 2050, with essentially complete decarbonisation of electricity generation by 2070.

In addition to the direct emissions of CO 2 from electricity generation there are also smaller directemissions of other greenhouse gasses - methane (CH 4) and nitrous oxide (N 2O). These account for

around 0.7% of the total direct emissions of greenhouse gases resulting from electricity production.There are also further indirect emissions of CO 2 and other greenhouse gasses resulting from the

4 For 2010-2020: DECC Energy Model, CCC abatement scenario, (extended ambition, central fuel prices); for 2025-2050: MARKAL modelling forthe CCC (80% trajectory), adjusted to take account of losses in transmission and distribution.


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extraction, transport and distribution of the primary fuels used in electricity generation. These indirectemissions have been estimated to add a further 12% (Carbon Tust, 2008) to the total (and areprimarily due to the fossil fuel based component of generation). For completeness, we have includedboth the direct and indirect emissions of all the greenhouse gases in the analysis for this study.

Figure 2.9: Low and High Scenarios for Future Carbon Intensity of UK Grid Electricity

Projection of Carbon Intensity of UK Grid Electricity

0.00

0.10

0.20

0.30

0.40

0.50

0.60

2005 2010 2020 2030 2040 2050 2060 2070

k g C O

2 p e r

k W h

Low Scenario

High Scenario

Notes: The above figure only includes the direct emissions of CO 2 from electricity generation. Resistive losses fromtransmission and distribution systems are included in the figures presented.

2.2 Indirect energy consumption and emissions fromtrains

A complete assessment of the impact or rail rolling stock needs to factor in the energy consumptionand emissions resulting from the production, disposal and maintenance phases, as well as the directenergy consumption considered in earlier sections. Whilst no quantitative information has beenidentified on the energy and emissions resulting purely from the rolling-stock manufacturing process,information is available on the breakdown (in tonnes) of material used in the construction of a typicalelectric vehicle unit. It is expected there would be some differences between different models ofrolling stock in terms of the relative breakdown of materials, but no model-specific information hasbeen identified. However, discussions with rolling stock manufacturers as part of this study have atleast indicated that there are no fundamental differences expected between conventional and high-speed trains. The assumption made for this study is therefore that the relative material breakdown byweight of different rolling stock is similar.

A number of data sources were consulted to obtain information on the emissions due to themanufacturing, recycling and disposal of the materials in question. Where data for specific materialswas not available, proxy data have been used when possible based on the closest equivalents. Theresults for the group of materials included are summarised in the following Table 2.6, together with theprimary source basis of the data. This dataset includes the materials utilised in analysis of embeddedemissions from rail infrastructure in later Section 2.3.


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Table 2.6: Total greenhouse gas emissions (in kgCO 2eq per tonne material) resulting from differentstages of the material lifecycle (production, recycling, other disposal)

MaterialTotal Greenhouse gas (GHG)emissions, kg/tonne material Primary Data Source

Production Aggregates 8 GHG CF (2009)Aluminium 11,000 GHG CF (2009)Bricks 192 GHG CF (2009)Concrete 1,090 DfT (2007)Copper 1,700.9 SimaPro, 2007Glass 840 SimaProLubricating oil 1,004.8 SimaProPlastic 3,100 GHG CF (2009)Plywood 887.1 SimaProSilt/soil 4 GHG CF (2009)Steel 3,100 GHG CF (2009)Synthetic rubber 2,774.1 SimaProWood 84.3 SimaPro, 2007

Recycling Aggregates -4 GHG CF (2009)Aluminium -9,000 GHG CF (2009)Bricks 10 GHG CF (2009)Concrete -4 GHG CF (2009)Copper 1,723.8 SimaPro, 2007Glass -315 SimaProLubricating oil 0 N/APlastic -1,500 GHG CF (2009)Plywood 250 SimaProSilt/soil 16 GHG CF (2009)Steel -1,300 GHG CF (2009)Synthetic rubber 40 SimaProWood 250 SimaPro, 2007

