PUBLIC

NLR-CR-2020-510 | February 2021

Destination 2050
A Route To Net Zero European Aviation

CUSTOMER: A4E, ACI-EUROPE, ASD, CANSO, ERA

NLR – Royal Netherlands Aerospace Centre
SEO Amsterdam Economics

1

EXECUTIVE SUMMARY
UNLIMITED DISTRIBUTION

Destination 2050
Net zero CO2 emissions 1 from all flights within and departing from the EU 2 can be achieved by 2050 through joint,
coordinated and decisive industry and government efforts. The European aviation industry is committed to
reaching this target and contribute to the goals set in the European Green Deal and the Paris Agreement.
Destination 2050 shows a possible pathway that combines new technologies, improved operations, sustainable
aviation fuels and economic measures. Absolute emissions are reduced by 92%, while the remaining 8% is removed
from the atmosphere through negative emissions, achieved through natural carbon sinks or dedicated technologies.
Royal Netherlands Aerospace Centre and SEO Amsterdam Economics conducted this study commissioned by the
representatives of European airports, airlines, aerospace manufacturers and air navigation service providers. It
assesses to what extent four groups of sustainability measures are able to reduce carbon emissions until 2050,
strongly influenced by policies and actions. The effects of these measures are compared to a hypothetical reference
scenario taking into account continuous demand growth and the recent COVID-19 impact. These sustainability
measures result in the following net CO2 emissions reductions in the year 2050:
111 MtCO2 through improvements in aircraft and engine technology:

•

o

o

60 MtCO2 by hydrogen-powered aircraft on intra-European routes and
51 MtCO2 by kerosene-powered or (hybrid-)electric aircraft;

•

18 MtCO2 through improvements in air traffic management (ATM) and aircraft operations;

•

99 MtCO2 through using drop-in sustainable aviation fuels (SAF);

•

22 MtCO2 through economic measures (carbon removal projects only).

The combined cost of these sustainability measures is modelled to impact ticket prices, resulting in a lower air travel

EU+ aviation net CO2 emissions (Mt)

demand. This would avoid 43 MtCO2 whilst maintaining an average compound annual passenger growth rate of 1.4%.
300

Decarbonisation Roadmap for European Aviation

250

17%
20%

200

6%

150

34%

100
50
0

1%

12%
8%

2018

2030

Hypothetical reference scenario
Improved technology (kerosene)
Improved technology (hydrogen)
Effect of hydrogen on demand

Net CO2 emissions
Improved ATM and operations
Sustainable aviation fuels (SAF)
Effect of SAF on demand

2050
Economic measures
Effect of economic measures on demand

Results are presented for all flights within and departing from the EU region2. Improving aircraft and engine
technology, ATM and aircraft operations, SAF and economic measures all hold decarbonisation potential. Modelled for
2030 and 2050, the impacts are linearly interpolated. The base year for this study is 2018.

1 While acknowledging that aviation is also responsible for non-CO climate impacts, the scope of this study is limited to a quantitative assessment of CO emissions.
2
2
Further study is required to develop a roadmap to take these non-CO2 emissions into account.
2 Specifically, the European Union (EU), the United Kingdom (UK), and the European Free Trade Association (EFTA).

i

2%

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A pathway to 2050

Implementing these measures could make 2019 the peak year in absolute CO2 emissions from European aviation,
thereby surpassing the industry target of carbon neutral growth from 2020 onwards. In the year 2030, net CO2
emissions are reduced by 45% compared to the hypothetical reference scenario as a result of continued fleet renewal,
improvements in ATM and aircraft operations and a substantial reliance on economic measures. Compared to the CO2
emissions in the year 1990, on which European Green Deal targets are based, this however means a 36% increase of
net CO2 emissions from European aviation. This is due to the fact that most substantial emission reductions measures
– a next generation of aircraft and substantial uptake of sustainable aviation fuel – take more time to materialise. It is
nonetheless essential that the foundations for post-2030 reductions are laid in the coming years, to realise net zero
CO2 emissions in 2050 and reduce reliance on economic measures.

A detailed look at flights within the EU

For flights within the EU2, the results highlight that net zero CO2 emissions in the year 2050 can be achieved with close
to zero economic measures. The largest contribution is made by hydrogen-powered aircraft introduced in 2035
followed by sustainable aviation fuels. Net emissions can be limited to 13 MtCO2 in the year 2030, estimated to be
55% below the emission levels in 1990 and thereby contributing to the implementation of the European Green Deal.
intra-EU+ aviation net CO2 emissions
(Mt)

120

Flights within the EU+ region

100
80
60
40
20
0

2018

Hypothetical reference scenario
Improved technology (kerosene)
Improved technology (hydrogen)
Effect of hydrogen on demand

2030

2050

Net CO2 emissions
Improved ATM and operations
Sustainable aviation fuels (SAF)
Effect of SAF on demand

55% of 1990 CO2
Economic measures
Effect of economic measures on demand

Intra-EU2 only. Modelled for 2030 and 2050, the impacts are linearly interpolated. The base year for this study is 2018.

Recommendations to industry and government

The measures leading to net zero CO2 emissions from European aviation need to be realised through collective
policies and actions by governments and industry. Both should work towards global commitment to a net zero
carbon future for aviation, to avoid differentiated policies, carbon leakage and transfer of activity. Europe should
maintain and evolve its leading position in sustainable aviation by the following policies and actions:
Industry should
 Continue to substantially invest in decarbonisation
 Develop more fuel-efficient aircraft and bring these
into operation through continued fleet renewal
 Develop hydrogen-powered and (hybrid-)electric
aircraft and associated supporting (airport)
infrastructure and bring these into the market
 Scale up drop-in SAF production and uptake
 Implement the latest innovations in ATM and flight
planning
 Compensate remaining CO2 emissions by removing
carbon dioxide from the atmosphere

Governments should
 Support industry investments by direct stimuli or by
reducing investment risk through a consistent and
long-term policy framework
 Stimulate further development and deployment of
innovations by funding research programmes and
promoting carbon removal technologies
 Work with the energy sector to ensure sufficient
availability of renewable energy at affordable cost
 Support the development of the SAF industry
 Contribute to optimising ATM, in particular by fully
implementing the Single European Sky
ii

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Improvements in aircraft and engine technology

By 2050, improvements in aircraft and engine technology and subsequent fleet replacement hold the largest promise
for decarbonising European aviation. This includes the introduction of a hydrogen-powered single-aisle aircraft on
intra-European routes in 2035. The generation of commercial passenger aircraft to be developed in the next 10 years
has potential to realise a step-change in energy efficiency. Introduced from 2035 onwards, these aircraft types are
forecast to reduce fuel burn by 30% or more per flight compared to predecessors. Range and capacity optimised
hybrid-electric regional aircraft are anticipated to bring down CO2 emissions by 50% per flight in that market segment.
Future small aircraft and rotorcraft, introduced from 2030, may become drivers for larger aircraft development.

Continued replacement of current aircraft with upcoming models would reduce emissions until 2040. Next-generation
future aircraft would yield aircraft-level CO2 emissions reduction of 30 to 50% compared to upcoming aircraft types.
Specifically for the intra-European market, a hydrogen-powered aircraft would enable zero-CO2 flight. At fleet level the
CO2 emissions reduction by upcoming and future aircraft reaches levels of 28 to 67% in 2050.
Future aircraft availability by 2035 requires technology readiness by 2027 to 2030. The proposed Partnership for
Clean Aviation provides a well-structured stimulus framework to realise this. A collaborative research programme
should also address more disruptive technologies modelled in this study, such as hydrogen-powered or other zeroCO2 emission aircraft. Collaboration and cross-pollination with other European and national R&D programmes and
instruments should be ensured. New technologies should be swiftly incorporated in commercial products, helped by
efficient new certification for disruptive technologies. Additional improvements should be delivered by accelerating
previous R&D results for market uptake, through new product offerings or upgrades to in-production aircraft.
Expedited replacement of older aircraft by state-of-the-art models may realise CO2 emission reductions even earlier.
Besides substantially reducing fuel consumption and fostering green technologies by design, the policies and actions
recommended in this roadmap would more firmly establish the European aviation sector as leading the way towards
sustainable aviation. With environmental concerns intensifying around the world, this offers Europe an important
first-mover advantage.
iii

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Improvements in air traffic management and aircraft operations

Improvements in ATM and aircraft operations are estimated to be a crucial opportunity to reducing CO2 emissions in
the short to medium term. Ensuring full and complete implementation of most measures by 2035 at the latest would,
furthermore, allow such benefits to continue yielding impacts between 2035 and 2050.

An array of improvements in ATM and aircraft operations yields a 5 to 6% system-level CO2 emissions reduction in 2030
and 2050 compared to the reference scenario. Requiring actions from all industry actors and governments, most of
these improvements could be realised by 2035. Within each of the three groups (highest / moderate / lowest impact),
the measures have not been sorted according to impact.
For Europe’s residents and visitors to enjoy the full benefits of the Single European Sky, it is imperative to move more
towards a network-centric and digital ATM system and requires political willingness to implement many of the
SESAR solutions. Regulation and R&D efforts must optimally support that goal. First and foremost, such a system
would include a renewed set of KPIs with clearly defined accountabilities; a seamless upper airspace; and an R&D
policy ensuring steady progress of new technology development and deployment. Better quantifying the anticipated
benefits following from fuel and CO2 optimized routing are near-term priorities.
Innovation in communication, navigation and surveillance equipment and processes should also be encouraged, such
that these can be swiftly put into practice. Beyond SES and SESAR, European governments and industry should
globally stimulate regions and States to improve ATM efficiency.
Finally, regulations and incentives should enable and encourage the rapid decarbonisation of ground operations.
Electric operational towing or taxiing solutions should be developed for all common aircraft and, when parked, aircraft
should use renewable energy. Along with possibly stimulating or supporting companies to make such investments,
European governments have a crucial role to ensure the supply of renewable energy can match its increased demand.

iv

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Sustainable aviation fuel

SAFs deliver a major contribution to achieving net zero carbon emissions in 2050. The supply of SAF may increase
from 3 Mt in 2030 to 32 Mt in 2050, equal to 83% of the total kerosene consumption. The SAF contribution is directly
linked to the development of industrial production capacity and strongly influenced by a supporting long-term policy
framework. SAF contribution in 2030 may be increased if a strong political support is given to SAF development. Over
time, life-cycle CO2 reduction increases to nearly 100% while production costs decrease.

Over time, SAF production volumes and life-cycle CO2 reductions increase while production costs decrease.
Crucial steps must be taken to scale up and commercialise SAF deployment. While making robust and transparent
sustainability criteria the foundation of a long-term policy framework, a diversified and sustainable feedstock base
should be established. This would combine biofuels from wastes, residues and non-food (lignocellulosic) crops as well
as e-fuels from renewable electricity and CO2 sourced from direct air capture. Multiple production pathways should be
tested in pilot and first-of-a-kind facilities. This increases technological learning, reduces risk and decreases production
costs. If the price gap with fossil fuels is overcome, SAFs could fulfil the entire kerosene demand from intra-European
flights, necessitating increasing the blending ratio allowed by ASTM certification from 50% currently to 100%.
To effectively address the price difference with fossil fuel throughout the value chain and thereby make SAF more
affordable, policies need to include measures to de-risk investments and boost production and off-take. These
measures could include financial incentives (e.g. carbon pricing, subsidies, auctioning mechanisms and capital grants)
and regulatory measures such as the implementation of an EU wide blending obligation. The timing and conditions
for implementing these measures are currently being investigated in ReFuelEU Aviation. To further reduce cost and
increase emissions reductions, a transparent monitoring and accounting framework should be implemented, similar
to the framework for renewable electricity. This would give airlines the possibility to claim the use of SAF in the most
economically efficient way across the fleet, regardless of where SAF has been physically uplifted.
v

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Economic measures

In the short term, smart economic measures are central in the reduction of carbon emissions from aviation. Such
measures assign a price to CO2 emissions ensuring that airlines take climate costs explicitly into account in their
business decisions. To ensure cost-effectiveness, economic measures must be market-based. The European Emission
Trading Scheme (EU ETS) is the mechanism that is implemented in Europe and which is complemented by the ICAO
CORSIA scheme for international flights. They trigger the acceleration towards the energy transition and bridge the
gap until breakthrough technologies and SAFs become widely available. By 2030, economic measures are expected
to reduce net CO2 emissions by 27% compared to the reference scenario.
Over time, breakthrough technologies and the use of SAF reduce the role of economic measures. The price of
allowances and carbon credits will increase as they become increasingly scarce. This will eventually lead to a price
whereby carbon removal projects become economically attractive to investors. In 2050, any remaining emissions can
therefore be balanced by carbon removal projects, which are assumed to lead to the issuance of additional emissions
allowances and carbon credits. A global approach is critical to prevent market distortion and carbon leakage.

Smart economic measures are a key mechanism to reducing carbon emissions, especially in the short term when
radical breakthrough technologies and SAFs are not yet widely available. The compliance costs to European airlines
would add up to around 3.6 billion euros by 2050 – € 165 per tonne CO2 – as allowances and carbon credits become
increasingly scarce.
Guaranteeing the quality of carbon credits through both industry action and policy intervention is key to realising
these necessary reductions in CO2. Implementing the global economic measure CORSIA is crucial to keeping
international aviation on track to reduce emissions and contribute to the net zero ambition globally. Earmarking of
revenues ensures the economic measures fully contribute to the development of aviation decarbonisation solutions.
Direct Air Capture is seen as important enabling technology for deployment in the short to medium term in order to
create high quality carbon allowance and credits.

vi

PUBLIC

NLR-CR-2020-510 | February 2021

Destination 2050
A Route To Net Zero European Aviation

CUSTOMER: A4E, ACI-EUROPE, ASD, CANSO, ERA

AUTHOR(S):
Elisabeth van der Sman
Bram Peerlings
Johan Kos
Rogier Lieshout
Thijs Boonekamp

NLR
NLR
NLR
SEO
SEO

NLR – Royal Netherlands Aerospace Centre
SEO Amsterdam Economics

NLR-CR-2020-510 | February 2021

Contents
1

2

3

4

5

6

Introduction

4

1.1 Context

5

1.2 Approach

11

1.3 Objective

11

1.4 Scope

12

1.5 Reading guide

15

Reference scenario

16

2.1 Introduction

16

2.2 Assumptions

16

2.3 Results

22

Improvements in aircraft and engine technology

26

3.1 Introduction

26

3.2 Upcoming technology

28

3.3 Future technology

31

3.4 Drivers and barriers

45

3.5 Policies and actions

47

Improvements in ATM and aircraft operations

53

4.1 Introduction

53

4.2 Airline operations

54

4.3 Airspace and air traffic management

57

4.4 Ground operations at airports

67

4.5 Drivers and barriers

70

4.6 Policies and actions

73

Sustainable aviation fuels

81

5.1 Introduction

81

5.2 Sustainability

82

5.3 Current EU policy framework

86

5.4 Feedstocks and production processes

86

5.5 ASTM certification

89

5.6 Production cost

90

5.7 Supply potential in 2030

94

5.8 Supply potential in 2050

98

5.9 Drivers and barriers

104

5.10 Policies and actions

106

Economic measures

114

6.1 Introduction

114

6.2 Types of pricing mechanisms

115

6.3 Smart economic measures

116
2

NLR-CR-2020-510 | February 2021

6.4 Approach

126

6.5 Drivers and barriers

131

6.6 Policies and actions

132

7

System changes and radical ideas

134

8

Assumption and impact modelling

137

8.1 Improvements in aircraft and engine technology

138

8.2 Improvements in ATM and aircraft operations

140

8.3 Sustainable aviation fuels

141

8.4 Economic measures

142

Destination 2050

144

9.1 Introduction

145

9.2 CO2 reduction

145

9.3 Overall policies and actions

151

9

References

154

Appendix A

Abbreviations

171

Appendix B

Consulted parties

176

Appendix C

Class-averaged improvement potential of upcoming aircraft

177

Appendix D

Future aircraft concept studies

179

Appendix D.1

Aircraft with drop-in fuels

179

Appendix D.2

Aircraft with non-drop-in fuels

181

Appendix E

Comparison to Waypoint 2050

184

3

NLR-CR-2020-510 | February 2021

1

Introduction

Since the foundation of the first airlines over a century ago, aviation has developed to become a crucial element of
modern society. Connecting people, businesses and families around the globe, it has contributed to global economic
wealth development and increased our understanding and appreciation for different continents and cultures. With
that understanding of the world we live in, however, also comes increased knowledge of how our consumption and
travel patterns affect our planet. Over the past few years, sustainability has grown to become a top priority for
governments, consumers and industry. Various sectors – such as energy generation, industry and automotive – are
making progress in reducing the environmental impact of both their own activities and their products and services.
Maintaining the benefits that aviation brings to the global community, the European air transport industry also has
committed to play its part in that sustainability transition (Aviation Round Table, 2020). Notwithstanding the
achievements realised in terms of reducing fuel consumption per passenger kilometre, reduced circa 45% between
1968 to 2014 (Kharina & Rutherford, 2015) and 80% since the introduction of the first jet aircraft (EUROCONTROL,
2019c), absolute CO2 emissions have continued to increase. Before the impact of COVID-19 drastically reduced air
travel, aviation was responsible for 2 to 3% of global anthropogenic CO2 emissions and it is expected that these
numbers are to rise tenfold if aviation does not change its course while other industries do (Cames, Graichen,
Siemons, & Cook, 2015; Pidcock & Yeo, 2016; Becken & Pant, 2020). Social phenomena such as flygskam (flight shame)
and wider questions about future mobility are also affecting the industry’s licence to operate and grow (Topham,
2019; BBC, 2019; EUROCONTROL, 2019c).
This report, initiated by European representatives of (regional) airlines, airports, aerospace manufacturers, and air
navigation service providers and prepared by Royal Netherlands Aerospace Centre and SEO Amsterdam Economics,
identifies pathways to substantially reduce aviation carbon emissions. Potential carbon emission reductions from
future aircraft and engine technology, improvements in air traffic management and aircraft operations, the use of
sustainable aviation fuels and economic measures are first identified. These are subsequently modelled and assessed
against a hypothetical reference scenario that includes activity growth as well as the recent COVID-19 impact in order
to identify the extent to which these efforts can help realise European and international goals. The report focusses on
areas where the initiators and governments (both European and Member States) play a leading role in developments.
Additional initiatives besides the ones included in this study are welcomed and other actors are encouraged to take
responsibility where they can. This concerns both the CO2 emissions considered in this study as well as other
environmental or sustainability impacts.
In addition to quantifying potential improvements, policies and actions are defined to help make the possibilities
identified a reality. As such, this report – as well as the five initiating parties – hope to inspire all stakeholders in the
aviation industry and governments to take action now to make Europe’s climate ambitions for 2030 and 2050 a
reality.
The remainder of this chapter is structured as follows. Section 1.1 presents the context of the study, providing among
other an overview of current environmental goals, the climate effect of aviation and past efforts to reduce this. Next,
Section 1.2 goes into detail on the approach taken and Sections 1.3 and 1.4 formally define the objective and scope of
the project. Last, Section 1.5 details the structure of the report and thereby serves as a reading guide to the remainder
of the report.

4

NLR-CR-2020-510 | February 2021

1.1

Context

This section discusses the context of this study in greater detail. Although some aspects have been highlighted in the
introductory paragraphs of this chapter, a thorough overview and understanding of this context is deemed critical for
the correct appreciation of the results presented in this report.
Section 1.1.1 first discusses the various international environmental goals and related policy developments. Next, the
costs and benefits of the aviation industry are put into perspective in Section 1.1.2. Then, relevant characteristics of
industry itself are discussed in Section 1.1.3. Last, Section 1.1.4 treats the impact of climate change on society and the
aviation sector in particular.

1.1.1

Climate and CO2 emissions reduction goals and policy
developments

According to the latest reports of the Intergovernmental Panel on Climate Change (IPCC), the rise of global average
temperatures – when compared to pre-industrial levels – has to be limited to 1.5° to 2° Celsius to prevent doing
further and irreversible harm to our planet (NASA, 2020; Sustainable Aviation, 2020a; Lamontagne, Reed, Marangoni,
Keller, & Garner, 2019; Becken & Pant, 2020). During the 21st Conference of the Parties of the United Nations
Framework Convention on Climate Change (UNFCCC) in Paris in 2015, the world set a climate goal based on these
insights: “Holding the increase in the global average temperature to well below 2°C above pre-industrial levels and to
pursue efforts to limit the temperature increase to 1.5°C above pre-industrial levels, recognising that this would
significantly reduce the risks and impacts of climate change” (UNFCC, 2015, Art. 2). The IPCC has determined that in
order to meet the 1.5° or 2° scenarios, net zero carbon must be achieved by 2050 or 2070 3, respectively (IPCC, 2018b).
DEFINITION: NET ZERO CARBON AND CARBON NEUTRALITY
The IPCC (2018a) states that “[n]et zero carbon dioxide (CO2) emissions are achieved when anthropogenic CO2 emissions
are balanced globally by anthropogenic CO2 removals over a specified period”. It does not limit CO2 removal to either
natural (e.g. afforestation efforts) or artificial sinks (e.g. dedicated technologies, such as Direct Air Capture and Storage).
Carbon reductions through avoided emission projects in other sectors, defined as activities that “result in a lower emissions
scenario compared to a hypothetical business-as-usual scenario as a result of a specific intervention” (Carrillo Pineda &
Faria, 2019), are not compatible with the IPCC definition.
Carbon neutrality is used by the IPCC as synonym for net zero CO2 emission. There are also organisations that use a broader
definition of carbon neutrality, in which it includes avoided emission projects. As these are excluded from this analysis, the
text refers to ‘net zero carbon’ or ‘net zero CO2’.

