sustainable aviation co2 road

Transcription

Sustainable Aviation
CO2 Road-Map
www.sustainableaviation.co.uk
SA CO2 Road-Map 2012 Guide Cover1.indd 1
03/09/2013 12:22
Sustainable Aviation CO2 Road-Map 2012
© Sustainable Aviation, March 2012
SUSTAINABLE AVIATION CO2 ROAD-MAP 2012
Sustainable Aviation is a unique alliance of the UK’s airlines, airports, aerospace manufacturers and
air navigation service providers. Together, we drive a long term strategy to deliver cleaner, quieter,
smarter flying. SA is the first alliance of its type in the world, and reports regularly on progress in
reducing aviation’s environmental impact.
Executive Summary
This document sets out Sustainable Aviation’s projection of future CO2 emissions from UK aviation.
Our projection is based on recently published UK-Government forecasts of aviation demand-growth,
together with our own assumptions concerning the deployment of technology, sustainable fuels,
operational measures and carbon trading.
We conclude that UK aviation is able to accommodate significant growth to 2050 without a substantial
increase in absolute CO2 emissions. We also support the reduction of net CO2 emissions to 50% of
2005 levels through internationally agreed carbon trading.
Projection of CO2 Emissions from UK Aviation
UK aviation can accommodate significant growth to 2050 without a substantial
increase in absolute CO2 emissions. We also support the reduction of net CO2
emissions to 50% of 2005 levels through internationally agreed carbon trading.
Government will play a key role in supporting research and development in aerospace technology,
encouraging the introduction of sustainable biofuels, delivering on infrastructure projects such as the
Single European Sky initiative, and working with other countries to establish a global sectoral
approach for regulating international aviation emissions based on carbon trading.
We do not support unilateral UK targets and measures as they would be unnecessary and counter
productive. Such measures would deliver no overall environmental benefit, but would result in carbon
leakage, market distortion, and the loss of economic benefits to our international competitors.
Recent and future developments in aircraft and engine technology will play a major role in reducing
UK aviation’s carbon intensity. We anticipate absolute CO2 emissions will continue to fall post-2050
due to the ongoing penetration into the fleet of new wide-body aircraft types entering service from
around 2035 onwards. The same technologies will also be deployed on a worldwide basis, with a
correspondingly greater CO2 mitigation impact.
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The potential for sustainable biofuels to reduce CO2 emissions from UK aviation has increased
dramatically over the past three years. During this period, two classes of sustainable fuel have been
certified for commercial use, and there has been considerable diversification in the range of potential
feedstocks and processing routes being developed. This area continues to develop rapidly.
Improvements in air traffic management and operational procedures will also play a material role in
reducing the carbon intensity of aviation in the coming decades.
Although UK aviation currently accounts for some 5-6% of global aviation’s CO2 emissions, this
proportion is likely to fall significantly over the next few decades due to rapid growth in large
developing aviation markets such as China, India, and Latin America. Looking forwards therefore,
significant UK influence over CO2 emissions from aviation will be achieved not through restricting the
scale of UK aviation activity, but rather through internationally focussed efforts.
Government should therefore:
•
support the development of more efficient aircraft and engine technologies which will be
deployed on a worldwide basis;
•
support the development and large-scale deployment of sustainable aviation fuels offering
very significant life-cycle CO2 savings relative to conventional fossil-based fuels;
•
work with international partners to enable more efficient air traffic management on nondomestic routes, within the context of increased capacity requirements;
•
press for agreement on and support implementation of a global carbon-trading solution
encompassing all of aviation and ensuring a level playing field for all participants.
Key areas in which this (2012) CO2 Road-Map differs from our previously published (2008) CO2 RoadMap are as follows:
•
The demand-growth trajectory upon which our Road-Map is based now takes account not only
of growth in passenger numbers but also of changes in the average distance travelled by
passengers, and of growth in cargo flights.
•
Our view of the extent to which more efficient engines and aircraft will impact fleet fuel
efficiency now benefits from greater clarity concerning the capabilities of aircraft types due to
enter service during the current decade.
•
Our assessment of the likely impact of sustainable fuels upon UK aviation’s CO2 emissions
takes account of the significant progress made in this field over the past three years.
•
Our assessment of the likely mitigation impact of improved air traffic management is now
based on a bottom up analysis which includes the impact - on flights which depart from UK
airports - of the fuel-burn reduction target adopted by the UK’s air navigation service provider.
•
The global aviation emissions objective to reduce net CO2 emissions to 50% of 2005 levels by
2050 using carbon trading is presented.
Aviation is a globally interconnected industry and needs a global solution to address its emissions in a
cost effective manner without introducing competitive distortions. Any unilateral targets and measures
that attempt to limit UK aviation’s emissions through capacity constraints or price-related demand
reduction will lead to carbon leakage, market distortion and the loss of economic benefit to our
international competitors. We do not support the inclusion of international aviation emissions in UK
carbon budgets. Our Road-Map shows that such unilateral policy measures are not necessary and
that UK aviation can accommodate significant growth to 2050 without a substantial increase in
absolute CO2 emissions. We also support the reduction of aviation’s net CO2 emissions to 50% of
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Contents
1 Introduction ................................................................................................................................. 5 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 1.10 2 Hypothetical “No-Improvements” Scenario ........................................................................... 10 2.1 2.2 2.3 3 Introduction ...................................................................................................................... 40 The Need for a Global Approach ..................................................................................... 40 Assessment of Potential Mitigation Impact ...................................................................... 40 Summary of Assumptions........................................................................................................ 42 8.1 8.2 9 Introduction ...................................................................................................................... 35 UK Initiatives .................................................................................................................... 35 Sustainability.................................................................................................................... 36 Overview of Sustainable Fuel Categories........................................................................ 37 Economics of Biojet ......................................................................................................... 37 Scale-Up and Deployment ............................................................................................... 38 European Advanced Biofuels Flightpath.......................................................................... 38 Assessment of Potential Mitigation Impact ...................................................................... 39 Carbon Trading ......................................................................................................................... 40 7.1 7.2 7.3 8 Introduction ...................................................................................................................... 21 Aircraft Technology – Overview of Options ..................................................................... 21 Engine Technology – Overview of Options...................................................................... 25 Fuel Efficiency Improvements – the Evidence Base........................................................ 27 Aircraft Fuel Efficiency Assumptions ............................................................................... 29 Impact on Fleet-Average Fuel Efficiency ......................................................................... 33 Sustainable Fuels...................................................................................................................... 35 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 7 Introduction ...................................................................................................................... 15 Air Traffic Management (ATM) ........................................................................................ 15 APU Substitution.............................................................................................................. 18 Aircraft Operations ........................................................................................................... 19 Assessment of Potential Mitigation Impact ...................................................................... 19 Improvements in Aircraft and Engine Efficiency ................................................................... 21 5.1 5.2 5.3 5.4 5.5 5.6 6 Introduction ...................................................................................................................... 13 Industry Motivation and Commitment .............................................................................. 13 Potential Mitigation Approaches ...................................................................................... 13 Improvements in Air Traffic Management and Operations ................................................... 15 4.1 4.2 4.3 4.4 4.5 5 Introduction ...................................................................................................................... 10 Demand Growth Projections ............................................................................................ 10 The Hypothetical “No-Improvements” Scenario............................................................... 11 Overview of Mitigation Opportunities ..................................................................................... 13 3.1 3.2 3.3 4 Sustainable Aviation .......................................................................................................... 5 UK Aviation’s Economic Value .......................................................................................... 5 Aviation and the Environment ............................................................................................ 5 UK Aviation in the International Context ............................................................................ 6 The First SA Road-Map – a Retrospective View ............................................................... 6 Motivation for an Updated Road-Map ................................................................................ 7 Methodology ...................................................................................................................... 8 Scope of the SA CO2 Road-Map ....................................................................................... 8 The Role of Government ................................................................................................... 8 Document Structure ........................................................................................................... 9 Demand Growth............................................................................................................... 42 Mitigation Assumptions .................................................................................................... 42 The Sustainable Aviation CO2 Road-Map ............................................................................... 43 www.sustainableaviation.co.uk
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9.1 9.2 9.3 9.4 9.5 © Sustainable Aviation, March 2012
The Road-Map ................................................................................................................. 43 Discussion – Average Rates of Improvement.................................................................. 43 Comparison of SA’s Projection with DfT’s CO2 Forecasts ............................................... 44 Comparison of SA’s and CCC’s Mitigation Assumptions................................................. 45 Conclusions ..................................................................................................................... 45 References ........................................................................................................................................... 47 APPENDIX A – Fleet Turnover Assumptions.................................................................................... 49 APPENDIX B – Distribution of Fuel-Burn .......................................................................................... 51 APPENDIX C – Less Likely Mitigation Options ................................................................................ 53 APPENDIX D – Comparing the 2008 and 2012 Road-Maps ............................................................. 55 APPENDIX E – Impact of Fuel Efficiency on Mission Fuel-Burn .................................................... 57 APPENDIX F – ATM efficiency improvements in NATS airspace ................................................... 58 www.sustainableaviation.co.uk
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1
Introduction
1.1
Sustainable Aviation
Sustainable Aviation (SA) is a unique alliance of the UK’s airlines, airports, aerospace manufacturers
and air navigation service providers. Together, we drive a long term strategy to deliver cleaner,
quieter, smarter flying. SA is the first alliance of its type in the world, and reports regularly on progress
in reducing aviation’s environmental impact.
Over the past 50 years, the aviation industry has delivered dramatic improvements in emissions. SA is
now looking at how the industry can deliver even more advances over the next 40 years. We are
undertaking work to reduce emissions from aircraft whilst on the ground, reviewing our CO2 Road-Map
and contributing to the roll out of the Departures Code of Practice.
SA supports a global agreement on aviation emissions with the goal of securing a 50% reduction in
global aviation’s net CO2 emissions by 2050 relative to 2005, as agreed by the International Air
Transport Association (IATA), Airports Council International (ACI), International Coordinating Council
of Aerospace Industries Associations (ICCAIA) and the Civil Air Navigation Services Organisation
(CANSO).
1.2
UK Aviation’s Economic Value
Aviation brings economic benefits to society as a whole and to the UK in particular, supporting trade,
investment and employment. In 2009, the combined activities of airlines, airports, ground services and
aerospace directly contributed £24.0 billion to UK GDP, whilst directly supporting 352,000 jobs in the
UK. The aviation sector’s supply chain contributed a further £16.6 billion to UK GDP in the same year
[OE, 2011].
The UK’s aerospace manufacturing sector is the world’s second largest, directly employing 105,000
people and directly generating £10.3 billion of UK GDP in 2009, with a further £7.6 billion of UK GDP
being generated by the aerospace sector’s supply chain [OE, 2011]. The sector brings further
economic benefits through the generation of intellectual property which frequently has spin-off benefits
in other sectors.
1.3
Aviation and the Environment
The aviation industry takes extremely seriously its responsibility to reduce its environmental impact, as
its track record illustrates. Over the last half-century, fuel-burn per passenger-kilometre has been
reduced by some 70 percent against a backdrop of progressively tightening noise and NOx
regulations.
The industry remains resolute in its drive to reduce emissions even further, as demonstrated not only
by the commitments of aircraft operators to refreshing their fleets with newer, more efficient aircraft,
but also by significant investment in ongoing research and development [SA, 2011], [SA, 2009] to
ensure that future generations of aircraft are even more efficient.
Recently the European Commission’s High Level Group on Aviation Research has published a vision
for aviation in 2050 entitled “Flightpath 2050” [HLG, 2011], calling for a reduction in CO2 emissions per
passenger kilometre of 75%, a 90% reduction in NOx emissions and a 65% reduction in perceived
noise emissions from flying aircraft. This vision is benchmarked against the capabilities of a typical
new aircraft in 2000.
However, aviation’s social and economic contribution to society is such that underlying demand for air
travel continues to rise, placing upward pressure on emissions. This Road-Map brings together
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analysis from the various sectors of the UK industry, together with demand-growth projections from
the UK’s Department for Transport [DfT, 2011], to provide a balanced view of the likely trajectory of
CO2 emissions from UK aviation over the period to 2050.
1.4
UK Aviation in the International Context
1
CO2 emissions from UK aviation currently correspond to around 5-6% of CO2 emissions from aviation
2
worldwide. Whilst UK aviation’s growth rates to 2050 will average around 2% per annum [DfT, 2011],
global growth rates are expected to be considerably higher due to the rapid development of emerging
markets in Asia and elsewhere. As a result, the proportion of global aviation’s emissions attributable to
the UK is likely to diminish over time. The most compelling opportunity for the UK to exert an influence
over CO2 emissions from aviation is therefore not by constraining demand for UK aviation, but rather
3
through investment in advanced technologies which can be deployed globally, earning export
revenues for the UK while contributing to a more environmentally efficient industry world-wide.
To illustrate the comparative scale of the global mitigation opportunity, analysis by IATA [IATA, 2010]
has shown that global commercial airline fuel efficiency has improved by over 30% in the past two
decades, saving over 400 million tonnes of CO2 per annum at current activity levels, relative to the
fleet efficiency in 1990. In contrast, total annual emissions of CO2 attributable to UK aviation
correspond to less than one tenth of this figure.
Since CO2 is a well-mixed greenhouse gas, the geographical or sectoral distribution of CO2 emissions
does not influence the climate system’s response to those emissions. Accordingly, the pursuit of the
most cost-effective mitigation opportunities, irrespective of sector or geography, should be
incentivised. Aviation should be therefore be regulated at the global level, avoiding a patchwork of
competing and conflicting national and regional emissions regulation which would lead to carbon
leakage and market distortions. We strongly oppose including international aviation in the UK carbon
budget or introducing national targets or measures aimed at reducing international aviation emissions.
If international aviation were included in the UK budget, this would lead to perverse policy decisions
that would not reduce global emissions, but would only give the illusion of a reduction in UK
emissions. For this reason we support the drive for a global sectoral agreement to regulate CO2
emissions from international aviation.
1.5
The First SA Road-Map – a Retrospective View
With the first version of the SA Road-Map [SA, 2008a], issued in December 2008, the UK aviation
industry presented for the first time a consensus view of its likely CO2 emissions trajectory to 2050.
The analysis therein was informed by input from all four sectors of the industry - manufacturers,
airlines, airports and the UK’s air navigation service provider.
Based on clearly laid out assumptions and calculations, the first SA Road-Map set out our view that
CO2 emissions from UK aviation would not - as some had suggested - occupy 50% or even 100% of
the UK’s carbon budget by 2050, but rather would return to below 2005 levels by 2050.
At the time of the first Road-Map’s publication, audited figures for actual CO2 emissions from UK
aviation were available up to and including 2006. Since that time figures for 2007-2009 have become
available [NAEI, 2011]. Figure 1 illustrates the level of agreement between actual CO2 emissions and
corresponding figures derived from the first Road-Map so as to take account of actual passenger
numbers.
1
Our interpretation of this phrase is set out in section 1.8
2
In terms of passenger numbers
3
This would include not only engine and aircraft technologies, but also bio-fuel technologies and ATM-related technologies.
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Figure 1 – Comparison of actual CO2 vs. the first SA CO2 Roadmap (adjusted for
actual passenger numbers). Data sources: [CAA, 2010], [NAEI, 2011], [SA,
2008a].
1.6
Motivation for an Updated Road-Map
Since our first CO2 Road-Map was conceived and developed, there have been a number of
developments which have a bearing on the likely future trajectory of UK aviation’s CO2 emissions. We
have taken the opportunity to revise our Road-Map, taking account of the latest evidence available to
us. Developments since late 2008 include the following:
4
•
The impact of the global economic downturn upon future levels of demand for UK aviation was
assessed by the UK’s Department for Transport in their growth forecast released in the
summer of 2011 [DfT, 2011].
•
The benefits of a more efficient single-aisle airliner will be seen earlier than previously
anticipated, due to the two largest manufacturers both offering a “re-engined” aircraft type in
this category, with entry into service expected around the middle of this decade.
•
The level of ambition of European aerospace research, and the timescale over which that
ambition extends, has benefitted from renewed focus. The European Commission’s High
Level Group on Aviation Research published in 2011 a vision for aviation in 2050 entitled
“Flightpath 2050” [HLG, 2011].
•
Certification for commercial aviation of two main classes of biofuel blends has been achieved.
In summer 2011, a small number of scheduled airline services commenced operations using
fuel partly derived from biomass. This area continues to develop rapidly.
•
The aviation industry now has visibility of the implementation of aviation’s incorporation in the
EU Emissions Trading Scheme.
•
At the global level, ACI, CANSO, IATA and ICCAIA collectively announced in 2009 a
commitment for the international aviation industry to pursue a 1.5% per annum improvement
in fuel efficiency up to 2020, to achieve carbon neutral growth from 2020, and to reduce net
carbon emissions (relative to 2005 levels) by 50% by 2050 [ACI, 2009].