Other Aggregates 10 GHG CF (2009)Disposal Aluminium 10 GHG CF (2009)Bricks 10 GHG CF (2009)Concrete 10 GHG CF (2009)Copper 10 GHG CF (2009)Glass 10 GHG CF (2009)Lubricating oil 3,938.6 GHG CF (2009)Plastic 40 GHG CF (2009)Plywood 10 GHG CF (2009)Silt/soil 10 GHG CF (2009)Steel 10 GHG CF (2009)Synthetic rubber 40 GHG CF (2009)Wood 10 GHG CF (2009)

Sources: GHG CF = Defra/DECC GHG Conversion Factors, 2009 update (forthcoming), Annex 9; SimaPro = Data from theSimaPro EcoInvent database (extracted 2007).

Notes: It is assumed that the alternative to recycling a material is disposal is to landfill = other disposal.

For each of the materials, the relevant factor from the Defra/DECC GHG Conversion Factors wasused (2009 update - Annex 9, forthcoming). In the absence of factors from this source, the SimaProlifecycle analysis software tool was used to calculate emissions associated with production andrecycling (where applicable) of most of the other material elements. The database values generallyrepresent average European production conditions, which is appropriate for the materials in question.For the rest of the materials listed above, alternative sources of data were used to obtain the energyusage to produce or recycle the material. These alternate sources are described below.

Glass: Because data on the energy used to produce or recycle toughened or laminated glass were notavailable, data for regular glass from the Defra/DECC GHG Conversion Factors have been used as a


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proxy. According to Berryman, 5 a glass recycling company, laminated and toughened glass can berecycled, though separating the laminate from the glass does add an extra step (and cost) to theprocess. After the glass is recovered, it is crushed and sold to the glass making industry. The glasswould be used for making bottles and glasses as opposed to being used for flat glass again. At thispoint the process of recycling is the same as that for non-laminated flat glass; thus, emissions forrecycling flat glass have been used as a proxy.

Lubricating Oil: No specific information on the emissions from recycling lubricating oil has beenidentified. Much of the waste oil collected for recovery in the UK is processed (by removing excesswater and filtering out particulates) and used as a fuel burnt in heavy industry and power stations. Forthis study, unrecycled lubricating oil is therefore assumed to be burned and the appropriate emissionfactor from the forthcoming 2009 update to the Defra/DECC GHG Conversion Factors has been used.The preferred option for lubricating oils is re-refining for reuse as a base lubricant, although thisdoesn't currently occur on a large scale in the UK. 6 In comparison to the cost of burning waste oil, thecost of recycling oil is relatively high, making it difficult for regenerated or laundered oil to compete withvirgin. In addition, it is not easy to market recycled lubricant, which is more poorly perceived to be ofpoor quality compared to its virgin alternative 7.

Concrete: DfT (2007) quotes a figure from the Carbon Trust for the production of concrete of 1.09tonnes of CO 2 per tonne of concrete. In the absence of other data, figures for the recycling or disposalof concrete are assumed to be similar to comparable figures for aggregates from the forthcoming 2009update to the Defra/DECC GHG Conversion Factors. [Relevant to the assessment rail infrastrucecovered in Section 2.3, but presented here for completeness].

Bricks: The emissions resulting from the production of bricks were taken from IJLCA (2003). In theabsence of other data, figures for the recycling or disposal of concrete are assumed to be similar tocomparable figures for aggregates from the forthcoming 2009 update to the Defra/DECC GHGConversion Factors. [Relevant to the assessement rail infrastruce covered in Section 2.3, butpresented here for completeness].

The net greenhouse gas emissions or a given train will vary significantly depending on the level ofrecycling of the component materials at the end of its life. Three scenarios have been set up toillustrate the sensitivity of this assumption(a) No recycling (low scenario);(b) 50% recycling (central scenario); and(c) 90% recycling (high scenario).

The following Table 2.7 provides a summary of the material composition of a typical electric rail vehicleand the corresponding production and disposal emissions for the different recycling scenarios. Figure2.10 illustrates the percentage breakdown due to different materials in terms of the vehicle tonnageand in terms of the net greenhouse gas emissions for different recycling scenarios.