More recently, the European Commission announced its European Green Deal aiming to become a climate neutral
(requiring net zero greenhouse gas emissions) continent by 2050 and presented its proposal for a European Climate
Law (EC, 2019i; EC, 2020d). With that, the Commission subscribes to the 1.5° C IPCC scenario. “All relevant climaterelated policy instruments” are to be reviewed and possibly revised by June 2021 (EC, 2019i, pp. 4-5). Possible changes
include reductions in the amount of free allowances for aviation in the EU Emissions Trading Scheme (EU-ETS) and
updates to both to the Renewable Energy Directive 4 (Simon, 2019) and the Energy Taxation Directive 5. The
Commission has furthermore noted that “the price of transport must reflect the impact it has on the environment”
3 “In model pathways with no or limited overshoot of 1.5°C, global net anthropogenic CO emissions decline by about 45% from 2010 levels by 2030 (40-60%
2
interquartile range), reaching net zero around 2050 (2045-2055 interquartile range). For limiting global warming to below 2°C CO2 emissions are projected to decline by
about 25% by 2030 in most pathways (10-30% interquartile range) and reach net zero around 2070 (2065-2080 interquartile range). Non-CO2 emissions in pathways that
limit global warming to 1.5°C show deep reductions that are similar to those in pathways limiting warming to 2°C. (high confidence)” (IPCC, 2018b)
4 Council Directive 2018/2001/EU, an update to the original renewable energy directive, 2009/28/EC.
5 Council Directive 2003/96/EC, recently reviewed by the European Commission (2019e). The European Commission has communicated to “look closely at the current tax
exemptions including for aviation and maritime fuels” (EC, 2019i, p. 10).

5

NLR-CR-2020-510 | February 2021

and that “fossil-fuel subsidies should end” (EC, 2019i, p. 10). For 2030, the European Commission proposed a
reduction of greenhouse gas emissions of 55% with respect to 1990 (Simon, 2020a) whereas the European Parliament
voted for a higher reduction of 60% (Simon, 2020b).
Specific to the aviation sector, various industry and governmental organisations have also formulated objectives
(Peerlings, 2020). The International Civil Aviation Organisation (ICAO) set goals for annual fuel efficiency
improvements (2% p.a. through 2050) and carbon-neutral growth (CNG) from 2020 (ICAO, 2016). The newly-launched
Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA), which starts its pilot phase in 2021, was
designed to achieve that latter goal. That target is also supported by the International Air Transport Association (IATA)
and Air Transport Action Group (ATAG), alongside the goal of reducing net emissions to 50% of 2005-levels by 2050
(IATA, 2020d; ATAG, 2020a). Going beyond that, the oneworld airline alliance committed to net zero carbon by 2050
(oneworld, 2020). At a European level, different participants in the aviation chain such as ACI EUROPE, the
International Airlines Group (IAG) and Sustainable Aviation UK have committed to reaching net zero CO2 emissions by
2050 (ACI Europe, 2019; IAG, 2019; Mace, 2019; Sustainable Aviation, 2020a) 6. Air France and British Airways offset
carbon emissions of all domestic flights since January 2020 and easyJet has done so for all flights from November 19th,
2019 (Air France, 2019; British Airways, 2019; easyJet, 2019). Finally, ICAO (2019b) has prioritised the development of
“a long-term global aspirational goal for international [civil] aviation CO2 emissions reduction” in October 2019,
targeting its definition in 2022 (ICAO, n.d.).
EU-ETS AND CORSIA
The EU-ETS and CORSIA are two important elements of the existing environmental aviation policy context in Europe.
Although both are economic measures, there are important differences between the two. The EU-ETS is a so-called cap and
trade system. Sectors to which the EU-ETS applies can emit no more emissions than allowed by the cap and need emission
allowances matching their emissions. Businesses get part of their allowances for free and can buy additional allowances on
the market. If there are no more allowances, no more greenhouse gases can be emitted. As the cap is progressively
reduced, the total amount of CO2 emissions is reduced as well.
CORSIA, on the other hand, is an offsetting scheme. This means that there is no cap on the total amount of CO2 emitted into
the atmosphere. Rather, the scheme requires participants (airlines) to offset the amount of CO2 they emit on top of a predetermined baseline value. Offsetting regularly takes the form of planting trees (such that an equivalent amount of CO2 is
captured and stored in biomass) or financing CO2 reductions in other industries. This way, the underlying market
mechanism aims to abate CO2 emissions in the most cost-effective way.
Additional details on EU-ETS and CORSIA are provided in Sections 6.3.1 and 6.3.2, respectively. The two mechanisms are
compared side-by-side in Table 34 in Section 6.3.3.

It is important to note that the targets just discussed concern emissions reductions expressed in absolute terms,
whereas goals in the past often used to discuss emissions reduction per passenger or per passenger-kilometre. A wellknown example are the goals set by a high level group commissioned by the European Commission in Flightpath 2050
and the related Strategic Research and Innovation Agenda submitted by the Advisory Council for Aviation Research
and Innovation in Europe. These aim to reduce CO2 and NOX emissions per revenue passenger kilometre by 75% and
90% respectively, and decrease perceived noise levels by 65%, all with respect to aircraft from the year 2000 (EC,
2011). Furthermore, these goals have steered the various Clean Sky programmes (Clean Sky, n.d.). The challenge with
such relative efficiency metrics is that the absolute emissions levels could continue to increase even if efficiency
continued to improve.

6 The UK commitments likely follow from the advice by the UK Committee on Climate Change (2019) to its government to include international aviation and shipping in

its (binding) national net zero 2050 targets

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NLR-CR-2020-510 | February 2021

1.1.2

Aviation as part of society

The European Parliament notes the aviation sector supports around 5 million jobs and contributes € 110 billion to the
European GDP per year (Erbach, 2018). If secondary – indirect, induced and catalytic – effects are included, these
numbers rise to 12 million jobs and a € 700 billion plus GDP contribution (ATAG, 2019). Similarly, the recent Aviation
Round Table (2020) notes almost 10 million jobs and € 672 billion in economic activity. Given EU totals of 227 million
jobs and € 17 trillion total GDP, aviation is estimated to be directly responsible for 1 in every 100 EU jobs
(approximately 5 per 100 with secondary effects) and slightly more than 1% of the EU GDP (rising to over 4% with
secondary effects) (IMF, 2019b; eurostat, 2019; Aviation Round Table, 2020). Without aviation, leisure and business
travel would not be the same as we know it today, and modern conveniences such as next-day global deliveries would
be limited. Put differently: through the connectivity it provides, aviation has grown to become an unmistakable
component of modern society and people’s need for mobility.
Benefits, however, do not come without costs. Limiting the present discussion to the scope of this report – CO2
emissions as part of broader environmental impact – pre-COVID worldwide commercial aviation was computed to be
responsible for between 2 and 3% of anthropogenic CO2 emissions (ATAG, 2018; EEA, EASA & EUROCONTROL, 2019;
Erbach, 2018). The most detailed computation states 2.4% (Graver, Zhang, & Rutherford, 2019), equal to 918 million
tonnes in 2019 (Graver, Rutherford, & Zheng, 2020). To that figure, passenger travel contributed the most at 85%,
with freight carriage (including belly cargo) causing the remaining 15% (Graver, Rutherford, & Zheng, 2020). In Europe,
departing flights in 2016 were responsible for 171 million tonnes of CO2 – approximately one-fifth of global aviation
emissions. European commercial aviation emissions have almost doubled between 1990 and 2016 (EEA, EASA &
EUROCONTROL, 2019) and correspond to 4.3 to 5.6% of total EU CO2 emissions 7 and 3.6 to 3.9% of total EU
greenhouse gas emissions 8 in 2016 (UNFCCC, n.d.; EEA, 2019). Taking other greenhouse gases and global warming
effects into account, the contribution from global aviation is approximated to be two to three times as large as CO2
alone (Grewe, et al., 2017; Grewe, 2019; Lee, 2018; Lee D. , et al., 2020; Lee D. , et al., 2009; EASA, 2020).
CO2 AND NON-CO2 INFLUENCES ON GLOBAL WARMING
In addition to CO2, there are other effects that have a positive or negative influence on global warming. This influence is
measured as radiative forcing (RF), expressed in Watts (of energy) per square metre (of the Earth’s surface area). Whereas
the CO2 contribution to RF is “well-understood” (Lee, 2018, p. 2), substantial uncertainty exists about other sources – such
as contrail formation and induced cirrus cloudiness.
Following the recent publication of EASA’s updated analysis of the non-CO2 climate impacts of aviation (EASA, 2020), the
European Commission commented that “unlike CO2 impacts, which directly correlate to the amount of fuel burned, the
complexity of measuring non-CO2 climate impacts – and the uncertainty regarding trade-offs between the various impacts –
makes targeted policy development in this area more challenging” (EC, 2020j). As further discussed in Section 1.4.2, nonCO2 effects are not included in the present study.

1.1.3

Workings of the aviation industry

What started out with linen and wood in a grass field over a century ago has evolved into a truly global industry, built
up of an intricate and complex network of stakeholders, suppliers, integrators, operators and authorities that
contribute to air transport. Despite the tremendous growth that the aviation industry has seen, profit margins are
limited and risks are substantial (Doganis, 2010).

7 3,941,273 kilotonnes without land use, land use change and forestry (LULUFC); 3,185,038 with LULUFC (UNFCCC, n.d.).

8 Total EU greenhouse gas emissions in 2016 were 4,441 million tonnes (EEA, 2019), yielding a share of 171 / 4441 = 3.85%. The European Aviation Environmental Report
states 3.6% (EEA, EASA & EUROCONTROL, 2019).

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Innovation is a key driver for the aviation industry. The sector generally takes a long-term perspective. Aircraft are
designed to have a lifespan of 20 to 30 years. It can take 15 years to develop from concept to production. This is
partially explained by the focus on safety and associated stringent certification requirements. Programmes normally
break even only after ten to twenty years of production (Sadraey, 2013; Buxton, Farr, & Maccarthy, 2006; Johansson,
2014) and manufacturers are often said to bet their entire company’s worth when committing to a new aircraft
(Raymer, 2002). Especially in times of major change – such as the transitions from wood to metal aircraft, or from
propeller-driven types to jets – not all manufacturers manage to survive, either because they committed to the new
technology too early, committed to the new technology not early enough, or committed to the wrong technology.
Manufacturers often develop families of aircraft, with each type offering different capacity and range. Similarly, new
concepts are regularly based on designs already in production. Due to the complexity of the product, intermediate
upgrades are difficult: a new engine usually requires changes to the wing, which in turn affects other parts of the
aircraft. Nevertheless, continuous and incremental developments are incorporated over the production lifetime of
aircraft.
These characteristics have a clear impact on the capability of the airlines together to take up novel aircraft in their
fleets. Long financial lifetimes make it very costly to replace existing technology frequently and airlines are dependent
on what new products are offered in the market. Another difficulty for airlines is that network and fleet planning have
a much longer time horizon than the day-to-day operations. Seemingly good decisions (buying an expensive but fuel
efficient new aircraft) might end up very different if circumstances change (decrease in oil price). Given limited profits,
an intense focus on operating costs is unsurprising.
Infrastructure planning challenges that airports face see a similarly long time horizon. Alike as well are the significant
investment costs related to infrastructure, comparable to what is observed in aircraft development. This is true for
terminal expansions or changes, but even more so for the addition of runways or new airport development. When
airports are located close to residential areas – as is quite common in Europe – land may not be readily available and
surrounding communities may be concerned about the impact on their local environment or on global warming, as
the London Heathrow expansion case shows (Morgan, 2020). Notwithstanding the validity of these interests, preCOVID aviation growth projections show the “capacity crunch” currently faced by various airports throughout Europe
is unlikely to lessen (EUROCONTROL, 2018b) – causing increasing delays and preventing more and more people from
travelling by air.

1.1.4

Effects of climate change on society and aviation

According to the UN IPCC there is scientific consensus that the climate is changing. As a result, the chance of extreme
weather events increases. Such events have a significant human cost, reduce economic productivity and increase the
costs associated with damage prevention or restoration.
Over the past 30 years damages resulting from climate-related weather events increased by a factor 20 (Swiss Re,
2018). In 2017 the weather-related damages amounted to $ 330 billion in 2017, making it the most costly year on
record. Around two-thirds of the damages were caused by hurricanes in the North Atlantic (Munich Re, 2018). In
addition, climate-related weather events are a main cause of humanitarian crises, such as food shortages. In 2018,
around 2 million people were displaced as a result of climate related weather events such as drought, floods and
storms (WMO, 2019). In 2017, between 8,000 and 10,000 people lost their lives due to extreme weather events (Swiss
Re, 2018; Munich Re, 2018), with heat being the most deadly. Adapting to climate change is also costly, especially for

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small island economies and low-income countries. Required investments for developing countries are estimated at
$ 140 – 300 billion in 2030 and $ 280 – 500 billion in 2050 (IMF, 2019a).
Weather related damages in Europe amounted to $ 24 billion in 2017 (Swiss Re, 2018). Going forward, the EEA
expects that the damages will be largest in Southern Europe (EEA, 2017). Extreme weather events may also enhance
the speed in which the climate changes. The emissions from wildfires in Italy and Portugal in 2017 for instance were
among the highest ever recorded (EC, 2019g). By the year 2100, two-thirds of the European population could be
affected by weather-related disasters, compared with 5% in 2018 (EC, 2018b).
The aviation sector is affected by climate change through changes in temperatures, precipitation, wind and storm
patterns and sea-levels.
Temperature
The years 2015 – 2018 were the four warmest on record (WMO, 2019). Europe experienced extreme heatwaves over
this period. Human-induced warming had already reached 1° C above pre-industrial levels (1850-1900) and is
increasing at approximately 0.2° C per decade (EC, 2018b). Temperatures in Europe are expected to rise faster than
the global average. In winter, warming is estimated to be strongest in north-eastern Europe and Scandinavia. In
summer warming is expected to be strongest in southern Europe. How does warming affect the aviation sector?
Warmer air is less dense which reduces the lift of aircraft. This means that the operational capacity of runways is
reduced. Airlines may experience runway length issues and could be forced to reschedule heavier aircraft to cooler
times of day, reduce payloads or depart with a higher thrust setting causing more noise and emissions (ICAO, 2018a).
Furthermore, airports may need to invest more in air conditioning systems. Extreme heat also causes damage to
runways and taxiways (EUROCONTROL, 2018a). In regions where temperatures and drought increase, there is a
heightened risk of desertification and sand storms, which may disrupt airport operations and damage aircraft. In
February 2020, sand storms in the Canary Islands for instance led to the closing of most of its airports. Extreme cold
on the other hand, may lead to the freezing of airport equipment. Furthermore, there will be a larger need for aircraft
de-icing, with anticipated associated increases in emissions. This reduces the efficiency of airport operations and may
lead to delays and cancellations (ICAO, 2018a). Temperature changes may also lead to changes in demand patterns
(EEA, 2017), not only in terms of destination (region) but also in terms of seasonality. Demand for destinations which
face extreme heat and water scarcity may decline. The same holds for winter sport destinations that are affected by a
reduction in snowfall (ICAO, 2018a). Demand changes not only affect airports and airlines but also the ANSPs.
Precipitation and humidity
Expectations with respect to precipitation (rain and snow) differ regionally. In Europe, wet regions are likely to get
wetter (Northern and Eastern parts) especially during winter, while dry regions (South of Europe) are getting dryer
especially in summer (EEA, 2017). Heavy precipitation reduces the efficiency of airport operations. Snow-clearance for
instance may cause delays and cancellations. In extreme cases, drainage systems may be inadequate causing damage
to airport infrastructure and assets and disrupting operations for a longer period of time. Less rain and longer periods
of drought calls for active water management (EUROCONTROL, 2018a). In some regions there may be an increase in
the level of humidity which increases the chance of morning fog (ICAO, 2018a). At airports without a modern ILS, this
also leads to disruptions.
Wind patterns
Temperature differences lead to changes in wind directions and speeds. The northern parts of central and western
Europe may see an increase in extreme wind speeds, whereas the opposite is true for southern Europe. Changes to
the prevailing wind directions affect runway use. Strong crosswinds reduce airport capacity and disrupt operations
when winds are too heavy to take off or land. Air turbulence may also increase which can cause re-routings, less
comfortable flights and heightened maintenance costs (EUROCONTROL, 2018a).
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Storm patterns
In some regions storm frequency and intensity may increase, whereas in others they may decrease (ICAO, 2018a).
Northern, north-western and central Europe may see an increase in severe autumn and winter storms. Also there
could be an increase in the number of cyclones in central Europe. In the Mediterranean the number of cyclones may
decrease in number, but increase in intensity. Heavy storms reduce airport and airspace capacity, causing delays,
cancellations, re-routings and additional fuel burn. Furthermore, storms may damage infrastructure and equipment.
Tropical storm Jebi, for instance, led to the inundation of Kansai airport in 2018, leaving thousands of passengers
stranded (WMO, 2019). With more heavy storms, the risk of lightning strikes also increases. Although aircraft are
designed to withstand lightning, it may cause damage to aircraft (EUROCONTROL, 2018a; ICAO, 2018a).
Sea-level rise
Rising temperatures also lead to a rise in sea-levels due to the melting of glaciers and ice. Over the 1993-2018 period,
the average sea-level rose by 3.15 mm per year. The 2018 sea-level was the highest ever recorded (WMO, 2019).
There is scientific consensus that sea-level rise will continue and possibly at an increasing pace (ICAO, 2018a). A
temperature increase of 1.5 ° to 2 °C, for instance, could trigger an irreversible loss of the Greenland ice sheet which
could lead to 7 meters of sea level rise, directly affecting coastal areas and low-lying lands and islands in Europe (EC,
2018b). Airports are sometimes located near large bodies of water away from built areas, which makes them
vulnerable to sea-level rise. Research indicates that a one metre rise in sea-level is expected to increase the risk of
inundation at 96 European airports when no further protectionist measures (such as building higher levees) are taken
(EUROCONTROL, 2018a). Airport infrastructure may need to be adapted or relocated which comes at a significant cost
(ICAO, 2018a).
To sum it up, extreme weather events reduce the efficiency of airport and airline operations, which may lead to delays
and flight cancellations. Disruptions in one region may have knock-on effects in other regions. Reduced operational
efficiency leads to additional costs. Damage to infrastructure and equipment as well as additional maintenance further
inflates costs.
A survey among European aviation stakeholders 9 showed a quarter of them is already experiencing the impacts of
climate change (EUROCONTROL, 2018a). On a global scale 74 percent of the stakeholders is experiencing the impacts
of climate change, as indicated by a survey 10 of the ICAO Committee on Aviation Environmental Protection (CAEP)
(ICAO, 2018a). Both surveys indicate that most stakeholders expect their business to be impacted by climate change in
the future. The most severe impacts are expected from increasing temperatures, changes in wind conditions and
increased precipitation. Sea-level rise was indicated as a potential risk by fewer respondents, probably because the
issue is more localised (ICAO, 2018a; EUROCONTROL, 2018a).
To limit the impacts of climate change, aviation stakeholders can implement adaptation measures. This requires a risk
analysis and a corresponding adaptation strategy (ACI World, 2020a). The survey among European stakeholders
showed that 52 percent have already started implement adaptation and resilience plans (EUROCONTROL, 2018a). On
a global scale the percentage is somewhat lower: 30 percent (ICAO, 2018a).
In addition to mitigation, the aviation sector also needs to take action to reduce its climate impact. Limiting the
climate impact will reduce the costs of adaptation measures in the future.

9 In total 93 responses were received including airlines, airports, ANSPs, civil aviation authorities and manufacturers across Europe. The authors indicate that there may
be a degree of self-selection bias with organizations that have a larger interest in the issue or are already taking measures being more likely to take part in the survey.
10 In total 88 responses were received including airlines, airports, ANSPs and member states.