•
Also at the global level, the UN’s aviation body, ICAO, declared in 2009 a requirement to
4
pursue improvements in fuel efficiency (defined as volume of fuel used per RTK performed)
of 2% per annum up to 2020, and an aspiration to pursue the same rate of improvement up to
2050 [ICAO, 2009].
RTK = revenue tonne kilometre
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•
1.7
Further, in 2010, ICAO resolution A37-19 set out an “aspirational goal of keeping the global
net carbon emissions from international aviation from 2020 at the same level”, together with
an intention to work with member states “to develop a framework for market-based measures
(MBMs) in international aviation” [ICAO, 2010].
Methodology
The approach taken in this issue of our Road-Map is as follows:
•
We first consider the likely growth in demand for UK aviation, using it to derive a hypothetical
“no-improvements” emissions scenario, corresponding to a constant level of technology,
operational practices and biofuel adoption.
•
We then consider in turn the potential for mitigation from the adoption of improvements in airtraffic management and operational practices, more efficient engines and aircraft, and the use
of sustainable biofuels. Having established the potential mitigation opportunity, we then set out
our assumptions concerning the extent to which that potential will be realised.
•
We also present the potential contribution of aviation’s participation in carbon trading, which
can deliver the most cost effective carbon reductions across the economy as a whole, and will
allow aviation to purchase carbon reductions from sectors where they may be achieved more
economically.
1.8
Scope of the SA CO2 Road-Map
In this document we interpret “UK aviation” to mean “flights which depart from UK airports”. This is
consistent with the accounting convention used by the UK to assess emissions from UK aviation. Our
use of this interpretation is motivated by the need for consistency with published figures and does not
imply support for or agreement with the corresponding accounting practice.
Besides carbon dioxide, emissions from aviation also include oxides of nitrogen (NOx), water vapour,
particulates, carbon monoxide, unburned hydrocarbons, soot and oxides of sulphur (SOx). The climate
impact of many of these is discussed in a separate paper [SA, 2008b]. This Road-Map focuses purely
on CO2.
1.9
The Role of Government
Bringing to fruition the projection set out in our Road-Map will not only require the continued
commitment and focus of the aviation industry itself, but will also rely on engagement from
Government, which should:
•
•
•
•
press for agreement on and support the implementation of a global carbon-trading solution
In reaching our view of the extent to which mitigation options identified in this document will reduce
CO2 emissions from UK aviation, we have assumed that suitable levels of Government engagement
will be achieved with respect to each of the above areas.
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1.10
Document Structure
The remainder of this document is structured as follows:
•
In section 2 we establish a hypothetical “no-improvements” scenario detailing the notional
growth in CO2 emissions from UK aviation that would take place assuming no improvements
in fleet fuel efficiency, no improvements in operational practices, and no adoption of
sustainable fuels.
•
In sections 3 to 6 we set out our assumptions and analysis concerning the potential for
aviation to improve its carbon intensity through a variety of measures.
•
Section 7 sets out the need for a global approach using carbon trading to reduce aviation’s net
emissions, and allowing aviation to fund mitigation actions in other sectors in those cases
where they can be achieved more cost effectively than within the industry itself.
•
Section 8 brings together the assumptions employed in our Road-Map.
•
Finally, section 9 presents the Road-Map itself along with a discussion of its key messages.
Comparisons with the results of other recent publications in this area are also presented.
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2
Hypothetical “No-Improvements” Scenario
SUMMARY – in the absence of any improvements in fleet fuel efficiency or in operational
practices, and assuming no use of biofuels, CO2 emissions from UK aviation would rise 150%
between 2010 and 2050, implying an average annual growth rate of 2.32%.
2.1
Introduction
In this section we identify the hypothetical trajectory that UK aviation’s emissions could be expected to
follow in the absence of any action to improve the industry’s carbon intensity. This “no-improvements”
trajectory then serves as a reference against which the potential impact of our anticipated
improvement activities can be assessed.
Our hypothetical “no-improvements” scenario assumes a constant level of technology, operational
procedures, and biofuel penetration, in which more aviation activity is delivered at the same load
factors using an increasing number of the same types of aircraft without changing over time the
manner in which they are operated, or the type of fuel used.
It is worth pointing out that this scenario does not correspond to a “business as usual” scenario, since
“business as usual” involves the rigorous pursuit of cost-reduction opportunities of which improving
fuel efficiency - and hence carbon intensity - is a major part.
2.2
Demand Growth Projections
5
In the previous SA Road-Map [SA, 2008a] we used forecasts of growth in passenger numbers
published by the UK’s Department for Transport (DfT) as the basis for our estimate of growth in
delivered aviation activity. Whilst this was an adequate proxy for our purposes, we were nonetheless
aware that a better proxy would have been a forecast of delivered revenue passenger kilometres
6
(RPKs) , on the basis that RPK growth also captures changes in the average distance flown by
passengers. Although a long-term forecast of RPK growth was not available to us at the time of the
previous SA Road-Map, the DfT’s most recent forecast document [DfT, 2011] tabulates RPK growth
for each of DfT’s three scenarios.
Figure 2 – comparison of DfT’s “Central” growth forecasts for passenger
numbers (pax) and revenue passenger kilometres (RPKs). Source: SA analysis
based on data from [DfT, 2011]
5
Passengers - often abbreviated to “pax”
6
RPKs – for a single flight, this term is the product of the number of passengers carried and the distance travelled
Page 10 of 58
Figure 2 compares DfT’s “Central” forecasts for growth in passenger numbers to the corresponding
7
forecast for growth in RPKs . The chart illustrates that the difference, whilst material, is not large, since
over the 40 year period RPKs are forecast to grow by a factor of 2.3, whilst passenger numbers are
forecast to grow by a factor of 2.2. Nonetheless, with respect to the growth in CO2 emissions that
would take place in the reference scenario, we believe that RPKs are more representative than
passenger numbers. For this reason we employ DfT’s “Central” RPK growth forecast in our reference
scenario. However, our usage of DfT’s growth forecasts does not imply our support for the policy
assumptions upon which those forecasts are based.
Whilst the above discussion refers to passenger flights, emissions from freight-only flights must also
be assessed for their significance. In addition to forecasts of RPKs, [DfT, 2011] also presents
forecasts of freight tonnes carried on freight-only flights, together with an estimate of the average
distance travelled by such flights. The following procedure establishes a common framework in which
growth forecasts of passenger activity and freight-only flights are combined in our hypothetical “noimprovements” scenario:
•
Freight-only flights accounted for 3.2% of UK aviation’s 33.4 MtCO2 emissions in 2010, with
8
the remainder being attributable to passenger-flights . Using these values we establish
separate baseline figures for CO2 emissions in 2010 from 1) passenger-flights and 2) freight
only flights.
•
Using DfT’s forecasts of freight tonnes carried on freight only flights, coupled with DfT’s
9
forecast of the average distance of freight only flights , we estimate the growth over time of
10
FTKs carried by freight-only flights.
•
The 2010 baseline emissions figures for each of the two flight categories is then scaled up according to the growth in delivered RPKs or FTKs relative to 2010 - to yield a trajectory for
each category. These can then be added to yield the total, as shown in section 2.3.
2.3
The Hypothetical “No-Improvements” Scenario
The hypothetical “no-improvements” scenario employed in the 2012 SA CO2 Road-Map directly tracks
the sum of the following two terms which are summarised in Table 1:
•
CO2 emissions arising from the growth in FTKs on freight only flights, derived from data
presented in Table G.12 of [DfT, 2011], and assuming that in 2010, freight only flights
accounted for 3.2% of UK aviation’s total 33.4 MtCO2 emissions (as set out in Table H.6 of
[DfT, 2011].
•
CO2 emissions arising from the growth in passenger RPKs set out in Table G.11 of [DfT,
2011], assuming that in 2010 passenger RPKs accounted for the remaining 96.8% of UK
aviation’s 33.4MtCO2.
In our hypothetical “no-improvements” scenario, illustrated in Figure 3, CO2 emissions from UK
aviation rise by 150% during the period from 2010 to 2050, implying an average annual growth rate of
2.32%. In subsequent sections of this document we examine opportunities for mitigating this growthdriven upward pressure on CO2 emissions from UK aviation.
7
DfT’s growth forecasts take into account the impact on demand of factors such as carbon pricing
8
Table H.6 of [DfT, 2011]
9
Table G.12 of [DfT, 2011]
10
FTKs = freight tonne kilometres
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Year
RPKs
(Billion)
MtCO2
Pax Flights
FTKs
(Billion)
MtCO2
Freighters
MtCO2
Total
CO2 Growth
Factor
CO2 %
Growth
2010
2015
2020
2025
2030
2035
2040
2045
2050
575
660
763
855
943
1035
1148
1280
1347
32.3
37.1
42.9
48.1
53.0
58.2
64.5
72.0
75.7
1.9
2.9
4.1
5.7
8.0
9.9
11.7
13.2
14.1
1.1
1.6
2.3
3.1
4.4
5.5
6.5
7.3
7.8
33.4
38.7
45.2
51.2
57.4
63.7
71.0
79.2
83.5
1
1.16
1.35
1.53
1.72
1.91
2.13
2.37
2.50
0
16
35
53
72
91
113
137
150
Table 1 – Key figures relating to the hypothetical “no-improvements” emissions
trajectory used in this CO2 Road-Map. Source: SA analysis based on “Central”
demand forecast from [DfT, 2011]. Use of DfT’s growth forecasts does not imply
SA support for the policy assumptions underpinning those forecasts.
Figure 3 – UK aviation CO2 emissions in a hypothetical “no-improvements”
scenario in which technology levels, operational practices, and biofuel
penetration levels remain unchanged from 2010. Scope: flights which depart from
UK airports, including passenger flights and freight-only flights. Source: SA
analysis based on “Central” demand forecast from [DfT, 2011]. Use of DfT’s
growth forecasts does not imply SA support for the policy assumptions
underpinning those forecasts.
Page 12 of 58
3
Overview of Mitigation Opportunities
3.1
Introduction
Although the aviation industry has made significant progress over the past few decades in reducing its
carbon intensity, principally through improvements in fuel efficiency, many opportunities for further
improvement remain. This section gives a brief overview of the wide variety of carbon mitigation
opportunities that may be envisaged. In subsequent sections we explore these opportunities in more
detail and set out our view of the extent to which some of them will contribute to reductions in UK
aviation’s carbon intensity.
3.2
Industry Motivation and Commitment
The increase in oil prices witnessed over the past decade or so has meant that fuel-related costs now
constitute a significantly greater percentage of airline operating costs than in the past. Figure 4
illustrates that since 2006 the global airline industry’s annual jet fuel bill has greatly exceeded $100
11
billion. IATA estimates that in 2011, fuel will account for 30% of global airline operating costs.
Charges associated with participation in carbon-trading schemes present additional fuel–related costs
to aircraft operators. We believe that the significance of fuel-burn within the balance of drivers
influencing aircraft and engine design, fleet renewal and operating practices is likely to increase still
further in the future.
Figure 4 – Global airline industry spend on jet fuel. Data source: IATA
11
The resulting incentive for improved fuel efficiency is clear. Aviation has made significant progress
over the past few decades in terms of reductions in fuel-burn per passenger kilometre. The significant
rises in fuel price observed over the past decade only strengthen the drivers for continued progress.
3.3
Potential Mitigation Approaches
In broad terms, the carbon footprint of a flight (per revenue tonne-kilometre) can theoretically be
reduced by a combination of the following:
11
•
Increasing the energy-per-unit-mass and/or energy-per-unit-volume of the fuel used.
•
Increasing the efficiency with which fuel energy is converted into thrust by the engine(s).
•
Increasing the aircraft’s aerodynamic efficiency (lift to drag ratio).
•
Reducing the structural weight of the aircraft for a given payload-range requirement.
•
Reducing engine weight.
•
Reducing the weight of aircraft systems and cabin infrastructure.
http://www.iata.org/pressroom/facts_figures/fact_sheets/Pages/fuel.aspx?NRMODE=Unpublished, viewed 04 Oct 2011
Page 13 of 58
•
Cruising at reduced speed.
•
Adapting aircraft design to maximise the advantages of reduced cruise speed.
•
Using an aircraft whose range capability does not greatly exceed the mission’s requirement.
•
Making full use of the aircraft’s mass-carrying capability at the desired range.
•
Optimising stage-length.
•
Adopting the most fuel-efficient route, taking weather and prevailing winds into account.
•
Avoiding queuing or holding, whether on the ground or in the air.
•
Replacing ground-based APU usage with lower-carbon power from airport infrastructure.
•
Taxiing using fewer engines, or by towing the aircraft.
•
Ensuring the aircraft and all its systems are operating at their most efficient state of
maintenance.
•
Using a lower carbon intensity sustainable fuel derived from biomass or waste.
•
Capturing carbon-dioxide from the air and using it to artificially manufacture aviation fuel.
•
Capturing carbon dioxide from the air and sequestering it.
•
Reducing net emissions through funding more cost-effective emissions reduction in other
economic sectors.
Each of these options is subject to the commercial realities of a highly-competitive industry, in which
fuel costs and carbon costs, while significant, are not the only drivers. Some of these options therefore
will not in our view contribute materially to reducing aviation’s carbon intensity before 2050, as we
discuss further in Appendix C.
Nonetheless, the remaining opportunities collectively present considerable scope for reducing the
carbon intensity of air travel. Subsequent sections of this document present our view of the extent to
which they will be pursued.
Page 14 of 58
4
Improvements in Air Traffic Management and Operations
SUMMARY
Improvements in air traffic management and operational practices have the potential to
improve the fuel efficiency of UK aviation by around 13.5% by 2050 relative to 2010. For the
purposes of our Road-Map, we assume a 9% improvement.
4.1
Introduction
In this section we examine the potential for improvements in aviation’s carbon intensity arising from
the more efficient operation and management of aircraft. We consider the following broad categories
of opportunity:
•
Air Traffic Management (ATM) - covering such aspects as optimised routing and altitude
profiles, and the reduction of queuing or holding. This category also includes the management
of aircraft flows on the ground.
•
APU substitution - consisting of the use of electrical power and conditioned air provided more
efficiently from airport infrastructure rather than from the aircraft’s own auxiliary power unit
(APU) when the aircraft is on the airport stand.
•
Aircraft operations – covering operationally-related sources of improvement such as higher
load-factors and the optimisation of fuel-loads.
4.2
Air Traffic Management (ATM)
4.2.1
Introduction
Allowing aircraft to follow fuel-optimal routings and altitude profiles offers potential for significant
reductions in CO2 emissions. Minimisation of queuing and holding offers some further scope for CO2
reduction. [CANSO, 2008] assessed the efficiency of global ATM provision and concluded that there
exists an opportunity to improve global ATM efficiency by an average of 3 to 4 percentage points.
However, the same report also makes clear that current ATM efficiencies in Europe are a few
percentage points lower than the global average. This leads to a greater than average opportunity for
ATM-related improvement in Europe.
Figure 5 – Distinction between typical stepped altitude profile and the optimal
altitude profile which reduces fuel-burn. Source: [SA, 2011]
Page 15 of 58
Opportunities for improvements in ATM and operational practices can be grouped broadly into groundbased opportunities and airborne opportunities. Examples of improvements currently being delivered
include:
•
ground-based: reducing taxi times, and improved taxiing techniques;
•
airborne: better climb profiles avoiding inefficient level segments, more direct routes,
improved access to fuel-efficient flight levels, achieving economic speeds, reducing reliance
on airborne holding and working towards better descent profiles (see Figure 5).
Several initiatives are underway to demonstrate and realise the potential savings that can be achieved
through more effective routing and management of aircraft.
12
•
[SA, 2011] describes the “Perfect Flight” live trial which took place in July 2010 and
demonstrated a reduction in CO2 emissions of some 11% on a flight from Heathrow to
Edinburgh, through the use of an optimal flight profile (see Figure 5) and the minimisation of
delay at all stages of the flight.
•
The ASPIRE initiative has demonstrated optimal flights on longer-haul routes across the
Pacific, and assesses the average fuel-burn reduction opportunity on routes between the US
13
and Australia/New Zealand to be in the region of 4% .
•
The European SESAR project aims to facilitate the defragmentation of European airspace to
enable significant ATM-related efficiency improvements within this busy region.
•
The Atlantic Interoperability Initiative to Reduce Emissions (AIRE) is working to demonstrate
and validate solutions for gate-to-gate improvements in emissions from flights in the Atlantic
region.
•
NATS (the UK’s air navigation service provider) has set a target to achieve a reduction of ATM
15
CO2 by an average of 10% per flight by 2020 , and has an active programme in place to
deliver this.