5 Berryman (www.berryman-uk.co.uk).6 http://www.wasteonline.org.uk/resources/InformationSheets/vehicle.htm7 DTI (2001), Waste Oil Recycling. Available at http://www.nnfcc.co.uk/nnfcclibrary/productreport/download.cfm?id=69


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Table 2.7: Material breakdown for typical electric rail rolling stock and corresponding net emissions ofgreenhouse gases for production and disposal at different recycling rates

Component Net GHG Tonnes GHGMaterial Tonnes % Total Tonnes CO 2eq /tonne train

Central Low High Central Low HighSteel 27.05 57% 66.41 84.13 52.23 1.41 1.78 1.11Aluminium 12.60 27% 81.96 138.73 36.55 1.74 2.94 0.77Copper 1.20 3% 3.08 2.05 3.90 0.07 0.04 0.08Glass 0.82 2% 0.56 0.70 0.46 0.01 0.01 0.01Lubricating oil 0.63 1% 1.87 3.11 0.88 0.04 0.07 0.02Wood 1.45 3% 1.47 1.30 1.61 0.03 0.03 0.03Plastic (and rubber) 3.43 7% 3.95 6.08 2.25 0.08 0.13 0.05Total 47.18 100% 159.31 236.09 97.89 3.38 5.00 2.08

Sources: Breakdown of materials used in typical electric rolling stock vehicle was sourced from DeltaRail (2007). GHG emissionfactors per tonne of material are based upon the data in Table 2.6.

Notes: Information is presented for the following recycling scenarios: Low = No recycling, Central = 50% recycling, High =

90% recycling of materials used in the production of the train at the end of its lifetime. The remainder (any materialsnot recycled) are assumed to go to landfill.

Figure 2.10: Proportional breakdown of materials used in electric rail rolling stock and corresponding netemissions of greenhouse gases for production and disposal at different recycling rates

Material breakdown of a typical electric train

Steel

Aluminium

Copper

Glass

Lubricatingoil

Wood

Plastic

Net GHG (no recycling)

Steel

Aluminium

Copper

Glass

Lubricatingoil

Wood

Plastic

Material Breakdown Net GHG Emissions Low (No Recycling)

Net GHG (50% recycling)

Steel

Aluminium

Copper

Glass

Lubricatingoil

Wood

Plastic

Net GHG (90% recycling)

Steel

Aluminium

Copper

Glass

Lubricatingoil

Wood

Plastic

Net GHG Emissions Central (50% Recycling) Net GHG Emissions High (90% Recycling)Sources: Breakdown of materials used in typical electric rolling stock vehicle was sourced from DeltaRail (2007). GHG emission

factors per tonne of material are based upon the data in Table 2.6.


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The final element in the evaluation of the relative lifecycle impacts of conventional and high-speed railis to take account of their respective levels of activity in terms of total lifetime vehicle km. Thefollowing Table 2.8 provides a summary of the estimated net emissions for the different trainsidentified earlier in Section 2.1.3. Under the assumption that high-speed rail vehicles travel roughly20% further in their lifetime compared to conventional equivalents the HSE and AGV trains taken asrepresentative for the 2025 timeframe appear to perform similarly per seat-km travelled.

Table 2.8: Characteristics of current and future rolling stock used for conventional and high-speed railand the net greenhouse gas emissions under the central recycling scenario

Conventional Rail High Speed Rail

TrainClass

91IC225

Class 390Pendolino

HitachiSuper

Express

Class373

Eurostar

TGVReseau

TGVDuplex

AVES103

Velaro

Shinkan-sen 700

Series

AlstomAGV

Seating Capacity 536 439 649 750 377 545 404 1323 650Vehicles per unit 11 9 10 20 10 10 8 16 14Tare mass(tonnes) 498 460 412 723 386 384 425 634 510

Mass per vehicle(tonnes) 45.3 51.1 41.2 36.2 38.6 38.4 53.1 39.6 36.4

Emissions fromproduction anddisposal, tonnesCO 2eq

1,682 1,553 1,391 2,442 1,304 1,297 1,435 2,141 1,722

Typical lifetimetrain-km (million) 12 12 12 15 15 15 15 15 15

Emissions overlifetime,kgCO 2eq/train-km

0.140 0.129 0.116 0.163 0.087 0.086 0.096 0.143 0.115

Emissions overlifetime,gCO 2eq/seat-km

0.26 0.29 0.179 0.22 0.23 0.16 0.24 0.11 0.177

Notes: Typical lifetime train-km for high-speed rail is based on a 30 year lifetime and information from Siemens on typicalannual travel of 500,000 km, with the typical annual travel by conventional rail taken to be 400,000 km.