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1.2

Approach

European aviation industry trade organisations ACI EUROPE, Airlines for Europe (A4E), ASD Europe, European Regions
Airline Association (ERA) and CANSO initiated this study and jointly identified the need to develop a roadmap for 2020
up to 2050 listing current and proposed future policies and actions that can contribute to meeting international
climate goals as set out in Section 1.1.
Rather than choosing either a top-down or bottom-up methodology, the current report fuses elements of the two in
order to combine the strengths of both. In this hybrid approach, an ambition level was determined that is both
consistent with realistic expectations of future developments in the areas of aircraft and engine technologies, air
traffic management and aircraft operations, sustainable aviation fuel, economic measures, as well as with
(international) climate and sustainability policymaking. These expectations were based on an extensive literature
review to which iteratively input was given by industry and research professionals – the full list of which is included in
Appendix B. Using this approach, this report presents a possible pathway towards the decarbonisation of international
aviation in Europe.
Notwithstanding the rigour with which this study was conducted, it is emphasised here that there are uncertainties to
this document – as holds for any work aiming to predict a thirty-year future. Conclusions and recommendations will
have to be updated as time progresses. Some developments might not bring the benefits anticipated from them,
whereas others – possibly even breakthroughs entirely unforeseen today – might surpass expectations. Similarly,
while some policies and actions now focus on developing innovative technologies and associated measures, others
will need to follow that support the delivery of their benefits to all stakeholders. It is thereby emphasised that this
report presents a pathway towards decarbonising European aviation but does not necessarily present the only way.
Uncertainty, however, can also lead to inaction – inaction that no-one can afford. As such, this report is presented as a
well-supported foundation for tackling the challenge of decarbonising aviation and guiding government and industry
action in the crucial following years to come.

1.3

Objective

This report has the objective to identify opportunities to achieve net zero CO2 emissions from all flights within and
departing from the EU 11 by 2050. Following the definition of ‘net zero’ carbon by the IPCC (2018a), this means that all
possibly remaining carbon emissions will have to be removed from the atmosphere through negative emissions,
achieved through natural carbon sinks (e.g. forests) or dedicated technologies (carbon capture and storage).
Destination 2050 considers improvements in aircraft and engine technology; improvements in ATM and aircraft
operations; sustainable aviation fuels; and economic measures. Most significantly, solutions of this kind will allow
retaining the social and economic benefits of aviation, while delivering substantial improvements in the level of CO2
emissions. The report does not merely list possible improvements, but also pays attention to the way these
improvements can be realised. This way, this study does not aim to be just an overview of opportunities, but a
document that initiates action from all parties involved.

11 The exact geographical scope of this study is defined in Section 1.4.1.

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This report is targeted at various audiences. First: industry professionals, which are the ones to commit to researching,
developing and implementing the innovations that are required. Second: European and national policy makers, which
play an essential role in setting the conditions that make innovation and market introduction possible, and ensure that
aviation can continue to benefit Europe’s economy and society. Last, fitting with the scale of the effort ahead and the
societal expectations concerning this topic, this report also hopes to inform a wider array of opinion leaders interested
in the decarbonisation of European aviation. Section 1.5 at the end of this chapter highlights the most relevant
sections of this report for each of these audiences.

1.4

Scope

This study is limited in scope in terms of geography (Section 1.4.1), emissions and emissions accounting (Sections 1.4.2
and 1.4.3) and flights considered (Section 1.4.4). Last, Section 1.4.5 defines and shortly explains the four areas in
which improvements are sought in the context of this study.

1.4.1

Geographical scope

In geographical scope, the study is limited to commercial flights departing from airports within the European Union
(EU), the United Kingdom (UK), and the European Free Trade Association (EFTA), consisting of Iceland, Liechtenstein,
Norway and Switzerland. This is visualised in Figure 1. For brevity and legibility reasons, EU+ is used to refer to EU27 +
UK + EFTA, unless explicitly stated otherwise.

Figure 1: Geographical scope: commercial flights departing from airports within the European Union (EU), the United
Kingdom (UK), and the European Free Trade Association (EFTA), consisting of Iceland, Norway, Switzerland and
Liechtenstein.
Norway and Iceland cooperate with current EU targets in aiming to reduce GHG emissions in 2030 by at least 40%
compared to 1990 levels. Both countries take part in the EU ETS since 2008 and as of 2021 will implement Effort
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Sharing regulation and LULUCF regulation. In 2017, Switzerland and the EU agreed to link their emissions trading
systems. The agreement entered into force on January 1st, 2020. Switzerland keeps a separate system, but its scope is
similar to the EU ETS and also includes aviation. The linking has resulted in the mutual recognition of EU and Swiss
emission allowances (EC, 2019g).

1.4.2

Emissions

This study is limited to CO2 emissions. Although, as described in Section 1.1, the impact of aviation on climate change
is wider, these effects are less well understood.
Although other emissions and climate effects, such as NOX, noise and contrail formation, are not modelled, some
attention is paid to these in a qualitative sense – in case impacts are expected to go hand in hand with the reduction
of CO2 emissions, or imply trade-offs. Carbon dioxide emissions related to surface airport access (both ingress and
egress), aircraft production and maintenance, and energy supply and heating of (airport) buildings are not taken into
account in this report, either due to resource limitations or data availability, or because these types of emissions are
addressed in other programmes 12.

1.4.3

Emissions accounting

To assess aviation’s carbon emissions in the EU+, all emissions from a flight departing from country of origin A towards
country of destination B are attributed to country A. This aligns with the UNFCCC reporting framework and the IPCC
Guidelines for National Greenhouse Gas Inventories (IPCC, 2006). The EU greenhouse gas emission inventories assign
emissions from international aviation to countries where the associated fuel is bunkered, and as such also only
incorporate emissions from departing flights (eurostat, 2019). These data are also submitted to the UNFCCC, and
represent the official data for international and EU climate policies. The global characteristic of the aviation industry is
also reflected in the 2006 IPCC Guidelines for National Greenhouse Gas Inventories (IPCC, 2006), which state that
“emissions from fuel use on […] aircraft engaged in international transport should not be included in national totals.
To ensure global completeness, these emissions should be reported separately.”
Arriving flights from outside the EU+ are excluded from the scope in order to respect international accounting
standards, and to avoid double counting of aviation emissions. Nevertheless, various parties in the air transport
system are making an effort to also reduce emissions on inbound intercontinental flights. The accounting rules applied
for this study do not undermine the importance of such efforts.

1.4.4

Flights

The analyses in this study primarily focus on scheduled passenger flights on subsonic aircraft. For these flights, impacts
of sustainability measures on emissions, passenger demand and number of flights offered are taken into account. In

12 For example, in 2019, ACI EUROPE has celebrated the 10 year anniversary of its Airport Carbon Accreditation programme, which focuses on reductions of emissions of
airports under direct control of airport operators. At the higher levels of the programme, it also requires monitoring of airline and other third party emissions, as well as
associated stakeholder engagement.

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addition, emissions from scheduled cargo operations are considered. However, estimation of demand impacts for air
freight – either carried in passenger or all-cargo aircraft – are out of scope.
Non-scheduled passenger and cargo operations are out of scope for the quantitative assessments. This includes all
charter flights, general and business aviation, cargo flights carried out by integrators (such as UPS, DHL and FedEx),
and all other forms of air traffic not included in OAG Schedules Analyser (Official Airline Guide, 2019) 13.
In addition, the study is limited to operational emissions generated by commercial aircraft. Although this includes both
air and ground components (such as taxiing and the use of auxiliary power units for ground power), emissions related
to airport facility operation and aircraft manufacturing or maintenance are (as substantiated in Section 1.4.2) not
considered. Finally, modal shifts (to e.g. high-speed rail or future developments such as Hyperloop) are not part of the
study, although the importance of air-rail complementarity is acknowledged.

1.4.5

Improvements

As indicated earlier in this introduction, this report looks at the possible reductions in CO2 emissions that can be
delivered by four groups – or pillars – of improvements:
•

improvements in aircraft and engine technology, including alternative energy sources, which are materialised
through replacement of current aircraft by new types;

•

improvements in air traffic management (ATM) and aircraft operations, which can be implemented without
replacement of current aircraft;

•

drop-in sustainable aviation fuels; and

•

economic measures.

These pillars are slightly different and more extensive than the ones adhered to by e.g. IATA, being “technology”,
“operations”, “infrastructure” and a “global market-based measure” (IATA, 2020b). Specifically, sustainable aviation
fuels 14 are taken separately from other technology developments. Operations and infrastructure improvements, the
latter of which IATA describes as the modernisation of air traffic management, however, are grouped in the present
report. The scope for economic measures is expanded beyond global market-based measures. Figure 2 provides a
graphical overview of the different groupings.
Recent industry publications, such as ATAG’s Waypoint 2050 (ATAG, 2020b), adhere to a structure more closely
matching Destination 2050: taking (drop-in) sustainable aviation fuels separately from technology and grouping
operations and infrastructure together.

13 General and business aviation is estimated to account for about 2% of total aviation CO worldwide (ICCT, 2019). Integrator and charter flights are likely to account
2
only for a small share of aviation emissions.
14 Which is an appropriately more narrow scope than the “low-carbon fuels” mentioned by IATA (2020b).

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NLR-CR-2020-510 | February 2021

IATA

aircraft technology
engine technology

technology

sustainable aviation fuels

Destination 2050
aircraft and engine technology
(drop-in) sustainable aviation fuels

aircraft operations

operations

air traffic management

infrastructure

ATM and aircraft operations

ground operations

global market-based measure

global market-based
other economic measures

economic measures

Figure 2: Comparison of groups ('pillars') of improvements between IATA (2020b) and Destination 2050

1.5

Reading guide

The main body of this report starts with presenting the reference scenario used as a basis for the analyses presented
in this report. This is the subject of Chapter 2.
Then, Chapters 3, 4, 5 and 6 each discuss one of the four groups of measures considered in the study:
• improvements in aircraft and engine technology;
• improvement in ATM and aircraft operations;
• sustainable aviation fuels; and
• economic measures.
Each of these chapters is structured in a similar fashion. Following an introduction, the main content of each chapter is
formed by a number of sections that detail possible improvements and measures and estimate their impact. Then,
drivers and barriers – or: challenges – that influence the effectiveness and adoption speed of the measures are
treated. As political and societal pressures to reduce CO2 emissions are drivers for all measures, these are not
repeated in the specific chapters. The last section of each of the Chapters 3, 4, 5 and 6 discusses policies and actions
that are needed to realise the benefits discussed. Often, these policies and actions are specifically intended to
strengthen drivers and mitigate or circumvent barriers.
Following the chapters related to the four groups of measures, Chapter 7 discusses a number of possible changes to
the air transport system at large, thereby spanning multiple domains. Next, Chapter 8 discusses the impact modelling
of the various potential improvements. Chapter 9 presents the main findings of this study and presents the path
forward to Destination 2050. This includes a comparison with current industry and governmental targets and lists a
number of policies and actions that are relevant to all measures considered in this study. A list of references and
supplementary appendices are included at the end of the report.
In addition to Chapter 9, which presents the key results, and Chapter 8, which summarises input values used for the
impact modelling, readers interested in the details of the measures and the methodology using which their impacts
are assessed are recommended to focus their attention on Chapters 3, 4, 5 and 6. Specific sections in each these
chapters present key actions and policies, of which industry professionals and policymakers should take note. Last,
Section 1.1 and the parts of Chapters 3 through 6 that discuss drivers and barriers are suggested to audiences
interested in deepening their understanding of the system-level challenges of decarbonising European aviation.
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2

Reference scenario
A hypothetical ‘no-action’ scenario is used as a reference for evaluating the impacts of the
sustainability scenario developed in this study. The reference scenario is based on EUROCONTROL’s
Challenges of Growth forecast. The impact of COVID-19 is taken into account by assuming that
traffic gradually recovers to pre-crisis levels by 2024. Growth factors per flight region are
subsequently applied to schedule data from OAG. Emissions are determined at flight level using a
combination of EUROCONTROL’s Base of Aircraft Data and the ICAO Emissions Databank. Load
factors and aircraft size are assumed to increase by 0.3% per year.
In the reference scenario traffic increases to 11.3 million departing flights and 1.4 billion passengers
in 2050. CO2 emissions in 2050 are estimated at 320 Mt. Compared to 2018 levels, this comes down
to increases of 55% (flights), 87% (passengers) and 67% (CO2 emissions).

2.1

Introduction

Destination 2050 seeks to identify different sustainability measures that could be implemented in the aviation sector,
and assess the impacts of these measures against a reference scenario. Estimated impacts are expressed in terms of (i)
passengers, (ii) aircraft movements, and (iii) CO2 emissions. For the horizon years 2030 and 2050, Chapter 8 presents
the reduction of CO2 emissions resulting from the proposed sustainability measures, compared against the reference
scenario presented in this chapter.
The reference scenario is a hypothetical ‘no-action’ growth scenario with regards to fuel efficiency improvements,
operational improvements and sustainable aviation fuels. This means that CO2 emissions in the reference scenario are
estimated based on the assumption that aircraft deployed until 2050 have the same fuel efficiency as in the base year,
2018. It should be noted that such a scenario is purely hypothetical. Even without additional sustainability measures,
fuel efficiency is likely to improve due to already implemented climate policies and a continued focus of airlines to
reduce fuel consumption. However, distinguishing between improvements in a ‘business as usual’ scenario compared
to an ambitious technology scenario requires additional assumptions on what is ‘business as usual’. Thus, using a
hypothetical ‘no-action’ scenario is the best way to provide a full picture of all the sustainability measures taken.
This chapter is structured as follows. Section 2.1 describes the assumptions made in the reference scenario regarding
the development of air traffic, load factors, aircraft size and fuel efficiency. Section 2.3 presents the reference scenario
in terms of passengers, aircraft movements and carbon emissions.

2.2

Assumptions

This section lists assumptions concerning traffic scenario, load factor development and aircraft size growth and
environmental regulation.

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2.2.1

Traffic forecast

An individual route level forecast for 2030 and 2050 is made, allowing estimation of the impact of various
sustainability measures at a detailed level. The worldwide airline schedule of 2018 forms the basis for the supply-side
forecast. This schedule is obtained from OAG Schedules Analyser, which provides information on scheduled passenger
flights by airline, route and aircraft type deployed. In addition, the source provides information on the elapsed time
between scheduled departure and arrival 15, which is used to estimate fuel consumption and emissions for each flight
(see box). On the demand side, origin-destination (O&D) 2018 passenger booking data from OAG Traffic Analyser
forms the basis for the analysis.
EMISSIONS MODEL
For the study we apply a highly detailed emissions model which estimates fuel consumption for each individual aircraft
operation during each flight phase. For the climb, cruise and descent phases the fuel consumption data is based on
EUROCONTROL’s Base of Aircraft Data (BADA). BADA is used extensively in the (scientific) literature to estimate fuel
consumption. It does not contain data for all aircraft types in operation, but recommends which types to use as synonyms.
For the LTO phase, fuel consumption is taken from ICAO’s Engine Emissions Databank. This databank contains fuel
consumption data for individual engine types in the LTO phase. To each aircraft type we attach a common engine type
based on the EUROCONTROL ANP database. CO2 emissions are directly related to fuel consumption and follow directly from
the model.

The number of passengers and aircraft movements in the reference scenario are estimated on the basis of external
industry forecasts. EUROCONTROL’s Challenges of Growth (Regulation and Growth scenario) (2018b) 16 is used as the
basis for the reference scenario. It provides a forecast of flight movements until 2040, by individual (European)
country.
We updated this scenario to reflect the impact of the COVID-19 crisis. Since the outbreak of the coronavirus
organizations such as ICAO, IATA, ACI and EUROCONTROL published traffic projections for the short and medium term.
As the virus spread and travel restrictions were tightened or reimplemented, these projections were revised
downward. The latest projections indicate that passenger traffic does not return to pre-crisis levels before 2024.
Table 1: Projections for passenger traffic by industry organizations
Source
ACI World (2020b)
ACI Europe (2020a)
EUROCONTROL
(2020b)
IATA (2020c)

Forecast
International markets are expected to recover to pre-crisis levels in 2024, domestic
markets in 2023
A survey among industry forecasters shows that full recovery is not expected before
2024/2025
Five year forecast indicates that traffic does not recover before 2024
Passenger numbers and RPKs are expected to recover in 2023 and 2024 respectively

However, uncertainties remain large and the projections indicate that the uncertainties are on the downside, meaning
that recovery may take longer than currently anticipated. Based on the latest projections, we assume that passenger
traffic recovers to 2019 levels in 2024.
The crisis might also change the way that we travel over the long-term. Surveys indicate that 30 – 40 percent of air
travellers expect to fly less for both leisure and business purposes when the pandemic is over (Rockland Dutton, 2020;

15 It should be noted that that airline schedules are “padded” by airlines to allow for ATC/airport related delays. Therefore their use is conservative and may slightly
overstate flight or block times and hence emissions.
16 EUROCONTROL’s Regulation and Growth forecast includes currently foreseen measures, namely a carbon price due to market based measures (EU-ETS and CORSIA)
combined with an improvement in load factor and increase in aircraft size. The modelling tools in this report control for these measures to prevent any double counting.
The reference scenario does not include any additional measures to address the climate impact of aviation.

17

NLR-CR-2020-510 | February 2021

Barclays, 2020). In its updated long-term forecast, IATA (2020a) assumes that air traffic follows a lower growth trend
after the crisis. Boeing (2020) however assumes that traffic levels will return to those previously anticipated.
We assume no structural changes to the long-term trend to make sure we do not underestimate future traffic and
CO2-emissions. For the period after recovery, until 2040, growth rates are sourced from EUROCONTROL’s Challenges
of Growth forecast. Challenges of Growth breaks down the growth rates in 5-year brackets. For the period 2040-2050,
we apply the growth rate reported for the period 2035-2040.
The forecast by EUROCONTROL does not provide a detailed breakdown of traffic by destination region. Therefore,
growth rates are differentiated by destination world region based on the Airbus Global Market Forecast (GMF) 20192038. This source provides RPK growth rates between 2019 and 2038 for 144 different region-pairs. Aggregate growth
rates based on EUROCONTROL are adjusted based on this regional breakdown, while keeping the overall growth rate
aligned with the values based on EUROCONTROL.
The sources used for our analysis present forecasts until 2038 (Airbus GMF) and 2040 (EUROCONTROL). Therefore,
assumptions need to be made on the growth forecast for the years thereafter. By analysing economic and aviationspecific forecasts until 2050, we conclude that relative growth rates of both European GDP and forecast air traffic do
not differ substantially from growth rates forecast for the period 2030-2040 (OECD, 2018b; Economist Intelligence
Unit, 2015; EUROCONTROL, 2013). Hence, we assume that growth rates reported for the latest time bracket (20352040 in the case of the used EUROCONTROL forecast, and 2028-2038 for the regional breakdown based on Airbus
GMF) continue during the period 2040-2050. Given the fact that the external forecasts do not provide data beyond
2040, this extrapolation leads to additional uncertainty. As traffic volumes grow, it could be argued that growth rates
gradually decrease, which is also supported by the lower growth rates towards the end of the horizon in the forecasts
consulted. As such, maintaining the growth rates for the period beyond 2040 possibly slightly overestimate demand
and emissions.
EUROCONTROL does not publish country-level forecasts specifically for air cargo operations. Overall, EUROCONTROL
forecasts a 3.5% annual growth rate for air cargo operations. Both Airbus (2019) and Boeing (2019b) present similar
growth rates for cargo traffic, and publish detailed growth rates for 131 global traffic regions. Therefore, the more
detailed Airbus forecast is used to estimate the increase of cargo operations between 2018 and 2050.
The next chapters present measures to reduce CO2 emissions from aviation across the four pillars described in Section
1.4.5. Based on these measures, a sustainability scenario is defined. This sustainability scenario is compared against
the reference scenario to estimate the impacts of the measures in terms of CO2-emissions. Figure 3 presents a
schematic overview of the approach. Chapter 8 describes the impact assessment in more detail.

18

NLR-CR-2020-510 | February 2021

Figure 3: Schematic overview of the approach

2.2.2

Load factor and aircraft size growth

Historically, the average number of passengers per flight has increased. It is expected that this trend will continue
during the following decades, particularly considering airport and airspace capacity constraints. Airline operations
become more (fuel) efficient by deploying aircraft with a larger seat capacity – up to a certain extent – and achieving a
higher load factor.
EUROCONTROL Challenges of Growth forecasts that the average number of passengers per flight increases by 0.6%
per year. This can be broken down into two components: load factor growth and aircraft size growth. First we
estimate to what extent load factor growth can realistically contribute to the increase in number of passengers per
flight. Data from IATA shows that worldwide industry load factors have increased by 0.58% per year between 2000
and 2018 (IATA, 2019c) (see Figure 4). During the period until 2050, it is assumed that this growth rate slows down, as
further increases in load factor become progressively more difficult to achieve. Hence, it is assumed that passenger
load factors are capped at 90 percent in 2050, which is deemed ambitious but realistic. In 2018, the average global
load factor was 81.9% (IATA, 2019c), implying an annual load factor growth rate of 0.3%.
As an example, Table 2 presents average load factors of the five largest European airlines. There are relatively strong
differences, particularly between network carriers and LCCs. The current high load factors of LCCs indicate that
average load factors of over 90 percent are possible to achieve, supporting this assumption.