4.2.2
14
Assessment of Mitigation Opportunity for UK Aviation
Before assessing below the opportunities for reducing UK aviation’s CO2 emissions through advances
in ATM efficiencies, we first set out the overlap and distinction between 1) CO2 emissions from flights
which depart from UK airports, 2) CO2 emissions from flights whilst under NATS control, and 3) CO2
16
emissions from flights whilst under the control of other ANSPs .
Each flight within NATS control can be regarded as falling into one of four categories: overflights,
domestic flights, inbound international, and outbound international. Notwithstanding the above
categorisation, each flight can be regarded as consisting of a number of distinct phases: ground
operations, climb, en-route, and descent. Not every phase of each UK-departing flight will take place
under NATS control (e.g. the descent phase of an outbound international flight occurs elsewhere).
Furthermore, not every flight under NATS control falls within the scope of our Road-Map. Over-flights
and inbound international flights, for example, do not originate from a UK airport and thus lie outside
our scope. NATS estimates that in 2006, CO2 emissions in NATS controlled airspace from flights
17
which departed from UK airports amounted to 12.3Mt.
We now consider the potential ATM-related CO2 reduction in each of three categories:
12
Video containing more detail available at http://www.sustainableaviation.co.uk/2010/perfect-flight/
13
Source: http://www.aspire-green.com/mediapub/docs/metricsappendix.pdf
14
http://www.sesarju.eu/
15
http://www.nats.co.uk/news/nats-on-target-for-10-co2-cut-by-2020-as-new-ceo-urges-faster-pace/
16
ANSPs = air navigation service providers
17
Only flights which depart from UK airports are within scope of our UK CO2 Road-Map
Page 16 of 58
•
Improvements implemented within NATS airspace by 2020: Appendix F details the
relationship between the CO2 reduction target adopted by NATS and the corresponding
impact on CO2 emissions from flights which depart from UK airports. In summary, we estimate
that total savings achievable on flights which depart from UK airports, as a result of successful
delivery of the NATS 10% target, amount to 3.9% of UK aviation’s CO2 emissions. Although in
the analysis presented in Appendix F this saving is expressed relative to the stated 2006
baseline, the phasing of delivery is such that the vast majority will be achieved post 2010. We
therefore take this 3.9% as being the available saving relative to the SA Road-Map’s 2010
baseline. To take account of possible uncertainties, in our Road-Map we conservatively
assume a contribution of 3.0% from this source.
•
Improvements implemented outside NATS airspace by 2020: We anticipate that other
ANSPs will also deliver improvements in ATM efficiency within the next decade, and that
these will yield CO2 reductions during the en-route and arrival phases of outbound
international flights once they leave NATS airspace. We conservatively estimate that the
benefit to these flights corresponds to two tenths of the 10% efficiency improvement targeted
by projects such as [SESAR]. In 2006, CO2 emissions outside NATS airspace attributable to
18
flights which departed from UK airports amounted to 25.7Mt . Saving 2% of these emissions
would yield a reduction of 0.51 MtCO2 relative to 2006 emissions, corresponding to 1.3% of
total UK aviation CO2 emissions in 2006. Again, due to the anticipated phasing of delivery of
these savings, we take this 1.3% as being relative to the Road-Map’s 2010 baseline. To take
account of possible uncertainties, in our Road-Map we take 1.0% as the likely contribution
from this source.
•
Other ATM-related improvements implemented 2020-2050: While many major airspace
improvements will have been delivered by 2020, there will remain further scope for
improvement in airspace structures as well as in technology to manage traffic flows and
improve separation minima so that aircraft can achieve more optimum flight profiles. New
navigation technologies, restructuring of airspace boundaries and traffic management
techniques offer potential for reductions in fuel-burn in excess of 5%, over and above savings
delivered prior to 2020. However, to allow for uncertainties concerning the level to which this
potential might be realised, we conservatively assume a further saving of some 2.5% of all
CO2 emissions from all UK originating flights which will become effective gradually between
2020 and 2050.
The above discussion is summarised in Table 2.
ANSP
Timescale
Phase of Flight
NATS
Pre 2020
Other
Pre 2020
NATS & Other
Post 2020
TOTAL
19
Saving (% of UK aviation CO2)
Assumed
Potential
All
3.0
3.9
En-Route, Descent
1.0
1.3
All
2.5
5.0+
6.5
10.0+
Table 2 – potential reductions in CO2 emissions from flights which depart from
UK airports, arising from anticipated improvements in ATM efficiency
18
38MtCO2 total [NAEI, 2011], minus the 12.3MtCO2 taking place in NATS airspace, leaves 25.7Mt outside NATS airspace.
19
Values rounded to the nearest 0.5%
Page 17 of 58
4.3
APU Substitution
Opportunities to reduce CO2 emissions from aircraft on the airport stand through the provision of
lower-carbon electrical power and/or conditioned air from airport infrastructure rather than from the
20
aircraft’s own APU were discussed in [SA, 2010a], [SA, 2011]. This approach also offers potential for
reducing noise and NOx emissions.
The Aircraft on the Ground CO2 Reduction (AGR) Programme [SA, 2010a], [SA, 2011] was developed
following two years of collaborative work involving Sustainable Aviation led by Heathrow Airport and
with the input of the Clinton Climate Initiative. The programme has a simple and pragmatic objective to
develop practical guidelines for airports working with partners to cut aircraft ground movement CO2
emissions and also improve local air quality. Heathrow was used as a case study, where it was shown
that ground emissions are approximately 30% of the airport's total footprint (excluding the en route
phase) and are therefore significant (see Figure 6).
Figure 6 – Carbon footprint of London Heathrow Airport, 2008, excluding
emissions from the en-route phase of flight. Source [SA, 2010a].
The programme captures best practices across the industry today with potential for even greater
efficiency improvements in the future. Practical action steps for airports, airlines, air navigation service
providers and ground handling companies to reduce emissions are clearly set out in the innovative
programme.
In addition to exploring reductions in APU usage, the programme also examined the CO2 savings
achievable through using a reduced number of engines when taxiing aircraft. It is estimated that these
two practices at Heathrow are already saving 100,000 tonnes of CO2 per year against a “do-nothing”
scenario, even after accounting for increased airport electricity consumption in place of APU usage.
The Airport Operators Association (AOA) is leading on extending the programme across other UK
airports and has already secured support from 23 airports across the country.
Recognising that there remain some uncertainties surrounding the potential impact on taxiway
capacity arising from significant deployment of reduced engine taxiing, for the purposes of our RoadMap we take account only of the benefits of APU substitution. Based on data presented in [SA, 2010a]
the potential future savings from APU substitution represent at least 50% of current CO2 emissions
from APUs. If this reduction is applied on a national basis to the level of APU emissions stated in DfT’s
21
2010 baseline it would represent a reduction of 0.2Mt in CO2 emissions from APUs, equivalent to a
0.6% reduction in UK aviation’s overall CO2 emissions. This assumes that the combined potential for
savings achievable at airports beyond Heathrow is of a similar magnitude to the remaining opportunity
at Heathrow itself.
20
APU = auxiliary power unit
21
Table H.6 of [DfT, 2011] – CO2 emissions from APUs at UK airports amounted to 0.4MtCO2
Page 18 of 58
The potential for APU substitution to deliver savings in CO2 emissions from UK aviation relative to a
2010 baseline is therefore estimated at around 0.6%. This compares well with separate studies carried
out by Zurich Airport and IATA, which have estimated potential of circa 0.6% fuel savings globally from
APU substitution. To account for uncertainties we take as input to our Road-Map an assumed 0.3%
saving from this source.
4.4
Aircraft Operations
We estimate the potential for reductions in UK aviation’s fuel-burn through improvements in aircraft
operational practices to be in the region of 2.9%. For the purposes of our Road-Map, we assume
improvements of 2.1% will be delivered by 2050, as set out below.
4.4.1
Passenger Load-Factor
An aircraft is at its most fuel-efficient when its load-carrying capacity is fully utilised. Aircraft operators
have achieved considerable success over the past decade with respect to increasing passenger load
22
factors through the use of increasingly sophisticated revenue management systems. Despite the
improvements already made, it is believed that there remains a small but material opportunity to obtain
further increases in passenger load factor, corresponding to an improvement in fuel-use per
passenger kilometre of some 2%, of which we conservatively take 1.5% as input into our Road-Map.
4.4.2
Optimised Fuel-Loads
It is recognised that on occasions the amount of fuel loaded into an aircraft’s fuel-tanks prior to flight is
23
in excess of that which is actually required to complete the mission . A common reason for this is
over-estimation of payload [ICAO, 2003]. We estimate that the potential for fuel-burn reduction,
without compromising safety, arising from more accurate fuel-loading is in the region of 0.5%. For the
purposes of our Road-Map, we assume 0.3% improvement from this source.
This phenomenon is distinct from fuel tankering, the latter being the intentional carriage of potentially
large volumes of fuel between airports for commercial reasons. Motivations for tankering are
discussed in [ICAO, 2003] and may include significant variations between airports of fuel price, quality
or availability, or may reflect a need to minimise turnaround times at busy airports. We do not takeaccount of any reductions in tankering activity within this Road-Map.
4.4.3
Other Operational Opportunities
Further opportunities for reducing aircraft fuel-burn through operational measures are available. These
include regular engine and airframe cleaning, the checking of door-seals for drag-inducing defects,
and the removal of dents from the aircraft’s external surfaces. These are discussed in [ICAO, 2003].
Small additional savings may be realisable through weight-reduction measures applied to cabin
24
interiors , and through the carriage of reduced amounts of potable water. We estimate the potential
for fuel-burn reduction arising from a combination of these measures to be in the region of 0.4%. For
the purposes of our Road-Map, we assume 0.3% improvement from these measures.
4.5
Assessment of Potential Mitigation Impact
Based on the discussion above, we conclude that the combined potential for improvements in ATM
and operational practices to reduce CO2 emissions from UK aviation is in excess of 13%. However,
taking account of uncertainties concerning the extent to which that potential will be realised in practice,
22
Corresponding to the proportion of installed seats actually occupied by passengers
23
After allowing for fuel-reserves required for safety purposes
24
As distinct from the improvements in cabin infrastructure discussed in section 5.2.4
Page 19 of 58
in our Road-Map we assume a 9% reduction in CO2 from UK aviation arising from improvements in
ATM and operations. Table 3 summarises the key figures presented in this chapter.
% CO2 Saving
Assumed
Potential
Deployment
Timescale
ATM
6.5
10+
To 2050
APU substitution
0.3
0.6
To 2030
Aircraft Operations
2.1
2.9
To 2050
9.0
13.5+
To 2050
Category
TOTAL
25
Table 3 – potential reductions in CO2 emissions from UK aviation, due to
anticipated improvements in ATM efficiency and operational practices
25
Values rounded to the nearest 0.5%
Page 20 of 58
5
Improvements in Aircraft and Engine Efficiency
SUMMARY
1) We calculate that introduction of the “imminent” generation of aircraft types will improve
the fleet-average fuel efficiency of UK aviation by some 17% by 2050, with the bulk of this
improvement delivered by 2040.
2) We take the view that introduction of the subsequent generation of aircraft types from 2025
onwards has the potential to improve fleet average fuel efficiency within UK aviation by a
further 26% by 2050, taking account of likely fleet penetration by that date.
26
3) This yields a combined potential improvement in fleet-average fuel efficiency of some 39%
arising from the introduction of more fuel-efficient engines and aircraft between 2010 and
2050.
4) Post 2050, improvements in fleet-average fuel efficiency will continue due to the ongoing
penetration into the fleet of aircraft types first entering service from the mid 2030s onwards.
However, those improvements lie beyond the time-horizon of our Road-Map and therefore
do not feature in our analysis.
5) Still further improvements in fleet-average fuel efficiency will be possible post 2050 due to
the entry into service of a further generation of new aircraft types towards 2050 (not
considered in our Road-Map).
5.1
Introduction
This section sets out our view of the potential for improvements in aircraft and engine fuel efficiency to
reduce UK aviation’s carbon intensity by 2050. We detail in turn:
•
technology options for improving aircraft and engine efficiency (sections 5.2 and 5.3);
•
the evidence base concerning past, imminent and potential future improvements (section 5.4);
•
our assumptions concerning the fuel efficiency of imminent and future aircraft, relative to their
respective predecessors (section 5.5);
•
our assumptions concerning the rate at which new aircraft enter into the fleet, and the
resulting impact upon fleet-average fuel efficiency (section 5.6).
5.2
Aircraft Technology – Overview of Options
5.2.1
Increasing Structural Efficiency
Reducing the structural weight of an aircraft can yield significant benefits for reduced fuel
consumption. Successive generations of aircraft have demonstrated impressive reductions in weight
through such measures as the use of advanced alloys and composite materials, manufacturing
27
processes, and lighter systems such as fly-by-wire .
For example, aircraft designed in the 1990’s were based on metallic structures, having up to 12% of
composite or advanced materials. In comparison, the A380, which has been flying since 2005,
incorporates some 25% of advanced lightweight composite materials generating an 8% weight saving
26
0.83 (representing a 17% improvement from “imminent generation” aircraft types) multiplied by 0.74 (representing a further
26% improvement from “next generation” aircraft types) yields 0.61 i.e. a combined improvement of 39%.
27
The reduction of engine weight (discussed in section 5.3) also contributes to a reduction in total aircraft empty weight.
Page 21 of 58
relative to similar metallic equipment. The A350 XWB will feature as much as 50% composite material,
including composite wings and parts of the fuselage, increasing the weight savings to as much as
15%.
Looking to the future, extensive usage of nano-materials could bring further weight savings. Examples
may include:
•
conductive nano-filler which increases the electrical conductivity of composite materials,
reducing the need for additional electrical grounding such as metallic grids or ground wirings;
•
inter-laminar reinforcements leading to a stronger vertical interconnection between composite
layers, requiring less material for a given stress;
Image: Airbus
•
intra-laminar reinforcement that grows carbon nanotubes directly on fibres. This would lead to
a stronger interconnection between carbon fibres and therefore would require less material for
a given stress capability.
Image: Airbus
Additive layer manufacturing (ALM) manufacturing is often referred to as 3D printing, as the technique
builds a solid object from a series of layers - each one printed directly on top of the previous one. The
raw material for ALM is a powder, which can be a thermopolymer or a metal; aluminium, stainless
steel and titanium 6-4 are common. Research on brackets has shown that ALM is a promising
technology that provides 40% weight saving.
5.2.2
Increasing Aerodynamic Efficiency
Reducing aerodynamic drag has a direct impact on fuel-burn. As Figure 7 illustrates, friction drag and
lift-dependent drag are the largest contributors to aerodynamic drag. Friction drag represents about
50% of aircraft overall drag, and is dominated by contributions from the fuselage and wings.
Page 22 of 58
Figure 7 – Aerodynamic drag elements of a modern aircraft. Source: Airbus.
Advances in materials, structures and aerodynamics currently enable significant lift dependent drag
reduction by maximising effective wing span extension. Wing-tip devices can provide an increase in
the effective aerodynamic span of wings, particularly where wing lengths are constrained by airport
(and/or hangar) gate sizes.
Friction drag is the area which currently promises
to be one of the largest areas of potential
improvement in aircraft aerodynamic efficiency
over the next 10 to 20 years. Possible
approaches to reducing friction drag include the
reduction of local skin friction through
encouraging laminar flow, either through passive
or active means. The BLADE project will conduct
large-scale flight test demonstration of laminar
wings on a flying test bed, commencing in 2014.
Image: Airbus
New aircraft architectures could provide further significant improvements. The Very Efficient Large
Aircraft (VELA) project has already researched blended wing concepts which would deliver per-seat
fuel consumption improvements of up to 32% over current aircraft designs.
5.2.3
Aircraft Systems
There are a number of options for fuel-burn reduction through improved aircraft systems exhibiting
lower weight and/or lower power requirements. For example:
•
The replacement of hydraulic systems with electrical systems on aircraft such as the A380 and
A350 brings weight benefits as well as simplicity and enhanced maintenance. Looking
forwards, further improvements are envisaged that move towards a 100% electrical system,
but continued research is necessary to achieve high power levels with reliability and
certification, together with the necessary cooling requirements.
•
The use of fuel cells for powering aircraft systems on board an A320 was demonstrated in
2008. Hydrogen-powered fuel-cells offer the potential for emissions-free electricity generation,
and could lead to significant weight savings through the replacement of several other systems
such as the auxiliary power unit (APU), ram air turbine, and batteries. However, offset against
those weight savings would be the weight of the hydrogen storage itself.
•
A wireless cabin could reduce the cabling weight associated with in-flight entertainment
systems etc.