In addition to the embedded emissions resulting from the production and disposal of materials for railrolling stock, there will also be emissions resulting from the in-service maintenance of rail rolling stock.Information was available from IJLCA (2003) on the average electricity, heating and drinking waterused, presented in Table 2.9. According to our research and consultation with industry experts for thisstudy, there is no reason to suggest that there should be any significant differences between figuresfor conventional and high-speed rail. Therefore the figures from Table 2.9 are taken to be applicableto both types of service.

Table 2.9: Estimated energy and water consumption per train-drive km for train maintenance andrefitting

Element Area Item Value Units2007 Net GHG,kgCO 2eq /tdkm

Train maintenance Operation Electricity 0.191 kWh/tdkm 0.117and refitting Heating 0.811 kWh/tdkm 0.149

Drinking water 3.881 kg/tdkm 0.000004

Sources: Activity data was sourced from IJLCA (2003), with corresponding net GHG per tdkm calculated for 2007 usingemission factors for electricity, gas and water use (supply and treatment) from the forthcoming 2009 update to theDefra/DECC GHG Conversion Factors.

Notes: tdkm = train-drive km, the number of km travelled by the train


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2.3 Energy consumption and emissions resulting fromrail infrastructure

In this section is discussed both the embedded energy consumption and emissions from railinfrastructure and the emissions resulting from its ongoing operation and maintenance.

The embedded emissions resulting from the construction and eventual decommissioning of railinfrastructure are expected to be very significant primarily due to the very large quantities of steel andconcrete used, which are both highly energy intensive in their production. Therefore in the evaluationof the relative significance of such emissions it is necessary to understand both:A. If there might be differences between the infrastructure required for conventional and high-speed

rail, and how significant these might be overall in terms of materials and construction emissions.B. If there are significant differences in the intensity of use of this infrastructure, and how that could

affect the comparison per seat-km or passenger-km over the lifetime of the infrastructure.

Both of these elements have been explored in detail as part of this study, through research andconsultation with rail industry experts. In terms of the potential differences between the infrastructurerequirements, the following provides a summary for different elements:

Stations: It is assumed that the requirements of stations for high-speed and conventional railservices would be the broadly similar, with few differences in total embedded energy fromconstruction and maintenance work on stations.

Track: The types of track that can be used for conventional of high-speed services are essentiallythe same. Both conventional ballasted track (with gravel driveway) and ballanstless track can beequally be used for conventional and high-speed services. The main difference for conventionalballasted track used for high speed services is that greater quantities of ballast are required withlarger stone sizes. Ballastless track has significantly higher embedded emissions due to thehigher volume of concrete (4-6 times more than ballasted track). However, some studies havesuggested that over its lifetime this may be offset to a significant degree by decreasedmaintenance.

Tunnelling: The construction energy use is expected to be broadly similar for both high speedand conventional rail requirements.

Distance and Curves: Conventional rail would not require banked curves due to the tiltingtechnology (e.g. as already used by Pendolino rolling stock in the UK). However, depending onthe required curvature, in some cases high speed lines may still require banked curves orsuperelevation, potentially adding to the embedded emissions.

Catenaries and other infrastructure: Both conventional rail and high speed require similarcatenaries infrastructure for electrification. Signalling equipment needs to be of higherperformance for high-speed rail services, but this is unlikely to affect the volume of componentmaterials and the corresponding greenhouse gas footprint.

Land area: Due to the pressure caused when two trains pass each other at high speeds (250-350kph), the width of the transport corridor for high-speed lines needs to allow for a greater distance

between tracks (1-2 metres) when compared with conventional rail. Whilst this might besignificant in terms of land-take, it is unlikely to have a significant impact in terms of energyconsumption and greenhouse gas emissions compared to the materials used in infrastructureconstruction.