19

NLR-CR-2020-510 | February 2021

Figure 4: Between 2000 and 2018 load factors increased by 0.58% per year (IATA, 2019c)

Table 2: Load factors of five largest European airline groups (source: airlines’ annual reports) 17
Airline
Lufthansa Group
Air France-KLM
IAG
Ryanair
easyJet

Financial year
2018
2018
2018
2018-2019
2017-2018

Load factor (RPKs / ASKs)
81.4%
88.1%
83.3%
96.0%
92.9%

The remaining growth in the number of passengers per flight will be achieved through an increase in aircraft size. The
average number of seats per flight is expected to increase by 0.3 percentage points per year until 2050. This is
consistent with the historically observed trend of increasing aircraft size. As an example, exit limits of the Boeing 737
show that the average number of seats per type increases with each generation (see Table 3). In addition, production
numbers show a shift towards the larger type: of the Classics 55% of the produced 737s were -300s, while 25% were 400s. In the Next Generation series 17% of the produced aircraft were -700s, and 72% -800s (Brady, 2019).
Table 3: Seat capacity for three generations of Boeing 737 (Boeing, 2013)
Type
Seats (exit limit)
Type
Seats (exit limit)

Classic
737-300
149
737-400
188

Next Generation
737-700
149
737-800
189

MAX
737 MAX-7
172
737 MAX 8
210

17 To align with the reporting in airlines’ annual report, this table presents load factors based on revenue passenger kilometres (RPKs) and available seat kilometres

(ASKs), while in this report passenger numbers are used as a main indicator. Calculating load factors based on RPKs and ASKs puts a higher weight on longer-distance
flights. If load factors tend to be lower on shorter flights, load factors based on passengers and available seats will turn out lower.

20

NLR-CR-2020-510 | February 2021

Flights versus passenger growth
Average annual growth rate (2018-2050)

2.5%
aircraft size: 0.3%

2.0%
load factor: 0.3%
1.5%

1.0%

Passengers: 2.0%
Flights: 1.4%

0.5%

0.0%

Figure 5: Forecast load factor and aircraft size growth between 2018 and 2050

2.2.3

Environmental regulation

The reference scenario assumes that no additional measures are taken in response to the Paris Agreement. This is in
line with EUROCONTROL’s most-likely scenario, which is a continuation of currently foreseen measures.
With regard to technology, operations and SAFs, the reference scenario is a hypothetical no improvements scenario.
This means that in the horizon years aircraft are no more fuel efficient than in the base year, and operational
efficiency remains unchanged as well. Moreover, the amount of SAFs deployed on commercial flights remains
negligible.
With regard to economic measures, currently (foreseen) policies (EU-ETS and CORSIA) are taken into account through
a mark-up on ticket price. It is assumed that 100% of the additional costs are passed on to the consumer. Most of the
incurred costs are sector-wide cost increases, for which economic theory suggests that these are fully passed through
(Koopmans & Lieshout, 2016). In some cases, cost increases might not apply to all competitors in a market. This could
for example be the case for competition in international hub markets, in which some airlines are not subject to local
or European measures. In such cases, airlines might choose to absorb (part of) the cost increase to avoid losing market
share. Such choices are difficult to model, as they are highly dependent on the market and the financial situation of
airlines. Therefore, we also assume 100% pass through in these cases, as a simplified assumption. As such, demand
impacts might be slightly overstated. However, considering the relatively low profit margins in the sector, the extent
to which airlines can absorb costs is limited.
Besides the cost impacts of (potential) environmental measures, people become increasingly aware of the impacts of
flying on climate change. Although relevant, such trends and developments have not been taken into account in
EUROCONTROL’s forecasts, and neither are they explicitly included in our forecast.

21

NLR-CR-2020-510 | February 2021

2.3

Results

This section presents the results of the reference scenario development, spanning a forecast for flights and passengers
(Section 2.3.1) and CO2 emissions (Section 2.3.2).

2.3.1

Flights and passengers

The total number of flights departing from EU+ airports increases from 7.6 million in 2018 to 12.4 million in 2050, an
increase of 1.4% per year (see Figure 6). The annual growth rate of scheduled cargo operations (3.0%) is higher than
for passenger operations (+1.4%), but accounts for only a very limited share of the total number of flights 18.
The number of air passengers increases by 2.0% per year between 2018 and 2050, increasing from 751 million

1500

12.5

1250

10.0

1000

7.5

750

5.0

500

2.5

250

0.0

0

Passengers departing from EU+ (mln)

15.0

2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050

Departing flights from EU+ (mln)

departing passengers in 2018 to 1.4 billion passengers in 2050 (see Figure 6).

Total flights

Total number of passengers (right axis)

Figure 6: Forecast flights and passenger growth from EU+ airports between 2018 and 2050
Figures 7 and 8 present the growth rates of operations and passengers, respectively, by world region. The majority of
flights are within Europe. The share of intra-European flights slightly decreases from 89% in 2018 to 87% in 2050, but
remains by far the most important destination region. In terms of passengers, the share of European destinations is
slightly smaller: 83% in 2018 decreasing to 80% in 2050. The strongest growth is expected in flights to the Middle East:
3.3% in terms of flights and 3.8% in terms of passengers. In 2050, this is the second largest destination region,
especially in terms of flights. 41% of the intercontinental flights departing from the EU is bound to this region. The
large hubs in the Middle East (Istanbul, Dubai, Abu Dhabi and Doha) also provide connections between Europe and
other world regions, most notably Asia/Pacific and Africa. In terms of passengers, Middle East, North America and
18 Interestingly, both EUROCONTROL and Airbus foresee a stronger growth in air cargo operations than for passenger operations. Recently however, air cargo growth

has slowed down following worldwide trade tensions, whereas passenger demand continued to grow. Over the long term however, worldwide international trade is
expected to continue its growth, which is a key driver of cargo traffic. The COVID-19 pandemic led to a surge in cargo operations, compensating the strong reduction in
belly capacity.

22

NLR-CR-2020-510 | February 2021

Asia/Pacific are the largest intercontinental destination regions, respectively accounting for 27%, 25% and 24% of the
intercontinental passengers.

1.3%

1.6%

ASIA/PACIFIC

1.3%
3.0%

1.8%
1.7%

327,000

155,000

NORTH AMERICA

596,000

9.7m

286,000 MIDDLE EAST
AFRICA

EUROPE

50,000

SOUTH AMERICA

Figure 7: Passenger flights from EU by destination world region. Flights in 2050, growth rates w.r.t. 2018

1.9%

2.1%

ASIA/PACIFIC

1.9%
2.2%

3.5%

2.3%

70m

NORTH AMERICA

15m

65m

1.1bln

50m

76m

MIDDLE EAST

AFRICA

EUROPE

SOUTH AMERICA

Figure 8: Passengers from EU by final destination world region. Passengers in 2050, growth rates w.r.t. 2018
While the majority of flights is intra-European, intercontinental flights produce a relatively high share of emissions
with a limited number of flights. Figure 9 plots the cumulative number of flights and CO2 emissions against the flying
distance. The figure shows that while over 90% of the flights take place on a route shorter than 3500 kilometres, these
flights account for only 46% of the CO2 emissions. This means that the majority of CO2 emissions stem from
intercontinental flights.

23

NLR-CR-2020-510 | February 2021

Figure 9: The 10% of the flights on routes over 3500 km account for the majority of CO2 emissions

2.3.2

Emissions

In the reference scenario, CO2 emissions from EU+ aviation are expected to increase by 1.6 percent per year until 2050
(see Figure 10). In 2018, estimated CO2 emissions for both passenger and cargo operations accrue to 189 Mt,
increasing to 192 Mt in 2019. The majority of these emissions, respectively 181 and 183 Mt, arise from passenger
operations. In 2030 aviation emissions are 16% higher than in 2018, and by 2050 CO2 emissions are 67% above 2018
levels. Emissions from scheduled cargo operations increase more rapidly (3.1% per year) than those from passenger
operations (1.5%), but account for a limited share of total emissions. In 2050, 93% of EU+’s commercial aviation
emissions are caused by passenger flights, while cargo flights account for the remaining 7 percent – increasing from
5 percent in 2018.
In the reference scenario, CO2 emissions from intra-EU+ aviation add up to 115 Mt by 2050. Flights to destinations
outside the EU+ are expected to emit 178 Mt of CO2 in the reference scenario. All these emissions need to be removed
to comply with the net zero goal for 2050. Hence, sustainability measures should in total yield a reduction of at least
293 Mt of CO2.

24

NLR-CR-2020-510 | February 2021

CO2 emissions from EU+ aviaition (MT)

350
300
250
200

Cargo flights
Outside EU+

150

Intra-EU+
100
50

2050

2048

2046

2044

2042

2040

2038

2036

2034

2032

2030

2028

2026

2024

2022

2020

2018

0

Figure 10: CO2 emissions from EU aviation in reference scenario

25

NLR-CR-2020-510 | February 2021

3

Improvements in aircraft and engine
technology
In terms of improvements in aircraft and engine technology, which enter the market through fleet
replacement, this study distinguishes between upcoming and future aircraft. The former are
currently available but have not completely materialised in fleets or will be in the next few years
and bring fuel efficiency improvements of 15 to more than 25% compared to their predecessors.
The latter are still to be developed.
For the largest share of aircraft – large single aisle and twin-aisle models – potential improvements
in fuel efficiency of 30% are foreseen, combining contributions from major propulsion technologies,
as well as wing, fuselage and tail technologies. For regional aircraft, an improvement of 50% is
modelled, based on more aggressive advances in (hybrid-electric) propulsion technology and
optimised capacity and range. Future regional, single aisle and medium sized twin aisle aircraft are
anticipated to enter into service between 2030 and 2035 and future large twin aisle aircraft in
2040. Fleet-level impact of both upcoming and future aircraft is computed assuming a 22.5-year
market penetration timeline. In addition to aircraft powered by kerosene (or sustainable drop-in
fuels), a hydrogen single aisle aircraft is modelled to enter service in 2035.
In order to realise the modelled efficiency improvements of future aircraft, individual enabling
technologies should be available at least five years prior to anticipated entry into service. The
proposed European Partnership for Clean Aviation addresses the need for a stimulus programme,
focused on achieving the required technology readiness for adoption in an aircraft development
programme. Industry partners should take the lead in such stimulus programmes in terms of
technology development and make sure relevant results are integrated into commercial products.
In addition to realising the required improvements in fuel efficiency, this further establishes the
leading position of European aerospace manufacturing. Research and technology infrastructures
must therefore be better supported. Certification requirements of disruptive technologies should
be clear and linkages between other R&D-efforts (supporting infrastructure; hydrogen; drop-in
sustainable aviation fuels) are to be ensured. Additional opportunities are presented by (re-)
assessing the market potential of innovations developed in the past and their possible
commercialisation as retrofittable product upgrade. Last, expedited replacement of older aircraft
by state-of-the-art models may realise CO2 emission reductions even earlier.

3.1

Introduction

This chapter presents possible technological improvements to aircraft and engines that contribute to reduction of
emissions of aircraft in the period between 2020 and 2050. The analysis is mostly limited to technology development
that enters the market through completely new aircraft (i.e., with a new type certificate) or through a major upgrade
of an already existing aircraft type. Such major upgrades typically involve major changes in the airframe and new
engines.
26

NLR-CR-2020-510 | February 2021

Upcoming and future technology
Consistent with other works (Sustainable Aviation UK, 2016; Sustainable Aviation, 2020a), this study distinguishes
between upcoming 19 and future technology. Upcoming technology is defined as technology that has already entered
into service and is still in production, or is estimated to enter into service in the next few years. The improvement
potential of upcoming technology until 2025 is relatively well-known, as well as the timeframe during which these
improvements can be delivered. Nevertheless, uncertainties do exist. This is even more so for future technology.
Although impact estimates at aircraft-level are sometimes available, empirical evidence of how these innovations
affect overall aircraft performance does not exist. As such, modelling assumptions are based on desk research.
Aircraft size classes
In addition to the split between upcoming and future technology, the analysis distinguishes between several aircraft
size classes in terms of seating capacity. These are defined and named as shown in Table 4. The share of 2018 CO2
emissions per class is computed in the present study, using the methodology described in Section 2.1.
Table 4: Aircraft classes and share of 2018 ASKs and CO2 emissions within the scope defined in Section 1.4
Class (abbreviation)
Small (S)
Regional (R)
Single aisle (SA)
Small/medium twin aisle (SMTA)
Large twin aisle (LTA)
Total

Seating
capacity
0 – 19
20 – 100
101 – 240
241 – 350
351 +

Example(s)
ATR42, ATR72, Embraer E175
Airbus A320 family, Boeing 737
Airbus A330, Boeing 787
Airbus A350, Boeing 777

Share of
2018 ASKs
0.01%
2.99%
56.4%
27.8%
12.8%
100%

Share of 2018
CO2 emissions
0.02%
3.78%
51.6%
30.3%
14.3%
100%

Even though the small aircraft class, comprised of general aviation and commuter aircraft and rotorcraft, is
responsible for only a fraction of current CO2 emissions, it is specifically included as the impact of innovation on
emissions is estimated to materialise most quickly there. Compared to seat categories as defined by ICAO CAEP (ICAO,
2013, p. 20), the upper boundary of the SA-class is raised from 210 to 240 to reflect the recent growth of single aisle
aircraft 20 and the expectation that that trend will continue (as discussed in Section 2.2.2). No separate category for
very large aircraft (VLA, encompassing previous types as the Boeing 747 and Airbus A380) is taken into account, as no
new aircraft of that class are currently expected.
Performance improvements and retrofits
Besides completely new aircraft or engine options, manufacturers provide smaller product enhancements during an
aircraft’s and engine’s production life and retrofits can (and should) be carried out on aircraft and engines that are
already in service. Where such product enhancements and retrofits are known or have been announced and they
have significant impact on the aircraft’s emissions, they are taken into account as well (such as previously the
introduction of winglets, or the upgrade of flight management systems described in Section 4.2.1). Still during the
entire 2020 – 2050 time frame, currently unknown product enhancements and retrofits may be introduced, for
example based on the CleanSky programmes, the European Framework Programmes, or the Horizon2020 programme.
Taking a conservative approach in this regard, these unknown product enhancements and retrofits by aircraft
manufacturers have not been taken into account in the impact modelling.

19 Referred to as ‘imminent technology’ by Sustainable Aviation UK (2016) and ‘known aircraft’ by Sustainable Aviation (2020a).

20 The Airbus A321neo as it is currently offered with a maximum seating capacity of 244 (Airbus, 2020a), but is typically equipped with a two-class cabin with 206 seats
(Flottau, 2015).

27

NLR-CR-2020-510 | February 2021

Significant, but smaller improvements that are largely at the discretion of an airline and maintenance organisation, are
treated in Section 4.2, such as weight reduction of cabin furniture and optimised maintenance intervals for weight or
fuel efficiency.
The remainder of this chapter will address various technological improvements in greater detail, with Section 3.2
discussing upcoming technology and Section 3.3 treating future technology. Last, Sections 3.4 and Section 3.5 discuss
drivers and barriers and present the policies and actions, respectively.

3.2

Upcoming technology

This section presents the improvement potential of upcoming technology: the return on previous efforts and
investment in research and development. As defined in Section 3.1, upcoming technology is currently available in the
marketplace or is estimated to enter service in the next few years, but has not fully materialised yet in airlines’ fleets.
Table 5 shows the upcoming aircraft that are currently foreseen in the regional 21, single aisle and twin aisle classes 22.
Upcoming aircraft that are a direct successor of a current airframe – including a new engine – are assumed to enter
the future fleet by one-to-one replacement. This is the case for the aircraft for which Table 5 shows a ‘legacy type’
(Embraer E2, Airbus A320neo, Boeing 737MAX, Airbus A330neo, Boeing 777X). Table 5 furthermore summarises the
improvement potential in terms of fuel burn per ASK and per flight 23 and entry into service of various upcoming
aircraft with respect to a reference aircraft. Seating capacities for upcoming and reference aircraft as well as fuel
consumption improvement data stem from the same source as much as possible, to ensure consistency 24. These
capacity comparisons provide a rough indication of the extent to which performance improvements depend on
aircraft growth and seat densification efforts (Hepher, 2013), or on technology improvement. In case legacy and
reference aircraft are different, this is because manufacturers chose to express the improvement potential of a new
model with respect to another (possibly competing) type. The data presented in the table is either based on results
from operational experience, or direct or media claims from OEMs 25. Because the future fleet of the reference
scenario used in this report is a mere extrapolation of the current fleet (with current aircraft models) composition
with respect to air traffic growth, 2018 aircraft market shares per route are assumed to remain unchanged for both
fleet replacement as well as fleet growth.
For current or previous generation aircraft that are not replaced by a designated successor 26, an improvement based
on the class-average is assumed. Table 6, summarising further details provided in Appendix A, defines the
improvement of a hypothetical class-averaged aircraft entering into service (‘EIS (upcoming)’) with respect to a
hypothetical reference aircraft, entered into service in the past (‘EIS (reference)’). An unweighted averaging of both
the performance improvement and entry into service dates (of both upcoming and reference aircraft) at aircraft
(sub)type level is used. Averaging performance is furthermore warranted as the introduction of replacement aircraft

21 Following the recent suspension and possible abandonment of the Mitsubishi SpaceJet (formerly: Mitsubishi Regional Jet) development (Perrett, 2020), this aircraft is

not included in the overview.

22 Because of the limited contribution to CO emissions by small aircraft, combined with the multitude of concepts currently being developed (as reviewed by e.g. ERA,
2

2020; Thomson, 2020), these have not been included in the current review.
23 The fuel burn improvement per flight was computed by subtracting the change in seating capacity from the improvement per ASK, the latter sourced from literature.
24 If fuel consumption improvements were based on unknown capacity data, typical seating capacity numbers were used. This is indicated with a superscript ‘T’.
25 Given the fact that OEMs often have to pay substantial compensation to their customers if their products do not realise performance estimates communicated earlier
on, these claims are assumed to be unbiased.
26 Examples include the regional Bombardier CRJ-series, the single aisle Airbus A318, the small/medium twin aisle Boeing 767, the twin aisle Airbus A340 and the large
twin aisle Boeing 747. The Boeing 757, a single aisle aircraft with the seat capacity of small twin aisles, is another prime example.

28

NLR-CR-2020-510 | February 2021

Table 5: Fuel efficiency improvement potential and entry into service of upcoming aircraft types, relative to reference types. For one-to-one replacements, legacy types are
indicated.

R
R
R
SA
SA
SA
SA
SA
SA

Upcoming
Type
ATR 72-600
E175-E2
E190-E2
A220-100
A220-300
E195-E2
A319neo
A320neo
A321neo

EIS
2011
2021
2018
2016
2016
2021
2019
2016
2016

Seats
72
80
97
120T

SA

A321neoLR

2018

206

SA
SA
SA

A321neoXLR
B737MAX7
B737MAX8

2023
2021
2017

200T
153T
178T

SA

B737MAX9

2018

193T

SA

B737MAX10

2020

SMTA
SMTA

A330-800
A330-900

SMTA

B787-8

Class

120
160
189
240

Legacy
Type

EIS

E175
E190

2005
2005

E195
A319
A320
A321

2006
1996
1988
1994

B737-700
B737-800

1997
1998

204T

B737-900
/ -ER

2001 /
07

2020
2018

250
294

A330-200
A330-300

1998
1994

2011

242T

SMTA
SMTA
LTA
LTA

B787-9
B787-10
A350-900
A350-1000

2014
2018
2015
2018

290T

LTA

B777-8

2024

355

LTA

B777-9

2021

395

330T
314
369

B777-200
(ER / -LR)
B777-300
(ER)

1995 /
2006
1998 /
2004

Reference
Type
CRJ700
E175
E190
E190 (est.)
E190
E195
A319
A320
A321

EIS
2001
2005
2005
2005
2005
2006
1996
1988
1994

Seats
70
76
97
106
106
156
180
220

Fuel efficiency improvement
Per ASK
Per flight
47.7%
46.3%
16%
10.7%
17.3%
17.3%
20%
6.8%
6.8% 27
25.4%
7.9%
19%
16.4%
20%
12.0%
23%
13.9%

757-200

1983

200T

30%

27.0%

757-200

1983

20%

17.0%

737 NG

1997
/
2014

200T
128T
160T

20 / 14%

177T

28

Source(s) and remarks
ATR (2020), Aircraft Commerce (2009)
Embraer (2016, p. 20)
Embraer (2016, p. 20), Gerzanics (2018)
Bombardier (2015), Embraer (2016, p. 20)
Bombardier (2015), Embraer (2016, p. 20)
Embraer (2016, p. 20), Hemmerdinger (2019)
Leahy (2016, p. 18), Aviation Week & S. T. (2007, p. 63)
Leahy (2016, p. 18), Aviation Week & S. T. (2007, p. 63)
Leahy (2016, p. 18), Aviation Week & S. T. (2007, p. 63)
Leahy (2016, p. 20), Polek (2015), Sustainable Aviation UK
(2016, p. 68), Boeing (2007)
Airbus (2019b; 2019c), Boeing (2007), Airbus S.A.S. (2020b)
Boeing (2013; 2014; 2019a), improvement difference
between early and late 737NG-models mostly dependent on
winglets. Based on current fleet materiality, the wingletequipped type is used as reference.