Page 23 of 58
•
5.2.4
The use of electric motors, installed in aircraft landing gear and powered by the aircraft’s APU,
present possible opportunities for reducing fuel-burn during taxiing. The concept has already
been demonstrated in trials. However, offset against the reduction in fuel-burn during the taxi
phase would be the weight of the motors themselves. The net benefit will therefore depend on
factors such as the ratio of taxi-distance to flight-distance.
Cabin Infrastructure Improvements
Total payload mass load factor is influenced not only by the proportion of installed seats that are
occupied, but also by the number of seats installed. The reduction of space occupied by cabin
infrastructure can have a significant impact on fuel-burn per passenger kilometre, by allowing the
installation of additional seats and hence the carriage of additional passengers without necessarily
reducing the living space available to each passenger. If the weight of the additional passengers –
including their luggage and seats – is offset by weight reductions in the redesigned cabin
infrastructure, then the reductions in CO2 per passenger kilometre can be substantial:
•
The SPICE galley concept by Airbus [SA, 2011] “can save 400-600kg of weight and enough
space to gain 2-3 economy seats, on a typical widebody aircraft seating 250-300
28
passengers” . The addition of 2-3 extra seats on such an aircraft can reduce fuel-burn per
passenger-kilometre by at least 1%, since the galley design’s reduced weight more than
offsets the weight of the additional passengers, their luggage and their seats.
•
New lighter and thinner seat designs offer potential for installing additional seats with little or
no weight penalty. An additional row of seating can offer improvements in fuel-burn per
passenger kilometre of 2% or more, when coupled with the installation of lighter-weight seats
29
across the entire aircraft .
5.2.5
Aircraft Design Choices
Although technology, materials and manufacturing technologies will continue to play a significant role
in supporting improved aircraft fuel efficiency, other potential improvements arising from alternative
aircraft design choices have also been documented:
•
[Poll, 2009] states that designing the aircraft for a cruise Mach number of around 0.65-0.7
30
reduces by about 10% the energy required to deliver a unit of revenue work , relative to that
at a design cruise Mach number of 0.85.
•
[ICAO, 2011] suggests that modest changes in design Mach number, design range and wingspan can lead to fuel efficiency savings of the order of several percent.
Aircraft cruising speeds are determined by a range of customer-driven requirements which include the
balance between fuel-related costs and time-related costs associated with owning and operating
aircraft. The expectation of significantly higher fuel and carbon prices over the in-service lifetime of an
aircraft could, in principle, change this balance to the extent that designing the aircraft for a slower
cruise speed (particularly for shorter flights where the time-penalty is likely to be small) may prove
economically attractive.
28
http://www.airbus.com/innovation/well-being/inside/spice/
29
Example: Assume 35 rows replaced with 36 rows due to thinner seat design enabling reduced seat-pitch with no loss of legroom. Assume seat weight reduction of 25% versus initial seat weight of 15kg. Assume weight of 1 passenger (including
luggage) is 100kg. Total weight after replacement (seats plus passengers plus luggage) is no greater than total weight before
replacement. Fuel-burn and hence CO2 per passenger-kilometre is therefore reduced by around 2.8%.
30
Related to the number of tonne-kilometres performed
Page 24 of 58
5.3
Engine Technology – Overview of Options
5.3.1
Introduction
31
The specific fuel-consumption (sfc) of a jet engine is characterised by two key aspects. Firstly,
thermal efficiency describes the effectiveness with which the fuel’s chemical energy is turned into
kinetic energy. Secondly, the propulsive efficiency indicates how well the kinetic energy is turned into
thrust.
•
Thermal efficiency is influenced by the temperatures and pressures reached in the engine’s
core. Cooling technologies and/or high-temperature materials therefore play a key role.
Thermal efficiency is also influenced by the component efficiencies of the compressor and
turbine, which can be improved through advanced design methods.
•
Propulsive efficiency is improved by increasing the
engine’s bypass ratio – a measure of how much air
travels around the core compared with that which
travels through the core. The bypass ratio of jet
engines has increased steadily over the past few
decades, and is set to increase further with the
adoption of ultra-high bypass ratio architectures such
as open-rotor solutions.
Although both of these efficiency factors are subject to
theoretical limits, significant reductions in specific fuel consumption beyond that of today’s engine
types are nonetheless possible. Open rotor engines, for example, are envisaged which could offer a
32
30% reduction in mission fuel-burn relative to today’s technology turbofans .
However, the engine’s influence on mission fuel-burn is not restricted to the specific fuel consumption
of the engine itself. A typical large jet engine can weigh several tonnes and weight minimisation is
therefore a key engine design driver. Weight reduction has the added advantage of reducing the thrust
requirement and can therefore have a positive benefit for emissions and noise as well as for fuel-burn.
5.3.2
Advances in Design Methods, Modelling and Analysis
The ongoing development of computational tools which enable high-fidelity physics-based modelling
coupled with the optimisation of design parameters continues to yield benefits for engine performance
and weight minimisation. The availability of high-performance computing facilities allows the
exploration of greater numbers of potential designs, in greater detail.
For example, modern computational fluid dynamics (CFD) analysis tools enable the design of high-lift
low-pressure turbine airfoils which can enable the same work to be achieved with a significantly
33
reduced blade count, leading to reduced weight .
Integration of different types of tools increasingly supports multi-disciplinary analysis connecting
materials modelling, manufacturing process modelling and component or system design. Such an
approach allows for location-specific mechanical properties within the same component, leading to
34
significant weight-saving potential .
31
Specific fuel consumption (sfc) - a measure of the amount of fuel used by an engine per unit time per unit of thrust - usually
expressed in pounds of fuel per hour per pound of thrust
32
Source: http://www.rolls-royce.com/technology_innovation/gas_turbine_tech/fans.jsp
33
Source: http://www.rolls-royce.com/technology_innovation/gas_turbine_tech/turbines.jsp
34
Source: http://www.rolls-royce.com/technology_innovation/material_tech/materials_process_modelling.jsp
Page 25 of 58
5.3.3
Thermal Management and Energy Management
Engine efficiency can be improved by minimising the proportion of air within the engine’s core which is
lost through seals, taken from the compressor for use as cooling in other parts of the engine, or taken
from the engine for use in aircraft systems.
•
The use of cooled cooling air, or the adoption of materials which do not need cooling at all,
may offer opportunities for reduced CO2 emissions from future engines.
•
Advanced seal designs, such as circumferential carbon seals or air-riding carbon seals, can
accommodate the variation of radial clearance over the engine’s full operational range, and
35
support improved thermal efficiency as a result .
5.3.4
Weight-Reduction Through Materials Technology
Composite materials offer considerable potential for reducing engine
weight. The use of polymer matrix composites (PMCs) is envisaged
within the nacelle, fan system, shaft support structures and casings.
Metal matrix composites (MMCs) may be suited to intermediate
temperature compressor rotor applications, while the use of ceramic
matrix composites (CMCs) in key high temperature areas may lead
36
to weight reduction and improved thermal efficiency .
•
•
Recent advances in manufacturing technologies will enable
future engines to benefit from the weight-saving advantages
of PMC fan-blades without compromising the aerodynamic
efficiency levels achieved by today’s metallic fan-blades.
Further weight savings are achievable through the use of
PMCs in the casing which surrounds the fan.
Image: © Rolls-Royce plc
The use of high-strength MMCs in the compressor (see Figure 8), could enable the
replacement of the traditional disc-and-blades arrangement with an integrally-bladed ring,
37
resulting in weight savings of up to 70% on those stages of the compressor to which it is
applied.
Figure 8 – weight reduction opportunity in compressor discs, arising from the use
of lighter, stiffer, stronger materials. From left to right: 1) disc with blades; 2)
integrally bladed disc (“blisk”); 3) integrally bladed ring (“bling”) representing a
37
weight reduction of some 70% versus 1) . Image © Rolls-Royce plc
The use of titanium aluminide as an aerofoil blade material offers the prospect of further weight
38
reduction in compressor and low-pressure turbine areas , through a 50% reduction in blade material
39
density . The lighter aerofoils can then be coupled with lighter discs, yielding further weight savings.
35
Source: http://www.rolls-royce.com/technology_innovation/gas_turbine_tech/transmissions_structures_drives.jsp
36
Source: http://www.rolls-royce.com/technology_innovation/material_tech/composites.jsp
37
Source: http://www.rolls-royce.com/technology_innovation/material_tech/composites.jsp
38
Source: http://www.rolls-royce.com/technology_innovation/material_tech/low_density_materials.jsp
Page 26 of 58
5.3.5
Advances in High-Temperature Materials
Increasing the engine’s thermal efficiency requires the development of materials or technologies
enabling the engine’s core to run at higher temperatures. Ceramic Matrix Composites (CMCs),
currently under development, offer the potential for higher temperature capability (and hence
increased engine thermal efficiency), reduced weight and reduced cooling requirements, the latter
leading to further improvements in overall efficiency.
5.3.6
Advances in Manufacturing Technology
Advanced joining processes such as solid-state friction welding, in which parts are rubbed together
under very high loads to create a single fused component, enable reductions in weight compared with
40
traditional joining methods .
Developments in advanced measurement technologies such as computerised tomography and highspeed coordinate measurement machines support progress towards higher performance products by
enabling the verification of manufactured geometric features such as complex 3D surfaces and
41
intricate cooling holes .
5.4
Fuel Efficiency Improvements – the Evidence Base
5.4.1
Improvements in Fuel Efficiency Already Achieved
Analysis by IATA [IATA, 2010] has shown that global commercial airline fuel efficiency has improved
by over 30% in the past two decades, saving over 400 million tonnes of CO2 per annum at current
activity levels, relative to the fleet efficiency in 1990.
Advances in engine and aircraft fuel efficiency form a key element of improvements in airline overall
fuel efficiency. Figure 9 illustrates progress made since 2000 in the fuel efficiency of new large
engines, demonstrating significant advances relative to the baseline engine.
Figure 9 – fuel efficiency of successive generations of large jet engines relative to
a year 2000 baseline, showing progress towards ACARE engine fuel efficiency
target.
39
Source: http://www.rolls-royce.com/technology_innovation/gas_turbine_tech/turbines.jsp
40
Source: http://www.rolls-royce.com/technology_innovation/manu_tech/ad_joining_technologies.jsp
41
Source: http://www.rolls-royce.com/technology_innovation/manu_tech/advanced_measurement.jsp
Page 27 of 58
5.4.2
The “Imminent” Generation of Aircraft
Aircraft representing the “imminent” generation of technology are already entering service or are
currently offered for sale to the market. These are aircraft whose fuel efficiency characteristics are
well-defined, as we discuss here. Their impact on CO2 emissions from UK aviation over the next 2 to 3
decades will be substantial, as set out in section 5.6 below. We consider 3 distinct aircraft categories:
•
In the Single-Aisle (SA) category – the Airbus A320neo “will deliver fuel savings of 15 per
42
cent” versus its predecessor and will enter service in 2015. The Boeing 737 MAX will have
43
“10-12 percent lower fuel burn than current 737s” and will enter service later this decade.
The Bombardier C Series will offer up to 20% fuel-burn improvement “compared to in44
production aircraft in the same category at a distance of 500 nautical miles” , and is due to
enter service in 2013.
•
In the Twin-Aisle (TA) category – the A350 XWB will enter service in 2014 and will offer a “25
45
per cent step-change in fuel efficiency compared to its current long-range competitor” . The
Boeing 787 entered service in 2011 and “uses 20 percent less fuel than today's similarly sized
46
airplanes” .
•
In the Very-Large (VL) category – the Airbus A380 entered service in 2007 and “burns 17 per
47
cent less fuel per seat than its nearest competitor” . The Boeing 747-8 Intercontinental is “16
48
percent more fuel efficient than the 747-400” and is due to enter service in early 2012. The
747-8 Freighter entered service in 2011.
5.4.3
The Drive Towards Future Generations of Aircraft
Recently the European Commission’s High Level Group on Aviation Research has published a vision
for aviation in 2050 [HLG, 2011], calling for a reduction in CO2 emissions per passenger kilometre of
75%, a 90% reduction in NOx emissions and a 65% reduction in perceived noise emissions from flying
aircraft. This vision, known as “Flightpath 2050” is benchmarked against the capabilities of a typical
new aircraft in 2000, and relates to the evolution of technological capability, rather than fleet-average
fuel efficiency.
The aviation industry is actively engaged in significant research programmes to develop and
demonstrate technologies which will support improved fuel efficiency in future aircraft. Some
examples include:
•
The FAA’s Continuous Lower Energy, Emissions and Noise (CLEEN) program has among its
goals to develop and demonstrate by 2015 “aircraft technology that reduces aircraft fuel burn
49
by 33 percent relative to current subsonic aircraft technology” .
•
The E3E programme aims to demonstrate engine core technologies to enable a fuel-burn
50
reduction of 15% relative to similar engines currently in service .
•
The Strategic Investment in Low-carbon Engine Technology (SILOET) programme is expected
51
to yield a 2% improvement in engine fuel economy, and is scheduled to complete in 2013 .
42
http://www.airbus.com/aircraftfamilies/passengeraircraft/a320family/, viewed 14 Feb 2012
43
http://boeing.mediaroom.com/index.php?s=43&item=2004, viewed 14 Feb 2012
44
http://csr.bombardier.com/en/products/aerospace-products/cseries-commercial-aircraft, viewed 14 Feb 2012
45
http://www.airbus.com/aircraftfamilies/passengeraircraft/a350xwbfamily/, viewed 14 Feb 2012
46
http://www.boeing.com/commercial/787family/background.html, viewed 14 Feb 2012
47
http://www.airbus.com/aircraftfamilies/passengeraircraft/a380family/environment/emissions/, viewed 14 Feb 2012
48
http://www.boeing.com/commercial/747family/747-8_background.html, viewed 14 Feb 2012
49
http://www.faa.gov/news/fact_sheets/news_story.cfm?newsId=11538
50
http://www.rolls-royce.com/civil/news/2010/100527_success_twoshaft_engine_research.jsp
51
http://www.rolls-royce.com/technology_innovation/research_programmes/gas_turbine_programmes/siloet.jsp
Page 28 of 58
•
The ValiDation of Radical Engine Architecture systeMs (DREAM) project has the aim of
52
advancing technologies which could collectively reduce specific fuel consumption by 27% .
•
The EU’s CleanSky Joint Technology Initiative is a 1.6 billion Euro aviation technologydevelopment program. Subprograms within CleanSky include:
5.5
o
“Smart Fixed Wing Aircraft” (SFWA) which aims to develop technologies enabling a
53
10% reduction in aircraft drag
o
“Sustainable And Green Engines” (SAGE) which will include an open-rotor
demonstrator, as well as a large 3-shaft engine demonstrator which will validate the
54,55
.
lightweight low-pressure system developed within other programmes
o
Green Regional Aircraft (GRA), demonstrating low weight structures and aerodynamic
56
developments for regional aircraft .
o
Systems for Green Operations (SGO), demonstrating new architectures and
57
technologies for electrical power generation, distribution, conversion and storage .
Aircraft Fuel Efficiency Assumptions
Here we set out our assumptions concerning the fuel efficiency improvements, relative to their
respective predecessors, of two successive generations of aircraft types. We consider in turn each of
the three categories of aircraft (SA, TA, and VL) identified in section 5.4.2 above.
5.5.1
Imminent Generation (G1) Aircraft
In section 5.4.2 above we presented the evidence base concerning the fuel efficiency of specific
“imminent” aircraft types in comparison with their respective predecessors. For the purposes of our
Road-Map, here we establish an average fuel efficiency improvement figure to employ in each of three
aircraft categories, relative to the corresponding fleet-average fuel efficiency in 2010. This is shown in
Table 4, alongside the entry-into-service date assumed within our Road-Map.
58
We assume that the fleet in 2010 was composed largely of the direct predecessors of the “imminent”
aircraft types discussed above. Overall, this assumption may prove conservative, due to the presence
of a number of older aircraft within the 2010 fleet, leading to a slight under-estimate of the fleet-wide
CO2-mitigation potential arising from the adoption of G1 aircraft. However, in the case of the “verylarge” aircraft category, this assumption overlooks the small number of A380s already in service on
UK routes by 2010. We do not believe the error introduced by this is material to the overall analysis.
Category
Single-Aisle
Twin-Aisle
Very-Large
Entry into service of aircraft type
2015
2011
2007
Fuel efficiency improvement relative
to predecessor aircraft types
13 %
20 %
17 %
Table 4 – assumed fuel efficiency improvement of “imminent” (G1) aircraft types
relative to their respective predecessors
52
http://www.rolls-royce.com/technology_innovation/research_programmes/gas_turbine_programmes/dream.jsp
53
http://www.cleansky.eu/content/page/sfwa-smart-fixed-wing-aircraft
54
http://www.rolls-royce.com/technology_innovation/research_programmes/gas_turbine_programmes/sage.jsp
55
http://www.cleansky.eu/content/page/sage-sustainable-and-green-engine
56
http://www.cleansky.eu/content/page/gra-green-regional-aircraft
57
http://www.cleansky.eu/sites/default/files/documents/fact_sheet_sgo_march_2011.pdf
58
Aircraft used on routes within, into or out of the UK.