These findings seem to indicate that broadly there are no anticipated differences between theinfrastructure requirements for conventional versus high-speed rail that might lead to significantdifferences in embedded or in-use (e.g. maintenance) energy consumption or net greenhouse gasemissions. However, the importance of differences in the intensity of use of the infrastructure forconventional versus high-speed rail can only be established with an estimate for the embedded andin-use emissions.

Estimates for the embedded emissions from new rail infrastructure have therefore been developedbased on materials use, materials transport (construction materials and excavated soil) and energyused for boring tunnels. The results of these calculations on embedded emissions are presented in


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Table 2.10. This table provides figures for central, low and high recycling scenarios and a split offigures for open track sections, tunnel track sections and an average for (a typical) 10% tunnels asproportion of the total line km. Separate totals are also presented for track using standard gravelballast and for ballastless track to give low and high estimates respectively on the total potentialembedded infrastructure emissions. Illustrative breakdowns of the materials use and greenhouse netgas emissions are also provided in Figure 2.11 and Figure 2.12, under assumptions of central (50%)recycling and 10% tunnelling.

The table and figures illustrate several points: First, the importance of the assumptions made ontunnelling (and bridges), which contribute significantly to the overall totals. Second, the type of tracklaid has a significant impact on the total embedded emissions - in the order of 30-40 tonnes CO 2eq perrail track km. Third there is an overiding impact resulting from the use of concrete and steel in thetotal GHG emissions, which can account for over 75% of the total embedded greenhouse gasemissions (from less than 50% of the raw materials used in the construction).

Whilst the embedded emissions look very large, they will be much reduced when distributed perpassenger carried over the track, which can be as high as 9-10 million per year for major city-to-cityservices alone (e.g. Eurostar) and higher still if services to multiple destinations are operated. This willbe explored in detail in the discussion of the main results (Section 3).

Figure 2.11: Breakdown by electric rail infrastructure element of the net embedded greenhouse gasemissions for (at a 50% recycling rate), annualised over the infrastructure lifetime

0 50 100 150 200 250 300

Gravel Bed

Ballastless Track

Tonnes CO 2eq per rail track km per year

Rails Rail driveway OHLE Structures and Wires

Tunnels Bridges (road / railway ) Cons truction of buildings

Material transport Tunnelling (10%) Notes: Figures are based on annualised emissions based on the anticipated lifetime of individual elements and with tunnels

estimated at 10% of the total km


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Figure 2.12: Proportional breakdown of materials used in electric rail infrastructure and correspondingnet emissions of greenhouse gases for production and disposal (at a 50% recycling rate)

Breakdown of Embedded Rail InfrastructureTonnes/track-km by Material

Steel Concrete

Grave l Al um ini um

Copper Soil

Bricks

Breakdown of Embedded Rail InfrastructureTonnes/track-km by Material

Steel Concrete

Grave l Alu mi ni um

Copper Soil

Bricks

Materials (conventional ballasted track) Materials (ballastless track)

Breakdown of Embedded Rail Infrastr uctureTonne GHG Emissions by Element

Steel Concrete

Grave l Al um ini um

Copper Soil

Bricks Trans port

Electricity

Breakdown of Embedded Rail InfrastructureTonne GHG Emissions by Element

Steel Concrete

Gravel Aluminium

Copper Soil

Bricks Transport

Electricity

GHG emissions (conventional ballasted track) GHG emissions (ballastless track)

Notes: Soil = soil excavated as part of construction activities for rail driveway and from tunnelling (estimated 10% of total km)

In addition to the embedded emissions resulting from the production and disposal of materials for newrail infrastructure, there will also be emissions resulting from the in-service maintenance ofinfrastructure and heating of track points to avoid de-icing in winter. Information was available fromIJLCA (2003) on energy for heating points, and consumption of energy and materials buildingoperation and maintenance. This data is presented in Table 2.11 and taken to be applicable to bothconventional and high-speed services. Based on illustrative energy

comparing environmental impact of conventional and high speed rail

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