A330-200
A330-300
767300ER 30
767-400ER
(est.)
777-200ER
777-300ER
777-200 ER
/ -LR

1998
1994

246
290

14.2% 29
14%

12.6%
12.6%

1988

261T

20%

27.3%

2000

296T

1995
2004
1995 /
2006

301
360
375 /
279

20%
25%
30%
25%

22.0%
13.5%
25.7%
22.5%
27.0% /
8.8%

Fehrm (2017)
Leahy (The A330neo - Powering into the future, p. 10)
Boeing (The Boeing 767 Family; 787 Dreamliner; 2005; 2018),
Trimble (2014), Norris (2012)
Boeing (The Boeing 767 Family; 787 Dreamliner; 2005; 2018),
Russell (2018)
Leahy (2007, p. 26)
Hepher (2013)
Norris & Anselmo (2016), Boeing (777, n.d. - a; 1998; 2015)
and Norris (2020)

777-300ER

2004

365

11.8%

Norris & Anselmo (2016), Hepher (2013) and Boeing (2009)

21.7% / 20.8% 31
20% 32

27 Data from Broderick (2018), Miller (2019), SeatGuru (2020) comparing a 140-seat A220-300 with a 100-seat E190 and a 40% decrease in fuel burn per ASK yields a 0% improvement per flight. As such, the performance for the A220-300 is assumed identical
to the A220-100, i.e. 6.8% per flight, and no information is provided regarding seats and the improvement per ASK.
28 Given a 14 to 20% increase in fuel efficiency per ASK would be largely negated by the increased seat count, it is assumed these numbers hold per flight.
29 Ferhm (2017) notes the seat mile fuel consumption of an A330-200 is 116.5% of that of an A330-800. As such, the A330-800 is (1 – 1/1.165) = 14.2% more efficient than the A330-200.
30 The 20% fuel efficiency improvement realised by the 787-8 over the 767-300ER is with respect to a reference aircraft without retrofitted winglets (Trimble, 2014).
31 Norris & Anselmo (2016) state the 777-8 is 13% more efficient than the 777-300ER, which is 10% more efficient than the 777-200ER. As such, the difference between the 777-200ER and the 777-8 is (1 – 0.87 × 0.90) = 21.7%. The 777-300ER is 9% more
efficient than the 777-200LR, yielding a 777-8 performance improvement over the 777-200LR of (1 – 0.87 × 0.91) = 20.8%.
32 Leeham News (2014) shows data from which the 777-9 (395 seats) can be derived to be 8.3% more efficient compared to a 777-300ER (configured with 344 seats). As this data is so different compared to other sources, this estimate is assumed to be
erroneous and as such neglected.

29

NLR-CR-2020-510 | February 2021

with much better or worse performance is unlikely, as such types would face substantial competitive disadvantages in
terms of acquisition and operational cost 33, respectively.
For the aircraft where no one-to-one replacement is identified this class-average improvement factor is applied to
incorporate efficiency improvements for all aircraft types. In case these aircraft are older (and therefore generally less
fuel efficient) than the reference aircraft with respect to which the fuel efficiency improvement of the average
upcoming aircraft is expressed in Table 6, these figures might be under-estimating the improvement potential. An
example would be the replacement of Boeing 747-400 aircraft (in the LTA class), which entered service in 1989 – prior
to the EIS reference of 2001. For aircraft that entered service after the indicated EIS reference date (such as the Airbus
A380), the opposite will be true, yielding an over-estimation of the improvement potential. Overall, these effects are
estimated to nullify each other.
Table 6: Class-averaged fuel efficiency improvement potential and entry into service of upcoming aircraft classes with
respect to average reference fleet at indicated year
Class (abbreviation)
Regional (R)
Single aisle (SA)
Small/medium twin aisle (SMTA)
Large twin aisle (LTA)

Fuel efficiency
improvement per ASK
27.0%
34

18.6%
23.5%

Fuel efficiency
improvement per flight
24.8%
14.8%
17.6%
19.2%

EIS
(upcoming)
2017
2018
2016
2020

EIS
(reference)
2004
2001
1996
2001

The higher improvement per flight in the regional class is caused by the fact that it includes the replacement of a jet
(CRJ700) by a turboprop (ATR72) aircraft. Given the trend of ‘classic’ regional jets (such as the CRJ-series) to outgrow
their class and move to the single aisle market, the implied assumption of a larger share of turboprops is deemed
warranted.
Table 7 shows what portion of (2018) ASKs and CO2 emissions is attributed to aircraft that do not have a one-to-one
replacement as identified in Table 5, and which improvement potential is therefore modelled using the class-averaged
data. These shares are fairly high in the twin aisle classes. In the small/medium class, this is due to the high materiality
of Boeing 787 (which does not have an upcoming replacement) aircraft already in the fleet. In the large class, this is
caused by Airbus A380 aircraft not having a direct replacement.
Table 7: Share of 2018 ASKs and CO2 emissions for which potential improvements due to upcoming aircraft are
modelled using class-averaged data. The remainder is modelled using the one-to-one replacements indicated in Table 5
(‘legacy’ replaced by ‘upcoming’).
Class (abbreviation)
Regional (R)
Single aisle (SA)
Small/medium twin aisle (SMTA)
Large twin aisle (LTA)

Share of 2018 ASKs for which classaveraged data is used, per class
65.12%
11.67%
42.65%
59.43%

Share of 2018 CO2 emissions for which
class-averaged data is used, per class
62.13%
13.88%
41.26%
65.69%

33 Although fuel(-related) costs can be expected to rise following increasing oil or carbon prices, this is not likely to dramatically influence the ratio of operating (including

fuel-related costs) and non-operating cost (including acquisition cost or cost of ownership) in the timeframe where the upcoming aircraft are introduced into the fleet.

34 Due to the calculation methodology and data base, no improvement figure per ASK is listed for the single aisle class. Further information is provided in Appendix B and

footnote 28 on page 31.

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NLR-CR-2020-510 | February 2021

3.3

Future technology

The previous section discussed the potential benefits of technological developments on upcoming aircraft. This
section looks further ahead. As such, it also takes a somewhat more fundamental approach. Section 3.3.1 therefore
starts with a thorough review of technological developments. Subsequent sections discuss how these technologies can
be combined, what CO2 reductions might thereby be realised and a notional timeline of possible entry into service of
future concepts utilizing these technologies. Section 3.3.2 does so for aircraft powered by kerosene, either fossilbased or in the form of drop-in sustainable aviation fuels (discussed more extensively in Chapter 5), drawing from the
recently proposed Partnership for Clean Aviation. Section 3.3.3 then looks at hydrogen-powered aircraft, based on the
recent study by McKinsey & Company (2020), including aspects as hydrogen production, availability and cost.

3.3.1

Technological developments

Whereas in some studies historical fuel efficiency improvements have been analysed to project the average yearly fuel
efficiency increase due to technology development, this study is taking an evidence-based approach, taking into
account published global research and innovation programs, including European, national, and industrial programs.
Many technological improvements of aircraft have been investigated in numerous research studies globally and in
particular in European research and innovation programmes (Framework Programmes, Horizon2020, in particular
Clean Sky 1 and 2), national programmes and regional initiatives. Some of these technologies have been incorporated
in currently flying and upcoming aircraft, other technologies performed below initial expectations and therefore were
not implemented. Many technologies are still being matured further, while still new technologies are invented.
Together they provide valuable estimates about what future fuel efficiency improvements can be expected at aircraft
level.
This study distinguishes between technologies with a major contribution to fuel efficiency and technologies with a
minor contribution to fuel efficiency. The boundary value is set at an indicative fuel efficiency improvement of 5% with
respect to current aircraft. Major technologies are drivers for the introduction of new generations and hence will be
discussed in more detail. Minor technologies are important as well (as will be explained with a number of examples),
but such technologies are not considered individually, because it is unclear which developments will make it to
commercial programmes. Next, the integration of technologies in aircraft concepts is considered and how
technologies taken into commercial aircraft programmes. Finally, major cross-links between the development of
technologies for different aircraft categories are identified.
The list of technologies starts from the technologies in the technology overview in (IATA, 2013), which is also
referenced in (IATA, 2020d). The reference (IATA, 2013) provides one of the most complete overviews of technologies
with their fuel efficiency benefits that have been obtained with a single study approach. The list is extended with
technologies that have been considered in aircraft concept studies (discussed later on), and has been further
extended with some specific technologies. Some of these technologies were already partly mentioned as future
concepts and technologies in (IATA, 2013); other technologies come from recent other developments that became
known to the authors from literature study and/or were provided by ASD partners.
Technologies with major fuel efficiency improvements are mainly found in the following categories: propulsion
architectures and the thermodynamic cycle, non-drop-in fuels and energy sources, wing and tail, and fuselage. These
are treated next in further detail.
31

NLR-CR-2020-510 | February 2021

Major propulsion architectures and thermodynamic cycles
In the propulsion technologies a split is made between conventional jet fuel propulsion technologies and alternative
fuel propulsion technologies. As these alternatives often include substantial changes to the aircraft configuration, they
are also considered at that level rather than individually.
For jet fuel (conventional or drop-in) based engines, major fuel efficiency improvements are expected from ultra-high
bypass ratio (UHBR) engines and from next generation concepts such as open rotor configurations, more radical
thermodynamic cycle changes, and turbo-electric propulsion architectures. Radical thermodynamic cycle changes may
include adaptive cycles to optimise the engine’s behaviour over a larger design range, intercooled, recuperated
bottoming cycle to re-use heat from the turbine, or composite cycles combining gas turbines with other engines such
as a piston engine or a steam turbine.
Turbo-electric propulsion architectures are based on innovation in a number of technologies which need to be
combined to obtain fuel efficiency gains. These technologies including high-power electrical generators, electrical
motors for aircraft, high-power distribution system, and possibly distributed propulsion and boundary layer ingestion.
Some propulsion architecture changes can be considered as well in combination with relocation of the engines, for
example open rotor tail installation and UHBR over wing or tail cone installation with boundary layer ingestion for
reduced net fuselage drag.
Non-drop-in fuels and energy sources
Non-drop-in fuels and energy sources for aircraft and associated propulsion technologies are widely investigated. An
important class of non-drop-in fuels are liquids and compressed gasses. Such non-drop-in fuels are used in aircraft
engines that have been adapted for the fuel, such as discussed in Goldmann et al. (2018) or in fuel cell based
propulsion systems.
Hydrogen especially has recently received increased attention, even though challenges remain. For once, it requires
extreme cooling to become liquid, or significant compression to increase the energy density towards the energy
density of current jet fuel. Both as liquid at cryogenic temperature and compressed (at 700 bar) the volumetric density
of hydrogen is still less than one third of the energy density of jet fuel. As a larger fuel tank is needed to store the
same amount of energy during flight, using hydrogen for aircraft propulsion requires changes to the aircraft
architecture as well. Concept architectures discussed by McKinsey & Company (2020) as well as presented by Airbus
(2020d) – the ZEROe concept aircraft – address this by stretching the fuselage 35 (for shorter-range aircraft) or moving
towards hybrid or blended wing bodies (for longer-range aircraft), which increase the amount of fuselage volume
available for energy storage. Moreover, not all challenges with respect to storing and distributing liquid hydrogen
(LH2) within the aircraft, combusting hydrogen in an efficient and low-NOX manner, and refuelling infrastructure and
technology have been addressed. Important advances are expected in the coming five to ten years (McKinsey &
Company, 2020). Similarly, implications for airport infrastructure are currently being researched and clarified.
Another important class of non-drop-in energy sources is based on electricity, which, in many studies, is stored in
batteries. Currently, however, the battery’s low specific energy (or, equivalently, high weight) would be a major
constraint to the use of batteries as an aviation fuel option. The specific energy is in the range of 200 Watt-hour per
kilogramme, which is 60 times lower than jet fuel. Although improvements are expected (Warwick & Norris, 2020),
this gap is not expected to be bridged soon. Volumetric energy density is also lower than for jet fuel, but of less
concern than the gravimetric energy density. Another important constraint is the need to have specific power for a
high discharge rate of the battery during certain flight phases (e.g., take-off). In current batteries, high power seems to
35 Or, for a constant fuselage length, trading seating capacity for space for fuel tanks.

32

NLR-CR-2020-510 | February 2021

result mostly in low specific energy and vice versa. Battery improvements are being investigated for other sectors than
aviation as well, although requirements are often different.
Fuel cells generate on-board electricity from hydrogen. Currently their specific power is 1-2 kW/kg for the core fuel
cell stack, excluding additional components for cooling, compression and so on, which is limiting their application
currently to demonstrators for very small aircraft. In case of other non-drop-in fuels, reformers may be used to
generate the hydrogen on-board aircraft.
The mechanical propulsive power in propulsion concepts associated with electricity as energy source is provided by
high power electric motors that drive propellers or ducted fans. The propulsors may be distributed on the wing and/or
aft-fuselage, potentially using wing and/or fuselage boundary layer ingestion. Full-electric, battery-based, electric
propulsion is emerging on the market for 2-seaters with a conventional aircraft architecture. Upscaling to higher
power levels requires major developments in all components, as previously mentioned. In addition, the electrical
power distribution system for the propulsive power needs to be developed for power values much higher than in
present aircraft. This is similar to the electric part of turbo-electric architectures, mentioned before.
For large aircraft, hybrid-electric configurations have been studied and may provide environmental benefits in a
shorter timeframe. A recent overview of electric and hybrid-electric concepts, designs and major design parameters is
presented by Brelje & Martins (2019). In such configurations the thrust is provided by both thermal engines and
electric motors.
When aircraft size and power requirements increase, the weight penalty associated to hybrid- and especially batteryelectric systems grows. The same occurs for fuel cells, which at higher power output, require larger cooling systems
which increase system weight. As such, for twin-aisle aircraft utilizing hydrogen, direct combustion is foreseen. For the
single-aisle class of aircraft, configurations combining fuel cells with direct combustion are anticipated. This way, some
of the benefits of fuel cell systems (increased reduction of climate impact thanks to zero NOX-emissions, as well as
reduced noise) can still be enjoyed in larger aircraft (McKinsey & Company, 2020).
Wing and tail
In the category of wing and tail technologies, major fuel efficiency improvements are expected from improved
aerodynamics such as from natural laminar flow, hybrid laminar flow, and active flow control (e.g., the Clean Sky
BLADE demonstrator (Clean Sky JU, 2018)). Each of these technologies can be applied to both wings and tails, whereby
the wings contribute the largest portion to potential increases in fuel efficiency. In addition, high aspect ratio wing
technology is expected to contribute to reduction of induced drag. For higher aspect ratio wings, load and flight
control needs to be innovated, including movables and smart alternatives for movables. There is a whole range of
technology concepts that have been investigated, including folded wing (to appear in the upcoming Boeing 777X) and
morphing wing concepts, up to first studies on major configuration changes such as strut/truss-braced wings. Such
technologies have shown to be enablers for wings with higher aspect ratios and increasing fuel efficiency. In these
studies wing folding is an enabler for wing span extension, while satisfying airport constraints.
Major fuselage technologies
In the fuselage-category, major promising technologies for improvement of fuel efficiency are coming from the use of
carbon fibre-reinforced plastic (CFRP) materials. Their application in fuselages started on Airbus A350 and Boeing 787.
Further applications to other families can be expected in future. Also further innovations are being investigated based
on innovative matrix materials in CFRPs enabling lighter designs and increased multi-functionality, with cabin, systems
integration and flexible cargo/passenger concepts, as for example investigated in the Clean Sky 2 Joint Technical
Programme (Clean Sky JU, 2015). Windowless cabins may be another contributor to fuel efficiency improvement on its
own (due to weight reductions). Nevertheless, given the important effects on the passenger experience, weight33

NLR-CR-2020-510 | February 2021

adding alternatives may have to be provided to compensate for the lack of windows, which in turn might counteract
the fuel efficiency improvement.
Minor technologies and their relevance for fuel efficiency improvement
Technologies with minor fuel efficiency improvements are emerging for almost any part of component of future
aircraft. Some of these minor technological improvements, as found in literature, are new materials, riblets, advanced
wing and flight control technologies such as advanced wingtips, gapless movables, multi-functional structures,
adaptive camber, span load control, manoeuvre load alleviation, active load alleviation, relaxed stability
augmentation, advanced fly-by-wire (including fly-by-light), morphing wings, advanced landing gear (compact, faired
undercarriage), and all-electric non-propulsive systems (such as flight control actuators, APU, etc.).
A feasible combination of several minor technologies may add up to a major reduction on aircraft level, if they do not
counteract. In addition, some minor technologies are relevant enablers for the major efficiency improvements. This
holds for example for many minor wing-related technologies, which contribute to the major wing concepts. For
example, electric flight controls and actuators (from the all-electric non-propulsive systems) and multifunctional wing
structures are potential weight-savers and therefore enablers for high aspect ratio wings. Some technological
improvements with minor fuel efficiency improvement may be very relevant for other objectives, such as innovative
cabin/cargo configurations (higher density/modular cabin and flexible passenger/cargo) for competitiveness. The
aspect of combining technologies is further elaborated next.
Integration of technologies into aircraft concepts
Aircraft concepts are defined and evaluated to investigate the integration of technologies at aircraft level. Studies may
concern conventional tube-wing-tail configurations or alternative configurations, such as box wing aircraft, C-wing
aircraft, double bubble fuselage aircraft, and blended wing body aircraft. Examples are listed in Appendix D. In
addition, integration of technologies have been demonstrated in large ground demonstrators, representative for
sections/parts/systems of an aircraft and sometimes tested in wind tunnels with representative flight conditions.
Furthermore the integration of technologies has been demonstrated as well in flight tests in existing aircraft or scaled
flight demonstrators.
Introduction of future technologies on the market
After successful evaluation of technologies in aircraft integration studies, further steps have to be taken before the
technology enters into service in airline fleets. Beneficial technologies may enter into service in different ways: as
retrofit, into an existing product line from a particular point in time (product enhancements through performance
improvement packages (PIPs) of technologies), into a new family member, a new family generation, or even a new
family.
Economic, business and other factors are important drivers for decision-taking. Some technologies requiring smaller
changes in certification and production may enter in a performance improvement programme. Other technologies
require such large investments (in particular in modifications and related certification) that they are only taken into
service through a new family member or generation.
In this report we can only sketch potentially successful directions of technological pathways for certain aircraft classes,
without aiming to predict the future decision process of aircraft manufacturers, influenced by many external factors.
In particular the timing of the start of commercial aircraft development programmes is sensitive. Nevertheless,
technologies need to be sufficiently developed before they are taken into their final development towards entry-intoservice in commercial aircraft development programmes. Timely technology readiness is needed to achieve the
environmental benefits associated with the technologies, as well as to put a competitive aircraft on the market.

34

NLR-CR-2020-510 | February 2021

Introduction of future aircraft technologies on the market may also require changes elsewhere in aviation. In
particular, changes in the on-board energy source for propulsion may require significant adjustments to the
infrastructure at airports. It is important for airports to have visibility on such technologies and their estimated entry
into service timelines as soon as possible, to be able to plan infrastructure development accordingly.
Technological pathways for the different aircraft categories and cross-links
Technological pathways may be different for the single aisle (SA), small/medium twin aisle (SMTA), and large twin aisle
(LTA) classes of aircraft. However, for conventional configurations many future technologies are scalable for these
various categories. Technology developments for one of the categories can often be re-used for the other categories.
The benefits may be somewhat different, since the scaling is not always linear and the operational characteristics of
the categories are different, such as the percentage of time that is spent in the different flight phases (e.g., cruise,
climb, descent, ground).
In addition, some technologies may lead to small changes in operational characteristics (e.g., open rotor
configurations may have a slightly lower cruise speed than current turbofans). In this report, for the evaluation of the
impact on CO2 emission, it is assumed that the future technologies will not significantly change the operational
characteristics of aircraft and stay in line with the traffic scenario underlying this study. Some more disruptive system
changes are qualitatively discussed in Chapter 7.
Technology pathways for aircraft technologies using non-drop-in fuels and energy sources for propulsion are quite
different. Fully-electric and hybrid-electric battery-based aircraft are likely to become technologically feasible for
aircraft with an increasing number of passengers and/or growing flight range as the specific energy of batteries
increases. A similar reasoning applies for hydrogen-based fuel cell or hydrogen combustion technologies regarding
specific power. This process therefore enables a learning curve towards the application of non-drop-in fuels and
energy sources based technology in large(r) passenger aircraft. Introduction of these technologies for the largest
aircraft and longest ranges is not expected before 2050.
For non-drop-in alternative liquids and compressed gasses as fuels, it is expected that novel aircraft architectures and
designs are an important technological pathway. For such a radical change, efficiency and effectiveness of the
technology development process from concept development to certification is an enormous challenge.