Page 29 of 58
5.5.2
Future Generation (G2) Aircraft
Our assessment of the fuel efficiency of G2 aircraft in each of the three categories is derived with
reference to the corresponding G1 aircraft, and is driven by three factors:
•
the entry into service (EIS) date of the G2 aircraft type relative to its G1 predecessor;
•
the rate of underlying improvement in aircraft and engine fuel efficiency through evolutionary
developments in technology;
•
any significant technologies or configurational changes which result in a step-change in
aircraft fuel efficiency over and above the assumed underlying improvement trend.
Clearly, when attempting to form a view of the likely capabilities of aircraft decades into the future, we
must be aware of the significant uncertainty in any assessment. The following constitutes Sustainable
Aviation’s judgement concerning each of the above three bullet points, and should not be interpreted
as a statement of intended product strategy. The decision to launch a new aircraft product is
influenced not only by technology readiness but by many other factors such as the market demand,
maturity of the in-service fleet, the prevailing economic situation, regulatory pressures and oil price
predictions.
1. Starting with the first of the above three factors, our assumed EIS dates for G2 aircraft are as
follows:
•
Single-Aisle – a value of 2025 is chosen to reflect a balance between several competing
factors. Although this will be only some 10 years after the introduction of the G1 aircraft in this
category, it is anticipated that technological developments by that time will warrant the
introduction of a new aircraft type which is significantly more fuel-efficient than the G1 aircraft.
•
Twin-Aisle – we assume a gap of approximately 20-25 years between G1 aircraft and their
successors in this category, leading to an approximate EIS of 2035.
•
Very-Large – in this category we assume a gap of approximately 30 years between G1
aircraft and their successors, leading to an approximate EIS of 2040.
2. Having established EIS dates in each of the three aircraft categories, we then assume an
underlying rate of development in technologies applicable to all three aircraft categories. A value
of 1.3% per annum is chosen based on a number factors:
•
The recently observed fuel efficiency improvement rate of successive generations of aircraft.
•
The strengthening commercial drivers related to increasing fuel-prices and carbon prices.
•
The availability of increasingly capable computational analysis and design tools.
This number is also broadly consistent with the underlying rate of improvement evident in the
assessment presented by CAEP’s Group of Independent Experts in [ICAO, 2011], as discussed in
section 5.5.3 below.
3. Finally we consider step-changes in efficiency arising from significant new technologies such as
open-rotor engines, laminar flow aerodynamics and alternative airframe configurations.
•
Single-Aisle – since the G1 aircraft in this category is a re-engined version of its predecessor
with largely the same airframe, the corresponding G2 aircraft will have the opportunity to
incorporate two generations of developments in airframe technology. Only part of this
opportunity will be captured in our representation of the underlying technology development
rate. The adoption of advanced ultra-high bypass ratio engines – for example open rotors - is
also considered likely, together with other significant technology changes. To encompass all
three of these factors we assume in this category a step change of 15% over and above the
underlying technology development rate.
Page 30 of 58
•
Twin-Aisle – we anticipate that the use of open rotor engines in this aircraft category is less
likely than in the single-aisle category. We also note that the transition from G1 to G2 aircraft
will offer the opportunity to advance by one generation of airframe technology, rather than two
generations as assumed for single-aisle aircraft. However, taking into account that the impact
of fuel efficiency improvements upon mission fuel-burn is greater for longer flights (as
discussed in more detail in Appendix E below), and taking also into account the stronger case
for the adoption of fuel-saving technologies on larger, longer range aircraft for which fuelrelated costs are arguably more significant relative to purchase cost, we also assume a stepchange of 15% in this category.
•
Very-Large – for similar reasons we assume a step change of 15% in this category.
Table 5 shows the outcome of applying the above assumptions to each of our three aircraft
categories, detailing the fuel efficiency of G2 aircraft relative to their respective G1 predecessors.
Category
Single-Aisle
Twin-Aisle
Very-Large
EIS of aircraft type
2025
2035
2040
Fuel efficiency improvement
relative to equivalent G1
59
aircraft type
25 %
38 %
45 %
Table 5 – assumed fuel efficiency improvement of “future” (G2) aircraft types
relative to their respective predecessors
Figure 10 illustrates the assumptions set out in the preceding paragraphs concerning the fuel
efficiencies of “future” (G2) aircraft in each of the three categories “single-aisle”, twin-aisle” and “verylarge”, relative to their respective G1 predecessors. The capabilities of G2 aircraft are determined with
reference to the improvement curve and step-change contributions described above.
Figure 10 – Technology development curve used to calculate the assumed fuel
efficiency of G2 aircraft types relative to that of their respective G1 predecessors.
Note that the efficiency of new aircraft (shown in this chart) is distinct from the
evolution of fleet-average fuel efficiency (not shown on this chart) which is also
influenced by fleet turnover rates.
59
Values rounded to the nearest whole percentage point
Page 31 of 58
5.5.3
Comparison with CAEP Fuel Efficiency Assumptions
In 2011, ICAO’s Group of Independent Experts (IEs) published a report [ICAO, 2011] exploring the
prospects for advances in fuel efficiency of new aircraft in 2020 and in 2030. The report considered a
number of technology scenarios (labelled TS1, TS2, TS3, and TS3-OR, in order of increasing
ambition) and their potential for improving the efficiency of aircraft types corresponding to the single60
aisle and twin-aisle categories used in this Road-Map . The IEs also recommended a target range of
efficiency improvement corresponding to a band lying between the TS2 and TS3 scenarios.
Figure 11 shows, for these two aircraft categories, our technology development assumptions set within
the context of the IEs’ technology scenarios and recommended target range, expressed relative to the
fuel efficiency of the corresponding G1 aircraft. With reference to the single-aisle chart within Figure
11, it should be noted that the announcements by both major aircraft manufacturers concerning the
offering to market of re-engined rather than all-new single-aisle aircraft post-date the IEs’ analysis.
In arriving at their conclusions the IEs chose not to take account of a number of “step-change”
technologies, including engine water-injection, turbofan intercooling, blended-wing-body aircraft
configurations and ultra-high bypass ratio turbofan engines. However, open-rotor engines (10%
reduction in fuel-burn) and hybrid laminar flow control (10% reduction in drag) were identified as
having potentially large benefits. The TS3 scenario (representing the more aggressive end of the IEs’
proposed fuel efficiency target) contemplates modest changes in aircraft configuration and mission
specifications such as range or cruise speed.
Figure 11 – comparison of assumed technology improvement rates against
technology scenarios identified by the CAEP Group of Independent Experts (IEs),
showing Single-Aisle (left diagram) and Twin-Aisle (right diagram) categories.
5.5.4
Freighter Aircraft
In recent years, sales of OEM freighter aircraft have become increasingly significant relative to the
traditional market for freighters converted from former passenger aircraft. This phenomenon, driven
largely by the very significant increases in fuel prices witnessed in the past decade, lends support to
SA’s belief that the fuel efficiency of the freighter fleet as a whole will improve no less quickly than that
of the passenger fleet. We do not therefore attempt to model separately the evolution of freighter fleetaverage fuel efficiency. Since the proportion of UK-departing tonne-kilometres carried on freighter
aircraft is relatively small in comparison with that carried on passenger flights (see section 2 above)
we do not believe that our assumptions will introduce any significant error to the overall analysis.
60
The fuel-burn reduction potential within the “very large” category was considered by the IEs to be not significantly different to
that in the “twin-aisle” category
Page 32 of 58
5.6
Impact on Fleet-Average Fuel Efficiency
In section 5.5 above, we set out our assumptions concerning the fuel efficiency and entry into service
timescales of imminent (G1) and future (G2) aircraft types. In this section, we address the issue of
fleet-turnover (the rate at which new aircraft types replace older aircraft in service), and show the
resulting impact of these aircraft upon fleet-average fuel efficiency in 2050, taking into account the
relative importance of the three aircraft categories (SA,TA and VL) within the overall fleet fuel-burn
distribution.
Appendix A presents our assumptions concerning the speed of fleet-turnover, whilst Appendix B
details the relative importance with the UK aviation fuel-burn mix of the three categories of aircraft.
The relevant figures are summarised in Table 6.
Aircraft Category:
Single-Aisle
Twin-Aisle
Very-Large
31%
42%
27%
“Imminent” (G1) aircraft
30 years
25 years
20 years
“Future” (G2) aircraft
25 years
20 years
20 years
Share of Total UK Aviation Fuel-burn
62
Fleet turnover
period
61
Table 6 – Relative significance of single-aisle, twin-aisle, and very-large aircraft
within UK aviation’s fuel-burn, and the fleet-turnover periods of successive
generations of aircraft in those same categories
For the purposes of our Road-Map, we have adopted a simple linear fleet-transition model, meaning
that a fixed proportion of the RPKs delivered in a particular aircraft category is transferred from “old” to
“new” aircraft types during each year of the fleet-turnover period applying to that category. This
transition is conducted independently of any underlying growth in total RPKs delivered.
As a result the percentage CO2 saving within that aircraft category, relative to the exclusive use of
“old” aircraft, rises linearly throughout the fleet-turnover period, and can therefore, for any interim year,
be calculated directly from a) the relative efficiencies of the “new” and “old” aircraft types and b) the
proportion of the fleet-turnover period that has elapsed.
To give a specific example, consider a 20-year fleet-turnover period within one of our three aircraft
categories, in which the “new” aircraft is 10% more fuel-efficient per RPK than its predecessor. At the
start of this period, all RPKs within that aircraft category would be delivered by aircraft of the “old”
model. One year later, 5% of RPKs delivered within that category would be on the “new model” with
the remainder being delivered by “old” model aircraft. The fuel saving at this point, relative to the
exclusive use of “old” aircraft, would be 0.5%. 10 years after commencement of the transition, RPKs
would be delivered 50% by “old” aircraft and 50% by “new aircraft” with a corresponding CO2 saving
(relative to the exclusive use of “old” aircraft) of 5%.
In any particular year, the CO2 saving across the entire fleet due to adoption of new aircraft in different
categories, is simply the sum of the savings in each of the three aircraft categories, weighted by the
relative importance of those categories.
5.6.1
“Imminent” Generation (G1) Aircraft
Due to our assumptions concerning EIS dates and fleet-turnover periods, in our Road-Map all fleet
transition from baseline to G1 aircraft will be complete by 2050. Adoption of G1 aircraft will therefore
result in a fleet-wide CO2 saving, due to relative to an all-baseline fleet, of 17%, as shown in Table 7.
61
See Appendix B
62
See Appendix A
Page 33 of 58
Fleet
turnover
63
factor
Fleet
weighting
64
factor
Fuel-burn
65
factor
Single-Aisle
1.0
0.31
Twin-Aisle
1.0
Very-Large
1.0
Fuel-burn relative to preturnover total
CO2
66
Saving
G1 aircraft
“Old” aircraft
0.87
0.27
0
0.42
0.80
0.34
0
0.27
0.83
0.22
0
Combined
0.83
67
17%
Table 7 – relationship between aircraft fuel efficiency improvements (G1 vs
baseline) and the resulting impact on fleet fuel efficiency in 2050
5.6.2
“Future” Generation (G2) Aircraft
Our assumed EIS dates and fleet-turnover periods relating to the transition from G1 to G2 aircraft
mean that fleet turnover for certain aircraft types will not be complete by 2050. However the method
employed above is nonetheless applicable, and yields the values shown in Table 8.
Fuel-burn relative to an
all-G1 fleet
Fleet
turnover
68
factor
Fleet
weighting
64
factor
Fuel-burn
69
factor
Single-Aisle
1.0
0.31
0.75
0.23
Twin-Aisle
0.75
0.42
0.62
0.20
0.11
Very-Large
0.5
0.27
0.55
0.07
0.14
G2 Aircraft
Combined
G1 Aircraft
0
0.74
CO2
70
Saving
71
67
26%
Table 8 – relationship between aircraft fuel efficiency improvements (G2 vs G1)
and the resulting impact on fleet fuel efficiency in 2050
63
1.0 representing completed fleet-turnover
64
Values representing percentage of fleet fuel burn, taken from Table 6 (31% represented as 0.31 etc)
65
Values taken from Table 4 (0.87 represents 13% improvement, etc)
66
Percentage saving in fleet-wide fuel-burn (and hence CO2) relative to an all-baseline fleet
67
Summation of fuel-burn on new aircraft, and any remaining old aircraft, in the three aircraft categories.
68
Values derived from a) EIS date given in Table 5, and b) fleet turnover period given in Table 6
69
Values taken from Table 5 (e.g. 0.75 represents 25% fuel-efficiency improvement relative to the G1 predecessor)
70
Percentage saving in fleet-wide fuel-burn (and hence CO2) relative to an all-G1 fleet
71
Fleet turnover is assumed complete in this category by 2050, so fuel-burn taking place on instances of the G1 aircraft is zero
Page 34 of 58
6
Sustainable Fuels
SUMMARY
We estimate that by 2050 sustainable fuels will offer between 15% and 24% reduction in CO2
emissions attributable to UK aviation. This assumption is based on a 25-40% penetration of
sustainable fuels in to the global aviation fuel market, coupled with a 60% life-cycle CO2 saving
per litre of fossil kerosene displaced. For the purposes of our Road-Map, we assume an 18%
reduction in CO2 emissions from UK aviation through the use of sustainable fuels.
6.1
Introduction
72
Sustainable biojet fuel (biojet) could play a vital role in reducing the carbon footprint of UK aviation
and the industry has been working on a range of initiatives to develop this opportunity.
In Europe a project has been launched to deliver annual production of 2 million tonnes of aviation
73
biofuel by 2020 . Support from the UK government, similar to that given by other countries, will be
necessary to make this a reality. Unlike ground transport or power generation, aviation is dependant
on liquid hydrocarbon fuels for the long-term and therefore the development of aviation biojet fuels to
meet this need should be a priority of government policy. The limited amounts of sustainable biomass
(for biofuels) available worldwide should be designated primarily for those sectors that do not have
alternatives. Aviation is one such sector. For road transportation, other than heavy goods vehicles,
alternatives exist and these should be further developed and stimulated.
We believe that biojet can potentially account for 40% of aviation fuel use by airlines operating out of
74
the UK, as stated in the EU white paper on the future of aviation . With a 60% improvement in lifecycle emissions, CO2 emissions would therefore be reduced by up to 24% as a result of biojet. Biojet
will be a global commodity, and accounting based on purchases of biojet will enable airlines to claim
emissions reductions, regardless of where in the world the biojet enters the supply chain.
Sustainable biojet fuels must satisfy strict criteria concerning suitability, sustainability and scalability,
as described in more detail in section 6.3 below.
6.2
UK Initiatives
A number of UK airlines are leading the way in supporting the development of sustainable aviation
fuels. Learning from mistakes made with earlier generations of biofuels aimed at other industries,
these airlines have worked together to support the uptake of robust sustainability principles for aviation
biofuels.
•
British Airways and Virgin Atlantic are founding members of the Sustainable Aviation Fuel
75
Users Group (SAFUG ), established in 2008, which now has 20 other airline members
(including Thomson Airways) and accounts for about 25% of worldwide aviation fuel demand.
76
SAFUG actively supports the Roundtable on Sustainable Biofuels (RSB ), which defines 12
key sustainability principles that suppliers must meet in order to become RSB certified.
72
In this chapter we use the terms biofuel or biojet to refer not only to fuels produced from biomass, but also to fuels derived
from various waste streams, including solids (e.g. municipal waste), liquids (e.g. used cooking oil) and gases (e.g. waste
gases from industrial facilities).
73
http://ec.europa.eu/energy/renewables/biofuels/flight_path_en.htm
74
http://ec.europa.eu/transport/strategies/doc/2011_white_paper/white_paper_com(2011)_144_en.pdf. See also Directive
2009/28/EC (Renewable Energy Directive)
75
http://www.safug.org/information/pledge
76
http://rsb.epfl.ch
Page 35 of 58
•
British Airways, in partnership with the Solena Group, is to establish Europe’s first sustainable
jet-fuel plant and plans to use the low-carbon fuel to power part of its fleet from 2015. The
new fuel will be derived from waste biomass and manufactured in a state-of-the-art facility that
can convert a variety of carbon-based feedstocks, destined for landfill, into aviation fuel.
•
Virgin Atlantic’s partnership with LanzaTech will see waste carbon monoxide gases from
industrial steel production facilities captured, fermented into ethanol using a naturallyoccurring microbe, and chemically converted for use as jet fuel. The new process utilises
gases normally flared off into the atmosphere as carbon dioxide – effectively recycling the
carbon and producing fuel with around half or less the carbon footprint of kerosene. Virgin
Atlantic plans to use the fuel in commercial flights out of Shanghai from 2014, and ultimately
hopes to bring the technology to the UK.
•
In October 2011 Thomson Airways was the first UK airline to fly customers on sustainable
biofuel on flight TOM 7446 from Birmingham to Arrecife. Daily operations will start from early
2012 for approximately six weeks.
•
Airbus is taking a leadership role with British Airways and Virgin Atlantic towards delivering the
2 million tonnes of biofuel mentioned above.
6.3
Sustainability
Aviation is a global industry with flights crossing borders each day, therefore harmonised and
consistent sustainability standards between and within regions will foster better practice within the
biofuel sector and enable aviation’s use of such fuel. SA is committed to strong sustainability
principles [SA, 2010b], consistent with those of the Sustainable Aviation Fuel Users Group, to ensure
biojet will:
•
not displace or compete with food crops or cause deforestation;
•
minimise impact on biodiversity;
•
produce substantially lower life cycle emissions than fossil fuels;
•
be sustainable with respect to land, water and energy use;
•
deliver positive socioeconomic impacts.
Commercial scale sustainable aviation fuels employed by SA member airlines will meet sustainability
standards consistent with and complementary to internationally recognised standards such as those
being developed by the Roundtable on Sustainable Biofuels.
Life-cycle CO2 emissions associated with biofuel use are influenced by such factors as the type of
feedstock, the processing route through which feedstock is turned into fuel, and any direct or indirect
land-use change which arises from the feedstock cultivation. Figures ranging between 10-95% CO2
77
saving from different feedstocks are frequently quoted . These generally do not include indirect land
use change (ILUC) impacts, i.e. where crops for biofuels are grown on agricultural land, displacing
other crops.
In general, the criterion of 50% reduction in life-cycle GHG emissions is currently accepted as the
78
yardstick for a sustainable biofuel. European regulations for classification of biofuel are expected to
increase the life-cycle requirement to 60% for all new biofuel plants from January 2018, and hence we
have assumed 60% life-cycle CO2 emissions savings for biojet in this Road-Map.
77
It should also be noted that biojet will generally have a much lower sulphur content than current aviation fuels and that
associated emissions of particulates will be lower, thus contributing to improvements in air quality around airports.
78
Communication 2010/C 160/02 http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:C:2010:160:0008:0016:EN:PDF
Page 36 of 58
6.4
Overview of Sustainable Fuel Categories
Currently two types of biojet are certified for use in aviation jet engines, blended with kerosene:
•
Synthetic Fischer-Tropsch (FT) based kerosene produced through high temperature biomass
gasification. FT kerosene is produced via biomass gasification followed by gas cleaning and
synthesis over appropriate catalysts and already today is approved for use in a 50% blend.
•
Hydro-processed Esters and Fatty Acids (HEFA), originating from plant, algal and microbial
oils. In the absence of technical restraints, market forces and legislation are the main drivers
for oil and fat selection. Algal oils can also replace vegetable oils in HEFA or similar
processes, but these will not be commercially available for around 5 years. Algal oils have
attracted significant interest from the aviation sector despite the very high infrastructure cost
for industrial scale cultivation.
The conversion of cellulosic and sugar based materials to biojet via the production of alcohols is in
advanced stages of testing and is expected to be in commercial production by 2016-2018. Pyrolysis
technology is under development and our current view is that it will likely become available towards
the end of the decade.
Many biofuel demonstration flights have taken place since 2008, the majority making use of HEFA
blended with conventional kerosene. Rigorous lab-testing and ground-testing have already led to the
approval for commercial use of FT and HEFA biofuels blended in a 50% ratio with conventional
kerosene. Certification is expected also for fuels such as ‘alcohol to jet’.
6.5
Economics of Biojet
For regular commercial use, biojet must become economically viable and cost-competitive over the
long-term compared to kerosene from fossil fuel sources. In the short-term, many biojet production
processes are not economic and carry material “first-of-a-kind” risks for investors. Government policy
should be targeted at reducing the investment risks and early commercial uncertainties. Given the
need to accelerate long-term sustainable options, there is a case for introducing temporary, nondistortive policy support and risk management approaches that will stimulate the market for biojet.
The first step should be to create conditions commercially attractive for producers to invest in biojet
production and to sell it at prices competitive with kerosene. This would lead to accelerating cost
efficiencies through economies of scale and technological development through learning.
In the long-term, biojet is expected to become competitive due to a number of factors, including:
•
Expected increase in fossil fuel prices, due to both demand and supply pressures.
•
Application of carbon pricing in global economies, with increasing costs of carbon.
•
Reducing biojet unit production costs due to economies of scale and technology learning.
•
Lower feedstock costs.
•
Reduced capital costs.
While the time scales of development and penetration of biojet for aviation are still uncertain,
government support will nonetheless bring forward the point at which biojet can compete effectively,
i.e. both biojet and oil-based fuel will be offered to end consumers at similar prices (see Figure 12).
Page 37 of 58
Costs and
prices
Fossil jet price + carbon cost
Fossil jet price
p
Biojet production costs
tnow
t1
Time
Point at which biojet becomes costcompetitive, without intervention
Figure 12 - Economics of biojet - At the current time (tnow) biojet production costs
are higher than fossil kerosene prices, even if the carbon costs of the fossil fuels
are included. Over time, a combination of scale and technological development
is expected to reduce the production costs of biojet, while fossil kerosene prices
and carbon costs are expected to increase. Without government support, biojet
would not become cost-competitive with fossil kerosene until point t1.
6.6
Scale-Up and Deployment
One of the biggest impediments to large scale use of biojet is the dearth of capital to fund scale-up
and rollout of the technology. This is often the most challenging stage in the development of a new
industry, when the level of capital required increases significantly (compared to early research and
technology demonstration), but significant commercial risks remain. However, some biofuel
technologies such as FT-SPK and HEFA are already at scale-up and deployment stage.
Existing policy mechanisms in the UK and Europe, such as the EU Renewable Energy Directive (EU
RED) are currently insufficient to support the development of aviation biojet, and some are providing a
disincentive for producers to invest in biojet production. Biofuel producers are making capital
investment decisions based on present Government policy, which prioritises heat, power and road
transport fuels. As a consequence, capital investment for renewable energy technologies is currently
being spread across those sectors at the expense of aviation. There is a clear need for governments
to provide appropriate positive incentives and support, for example through the provision of loans and
loan guarantees. This could be structured in ways to unlock private sector sources of capital. One
possible policy measure is that aviation biojet suppliers should qualify for tradeable certificates within
incentive regimes provided for by national applications of the EU RED, such as Renewable Transport
Fuel Certificates in the UK.
From 2012, with the inclusion of aviation in the EU ETS, the cost of carbon will be added to the cost of
buying fossil kerosene. These costs are likely to increase over time. Aircraft operators will be able to
mitigate their exposure to the EU ETS by using biojet instead of fossil kerosene. As the price of
carbon increases, this will provide an increasing financial incentive for the take-up of biojet, although
for the foreseeable future the price of carbon will only give a modest incentive compared to tradeable
certificates for production associated with the EU RED.
6.7
European Advanced Biofuels Flightpath
The European Commission, Airbus, and high-level representatives of the aviation and biofuel
producers industries, including UK-based airlines involved in SA, have joined forces to develop the
Page 38 of 58
73
European Advanced Biofuels Flightpath to promote production, distribution, storage and use of
sustainably produced and technically certified biofuels.
The aim of the initiative is the commercialisation of sustainably produced paraffinic biofuels in the
aviation sector, by reaching 2 million tonnes of consumption by 2020. This objective from EC DG
Energy is complemented by a target from EC DG Move of 40% renewable low carbon fuels for
79
aviation by 2050 .
6.8
Based on the significant developments in the alternative fuels arena which have taken place since our
first Road-Map was published, and with over 1000 commercial flights by European airlines using
biofuel, we now estimate that significant deployment of aviation biofuels in commercial flights will
commence around 2015 rather than around 2020 as previously assumed.
Given the need to develop long-term sustainable fuel solutions and the rapid shift in support from
many governments around the world, we are optimistic that the challenges related to the required
sustainability and scalability of these fuels can be overcome – with government support. The extent of
progress made over the past three years, particularly with respect to diversification of potential
feedstocks and processing routes, leads us to a more optimistic assessment of biojet’s potential than
was adopted in our 2008 Road-Map.
Furthermore, recent research such as that described in [PARTNER, 2010] has highlighted the
potential for biofuels to achieve higher life-cycle carbon savings per litre biofuel than was previously
supposed in our 2008 Road-Map.
Consequently, we estimate that, by 2050, sustainable fuels could offer between 15 and 24% reduction
in CO2 emissions attributable to UK aviation by 2050. This assumption is based on a 25-40%
penetration of sustainable fuels into the global aviation fuel market, coupled with a 60% life-cycle CO2
saving per litre of fossil kerosene displaced.
Our deployment estimate is somewhat higher than the suggested estimate for planning of around 10%
penetration made in [CCC, 2011]. However, the same report also presented alternative scenarios in
which the level of sustainable fuel penetration in UK aviation was considerably higher than 10%,
80
particularly in a world without carbon capture and storage .
For the purposes of our CO2 Road-Map, from within the range of 15-24% set out above, we take as
our central estimate an 18% reduction in CO2 emissions from UK aviation through the use of
sustainable fuels.
79
http://ec.europa.eu/transport/strategies/2011_white_paper_en.htm
80
CCS has not been incorporated in our present analysis, but will be considered for possible incorporation when the Road-Map
is next updated
Page 39 of 58
7
Carbon Trading
SUMMARY – although the aviation industry will continue to make significant reductions in its
own carbon intensity, a global carbon trading scheme will be required to enable aviation to
contribute to overall carbon reductions beyond those achievable within the industry itself. We
emphasise that international aviation requires a global approach in order to avoid market
distortions and carbon leakage.
The global aviation industry has set out a goal for aviation to reduce its net emissions in 2050
to 50% of levels in 2005 through participation in carbon trading. In this Road-Map we illustrate
the extent of carbon trading required to allow UK aviation to achieve the same goal.
7.1
Introduction
As discussed in the preceding sections, the aviation industry expects to make very significant
reductions in its carbon intensity over the next few decades through a combination of operational
improvements, advances in engine and aircraft technologies, and the adoption of sustainable fuels.
Nonetheless, the value of aviation to society and the economy is such that, in the international context,
strong growth in demand is likely to result in an increase in absolute CO2 emissions from global
aviation. Further reduction in global aviation’s CO2 emissions can best be addressed through
establishing global net emissions reduction targets within a carbon trading policy framework. Carbon
trading, implemented properly, delivers certainty in reductions of emissions as opposed to the
uncertainty of taxes and charges.
Carbon trading is by far the most effective economic instrument to reduce net emissions in the aviation
sector. The UK Government has long recognised that some sectors of the economy will be able to
reduce emissions more cost-effectively than others, hence the need for a cap and trade solution. The
EU ETS, implemented in a manner that does not distort air transport markets and avoids international
dispute, can be a first step towards a global carbon trading solution.
7.2
The Need for a Global Approach
There is no climate impact of international aviation that can be confined to the UK. Emissions from the
aviation sector which impact the global climate must be addressed at a global level, through
appropriate international bodies such as ICAO. The UK government should continue to support work
through such international organisations to achieve effective international measures, in particular
trading, while working to ensure that international aviation emissions are excluded from national
emissions inventories.
We strongly oppose including international aviation in the UK carbon budget or introducing national
targets or measures aimed at reducing international aviation emissions. If international aviation were
included in the UK budget, this would lead to perverse policy decisions that would not reduce global
emissions, but would only give the illusion of a reduction in UK emissions. For this reason we support
the drive for a global sectoral agreement to regulate CO2 emissions from international aviation.
7.3
In a carbon trading framework, the level of mitigation will ultimately be set by regulators. We believe
that targets should be established at the international level in line with relevant scientific evidence.
Globally, policy should be coordinated on a pathway towards a global target for aviation within a
carbon trading framework which would complement technological developments, operational
improvements and the use of sustainable fuels.
Page 40 of 58
We believe that the appropriate target for international aviation is to reduce overall net emissions by
50% by 2050 relative to 2005 levels. This target has been proposed by all major elements of the
international aviation industry [ACI, 2009].
In this Road-Map, our assumed trajectory of net CO2 emissions from UK aviation is composed of two
elements:
•
To reflect the emissions cap associated with the incorporation of aviation into the EU ETS, we
assume a level of net CO2 emissions from 2012-2020 corresponding to 95% of CO2 emissions
from UK aviation in 2005.
•
From 2020 onwards we assume a gradual reduction in net CO2 emissions, reaching 50% of
2005 levels by 2050. The exact trajectory of this reduction remains to be determined by
governments – we have assumed a linear trajectory pending future clarity on this issue.
Page 41 of 58
8
Summary of Assumptions
8.1
Demand Growth
Table 9 summarises the emissions trajectory within our hypothetical “no-improvements” scenario,
which represents growth in demand for aviation from 2010 to 2050.
Year
2000
2030
2050
Emissions (% vs 2010) in a hypothetical
“no-improvements” scenario
100
172
250
Table 9 – hypothetical “no-improvements” emissions trajectory assuming a
constant level of technology, no change in operational procedures, and no
biofuel adoption
8.2
Mitigation Assumptions
Table 10 sets out a summary of our views concerning the potential for and likely extent of reductions
in UK aviation’s carbon intensity through a combination of improved operational practices, more
efficient aircraft, and the use of sustainable fuels.
81,82
Fleet Carbon Efficiency Benefit (%)
Measure
ATM and Operations
Engine and
Airframe
2030
2050
Potential
Assumed
Potential
Assumed
7
4.5
13.5
9
“Imminent” Aircraft
13
17
“Future” Aircraft
1.5
26
Sustainable Fuels
TOTAL
83
10.5
7.5
24
18
28.5
24.5
59.5
54
Table 10 – impact of measures to improve carbon efficiency of UK aviation, by
2030 and 2050
81
taking into account extent of deployment by the specified date.
82
Values rounded to nearest 0.5%
83
Note that the total is not the arithmetic sum of the individual contributions, since each successive percentage reduction is in
relation to what remains after the previous reductions have been taken into account. For instance a reduction of 50% followed
by another reduction of 50% would yield a combined reduction of 75%.
Page 42 of 58
9
The Sustainable Aviation CO2 Road-Map
SUMMARY – based on our assumptions and analysis, we conclude that UK aviation is able to
accommodate significant growth to 2050 without a substantial increase in absolute CO2
emissions. We also support the reduction of net CO2 emissions to 50% of 2005 levels through
internationally agreed carbon trading.
9.1
The Road-Map
Having in previous sections set out the individual elements of our Road-Map and the assumptions that
we have made, in this section we now combine these assumptions to produce the Road-Map itself.
Figure 13 – Sustainable Aviation CO2 Road-Map, showing that UK aviation can
accommodate significant growth to 2050 without a substantial increase in
absolute CO2 emissions. We also support the reduction of net CO2 emissions to
50% of 2005 levels through internationally agreed carbon trading.
9.2
Discussion – Average Rates of Improvement
Taken together, our mitigation assumptions combine to yield an average rate of improvement in fuelburn per tonne-kilometre (responsible for the uppermost of the three brackets on the right hand side of
Figure 13) of some 1.44% per annum, of which an average of 1.21% per annum arises from the
deployment of more fuel-efficient aircraft. When the impact of sustainable fuels is taken into account,
the average annual rate of improvement in carbon intensity is 1.93%.
The rate of improvement in fleet-average aircraft fuel efficiency (1.21% per annum) is rather lower
than the assumed rate of improvement in the fuel efficiency of new aircraft (1.3% p.a. plus stepchanges) which we set out in section 5.5 above. There are two reasons for this:
•
The average improvement rate in fleet-average fuel efficiency is calculated over the 40-year
period 2010 to 2050. However, our Road-Map takes account of aircraft types entering service
up to and including 2040. This means that the technological or product developments taking
place post 2040 do not influence our Road-Map within the 2050 time-horizon.
•
Our assumption of a 2035 entry into service (EIS) for the second generation (G2) wide-body
aircraft, and a 2040 EIS for the G2 very-large aircraft, coupled with a 20-year fleet turnover
Page 43 of 58
period in both cases, means that many G1 aircraft in these two categories will not have been
replaced by 2050. The full impact on fleet-average fuel efficiency of the technology embodied
in the G2 wide-body and very-large aircraft types will therefore not be realised until after 2050.