3.3.2

Kerosene-powered or (hybrid-)electric aircraft

The previous section reviewed and described individual as well as related technological developments that have the
potential to contribute to substantial reductions in CO2 emissions. This is done through the process of fleet
replacement. This section shows how technologies are combined on modelled future kerosene-powered or (hybrid-)
electric aircraft concepts in the different classes identified in Section 3.1. The modelling of estimated impacts and
product availability is largely based on the proposed Clean Aviation programme (Clean Aviation Partnership, 2020),
and supported by additional literature.
THE PROPOSED EUROPEAN PARTNERSHIP ON CLEAN AVIATION
The Clean Aviation Strategic Research and Innovation Agenda is a proposal to guide aircraft development in the upcoming
Horizon Europe framework programme. It addresses all aircraft segments: the medium and long-range segments, that are
currently the highest contributors to aviation carbon emissions, as well as short-range segments and mobility solutions,
with a regional flying demonstrator and several ground demonstrators to test the maturity of hybrid-electric propulsion
solutions. Specific markets in Europe, such as regional aviation, offer opportunities to develop, test and demonstrate
hybrid, full-electric and hydrogen solutions. The experience gained in this market is anticipated to provide important
insights for the electrification of larger aircraft in the longer term.
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NLR-CR-2020-510 | February 2021

Entry into service (EIS) dates are based on historical trends. Table 5 shows that new SA, SMTA, and LTA aircraft
generations have entered into service about 20 to 25 years after their preceding generations. This corresponds well
with the average age at which airframes are withdrawn from service, noted in Section 8.1 to be 22.5 years. The
modelling of future aircraft types does not distinguish between different sub-types (with different seating capacities
and/or flight ranges) within each family. Similarly, EIS dates are nominal estimates: some types might arrive in the
market slightly earlier, whereas others arrive slightly later. This is assumed not to affect overall modelling. Fleet
replacement itself – governed by the aforementioned decommissioning age of 22.5 years – happens gradually, such
that the fleet at all times consists of a mix of aircraft of different ages of older and newer types and variants.
For the different classes of aircraft, the remainder of this section discusses applicable technologies, entry into service
dates and the estimated fuel efficiency improvement, compared to the upcoming class of aircraft discussed in Section
3.2. It is important to stress the fuel efficiency improvement solely includes an estimated reduction in the energy used
by an aircraft. As compatibility with 100% drop-in sustainable aviation fuels is assumed, the potential CO2 reduction
can be higher. That part of the possible emissions reduction is accounted for in Chapter 5 36.
Single aisle (SA)
As seen in Table 5, the latest introduction of families have been the Airbus A320neo in 2016 (start of replacing
A319/A320/A321 with EIS 1996/1988/1994) and the Boeing 737MAX in 2018 (start of replacing B737700/800/900/900ER with EIS 1997/1998/2001/2007). Again taking 20 years to the next family, the introduction of a
new SA family generation is therefore modelled to be in 2035.
For this generation advances are modelled both in aircraft configuration and in aircraft engines, leading to an ultraefficient aircraft configuration with ultra-high bypass engines, possibly open rotor. A conventional tube-wing-tail
configuration is assumed that employs major technologies with laminar, high aspect ratio and laminar wing, laminar
tail, and lighter (e.g. advanced carbon fibre reinforced) fuselage with integrated modular cabin and passenger/cargo
flexibility, and thereby reduced fuel burn and CO2 emissions. Current UHBR architectures are assumed to be further
improved and optimised for a range of conditions through geometry variations, as well as more efficient electricity
generation. This would contribute to a fuel efficiency improvement of 30%, as specified in Table 8.
Table 8: Modelled fuel efficiencies for future generation SA, SMTA and LTA aircraft, with respect to upcoming
generation
Technology
SA/SMTA/LTA
Major propulsion
technology (integrated)

Potential fuel efficiency
improvement per flight

Remarks

18%

Upcoming UltraFan 37 and further cycle improvements

Major airframe
technology

15%

Wing technology: about 9%, based on NLF (Goold, 2018);
high aspect ratio wing and combined with (hybrid-)laminar
flow technologies and other technologies (Liu, Elham,
Horst, & Hepperle, 2018).
Tail technology: about 1% (EC, 2019f; Clean Sky JU, n.d.)
Fuselage technology: about 6% (Large Passenger Aircraft
Platform 2 in Clean Sky JU, 2015)

Total (multiplicative)

30% 38

36 Future aircraft in the ‘small’ class form an exception to this (accounting) rule.

37 Rolls Royce estimates its upcoming UltraFan, aiming for a bypass ratio of 15, to deliver a 25% fuel burn reduction compared to first-generation Trent-powerplants with

demonstration in 2025 (Norris, 2014; Thisdell, 2019; AIN Online, 2019). The fuel burn reduction of the Trent XWB with respect to the original Trent engine is 15%. Hence
the benefit of the upcoming Ultrafan is about 10 to 15% with respect to the Trent XWB, powering the Airbus A350.
38 As an example of the total (multiplicative) computation: here it has been computed as 1 - [ (100-18) × (100-15) / (100 × 100) × 100% ], representing consecutive
reductions.

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NLR-CR-2020-510 | February 2021

Small/medium twin aisle (SMTA)
The latest upcoming SMTA aircraft families introduced have been the Airbus A330-800/900 family (in 2020 and 2018)
replacing the Airbus A330-200/300 (with EIS in 1998, 1994), as well as the introduction of the Boeing 787-8/9/10 (in
2011, 2014 and 2018). Introduction of the new families is therefore expected between 2031 and 2040, leading to a
modelled EIS in 2035.
The assumptions for technology deployment and subsequent 30% fuel efficiency improvement on this generation of
SMTA aircraft are identical to the assumptions for the SA model. This is further detailed in Table 8.
Large twin aisle (LTA)
Latest introduction of families have been the Airbus A350 family (in 2015 and 2018) and the Boeing 777X family with
the B777-8/9 (expected in 2023 and 2021) replacing the Boeing 777-200ER/-300ER (EIS 1997 and 2004). Entry into
service of a future LTA-family is therefore modelled in 2040.
For this generation advances are modelled both in aircraft configuration and in propulsion, leading to an ultra-efficient
aircraft configuration with ultra-efficient propulsion, with optimised airframe integration. It is assumed that the
engine are compatible with 100% drop-in fuel. More specifically, major fuel efficiency improvements like hybridlaminar high aspect ratio wing, hybrid-laminar tail, further radical improvements to the UHBR engines, hybridisation of
APU functions, and further advanced carbon fibre reinforced fuselage with integrated modular cabin and
passenger/cargo flexibility are assumed.
Even though the technology is slightly different (e.g. hybrid-laminar rather than natural laminar flow technology), the
same fuel efficiency improvement as for the SA and SMTA models. Besides the technological differences it is taken
into account that the EIS of LTA is 5 years later than the EIS for SA/SMTA, which allows for further technology
development fully directed towards LTA, taking on the lessons learned from the SA/SMTA development. Overall it is
therefore expected that the fuel efficiency improvement of 30% (following Table 8) at aircraft level can also be
obtained for LTA.
Regional (R)
Aligned with industry statements made in press and industry reports (Warwick, 2019b; ERA, 2020) it is modelled that
hybrid-electric, distributed propulsion can be advanced to enter into service in 2035. This disruptive step in propulsion
is assumed to be integrated into a highly efficient aircraft configuration.
More specifically, it is assumed that the hybrid-electric, distributed propulsion is based on parallel hybrid engine
architecture. The thermal engines are sized optimally for cruise condition with batteries supplying additional power to
cover the peak power loads. This is a common hybrid electric architecture (e.g. Zill, et al., 2020). Additional propulsion
units are located at the wing tips. The airframe architecture includes an unswept, high aspect ratio wing, the landing
gear is fuselage mounted, and a V-tail is introduced, as in the PHA2-TipProp configuration in Strack, Chiozzotto,
Iwanizki, Plohr & Kuhn (2017), which is the most efficient configuration among many configurations studied in this
paper.
In terms of fuel efficiency improvement, Strack, Chiozzotto, Iwanizki, Plohr & Kuhn (2017), show a 40% reduction by a
turbo-electric turboprop aircraft with electrically driven propellers at the wing tips (a so-called TipProp configuration),
a design: range of about 1500 kilometres and a seating capacity of 70 passengers achieves, compared to technology
introduced into service in 2000. The reference turboprop aircraft has length of 27 metres, which is similar to the
length of the 70-seater aircraft ATR-72. The reduction of fuel efficiency due to airframe improvements is 12%; the
reduction of fuel efficiency due to engine improvements is 32%. The latest ATR-72 entered into service in 2011, with
improved engine technology with respect to the preceding ATR-72 version equipped with EIS 2000 technology.
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NLR-CR-2020-510 | February 2021

Assuming a 5% improvement from 2000 to 2011, the fuel efficiency of the TipProp configuration with respect a
modern turboprop aircraft is 37%. Noting the increased fuel efficiency of turboprop aircraft compared to regional jets
(ATR, 2018; Babikian, Lukachko, & Waitz, 2002; Ryerson & Hansen, 2010), of which the latter currently have a 45%
market share in terms of flights, a total fuel efficiency improvement of 50% is deemed achievable for the TipProp
configuration with respect to regional jets, consistent with the Clean Aviation Partnership (2020). Alternatively, if
payload capacity and/or range of this configuration are reduced (currently, 94% of the flights operated by aircraft in
the regional class is shorter than 1000 kilometres), larger reductions in fuel burn may be realised, for example due to
additional benefits of hybrid-electric propulsion. On the other hand, efficiency improvements might be slightly smaller
for regional aircraft seating more than 70 passengers. As such, a 50% fuel efficiency improvement is modelled for the
entire class.
Table 9: Modelled fuel efficiencies for future generation Regional aircraft, with respect to upcoming generation
Technology Regional
Major propulsion
technology (integrated)
Major airframe
technology
Total (multiplicative)

Potential fuel efficiency
improvement per flight
41%
15%

Remarks
Hybrid-electric turboprop (ATR, 2018; Babikian, Lukachko,
& Waitz, 2002; Ryerson & Hansen, 2010) using a TipProp
configuration (Strack, Chiozzotto, Iwanizki, Plohr, & Kuhn,
2017)

50%

Small (S)
These aircraft are modelled to use full electric concepts using propulsion based on hydrogen fuel cells, augmented
with advanced batteries. The larger and/or earliest aircraft in this class are assumed to use hybrid-electric technology
and bi-fuel concepts, allowing to switch between fuels.
The efficiency improvements anticipated in the regional class (50% lower fuel burn) from 2035 are foreseen to reach
possible conventionally powered (i.e. kerosene or drop-in SAF) aircraft in the smaller class five years earlier, in 2030.
Nevertheless, it is all but certain that a future generation small aircraft will draw its energy from (fossil or sustainable)
kerosene. A wide array of aircraft and propulsion concepts are currently being designed or developed for market entry
in the small class in the coming decade (ERA, 2020; McKinsey & Company, 2020), and many of the aircraft and
propulsion concepts for small aircraft put less stringent weight-related requirements on the technologies for the
smaller aircraft in the category than for larger aircraft. Such small aircraft developments may also become drivers for
the regional aircraft development later on.
Due to the impact of energy source on aircraft weight and total energy requirement, it is not possible to compare the
fuel (or: energy) efficiency of these alternatively-powered aircraft with current or upcoming models. Because of this,
the 99% reduction in CO2 emissions is modelled, to be achieved regardless of exact technology and fuel source. A
figure of 99% is used as it provides an achievable CO2 reduction potential, even if future small aircraft will be
kerosene-based. It is found by combining the 50% lower fuel burn (from the regional class) with 95 to 100% lower lifecycle emissions of SAF in 2050 39 (determined in Table 30 in Section 5.8.2). This introduced a small accounting
inconsistency, as the entire improvement is accounted for in the technology-pillar, even though some of this reduction
in CO2 emissions is attributable to alternative energy sources. Given the low contributions of small aircraft to CO2
emissions (≈ 1 %), it is considered immaterial. For that same reason, the slightly more simplistic modelling approach
(compared to regional and larger aircraft) is deemed sufficiently accurate.

39 As the future small aircraft will be modelled to enter into service in 2030, its fleet materiality in that year will be low. Considering the fact that after 2030, the results
are only modelled in the horizon year 2050, the life-cycle emissions of SAF in 2050 are deemed relevant.

38

NLR-CR-2020-510 | February 2021

Table 10: Modelled reduction of emission for future generation Small aircraft, with respect to upcoming generation
Technology Small

Total

3.3.3

Potential reduction of
CO2 emissions per flight

Remarks

99%

Numerous feasible propulsion technology options (e.g.
hybrid-electric, bi-fuel, hydrogen fuel cells and/or advanced
batteries). Energy-source independent estimate for CO2
emissions reduction potential, based on conventionally
powered aircraft (energy efficiency improvement as for
regional class, but entering into service five years prior) and
SAF (based on Section 5.8.2).

Hydrogen-powered aircraft

In addition to the kerosene-powered aircraft modelled in Section 3.3.2, possibly operated with substantial amounts of
SAF as discussed in Chapter 5, hydrogen-powered aircraft form another pathway to reducing CO2 emissions. As these
aircraft do not combust hydrocarbons, they do not emit CO2 at all.
This section goes into further detail. Section 3.3.3.1 defines the aircraft modelling parameters and discusses energy
demand. The associated supply of hydrogen is analysed in Section 3.3.3.2. Last, Section 3.3.3.3 discusses cost
implications – of both technology as well as energy supply.

3.3.3.1

Aircraft modelling

Fitting with renewed interest form both the aeronautical community as well as the energy industry, and largely based
on the aforementioned study into hydrogen-powered aviation conducted by McKinsey & Company (2020), a single
aisle (hybrid-) hydrogen-powered aircraft, capable of transporting 165 passengers over a range of 2000 kilometres 40,
is modelled for entry into service by 2035. This timeframe is consistent with the recently published Sustainable and
Smart Mobility Strategy (2020i).
In the modelling, its operational use is limited to intra-European flights below 2000 kilometres. Besides respecting the
range limitations of the aircraft, this also acknowledges that hydrogen availability and supporting infrastructure might
not be available outside the EU+ to the extent it is estimated to be inside the EU+.
HYDROGEN-POWERED AVIATION IN OTHER CLASSES
In addition to the potential for hydrogen-powered aircraft in the single aisle class, McKinsey & Company (2020) note
possibilities in other market segments – ranging from smaller commuter aircraft to large twin-aisle aircraft. For numerous
reasons, these are not modelled in this study 41.
For the larger aircraft classes, modelling by McKinsey & Company shows increased energy consumption and a higher cost
per available seat kilometre (compared to reference aircraft powered by sustainable aviation fuel). Both are trends in the
wrong direction. In addition, using hydrogen-powered aircraft for long-haul routes requires hydrogen availability and
associated infrastructure around the world. Non-European studies that foresee the introduction of hydrogen in aviation
substantially later (after 2050) show this global availability might not be realistic (Bruce, et al., 2020).

40 In September 2020, Airbus (2020c) revealed three zero-emission concept aircraft that use hydrogen as an energy source. This set includes a turbofan design capable of
transporting 120 to 200 passengers over a range of more than 2000 nautical miles (over 3500 kilometres). As detailed information about this concept, to the extent
documented by McKinsey & Company (2020) is not publicly available, the latter concept is used as basis for the modelling performed in this study.
41 Notwithstanding the facts presented and reiterating the substantial amount of uncertainty associated to estimating (especially longer-term) technology development,
the possibility of the introduction of hydrogen-powered aircraft in other classes is acknowledged.

39

NLR-CR-2020-510 | February 2021

That reasoning also partially applies to the aircraft in the smaller classes, often used to connect smaller airports, towns and
cities. Investments in infrastructure and fuel supply are likely to weigh heavier on smaller airports. Furthermore, due to the
lower share of CO2 emissions these aircraft contribute to (as shown in Section 3.1) and other decarbonization opportunities
(e.g. hybrid-electric propulsion), the introduction of a hydrogen-powered aircraft is considered here most likely for singleaisle aircraft.

Energy demand
The total demand for energy – in the form of liquid hydrogen – is computed by evaluating the energy efficiency
improvement compared to upcoming aircraft in the SA-class. For a 165-passenger mission of 2000 kilometres,
McKinsey & Company (2020) anticipate an energy demand of approximately 48 MWh 42. For an upcoming SA-aircraft,
which is used as reference for the future generation, the energy demand on a similar mission is estimated at about 75
MWh, yielding a difference of approximately 35%. This is slightly higher (7%, multiplicative) than estimates by
McKinsey & Company (2020), who note a 4% reduction in energy demand. This difference is partially explained by
possible uncertainties in the data retrieved from that study (notably with respect to the reference aircraft) and the
slightly reduced cruise Mach number 43 of the hydrogen-concept proposed by McKinsey & Company.
A NOTE ON ENERGY DENSITIES
The energy demand comparison in this section is expressed in units of energy (megawatt hour) rather than units of mass
(such as kilogrammes or tonnes). This is due to the fact that for each kilogramme, liquid hydrogen has 2.8 times the energy
content of a kilogramme of kerosene.

Taking the aforementioned energy efficiency improvement of 35% into account, the total energy demand for flights in
the market segment in which the hydrogen-SA aircraft is modelled (intra-EU+ flights below 2000 kilometres) is
computed to be 3.7 Mt of liquid hydrogen in 2050.

3.3.3.2

Hydrogen availability

Even though the future hydrogen-SA is modelled to enter into service in 2035, the availability of hydrogen is assessed
for both 2030 and 2050 based on multiple sources. This combination of assessments provides information about the
likely availability of hydrogen in 2035. Furthermore, this provides input to Chapter 5, in which hydrogen is used as a
feedstock for the production of synthetic sustainable aviation fuels through the power-to-liquid process.
HYDROGEN PRODUCTION PATHWAYS
Most hydrogen today is produced through steam methane reforming. This process is based on fossil feedstocks and
therefore not renewable. Efforts to switch to green hydrogen are observed in various States, although development will
require further time and effort. Of multiple renewable pathways, electrolysis is most relevant, as it shows the largest
potential of industrialisation.
Electrolysis breaks down water into hydrogen and oxygen by electricity. Electrolysers consist of an anode and a cathode
separated by an electrolyte. Four main types of electrolysers can be identified: Alkaline Electrolysis (AE), Proton Exchange
Membrane Electrolysis (PEM), Anion Exchange Membrane Electrolysis (AEM) and Solid Oxide Electrolysis (SOE). Alkaline
electrolysis has low installation costs, is commercially available, and has long life span, but requires high maintenance and is
not flexible with variable input power (Khalilpo, 2019). Proton Exchange Membrane Electrolysis is flexible with input power,
but has a short life span and is only seeing initial commercial application.

All studies referred to here, produce hydrogen through electrolysis using renewable electricity.
2030
“A hydrogen strategy for a climate-neutral Europe” by the EC sets out a strategic objective for the production of
hydrogen in the EU (EC, 2020b) and the study “Opportunities arising from the inclusion of Hydrogen Energy

42 Based on a tank weight of 4 tonnes, a gravimetry index of 35% and an energy density of LH

2 of 34 kWh per kilogramme (4 × 0.35 × 34 = 47.6 MWh).
43 McKinsey & Company (2020) foresees a cruise Mach number of 0.72, whereas current aircraft in the SA class generally cruise around Mach 0.78.