9.3
Comparison of SA’s Projection with DfT’s CO2 Forecasts
As described in section 2.2 above, our CO2 Road-Map takes as its starting point forecasts of demand
growth based upon the “Central” scenario within [DfT, 2011], in which DfT’s own forecasts of CO2
emissions from UK aviation, and the underlying assumptions, are also set out. Therefore in this
section we compare DfT’s CO2 forecasts and assumptions against those set out in this Road-Map.
Figure 14 – Comparison of SA’s view of absolute and net emissions in relation to
DfT’s “Central” CO2 forecasts
Figure 14 demonstrates that SA’s projection of absolute CO2 emissions from UK aviation in 2050 is
some 22% lower than that set out in the corresponding DfT CO2 forecast. Table 11 presents a
84
comparison of DfT’s mitigation assumptions against those employed by SA in this Road-Map.
[DfT, 2011]
ATM and Operations
Sustainable Fuels
0
9%
2030
0.5 %
8%
2050
2.5 %
to 2020
New aircraft efficiency
improvement relative to
2000
Carbon Trading
SA CO2 Roadmap
Various
2020-2030
17.5 - 21.5 %
2030-2040
24.5 – 27.5 %
2040-2050
29.5 – 31.5 %
2050
0
85,86
18 %
NB
87
13 %,
NB 35 %
WB
88
17 – 20 %
WB 50 – 54 %
As required to reduce net CO2
emissions to 50% of 2005 levels
Table 11 – Comparison of CO2 mitigation assumptions responsible for the
differences set out in Figure 14
84
Corresponding to the “Central” scenario, as set out on page 82 of [DfT, 2011]
85
Values derived from Table 4, Table 5 and Table 10
86
Values rounded to nearest whole percentage point
87
NB – narrowbody aircraft, corresponding to the “single-aisle” category discussed in section 5
88
WB – widebody aircraft, corresponding to the “twin-aisle” and “very-large” aircraft categories discussed in section 5
Page 44 of 58
DfT’s view of the rate of improvement in fleet average fuel efficiency is set out in Table 3.4 of [DfT,
2011], in which a value of 0.9% per annum is shown for the “Central” case, covering the period 2010
to 2050. This compares with the corresponding value of 1.21% from our Road-Map. Reasons for the
difference can be inferred from Table 11.
9.4
Comparison of SA’s and CCC’s Mitigation Assumptions
[CCC, 2009] examined the potential for UK aviation to reduce its carbon intensity, identifying a trio of
scenarios entitled “Likely”, “Optimistic” and “Speculative”. The range of mitigation levels used by the
CCC across those three scenarios is compared in Table 12 with our own mitigation assumptions
which we have used to assemble this Road-Map.
With regard to the potential for sustainable fuels to reduce CO2 emissions from UK aviation, it is clear
that SA’s position is considerably more optimistic than that of [CCC, 2009]. However, in relation to
ATM and operations, and also with regard to advances in fleet fuel efficiency, the figures align fairly
well. [CCC, 2009] did not consider the impact of carbon trading on net CO2 emissions.
[CCC, 2009]
ATM and Operations
Sustainable Fuels
85
6 - 13 %
9%
2030
1 – 2.5 %
8%
2050
5 - 15 %
18 %
0.8 – 1.5 % p.a.
1.21 % p.a.
N/A
As required to reduce net
CO2 emissions to 50% of
2005 levels
Average annual improvement in fleet
89
fuel efficiency to 2050
Carbon Trading
SA CO2 Roadmap
2050
Table 12 – comparison of CO2 mitigation assumptions set out in this CO2 RoadMap against those set out in [CCC, 2009]
9.5
Conclusions
This document has set out Sustainable Aviation’s projection of future CO2 emissions from UK aviation,
taking account of the UK government’s forecasts of growth in demand. We conclude that UK aviation
is able to accommodate significant growth to 2050 without a substantial increase in absolute CO2
emissions. We also support the reduction of net CO2 emissions to 50% of 2005 levels through
internationally agreed carbon trading.
Government will play a key role in supporting research and development in aerospace technology,
encouraging the introduction of sustainable biofuels, delivering on infrastructure projects such as the
Single European Sky initiative, and working with other countries to establish a global sectoral
approach for regulating international aviation emissions based on carbon trading.
We do not support unilateral UK targets and measures as they would be unnecessary and counter
productive. Such measures would deliver no overall environmental benefit, but would result in carbon
leakage, market distortion, and the loss of economic benefits to our international competitors.
Recent and future developments in aircraft and engine technology will play a major role in reducing
UK aviation’s carbon intensity. We anticipate absolute CO2 emissions will continue to fall post-2050
due to the ongoing penetration into the fleet of new wide-body aircraft types entering service from
89
As distinct from the fuel-efficiency of new aircraft
Page 45 of 58
around 2035 onwards. The same technologies will also be deployed on a worldwide basis, with a
correspondingly greater CO2 mitigation impact.
The potential for sustainable biofuels to reduce CO2 emissions from UK aviation has increased
dramatically over the past three years. During this period, two classes of sustainable fuel have been
certified for commercial use, and there has been considerable diversification in the range of potential
feedstocks and processing routes being developed. This area continues to develop rapidly.
Improvements in air traffic management and operational procedures will also play a material role in
reducing the carbon intensity of aviation in the coming decades.
Delivery of the above will be contingent upon suitable levels of support from Government, which
should:
•
•
•
•
press for agreement on and support the implementation of a global carbon-trading solution
Aviation is a globally interconnected industry and needs a global solution to address its emissions in a
cost effective manner without introducing competitive distortions. Any unilateral targets and measures
that attempt to limit UK aviation’s emissions through capacity constraints or price-related demand
reduction will lead to carbon leakage, market distortion and the loss of economic benefit to our
international competitors. We do not support the inclusion of international aviation emissions in UK
carbon budgets. Our Road-Map shows that such unilateral policy measures are not necessary and
that UK aviation can accommodate significant growth to 2050 without a substantial increase in
absolute CO2 emissions. We also support the reduction of aviation’s net CO2 emissions to 50% of
Page 46 of 58
References
[ACI, 2009]
A Global Sectoral Approach for Aviation (ACI, CANSO, IATA, ICCAIA),
presented to ICAO’s High-Level Meeting on International Aviation and Climate
Change, Oct 2009
http://www.canso.org/cms/streambin.aspx?requestid=E040EEFF-4FF9-4DEB-B78D-FE66B70FDE6C
[CAA, 2010]
CAA Airport Statistics for 2010
http://www.caa.co.uk/default.aspx?catid=80&pagetype=88&sglid=3&fld=2010Annual
[CANSO, 2008]
ATM Global Environment Efficiency Goals for 2050
http://www.canso.org/cms/streambin.aspx?requestid=DD79F925-E59D-4314-8AAA-C966F382FD0E
[CCC, 2009]
Meeting the UK Aviation target – options for reducing emissions to 2050
http://hmccc.s3.amazonaws.com/Aviation%20Report%2009/21667B%20CCC%20Aviation%20AW%20COMP%20
v8.pdf
[CCC, 2011]
Bioenergy Review – December 2011
http://www.theccc.org.uk/reports/bioenergy-review
[DfT, 2007]
UK Air Passenger Demand and CO2 Forecasts (UK Department for Transport,
Nov 2007)
http://webarchive.nationalarchives.gov.uk/+/http://www.dft.gov.uk/pgr/aviation/atf/ukairdemandandco2forecasts/air
passdemandfullreport.pdf
[DfT, 2011]
UK Aviation Forecasts (UK Department for Transport, Aug 2011)
http://assets.dft.gov.uk/publications/uk-aviation-forecasts-2011/uk-aviation-forecasts.pdf
[GbD, 2003]
Air Travel – Greener by Design: The Technology Challenge
http://www.greenerbydesign.org.uk/_FILES/publications/GbD - 2003 The Tech Challenge.pdf
[HLG, 2011]
Flightpath 2050: Europe’s Vision for Aviation (High Level Group on Aviation
Research, April 2011)
http://www.acare4europe.org/docs/Flightpath2050_Final.pdf
[IATA, 2010]
Aviation and the Environment (presentation at 66th AGM)
[ICAO, 2003]
Operational Opportunities to Minimize Fuel Use and Reduce Emissions
(Circular 303-AN/176, International Civil Aviation Organization, February 2003)
[ICAO, 2009]
Declaration of the High-level Meeting on International Aviation and Climate
Change (HLM-ENV/09)
http://legacy.icao.int/env/ClimateChange/PoA.htm
[ICAO, 2010]
Resolution A37-19: Consolidated statement of continuing ICAO policies and
practices related to environmental protection – Climate change
http://legacy.icao.int/env/A37_Res19_en.pdf
[ICAO, 2011]
Report of the Independent Experts on the Medium and Long Term Goals for
Aviation Fuel Burn Reduction from Technology (ICAO Document 9963)
http://store1.icao.int/documentItemView.ch2?ID=10260
[Lackner, 2009]
Capture of Carbon Dioxide from Ambient Air (Eur. Phys. J. Special Topics 176,
93-106, (2009))
[NAEI, 2011]
UNECE Emissions Estimates to 2009: Carbon Dioxide as Carbon (National
Atmospheric Emissions Inventory, March 2011)
http://naei.defra.gov.uk/emissions/emissions_2009/summary_tables.php?action=unece&page_name=C09.html
[OE, 2011]
Economic Benefits from Air Transport in the UK (Oxford Economics, 2011)
Page 47 of 58
[PARTNER, 2010]
Life Cycle Greenhouse Gas Emissions from Alternative Jet Fuels (Stratton et al)
http://web.mit.edu/aeroastro/partner/reports/proj28/partner-proj28-2010-001.pdf
[Poll, 2009]
The Optimum Aeroplane and Beyond (The Aeronautical Journal, Vol. 113, No.
1140, Mar 2009)
[SA, 2008a]
Sustainable Aviation CO2 Roadmap, Dec 2008
http://www.sustainableaviation.co.uk/wp-content/uploads/sa-road-map-final-dec-08.pdf
[SA, 2008b]
Non-CO2 climate change effects of aviation emissions (Sustainable Aviation,
Nov 2008)
http://www.sustainableaviation.co.uk/wp-content/uploads/nonco2papernov08.pdf
[SA, 2009]
Sustainable Aviation Progress Report 2009
http://www.sustainableaviation.co.uk/wp-content/uploads/sa-second-review-final.pdf
[SA, 2010a]
Aircraft on the Ground CO2 Reduction Programme
http://www.sustainableaviation.co.uk/wp-content/uploads/aircraft-on-the-ground-best-practice-guidance-june2010.pdf
[SA, 2010b]
Sustainable Alternative Fuels Progress Paper
http://www.sustainableaviation.co.uk/wp-content/uploads/sustainable-alternative-fuels-progress-paper-summer2010.pdf
[SA, 2011]
Sustainable Aviation Progress Report 2011
http://www.sustainableaviation.co.uk/wp-content/uploads/sa-progress-report-2011.pdf
[SESAR]
The Future of Flying
http://www.sesarju.eu/sites/default/files/documents/reports/magazinecitizens_EN_web.pdf
Page 48 of 58
APPENDIX A – Fleet Turnover Assumptions
Introduction
In this document we use the term “fleet-turnover period” to refer to the number of years, following the
90
entry into service of a new aircraft type in a particular category , before the fuel-burn taking place on
the remaining examples of the older aircraft type within the same category, on routes falling within the
scope of “UK aviation”, is considered no longer material to this analysis.
We emphasise the distinction between this definition (based on the distribution of fuel-burn between
older and newer aircraft types within the same category) and an alternative definition which might be
based on the number of instances of the older aircraft type still in service.
Our motivation for making this distinction is based on the observation that older, less fuel-efficient
aircraft types will typically be used less intensively than their more fuel-efficient successors, and so will
have less of an influence on total fuel-burn.
Generation 1 (G1) or “imminent” aircraft
91
•
Single-Aisle – although significant numbers of orders have been placed for the “re-engined”
G1 aircraft from Boeing and Airbus, the order backlog is such that examples of the current
generation aircraft will nonetheless continue to enter service for a number of years. The point
at which fuel-burn within the remaining fleet of current generation aircraft is no longer material
in comparison with that taking place on the G1 fleet will be correspondingly further into the
92
future. We therefore estimate a 30-year fleet turnover period for this category .
•
Twin-Aisle – in this category, although the Boeing 757 is no longer in production, the
combined order backlog for other existing types - such as the Boeing 767, Airbus A330 and
Boeing 777 - is very significant. However, the operating costs of aircraft in this category are
arguably more sensitive to fuel-related elements than in the single-aisle category. Coupled
with the greater percentage efficiency improvement offered by the G1 types in this category
versus their respective predecessors (compared with that in the single-aisle category), this
suggests a swifter transition towards the newer types. We therefore assume in this category a
25-year fleet-turnover period.
•
Very-large - we assume that, from now on, all examples of aircraft entering service on
routes which depart from UK airports will be of the G1 types rather than the previous type.
Given the significant fuel-burn benefits of the newer types over their predecessor we assume
a fleet-turnover period of 20 years in this category.
93
94
Generation 2 (G2) or “future” aircraft
•
95
Single-Aisle – based on our assumed entry-into-service (EIS) date of G2 single-aisle
aircraft types, it is likely that production of the G1 single-aisle aircraft types will still be in
progress at that point. However, since the percentage improvement in fuel efficiency of the G2
single-aisle type versus its G1 predecessor is assumed to be much more significant than that
of the G1 aircraft versus its corresponding baseline aircraft, we take the view that the fleet-
90
Single-aisle, twin-aisle, or very-large
91
This category includes such aircraft as the Airbus A320neo, the Boeing 737 MAX and the Bombardier C Series
92
The sensitivity of the overall fuel-burn estimate to variations in the fleet-turnover period in the narrow-body category is fairly
low due to the small proportion of UK aviation fuel-burn that takes place on aircraft in this category (see Appendix B for more
details).
93
This category includes the Boeing 787 and the Airbus A350 XWB
94
This category includes the Airbus A380 and the Boeing 747-8.
95
Discussed in section 5.5 of the main document
Page 49 of 58
turnover period for introduction of the G2 aircraft will be shorter than that for the introduction of
the G1 aircraft. We therefore assume a 25-year fleet-turnover period from G1 to G2 aircraft in
this category.
•
Twin-Aisle – our assumed EIS date for the G2 twin-aisle aircraft type is some 20 years after
the introduction of its G1 predecessor. We consider it unlikely that that there will be a
significant overlap of production runs of G1 and G2 aircraft types. Furthermore, the sensitivity
of this category to fuel cost will drive swift uptake of G2 aircraft to replace existing examples of
the G1 predecessor. As a result we assume full fleet-turnover in this category within 20 years
of EIS of the G2 aircraft.
•
Very-large – as with the twin-aisle category (and for the same reasons) we assume full fleetturnover in this category within 20 years of EIS of the G2 aircraft.
96
Depending on assumed EIS date and fleet-turnover period , some aircraft categories may not have
completed fleet-turnover from G1 to G2 aircraft types by 2050 in our model.
96
As set out in Table 6 within section 5
Page 50 of 58
APPENDIX B – Distribution of Fuel-Burn
This appendix sets out the distribution of aviation’s fuel-burn between flights of different lengths and
between different categories of aircraft. A summary is given in Table 13.
Figure 15 illustrates the time-history of the UK distribution over the past few years. Looking specifically
at 2010 data:
•
Figure 16 shows the distribution of fuel-burn by flight-distance and aircraft category, both for
UK and for global aviation. Whereas globally, fuel-burn is split roughly equally between
narrow-body and wide-body aircraft, the majority of fuel-burn attributable to scheduled
passenger flights which depart from UK airports takes place on wide-body aircraft on long-haul
flights.
•
Figure 17 shows how the wide-body fuel-burn is distributed between “very-large” and “twinaisle” aircraft categories.
Although the analysis underpinning these figures is based on scheduled passenger flights only, due to
a difficulty in sourcing data for charter and freight-only flights, we believe that this does not alter
materially the conclusions concerning the dominance of the wide-body aircraft category within the fuelburn distribution on flights which depart from UK airports, and the approximately equal significance of
narrow-body vs wide-body aircraft within global aviation’s fuel-burn distribution.
Aircraft Category
Narrowbody
Widebody
Share of Fuel-Burn
Flights which depart from UK airports
Global
Single-Aisle
31 %
51 %
Twin-Aisle
42 %
38 %
Very-Large
27 %
11 %
100%
100%
TOTAL
Table 13 – summary of data presented in this appendix – proportion of fuel-burn
taking place within aircraft of different categories. Scope: 2010, scheduled
passenger flights. Source – Rolls-Royce analysis based on data from OAG.