40

NLR-CR-2020-510 | February 2021

Technologies in the National Energy & Climate Plans” (Trinomics, 2020) commissioned by the Fuel Cells and Hydrogen
2 Joint Undertaking (FCH 2 JU) estimates the amount of hydrogen demand based on a low and high scenario analysis.
Both do so for 2030.
EC (2020b) sets out a strategic objective to produce 10 Mt (equal to 333 TWh) of renewable hydrogen 44 in the EU by
2030. The EC plans are backed-up by the plans laid out by Hydrogen Europe, an industry initiative, which presented
the vision to install 40 GW of electrolyser capacity in the EU and 40 GW in North Africa and Ukraine by 2030 45. Van
Wijk & Chatzimarkakis (2020) foresee an infrastructure connection with North Africa and Ukraine to import around
3 Mt of renewable hydrogen by pipeline 46. EC (2018c, p. 87) highlights that “hydrogen and e-fuels could actually be
globally traded commodities and imported from regions with comparatively cheaper, abundant renewables”. At the
same time however, the EU aims to increase its energy independence.
The strategic objective by the EC (2020b) foresees that in total 13 Mt of renewable hydrogen is available based on EU
production in combination with imports. This hydrogen can be used by industry, transport, power and buildings
sectors. Division between sectors is not specified in the EC strategy. On the other hand, Trinomics (2020) estimates
renewable hydrogen demand in 2030 will range between 24 TWhH2 per year in the low scenario and almost 106 TWhH2
per year in a high scenario. This would be equal to a range between 0.7 Mt and 3.2 Mt. Both scenarios assume the
hydrogen is produced in the EU: no imports are considered.
The two studies show that there is a substantial difference between the strategic objective set out by the EU (13 Mt)
and the estimated demand based on the FCH 2 JU study (1.9 Mt on average). The amount of hydrogen produced in
the EU used in the modelling is calculated as the average of these two figures (5.95 Mt). In order to ensure a
consistent ambition level with respect to the amount of hydrogen available for import, the aforementioned 3 Mt is
scaled by that same factor 47 to arrive at 1.8 Mt. This leads to a total hydrogen availability of 7.8 Mt in 2030.
The amount of hydrogen available for aviation is estimated by first considering the share allocated to transport and
then by further specifying the share for aviation. Trinomics (2020) estimates the share for transport will lie between
30 and 43% in 2030 with aviation using between 11 and 35% of this amount. By taking the averages of these ranges
the total amount available for aviation would be 8% in 2030, equal to 0.65 Mt.
2050
According to the study “Opportunities arising from the inclusion of Hydrogen Energy Technologies in the National
Energy & Climate Plans” commissioned by the FCH 2 JU (Trinomics, 2020), the 1.5 LIFE and 1.5 TECH scenarios assume
a hydrogen consumption of 68 to 76 Mt in 2050. According to the ASSET-study “Hydrogen generation in EuropeOverview of costs and key benefits” for the EC (Cihlar, et al., 2020), hydrogen production could range between 20 and
120 Mt in 2050. The higher value would correspond to 500 GW of electrolyser capacity.
Averaging both sources, the amount of renewable hydrogen produced in the EU is estimated at 71 Mt in 2050. The
share of imported hydrogen is assumed to remain constant between 2030 and 2050. The amount is therefore scaled
up based on the increase in EU production. This would result in 21 Mt of imported hydrogen (23% of total). By 2050,
92 Mt of hydrogen are therefore available based on EU production and imports combined.

44 This would be achieved by directly connecting renewable electricity to the electrolysers, or by ensuring that certain conditions are met, including the additionality of

the renewable electricity used.

45 The Hydrogen Europe paper differs from the EC vision in the amount of hydrogen produced in the EU based on the installed electrolyser capacity, it assumes that 4.4

Mt (equal to 173 TWh) can be produced based on the 40 GW electrolyser capacity.

46 Of the 40 GW of capacity installed in North Africa and Ukraine, 32.5 GW would be built for the export market.
47 5.95 / 10, or 59.5%.

41

NLR-CR-2020-510 | February 2021

The 1.5 LIFE and 1.5 TECH scenarios presented by Trinomics (2020) assume that the transport sector will consume
between 38% and 42% of the total amount of hydrogen. On average this would result in 40% of the hydrogen being
allocated to the transport sector by 2050. Assuming the hydrogen will be equally divided between road, maritime and
aviation, it would lead to 13% being delivered to aviation, equal to 12.3 Mt.

3.3.3.3

Cost implications

The cost implications of a hydrogen-powered aircraft materialise in two ways. First, there is the cost of hydrogen
itself. Second, there are cost impacts that follow from the characteristics of the hydrogen-SA aircraft as modelled in
this study. Based on the combination of these two, the CO2 abatement cost of the hydrogen-SA aircraft can be
computed.
Hydrogen production cost
The expected production costs of renewable hydrogen including liquefaction, based on a number of sources, are
shown in Table 11. Costs strongly depend on renewable electricity prices. As the data shows, prices are generally
expected to reduce over time.
Producing hydrogen outside of Europe, where renewable energy is available at lower prices, may significantly lower
the costs. To produce large amounts of hydrogen for fuel, the renewable electricity should come for additional
installations specifically built to supply fuel factories. The prices will vary depending on the type of installation and the
geographical location.
Table 11: Renewable liquid hydrogen minimum selling prices based on multiple sources in 2030 and 2050
Year
2030
2030
2030
2030
2050
2050
2050
2050

Source
Trinomics (2020)
McKinsey & Company (2020)
McKinsey & Company (2020)
Van Wijk & Chatzimarkakis (2020)
McKinsey & Company (2020)
McKinsey & Company (2020)
Van Wijk & Chatzimarkakis (2020)
International Energy Agency (2020)

Scope
EU
EU
import
EU + import
EU
import
EU + import
Global

Production cost of renewable LH2 (€/kg)
5.5
3.1
2.8
2.2
2.0
1.8
1.8
2.7

The minimum selling price of liquid hydrogen is 2050 is estimated based on the production costs given by the three
sources in Table 11. Averaging the cost of hydrogen produced in the EU (taking up a share of 85%) and imported from
McKinsey & Company (2020), EU-produced and imported hydrogen (from van Wijk & Chatzimarkakis, 2020) and
globally-produced hydrogen (International Energy Agency, 2020), an average price of € 2200 per tonne in 2050 is
determined 48. The production process for renewable hydrogen is assumed fully carbon neutral by 2050.
Technology cost
Explicitly associated to the switch to hydrogen technology, McKinsey & Company (2020) foresee a 31% increase in
aircraft capital expenditure (cost of the tank structure, fuel distribution and larger fuselage) and 47% increase in
maintenance cost (due to the larger fuselage). Longer refuelling times are likely to cause 7% less flight cycles. In
addition, the reduced seating capacity (165) compared to the average capacity of SA-aircraft operating flights below

48 It should be noted that large investments in new infrastructure are needed, such as refuelling trucks, ships or pipeline including on-site liquefaction facilities or on-site
production and storage of liquid hydrogen.

42

NLR-CR-2020-510 | February 2021

2000 kilometres (187, based on year 2050) decreases productivity 49 by approximately 12%. As the aircraft is modelled
to be used on shorter flights, the slightly lower cruise speed (Mach 0.72 versus Mach 0.78), is not estimated to have a
material effect on productivity. The combined decrease in productivity is 18%.
Using the average cost per available seat kilometre of current single aisle aircraft (Airbus A320 and Boeing 737 Next
Generation) reported to the IATA Aircraft Cost Management Group as baseline (IATA, 2019b), Table 12 shows how the
aforementioned cost increases for the hydrogen-SA in different steps. First, changes in CAPEX, MRO and (lower)
productivity yield an increase of 1.3 cents per ASK, or 26%. Second, including the costs associated to switching the
energy carrier from kerosene to LH2 yield a further increase of 14%, following from the price difference between liquid
hydrogen and fossil kerosene (€ 2200 versus € 690 per tonne) and the higher energy density of liquid hydrogen (120
MJ/kg LHV versus 43 MJ/kg) 50. The multiplicative cost change is then determined to be slightly above 1.6 cents per ASK,
equivalent to 31% of reference CASK.
Table 12: Cost per available seat kilometre for hydrogen-SA, excluding and including the influence of energy carrier
(2050 LH2 prices) on fuel and oil cost (based on McKinsey & Company, 2020; IATA, 2019b; van Wijk & Chatzimarkakis,
2020; International Energy Agency, 2020)
CASK-factor
Fuel and Oil
Aircraft Ownership
Maintenance and
Overhaul
Flight Deck Crew
Flight Equipment
Insurance
Air Navigation
Charges
Airport Charges
Station and Ground
Total
Difference

Current CASK
(737NG / A320)
€ 0.0194
€ 0.0092
€ 0.0083
€ 0.0057
€ 0.0001
€ 0.0027
€ 0.0042
€ 0.0031
€ 0.0527

Changes due to
CAPEX and
Productivity
MRO
+ 31%
(€0.0029)
+ 47%
(€0.0039)

+ 18%
(€ 0.0022)
+ 18%
(€ 0.0022)
+ 18%
(€ 0.0010)
+ 18%
(€ 0.0000)
+ 18%
(€ 0.0005)
+ 18%
(€ 0.0007)

HydrogenSA CASK,
excl. LH2
€ 0.0194

Changes due
to energy
carrier (LH2)
+ 14 %
(€ 0.0027)

HydrogenSA CASK,
incl. LH2
€ 0.0221

€ 0.0143

€ 0.0143

€ 0.0145

€ 0.0145

€ 0.0067

€ 0.0067

€ 0.0001

€ 0.0001

€ 0.0032

€ 0.0032

€ 0.0049
€ 0.0031
€ 0.0661
+ € 0.0134
(+ 26%)

€ 0.0049
€ 0.0031
€ 0.0688
+ € 0.0162
(+ 31%)

CO2 abatement cost
Based on the cost difference per ASK (from Table 12) and CO2 emissions per ASK for the relevant market segment and
timeframe (intra-EU+ flights below 2000 kilometres in 2050; 72 gram) the CO2 abatement cost of hydrogen as used in
this study is estimated here to be equal to approximately € 225 per tonne 51.

49 Productivity refers to the amount of ‘product’ that is produced by an aircraft per unit of time. This is customarily expressed in seat-kilometres per unit of time, and
hence a product of seating capacity and speed.
50 This means that the energy content of one tonne of kerosene in LH form costs €2200 × 120/43 = €790.
2
51 With 72 gCO /ASK, ‘producing’ one tonne of CO requires 1000 / 0.072 = 13,900 ASK. Multiplied with the cost differences yields 13,900 × €0.0162 = €225.
2
2

43

NLR-CR-2020-510 | February 2021

3.3.4

Potential impact overview

Whereas Table 5 presented the potential impact of specific upcoming aircraft types and Table 6 detailed this
information at a class-level, Table 13 shows the potential impact of future aircraft. This table combines previously
presented information in Section 3.3. The overview shows substantial fuel efficiency improvements and CO2 emissions
reduction to be delivered by aircraft modelled to first enter into service between 2030 and 2040.
‘BEYOND FUTURE’ AIRCRAFT
If research and innovation in technology and aircraft development will continue, the second half of this century will see the
introduction of even more advanced ‘beyond future’ types. These will someday replace the aircraft modelled in this section.
As this study investigates CO2 emission reductions in 2030 and 2050, such aircraft types are however not treated in this
report: given the 20 to 25 year production cycles identified earlier would mean that such ‘beyond future’ aircraft would
enter into service between 2050 and 2065 and thereby would not be able to affect 2050 CO2 emissions.
Fleet replacement – through which new technologies are brought into operational use – will of course continue in the years
following initial entry into service. As such, new aircraft are delivered each year, realising further fuel efficiency
improvements and emission reductions.

As stated in the introduction to Section 3.3.2, this chapter primarily investigates technologically-driven improvements
in fuel efficiency (i.e., reductions in energy demand). These are expressed relative to the performance of upcoming
aircraft (presented in Section 3.2). The use of SAF, discussed in Chapter 5, can yield further CO2 emissions reduction.
This also means that the potential additional SAF-related emissions saving is accounted for under the SAF-pillar.
The aircraft in the small class as well as the hydrogen-SA form an exception to this rule. As the fuel efficiency
improvement is unsure due to its dependency on the technology pathway (in case of the small aircraft, further
explained in Section 3.3.2) or the technology necessitates the use of non-fossil fuels (in case of the hydrogen-SA),
Table 13 reports the full CO2 emissions reduction potential. These savings are therefore also accounted for in the
aircraft and engine technology pillar.
Table 13: Estimates on future aircraft technologies, EIS, energy efficiency improvement (per flight) and CO2 emissions
reduction (per flight) for impact modelling. Effects of alternative energy sources only included for ‘Small’ and
‘Hydrogen-SA’ aircraft. Further CO2 emissions reduction for other classes, based on the use of drop-in SAF, is treated in
Chapter 5.
Class

Small (S)

Regional
(R)

SA

Energy
efficiency
improvement

CO2
emissions
reduction

N.A.

99%

EIS

Major technologies

2030

Hybrid-electric and bi-fuel concepts.
Possible full electric propulsion
concepts based on hydrogen fuel cells
and/or advanced batteries.

2035

Hybrid-electric, distributed propulsion
coupled with highly efficient aircraft
configuration

50%

2035

Advanced ultra-efficient aircraft
configuration and ultra-efficient thermal
engines, ultra-high bypass (possibly
open rotor)

30%

Remarks

50% (excl.
reduction due
to drop-in
SAF)
30% (excl.
reduction due
to drop-in
SAF)

44

NLR-CR-2020-510 | February 2021

Class

HydrogenSA

EIS

Major technologies

2035

SMTA

2035

LTA

2040

3.4

High-efficient hydrogen(-hybrid)
Advanced ultra-efficient aircraft
configuration and ultra-efficient thermal
engines, ultra-high bypass (possibly
open rotor)
Advanced ultra-efficient aircraft
configuration, ultra-efficient propulsion
using drop-in SAF with optimised
airframe integration, hybrid APU.

Energy
efficiency
improvement
35%

30%

30%

CO2
emissions
reduction
100%

Remarks
165 passengers,
2000 km range,
31% higher CASK
(excl. LH2-cost).

30% (excl.
reduction due
to drop-in
SAF)
30% (excl.
reduction due
to drop-in
SAF)

Drivers and barriers

Following the industry characteristics discussed in Section 1.1 and various remarks on technology development in the
previous section, the present treats some of the important drivers and barriers influencing the development and
adoption of new aircraft technology.

3.4.1

Drivers

An increased focus on reducing fuel consumption and environmental impacts is an important driver. The fact that fuelburn reducing technologies generally also yield reductions in operating costs supports this driver from a more
business-oriented perspective.
Strong focus on research and innovation
Europe has a strong collaboration network in research and innovation, also towards high technology readiness levels.
In various past and current programmes, projects aim to develop innovative technologies for improving performance
– notably in terms of fuel efficiency. Technologies developed in Clean Sky and Clean Sky 2, for example, provide a solid
basis for maturation, integration and further expansion for focused needs not covered yet. As such programmes
reduce the risk of technology development, they increase the speed of research and innovation and help to rapidly get
technology to the market. This provides a firm basis for the challenges ahead.
The higher TRL research and development is supported by a more fundamental research infrastructure. Numerous
facilities and methods are available across Europe in which new technologies can be assessed and optimised at
affordable cost as well as demonstrated – if the technologies reach that stage. This includes low and high fidelity
simulation, multidisciplinary analysis and optimisation, ground testing, large-scale integrated ground test
demonstrators, and scaled as well as full-scale flight testing.
The recently proposed European Partnership for Clean Aviation encompasses the entire aforementioned
infrastructure and orients it towards the development of the aircraft and engine technologies required for
decarbonising aviation. Its timeline – delivering the results in 2027 – aligns very well with the anticipated entry-into45

NLR-CR-2020-510 | February 2021

service dates of the aircraft modelled in this study. This is a major driver towards quick adoption of the latest available
innovations.
Cross-pollination inside and out
The fact that aircraft of different weight and size classes are able to share technologies is a major driver. It both
reduces development risk – as investments can be recuperated over a larger number of products – and enables
simultaneous innovation on multiple fronts. Even if particular technologies are not directly interchangeable,
knowledge gained during development of one such technology supports the development of others.
In addition to cross-links between developments for different aircraft families, aviation can benefit from
developments elsewhere. Emerging technologies in other sectors such as sustainable fuels, battery technology, fuel
cell technology, and hydrogen technology have large potential for reduction of emissions in these other sectors, with
hydrogen even offering zero carbon emission during flight. Driving forces in these sectors are also driving towards
their application in aircraft, keeping in mind that the aircraft requirements typically are quite different and more
challenging (for example, electric batteries used in road vehicles might be too heavy for direct use in aircraft
propulsion). It undeniably stimulates R&D in these areas.
Potential first mover advantage
Tightly linked to the Partnership for Clean Aviation mentioned before, Europe and its aviation industry are seen to be
well-equipped to take the lead in the development of more efficient aircraft. When the focus on decarbonisation
increases in other parts of the world, this leading position presents a major competitive advantage for European
manufacturers and supporting value chains.
Ambitious European hydrogen strategy
The ambitious European hydrogen strategy is a key factor enabling the introduction of hydrogen-powered aircraft.
The expected cost reduction in renewable electricity prices and electrolyser technology will enable the upscaling of
the hydrogen economy and make renewable hydrogen cost-competitive with fossil-based energy sources. The
application of large amounts of hydrogen in all sectors of the economy will enable further cost reductions in terms of
infrastructure and standardization. For aviation, the CO2 abatement costs of hydrogen are estimated to be cost
competitive with other technologies. Additionally, combusting hydrogen rather than kerosene reduces the emissions
of sulphates, particulate matter and nitrogen oxides leading to co-benefits in terms of improving air quality around
airports and reducing non-CO2 effects.

3.4.2

Barriers

The drivers mentioned in Section 3.4.1 are factors that stimulate the development and market penetration of new
technology; the challenges described here make this more difficult. Although these are split into a number of groups,
they are primarily caused by one and the same aspect: the high levels of complexity of both individual products as well
as of the aviation system at large.
Interdependencies
A primary consequence (if not inherent characteristic) of this complexity are numerous interdependencies. Design
improvements yielding benefits in terms of fuel efficiency and CO2 emissions might have adverse effects elsewhere if
these are not properly mitigated. Or put differently: additional efforts are required to improve fuel efficiency while at
the same time meeting design requirements with respect to other performance characteristics (e.g., range, noise,
NOX), safety, total cost of ownership, crew working environment and passenger experience. For hydrogen, the effect
of hydrogen combustion on non-CO2 emissions and their related climate impact (not considered in this study) are
46

NLR-CR-2020-510 | February 2021

relevant items of further research, in addition to improving understanding of the effects of its implementation on
aircraft design and operation, and airport infrastructure.
In addition to the challenge of meeting possibly conflicting goals in the design and development of an aircraft, the
resulting product and infrastructure are heavily integrated. Whereas hydrogen-based propulsion allows achieving
significant reductions in aircraft emissions, it not only requires a significant aircraft redesign but also needs changes to
airport infrastructure and maintenance equipment. Amplified by the fact that the previous sixty years were spent on
optimising the air transport system as it exists today, there is substantial lock-in.
High levels of risk and cost
Combining the dependency on and impact of external developments with the previously discussed capital intensity
and long time horizon of the industry (Section 1.1) rapid large-scale innovation requires excellent mastering of the
development risks. Funds, required for either technology R&D, product development, product acquisition or
infrastructure building, can only be committed gradually with reduction of uncertainties in external trend estimates
spanning years or decades into the future. The fact that it takes many years for aircraft programmes to break even
further contributes to relatively long periods between multiple generations of aircraft – as new investments may be
limited until a previous one has been largely recouped.
Certification uncertainties
Linked to the problem of determining the suitability of particular technologies is the question of certifiability. There is
a long tradition of certification of aircraft with new technologies, which has led to very low safety risk. Both parties
have to learn about the new technologies in parallel: aircraft and engine manufactures (and their supply chains) aim to
develop certifiable designs, whereas certification authorities develop certification rules and means of compliance that
may depend on the design choices of the aircraft and engine manufacturers. This issue is also noted by Bruce and
Spinardi (2018), who state that knowledge lock-in is one of the key barriers to innovation in aircraft design.
Certification is a costly and lengthy process that can only be changed without compromising safety.
Certification is even more challenging with the introduction of new, disruptive technologies such as (hybrid)-electric
propulsion and hydrogen-powered aircraft. The first actions to overcome the potential barrier have already been
taken with the establishment of EUROCAE working groups WG80 “Hydrogen and Fuel Cells” and WG113 “HybridElectric Propulsion”. This way, factors currently acting as a barrier towards technology uptake, such as uncertainty
with respect to certification, can be turned into a driver – if certification standards are in place, technology
development can become more focused and more effective.

3.5

Policies and actions

The previous sections discussed the market implementation of numerous readily available or upcoming aircraft types,
as well as the development of a next generation of aircraft with the potential of making significant contributions
towards decarbonising aviation. However, as stressed by especially the challenges listed in Section 3.4.2, these will not
simply manifest themselves. Policies (Section 3.5.1) from governments and actions (Section 3.5.2) from sector parties
alike are required to make the potential identified a reality.
The sections both treat upcoming (EIS up to 2025) and future (EIS beyond 2025) aircraft. Given the fact that the
upcoming aircraft treated in Section 3.2 are – or will soon be – available for purchase, their fate is mostly in the hands
of airplane operators. On the other hand, R&D-stimuli can play a decisive role in the development and maturation of
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future technology. As such, the policies are predominantly geared towards future technology, whereas the actions
mostly concern upcoming aircraft.