Figure 15 – Distribution by aircraft category of UK fuel-burn on scheduled
passenger flights, covering the years 2004-2010 (based on actual data) and 2011
98
(based partly on anticipated schedules). NB = narrow-body; WB = wide-body .
Source – Rolls-Royce analysis based on data from OAG.
Page 51 of 58
Figure 16 – Distribution of fuel-burn on scheduled passenger flights in 2010 by
aircraft category and distance. Scope: UK (left), Global (right). NB = narrow97
98
body ; WB = wide-body . Source – Rolls-Royce analysis based on data from
99,100
OAG
.
Figure 17 – Distribution of fuel-burn on scheduled passenger flights in 2010,
showing the distinction between very-large (VL) aircraft and twin-aisle (TA)
aircraft. Scope: UK (left), Global (right). Source – Rolls-Royce analysis based on
99,100
data from OAG
.
97
Equivalent to the “single-aisle” aircraft category used in this document
98
In these charts, the “wide-body” (WB) category covers both “twin-aisle” and “very-large” aircraft. The distribution of fuel-burn
between those two subcategories is shown later in this Appendix.
99
UK chart - fuel burn data cover 93.9% of OAG scheduled passenger data
100
Global chart - fuel burn data cover 94.7% of OAG scheduled passenger data
Page 52 of 58
APPENDIX C – Less Likely Mitigation Options
In this appendix we review carbon-reduction options which do not feature in our current assumptions
concerning UK aviation. Some of these options may become feasible in the future but we have chosen
not to take account of them at present.
Multi-Stage Long-Haul Travel
The fuel required to raise an aircraft to its cruising height represents an overhead which has a
particularly detrimental impact on the overall fuel efficiency (per kilometre) of shorter flights. Fuel
efficiency on longer flights, on the other hand, suffers from the need to carry over significant distances
not only a heavier fuel load but also the weight of aircraft structure required to contain the additional
fuel. The balance or trade-off between these two effects gives rise to an “optimum” flight distance, at
which fuel-burn per kilometre travelled is minimised.
[GbD, 2003] gives a detailed discussion of the impact of design range on payload fuel efficiency. It
101
concludes that, on a journey of 15,000km (around 8,000 nm ), fuel-burn can in principle be reduced
by almost 30% through employing an aircraft whose design range is 5,000 km instead of 15,000 km,
taking the journey in three equal stages.
In practice however, the likely reduction in fuel-burn arising from such measures is likely to be limited
since there are many barriers to realising such savings in service:
•
Referring to Figure 16 in Appendix B, we can see that the proportion of global aviation’s fuelburn taking place on flights over 6000nm is relatively small. Furthermore, looking specifically
at the distribution of fuel-burn on flights which depart from UK airports (also Figure 16) we can
see that there is very little fuel-burn taking place on flights over 5500nm. The number of longrange flights over which significant fuel-burn savings could be achieved through a multi-stage
approach is therefore extremely limited in the context of UK aviation.
•
The savings possible through adopting a multi-stage approach to flights in the 4000-6000nm
distance band would be eroded by competing factors such as increased time-related costs, or
by increased journey distances arising from a lack of suitably placed interim airports,
particularly on trans-oceanic or trans-polar routes.
We do not at present consider that the adoption of multi-stage long-haul travel presents
significant opportunities for genuine reductions in CO2 emissions from UK aviation.
Hydrogen as an Aviation Fuel
The CO2 emissions index of a fuel is usually defined as the ratio of the mass of CO2 produced to the
mass of the fuel burned. In the case of kerosene the value is 3.15. Fuels with lower CO2 emissions
indices do exist, but in many cases are unsuitable for use as aviation fuels. One fuel which is often
discussed as an alternative to kerosene in the longer term is liquid hydrogen.
Liquid hydrogen produces no carbon dioxide at the point of combustion (in other words its CO2
emissions index is zero), and might at first sight appear attractive as an aviation fuel from that
perspective. In principle, if produced by electrolysis of water using low-carbon electricity, hydrogen
could also benefit from a very low life-cycle carbon footprint.
In practice however, unless electricity production is entirely decarbonised, the prioritisation of lowcarbon electricity for hydrogen production would likely displace other electricity demand onto higher101
Approximately equal to the distance from Chicago to Sydney, or from London to Perth.
Page 53 of 58
carbon power generation. Alternatively, production of hydrogen from methane or other hydrocarbons
is accompanied by the release of CO2 which would need to be captured and sequestered to achieve a
low life-cycle carbon footprint.
From a practical standpoint, although hydrogen’s energy per unit mass is almost three times that of
kerosene, its energy per unit volume (even in liquid form) is only around one quarter that of kerosene.
Fuel tanks would therefore need to be much larger to accommodate the greater volume of hydrogen
fuel, and this has significant implications for airframe design. The requirement to operate parallel refuelling infrastructures during several decades of transition from kerosene to hydrogen would also
increase costs and system complexity.
We do not currently believe the use of hydrogen as a fuel for the primary propulsion of
commercial aircraft is likely on a significant scale before 2050.
Fuel Manufacture from Artificially Captured CO2
The synthesis of hydrocarbon fuels by combining hydrogen (obtained through electrolysis) with
artificially captured CO2 has been proposed and is under development. However, the overall energy
requirements for this process are such that arguably it would only be attractive once most other
sectors have decarbonised and low-carbon electricity is in plentiful supply.
We do not take account of any contribution from this approach within our current Road-Map.
Sequestration of Captured CO2
The direct capture of CO2 from the exhaust of aircraft engines in flight is clearly impractical, since the
weight of CO2 produced by burning kerosene is some three times that of the fuel itself, whilst the size
and weight of the equipment required to effect the capture would also be prohibitive. If aviation’s CO2
emissions are to be captured with a view to sequestration, the extraction must therefore be performed
not from CO2-rich aircraft exhaust streams but rather from ambient air in which the CO2 concentration
is extremely low (around 0.04% by volume).
Clearly, the absorption of CO2 from ambient air is carried out on a large scale by growing plants.
However, the permanence of sequestration associated with this form of capture is far from clear, being
vulnerable to disruption through fire, logging or decay.
An alternative mechanism for the capture of CO2 from ambient air using an artificial device is proposed
in [Lackner, 2009]. Such a device, if realised, could provide a stream of CO2 suitable for permanent
sequestration. However, much development work remains to be done to bring the concept to
commercial reality.
We do not take account of sequestration of captured CO2 in our current Road-Map.
Page 54 of 58
APPENDIX D – Comparing the 2008 and 2012 Road-Maps
Hypothetical “No-improvements” Scenario
In our 2008 CO2 Road-Map we based our hypothetical “no-improvements” scenario purely on growth
in passenger numbers, based on DfT’s 2007 passenger forecasts [DfT, 2007]. Although DfT’s 2011
forecasts for passenger numbers [DfT, 2011] are noticeably lower than the corresponding figures from
DfT’s 2007 forecasts, in this 2012 Road-Map we are able to use what we believe is a more
102
appropriate proxy for growth, namely a forecast of RPKs
delivered on passenger flights plus an
103
estimate of FTKs delivered on freighter aircraft.
This migration, from a demand forecast based purely on passenger numbers to one which not only
accounts for forecast changes in average distance flown but also incorporates growth in freight-only
flights, results in an average rate of growth in demand for UK aviation which, during the period 20102050, is actually slightly higher than that assumed in our 2008 Road-Map, as Table 14 shows.
ATM and Operations
In this category, although the bottom-up analysis in the 2012 Road-Map (set out in section 4 above) is
much more detailed than the simple top-down analysis used in the 2008 Road-Map, the results relative to a common 2010 baseline - show fairly good agreement, as shown in Table 14.
Engine and Aircraft Technology
In this 2012 Road-Map we have split the aircraft fleet into three distinct categories, as described in the
main text, and have based our assumptions concerning the improvement of fleet-average fuel
efficiency within each category purely on the introduction of distinct aircraft types into the fleet.
Improvements in fleet-average fuel efficiency in the early years are therefore based on the impact of
the introduction of the “imminent” generation of aircraft types whose characteristics are known, rather
than on some estimate of overall rates of improvement, as was used in the 2008 Road-Map.
Due to recent changes in economic outlook, our assessment of the timescales over which future
generations of aircraft will enter service now spans a more extensive period than that assumed in the
2008 Road-Map. The consequence of this is that, while our 2008 Road-Map anticipated the entry into
service of two distinct “future” generations of aircraft, the second of these is now assumed to fall much
nearer to 2050 than was previously assumed. Its impact on fleet-average fuel efficiency by 2050 is
therefore considered not material to the analysis and as a result it is omitted altogether from the 2012
Road-Map. The significance of this change for fleet-average fuel efficiency is shown in Table 14.
Sustainable Biofuels
Our assessment of the potential for biofuels to reduce aviation’s CO2 emissions now benefits from
greater clarity than was available at the time of our 2008 Road-Map. Since then, two types of aviation
biofuel blend have been approved for commercial use, the range of feedstocks and processing routes
under development has increased considerably, more detailed research has been undertaken to
establish the life-cycle benefits of various types of aviation biofuels, and sustainability standards have
been set. Our view is that the potential for aviation biofuel adoption is now considerably greater than
was considered likely at the time of our 2008 Road-Map, as shown in Table 14.
102
RPKs = revenue passenger kilometres
103
FTKs = freight tonne kilometres
Page 55 of 58
Carbon Trading
In our previous Road-Map we chose not to represent the potential contribution of carbon trading to
reducing UK aviation’s net emissions, due to a paucity of relevant information. Since that time, details
of aviation’s incorporation into the EU ETS have been established, and the prospect of a global carbon
trading system has strengthened considerably. In our 2012 Road-Map, we illustrate the level of carbon
trading required to allow UK aviation to reduce net CO2 emissions in 2050 to half of 2005 levels, in line
with the global aviation industry’s declared aspiration.
Summary
Edition of SA CO2 Road-Map:
Period
2000-2050
Average demand-growth rate
Reduction in
Fleet Average
Carbon Intensity
106
in 2050
2008
2012
104
2010 – 2050
105
2.32% p.a.
2.12% p.a.
2.32% p.a
ATM / Operations
10%
7%
9%
Aircraft and Engine
62%
56 %
39%
Biofuels
10%
10%
18%
0
As required to
reduce net
emissions to
half of 2005
levels
Carbon Trading
0
Table 14 – comparison of assumptions used in the 2008 and 2012 Sustainable
Aviation CO2 Road-Maps
104
This column shown for context only
105
These two columns should be used as the basis for comparison
106
Values rounded to the nearest whole percentage point
Page 56 of 58
APPENDIX E – Impact of Fuel Efficiency on Mission Fuel-Burn
Since a proportion of an aircraft’s propulsive thrust is used to keep the aircraft aloft, any reduction in
aircraft weight enables a reduction in required thrust, which itself enables a further reduction in weight
arising from the reduced fuel requirement. This “virtuous circle” enhances the savings in mission fuelburn that can be achieved through the introduction of new technologies or operational procedures.
Improving engine fuel efficiency, for example, means that less fuel is required to produce the same
level of thrust. However, the thrust requirement is itself reduced because less fuel needs to be carried
to achieve the same payload-range performance, and the aircraft as a whole is therefore lighter. In the
context of a “clean-sheet” aircraft design, certain design choices then become available. Since
achieving the desired mission requires less fuel, smaller and lighter fuel tanks can be specified, wings
can be made smaller and lighter because less lift is required, and engines can be specified with a
lower maximum thrust. These adjustments themselves reduce the thrust requirement even further.
Improving aircraft aerodynamic efficiency can lead to a similar chain of additional effects – reducing
the aircraft’s drag means that engine thrust requirements are reduced, leading to reduced fuel-burn
and the potential for re-optimising the aircraft design as outlined above. The use of advanced
materials or assembly methods resulting in a lighter airframe allows a similar story to be explored, as
does the successful adoption of efficient operational procedures which reduce mission fuel-burn.
The significance of this effect depends on the mission length – for a longer flight the effects become
more pronounced as the benefits of carrying less fuel accumulate over a greater distance. Since longhaul flights figure prominently in UK aviation’s fuel-burn profile (as shown in Figure 16 within Appendix
B), this effect is therefore of considerable relevance to this UK-centric CO2 Road-Map.
As an illustration of the significance of this effect, Table 15 presents indicative values - for a typical
twin-engined wide-body airliner - of the impact on mission fuel-burn of improvements in engine fuel
efficiency, with and without re-optimisation of the airframe configuration, at different mission-ranges.
These figures, which do not assume any changes in airframe technology level, illustrate the significant
benefits for long-range mission fuel-burn that be obtained through improvements in fuel efficiency.
AIRFRAME CONFIGURATION
Improvement in engine
RE-OPTIMISED
107
10 %
20 %
10 %
20 %
Trans-Atlantic
11 %
25 %
15 %
28 %
Trans-Pacific
12 %
26 %
15 %
29 %
Very long range
13 %
27 %
16 %
30 %
fuel efficiency
Approximate
improvement in
108
mission fuel-burn
UNCHANGED
Table 15 - indicative values, for a typical twin-engined wide-body airliner,
illustrating the impact of engine fuel efficiency improvement on mission fuelburn, and its dependence on mission length. Note that these figures do not
assume any changes in airframe technology level.
107
Improvement in specific fuel consumption (sfc), assuming no impact on nacelle geometry or engine weight
108
Source: Rolls-Royce model of a typical twin-engined wide-body airliner. Values rounded to the nearest whole percentage
point
Page 57 of 58
APPENDIX F – ATM efficiency improvements in NATS airspace
This appendix relates to section 4.2.2 of the main document, and sets out how the ATM efficiency
target adopted by the UK’s air navigation service provider (NATS) will impact CO2 emissions from
flights which depart from UK airports.
As stated in the main text, each flight within NATS control can be regarded as falling into one of four
categories: overflights, domestic flights, inbound international, and outbound international.
Notwithstanding the above categorisation, each flight can be regarded as consisting of a number of
distinct phases: ground operations, climb, en-route, and descent. Not every phase of each flight will
take place under NATS control, for instance the descent phase of an outbound international flight
occurs elsewhere. Furthermore, not every flight under NATS control falls within the scope of our RoadMap, for example over-flights and inbound international flights do not originate from a UK airport and
thus lie outside our scope.
The NATS target refers to a reduction of CO2 emissions from flights under NATS control by an
average of 10% per flight, by 2020 relative to a 2006 baseline. CO2 emissions from flights under NATS
control in 2006 amounted to 25Mt. The target saving is therefore equivalent to 2.5Mt of 2006
emissions, although with growth in traffic to 2020 the target amount may increase.
Total CO2 emissions in NATS controlled airspace in 2006 from flights which departed from UK
109
airports are estimated by NATS at 12.3Mt. This includes 1Mt from airports (taxiing and take-off roll),
110
7.3Mt from domestic airspace and 4.0Mt in North Atlantic airspace under NATS control. This 12.3Mt
111
is 49% of NATS total baseline emissions of 25Mt in 2006 .
The climb phase of flight is known to offer one of the most significant opportunities for efficiency
improvement because aircraft in this phase are at their heaviest with high thrust settings required to
climb to more efficient cruise levels. Current airspace structures and air traffic flows also often require
aircraft to level off and then to re-apply power in a ‘stepped climb’ prior to reaching efficient cruise
altitudes. Based on NATS analysis, we have assumed that improvements in climb efficiency account
for four tenths of the NATS overall 10% improvement target, resulting in a reduction of 1.0Mt (relative
to 2006 emissions) from improvements made in the climb phase of flights under NATS control. The
entirety of this saving lies within scope of our Road-Map, and amounts to some 2.6% of UK aviation’s
total emissions in 2006.
Further opportunities for reducing emissions through NATS ATM improvement are available in relation
to the ground-operations, en-route and descent phases of flights. NATS estimates that the available
saving relating to flights which depart from UK airports lies in the region of 0.5 MtCO2 relative to the
2006 baseline. This corresponds to a further 1.3% of UK aviation’s total emissions in 2006.
We estimate therefore that total savings achievable on flights which depart from UK airports, as a
result of successful delivery of the NATS 10% target, amount to 3.9% of UK aviation’s CO2 emissions.
Although in the above analysis this saving is expressed relative to the stated 2006 baseline, the
phasing of delivery is such that the vast majority will be achieved post 2010. We therefore take this
3.9% as being the available saving relative to the SA Road-Map’s 2010 baseline, as we discuss
further in section 4.2.2 of the main document.
109
Only flights which depart from UK airports are within scope of our UK CO2 Road-Map
110
Not to be confused with domestic flights
111
NATS baseline also includes emissions within NATS airspace from over-flights, and from inbound international flights
Page 58 of 58
E: [email protected]
T: 020 7799 3171
SA CO2 Road-Map 2012 Guide Cover1.indd 2
03/09/2013 12:22

sustainable aviation co2 road

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