3.5.1

Policies

Research and development and supporting stimulus programmes
With new aircraft programmes ahead in the 2030s, Europe now has the opportunity to position itself as the global
leader to reduce the impact of aviation on the climate change with competitive products.
To achieve the predicted impact, coordinated and collaborative European policy is needed to have technology ready
for adoption in aircraft development programmes five years before the modelled entry-into-service. As Bruce and
Spinardi (2018, p. 43) write, “we need policy initiatives targeted towards the knowledge practices of specific sectors.
In the case of aviation, funding basic R&D seems futile unless it is accompanied by support for operational
implementation that addresses the risk-adverse nature of the industry by building a knowledge base with regard to
commercial viability and reliability”, pointing to examples of military sponsorship of carbon fibre application or
“specific environmental and efficiency-orientated programmes”. In the civil European context, this suggests to have
stimulus programmes for environment and efficiency, specifically oriented on aviation.
A stimulus programme with a clear focus towards achieving this technology readiness is proposed in the Strategic
Research and Innovation Agenda by the proposed European Partnership on Clean Aviation (Clean Aviation
Partnership, 2020). Three key thrusts for R&I efforts are identified, all addressing innovation in aircraft architectures
and engines:
•

Hybrid electric and full electric architectures

•

Ultra-efficient aircraft architectures to address the short, medium and long range needs

•

Disruptive technologies to enable hydrogen-powered aircraft

The aircraft categories selected for demonstration in the programme are the regional aircraft and the short-medium
range aircraft with key technologies and architectures and EIS as modelled in Table 13. For other aircraft segments
(small aircraft and long range aircraft), the impact of Clean Aviation is expected via scaling and transfer of technology.
Fitting with the barriers identified in Section 3.3.2, policies should aim to reducing uncertainty and risk. Uncertainty
stimulates risk-averse behaviour, whereas an innovative and entrepreneurial mindset should be stimulated and
nurtured.
Supporting the disruptive developments in Clean Aviation, a clear policy is needed with respect to the certification of
the disruptive technologies that are investigated to overcome the barrier of certification uncertainty. Virtual
certification, exploring digital methods in combination with physical testing, can reduce the cost and time for
development, validation, and certification, while maintaining or improving the safety (Clean Aviation Partnership,
2020, Section 2.8).
Research and Technology Infrastructures are essential to test and validate new technologies and platforms. Recently,
a EU funded study found that a large increase of investments into RIs is required for the EU to remain competitive
with other countries such as USA and China (RINGO, 2020). Additional funding is also required to be used for
enhanced collaboration and providing access to existing facilities.

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While Clean Aviation is focusing on the technologies for the low-emission aircraft concepts, another stimulus
programme, a Collaborative Research programme will have to address the following (Clean Aviation Partnership,
2020, Annex):
•

Breakthrough technologies towards zero-emission aiming at potential technologies for the next aircraft
generation and disruptive technologies for long term products (EIS from 2035)

•

Transverse technology enablers to have the means to accelerate an affordable decarbonisation by leveraging
all steps of the product lifecycle from early trade-offs up to certified operational aircraft joining the fleet.

Stimulus programmes, which might receive partial or additional funding from proceeds of the EU-ETS, should cover
the entire innovation chain, having a tailor made approach to each phase of the chain. One must fund new, disruptive,
low-TRL ideas as well as applied and more industrial research. The right framework conditions must be in place:
funding intensity should be appropriate, and the right parties, facilities and expertise should be involved. In an
innovation funnel approach, in the beginning a larger number of smaller projects should be funded to investigate
potential solutions. Selecting the most appropriate solutions, the number of projects will reduce. The depth of the
research and the corresponding funding intensity per project will increase. Especially the development of first-of-akind innovative hydrogen technologies is relevant. The EC indeed indicated such efforts might be supported by the EUETS Innovation Fund (EC, 2020e).
While the medium and long range aircraft segments provide the bulk of improvement potential identified in this
report, it is important that research activities related to electrification are maintained and where possible, enhanced.
This includes, amongst others, the understanding of implications of electrification on airport infrastructure (e.g. in
terms of charging and/or battery swapping capabilities). In a similar way, the large-scale future introduction of
hydrogen for aircraft propulsion will also likely require major infrastructural changes at airports. It is important to
understand these implications – not in the least from a more holistic sustainability perspective, and include them into
the above mentioned stimulus programmes.
In addition to policies focused on technology development, policies supportive of SAF need to be put in place in a
coordinated manner. Coherency between SAF and propulsion developments and investments need to be maintained,
including enabling a 100% blending limit for drop-in SAF (discussed in Section 5.10.2) and the introduction of
hydrogen.
There are relevant potential connections with other preparations for Horizon Europe to be made for better
coordination and exploitation of results (spin-in/spin-off). For example, the Fuel Cell and Hydrogen Joint Undertaking
may clearly link to the hydrogen thrust of Clean Aviation. The Circular Economy Action Plan, one of the main blocks of
the European Green Deal, is also a relevant link. Whereas Clean Aviation addresses the emissions due to the
operations of aircraft, also opportunities to further improve the ecological footprint of the aircraft lifecycle from
production to recycling should be explored. This is just one of the potential links with the proposed Made In Europe
partnership. Furthermore, coordination with national and regional programmes, as already initiated in Clean Sky 2, is
needed for complementing the strong European R&D stimulus programmes.
Technology uptake and operational implementation
As the potential improvements of new technologies will only contribute to reducing CO2 emissions when they are
fitted on aircraft which enter the market, it is the crucial responsibility of industry actors to develop these products
and implement them into their fleets. Although these are and should remain business decisions, various government
policies can support technology uptake.

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This report does not assume an increased rate of fleet renewal, but adheres to the historical average of 22.5 years.
Nevertheless, to possibly reduce this, or ensure fleet renewal is not slowed, regulatory factors can push deployment
of technology, or reduce business case uncertainty associated with the introduction of new aircraft.
This can take various forms, driven by both government policy as well as industry actions (treated in Section 3.5.2). In
the former category, options include but are not limited to opportunities to enable emission-based airport slot
assignment, sustainability requirements for public service obligation routes, and CO2 emissions standards targeting
engine and aircraft manufacturers. The 2016 ICAO CO2 standard for subsonic aircraft, which applies to new aircraft
types from 2020 onwards, should be rapidly adopted in national or European regulations. Recent research shows “the
CO2 standard at its current stringency is unlikely to promote additional fuel burn reductions beyond what industry has
already accomplished” (Zheng & Rutherford, 2020, p. 15), suggesting that the standard furthermore needs to be made
more stringent in order to be consistent with a net zero 2050 pathway. Extending this standard to in-service aircraft is
expected to be effective in phasing out the most inefficient aircraft in the current fleet, but is a rather extreme
measure. Incentives to ‘early retire’ older in-service aircraft and replace these with newer, more fuel-efficient aircraft,
can also be used 52.
Further research and analysis is required to determine which (combination) best achieves the intended goal, ensuring
the implemented policies cannot be circumvented. In addition to the more rapid uptake of entirely new technologies,
such regulatory factors can further stimulate the development of retrofits and product updates to in-service aircraft.
This has yielded success in the past regarding noise (e.g., the development and installation of hush kits).
Besides these stimuli, policies should be put in place to standardise and promote the availability of new infrastructure
to support more disruptive types of aircraft. As further elaborated in Section 4.6, this includes charging facilities at
airports using renewable electricity as well as infrastructure for storage and distribution of hydrogen. Again, this
should go hand-in-hand with technology development. This way, progress in terms of infrastructure development will
reduce market uncertainty required for the necessary investments in technology, and vice versa.
Last, especially as development and production processes change or new technologies and concepts are incorporated
into commercial products, up-skilling and re-skilling of the European workforce is likely to be required. Governments
can play an important role in supporting this.

3.5.2

Actions

In addition to supporting policies from government and regulators, there are numerous actions to be taken by the
industry itself.
A step up in R&D and stimulus programmes
Aligned with the European policies for stimulus programmes, the industry should invest in these stimulus
programmes. In Clean Aviation, this will be as partner in the proposed Partnership for Clean Aviation; for the
Collaborative Research programme the industry participation should contribute to the exploitability of the project
results. Given the focus on technology development of these programmes, engine and aircraft manufacturers and
their supply chains are in the position to take a key role. Airport operators can fulfil an important role in ensuring the
development of possibly different infrastructure and handling that suit the needs of future aircraft.

52 As explained at the end of Section 3.5.2, such a measure is not included in the modelling performed.

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In Clean Aviation, the industry should take the lead in the technical execution of the work to achieve the predicted
impact on aircraft level, taking into account that these impacts only materialise when the technology is introduced in
aircraft that enter the market. The industry should therefore keep sufficient focus in the Clean Aviation programme
towards achieving the technology readiness for adoption in aircraft development programmes.
Key attention should also go out to the development of the (technology required for) hydrogen-powered aircraft
foreseen to enter into service from 2035 on select intra-EU+ flights. Although some test flights have been made using
hydrogen as aircraft propellant in the past, operational application in a commercial aircraft would be a world’s first.
Aircraft technology research topics include safe and efficient storage of liquid hydrogen and distribution throughout
the aircraft, fuel cell systems and hydrogen turbines. In terms of aviation infrastructure, refuelling systems need to
developed and operational implementation has to be thought through.
Research establishments and academia should take the lead in providing innovative technological solutions as well in
the stimulus programmes, based on their extensive knowledge and proven innovation capabilities. This contributes to
the progress through the lower TRL level. In addition, they should contribute with methods and facilities for reaching
the highest TRL levels, for which the methods and facilities need to be innovated to the level needed for the disruptive
aircraft and engine technologies and configurations.
Progress in TRL levels should be shown on demonstrators showing the appropriate industrial level of integration.
Ground demonstrators will be developed at various scales, sizes, and levels of representativeness, including wind
tunnel tests. In-flight demonstrator should be developed as well as scaled flight tests, flying test beds, and flight
demonstrators. Virtual demonstrators, combined with physical demonstrators, should be exploited as well.
New business models should be investigated to the earliest affordable introduction of emission-reducing technologies.
This also includes opportunities for product enhancements and retrofits based on past technology development in
Horizon 2020 (including Clean Sky 2) and Clean Aviation. New business models should also be investigated in view of
potential disruptive changes to the traffic scenario due to the increase of traffic demand, such as more direct
connections with smaller aircraft or carrying out the same flight with larger aircraft.
Besides policies that coordinate efforts in technology and (drop-in and non-drop-in) SAF development, industry
actions should also keep an aligned connection. Specifically, aircraft and engine manufacturers should guarantee their
products can safely and efficiently support blending levels of up to 100%.
Technology uptake and operational implementation
Following lower-TRL research and development efforts, industry should primarily ensure the latest available
technology is transferred from testing facilities to the operational environment. As highlighted in Section 3.4.1, the
timeline proposed in the Clean Aviation programme aligns very well with market uptake in the timeframe adhered to
in this study. In order to speed up the product development cycle, industry should remain focused on the further
maturation of technologies as high-fidelity simulation and scaled flight testing. With the involvement of the
authorities, regulations can be adopted towards the use of such technologies, in order to contribute to accelerated
certification, without compromising safety.
In addition to bringing to market new technologies, aircraft and engine manufacturers might re-evaluate results from
previous applied R&D-projects, such as Clean Sky and Clean Sky 2. Given the increased climate ambition, higher
societal awareness and growing cost of carbon abatement, the business case for commercialisation might today be
different from when innovations were shelved. This not only holds for technology developed earlier, but also for
newer innovations – that should be made available for retrofitting or other forms of performance improvement
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programmes for in-production aircraft. This way, relevant developments from partially publicly-funded programmes
can also deliver benefits for European travellers and citizens.
For European operators and manufacturers in concert, it might be worthwhile to explore opportunities of developing
derivative designs specifically suited for the European market. The hydrogen-powered single aisle aircraft anticipated
in this report and designed for a range of 2,000 kilometre is a key example of this. Although the performance of
current aircraft used on intra-European routes makes it possible to deploy these aircraft flexibly and allows
manufacturers to sell them in larger quantities, it also adds weight and thereby reduces efficiency.
Looking further ahead, and aligning with policy recommendations in this area discussed in Section 3.5.1,
manufacturers should contribute to standards for, for example, connectors for electric charging, the design of
interchangeable battery packs and hydrogen-refuelling infrastructure. Airport operators should furthermore ensure
the availability of relevant infrastructure for these novel concepts, once these requirements have been identified –
requiring joint efforts by airports, operators, aircraft manufacturers and other parties involved in the ground handling
process. In a shorter term, they can – together with regulators – explore the possibilities of using locally CO2
modulated airport landing charges 53 in order to financially incentivise operators to use aircraft types with lower CO2
emissions while maintaining level playing field and avoid traffic displacement to airports with different policies.
Fleet renewal
Once new technologies are incorporated into aircraft products, operators are the ones to bring these types into
service. Based on historically observed trends, this study models replacement of individual aircraft takes place 22.5
years after they were delivered to their first customer. In order to realise the contribution that improvements in
aircraft and engine technology are projected to make to decarbonising European aviation, this fleet renewal rate
should be maintained.
EARLY FLEET RENEWAL
Numerous parties have pointed to the COVID-19 crisis as an opportunity for retiring older airframes form service early, as
capacity is strongly reduced (Aviation Round Table, 2020; Saeed, 2020). Indeed, various operators around the world have
done so (Pallini, 2020; ICF & Petchenik, 2020; Falcus, 2020; Broderick, Massy-Beresford, Schofield, Flottau, & Goldstein,
2020). By reducing fleets to the most modern and most fuel-efficient aircraft, fuel cost and CO2 emissions can be quickly
reduced.
Notwithstanding this possibility of realising emissions reductions in the short term, this study does not specifically address
the effect of such a measure. The reason for this follows from choices made concerning the project scope, which evaluates
emission reductions in 2030 and 2050, and not the intermediate years. Given the average airframe retirement age of 22.5
years, 2030 estimates of CO2 emissions would only be affected if airframes that are younger than 12.5 years in 2020 would
be ‘early retired’. Put differently: removing currently 15-year old airframes from service in 2021 would in the modelling
used in this report not affect the CO2 emissions estimate for 2030, as by then, these airframes would have reached 24
years, and be retired anyway. Although there might be some airframes currently below 12.5 years for which immediate
withdrawal from service might be an option, it was not considered in this report.

53 Challenges of this have been recently reviewed by ACI Europe (2020b)

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4

Improvements in ATM and aircraft
operations
Improvements in ATM and aircraft operations are estimated to be able to make an important
contribution to reducing aviation’s CO2 emissions in the short to medium term. Fitting with the
highly complex and interdependent environment of air traffic operations, improvements are
clustered in three areas: airline operations, airspace and air traffic management, and ground
operations at airports.
Specifically, improved flight planning, weight reduction and improved airframe condition and
maintenance are modelled to reduce fuel burn for aircraft operators by approximately 3%. In
addition to better flight efficiency, the realisation of the Single European Sky is anticipated to yield
the largest benefits. Based on recent literature, an improvement potential of 3.5% (departing
intercontinental flights from the EU+ region) to 7.1% (flights within the EU+ region) is modelled.
Improvements to ATM outside Europe are estimated to add additional savings of 2.1% for flights
that depart to a non-European destination. In a slightly longer term, wake energy retrieval is
anticipated to be able to contribute a 3% reduction, applicable to 50% of flights. Lowering
emissions from aircraft ground movement and APU usage through the introduction of electrical
operational towing and using electrical ground power, has the potential of realising CO2 cuts by
1.5% to 3% per flight – depending on the aircraft type and mission.
In order to achieve these reductions, it is crucial for actors – both governments and industry – to
work in concert. As it is the largest potential gain, realisation of a network-centric and digital Single
European Sky is considered essential. Further policies and actions are required to realise and
implement continued development and uptake of communication, navigation and surveillance
equipment with improved capabilities. At airport-level, efforts should focus on rapidly
decarbonising ground operations by reducing APU usage and taxi emissions, and in general
preparing for a more-electric future. This will not only reduce the climate impact of aviation, but
also has the potential of delivering important co-benefits in terms of lowering noise and reducing
other emissions.

4.1

Introduction

The operational environment of air transport is a (highly) regulated and complex one, in which a large number of
actors are collectively responsible for a safe and efficient air transport. Within this environment, airlines, air
navigation service providers (ANSPs), airports, ground handling agents, aircraft manufacturers (OEMs) and other
parties influence air transport operations and the efficiency of the operational process. Some relationships are mostly
one way (such as an OEM prescribing maintenance intervals or a minimum equipment list), whereas others are of a
much more collaborative nature (such as the way airlines and ANSPs plan and conduct a flight).

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The remainder of this chapter addresses numerous operational improvements that have the potential to reduce CO2
emissions. These reductions will generally also make a positive contribution towards lowering other emissions, such as
NOX and soot 54. Despite the strong interdependencies between actors involved, the analysis presented in this section
divides potential improvements into three categories: airline operations (Section 4.2), airspace and air traffic
management (Section 4.3) and ground operations at airports (Section 4.4). At the end of each of these sections, the
potential impact of all measures in that category are summarised.
At the end of the chapter, Section 4.5 discusses drivers and barriers influencing these improvements, whereas Section
4.6 elaborates on policies and actions that can be used to strengthen drivers and circumvent barriers to
implementation, and thereby contribute to the realisation of the improvements considered.

4.2

Airline operations

The improvements grouped in the category airline operations concern the way in which aircraft are used by airlines.
Even though more and more airlines report on their efforts of reducing CO2 emissions, Becken & Pant (2020) note that
there “surprisingly” are still many that do not, and that even “for those that do, a very broad range of reduction
opportunities could be identified”. Focussed on three groups of measures, this section discusses flight planning and
execution (Section 4.2.1), weight reduction (4.2.2) and airframe condition and maintenance (4.2.3). The results are
summarised in Section 4.2.4.
As load factor growth is also part of the reference scenario, it is not taken into account as potential environmental
improvement.

4.2.1

Flight planning and execution

The core business of an airline is obviously carrying out flights, which includes flight planning and subsequent
execution. Based on decisions made in the preceding network and schedule planning stages, in which flight
frequencies and aircraft types are assigned to city-pairs to be connected, actual flight planning only takes place a few
hours before the associated departure. It is concerned with choosing the best flight trajectory, considering all relevant
factors – such as payload, weather conditions, air traffic control tariffs, fuel prices and the actual traffic situation,
including restrictions. For most airlines, this is a largely computer-automated (or at least: computer-supported)
process in which manual input is steadily decreasing. Nevertheless, airlines do adjust optimisation algorithms and
optimisation priorities to their own needs. A full-service carrier with substantial transfer traffic is generally operating
from a (large) hub, and will place most emphasis on punctuality and slot availability (to prevent network disturbances
downstream, which are often costly to recover), whereas a low-cost airline is likely to focus primarily on route, fuel
efficiency and cost. All things equal, however, airlines will aim most economical flights – which might result in less
fuel-efficient routing.
As flight planning and execution are the primary drivers of operating cost, it is in the best business interest of airlines
to optimise those activities. Despite that fact, improvement potential is seen. Using newer flight planning software,
various airlines have reported fuel savings of 2.6 to 3% (GreenAir Communications, 2018; Honeywell, 2019); improved
flight management systems (FMS) envisioned to enter the market in 2024 and also available for implementation in
54 Per Section 1.4.2, these emissions have not been studied in detail.

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aircraft flying today would yield potential benefits of 3 to 4% (Sheppard, 2019; Thisdell, 2020). In a more experimental
setting, Gosnell, List and Metcalfe (2016) investigated the potentially beneficial effects of information provision and
incentivising airline captains on reducing fuel burn. Based on a field experiment involving 40,000 flights, they estimate
a CO2 reduction potential of 838 to 2,200 tonnes in a period of 8 months, computed for this study to be equivalent to
up to 0.2% of the estimated total emissions of the test flights. Lastly, EUROCONTROL (2019b) noted that in 2018, filed
flight plan distances were on average 0.4% longer than the “shortest constrained route” made available to airlines.
Nevertheless, actually flown trajectories were 1.3% shorter than the shortest constrained route (for example using
more efficient re-routing mid-flight, instigated by either the pilot or air traffic controller), severely limiting the
improvement potential 55.
Summarising the more straightforward improvements discussed in the previous paragraphs while considering that
some of these improvements are not mutually compatible 56, a generic improvement potential of 2% is assumed, to be
realised over a five-year period starting in 2020 and delivered by improved flight planning, information provision and
pilot awareness. To correct for improvements that have already been realised, the improvement is applied to 75% of
the flights. From 2025, an additional 1% is assumed following FMS-updates 57, to be realised over the course of ten
years. This transition period is somewhat longer as hardware changes are necessary.

4.2.2

Weight reduction

In addition to the way a flight is planned and executed, airlines have some control over the configuration of the
aircraft used and thereby over the weight of an aircraft. As every kilogramme requires additional fuel to be
transported, weight reductions can bring relevant savings in fuel consumption and CO2 emissions. Note that weight
reduction of the aircraft (structure) itself, for example through the extended use of composite materials, was already
covered in Chapter 3 and is therefore not considered here.
Over the last few years, many airlines have replaced paper cockpit manuals by electronic systems, annually saving
between 200 to 12,000 tonnes of CO2. Similarly, Finnair expects that lower weight cargo containers reduce their
carbon emissions by 2,500 tonnes each year (ATAG, 2015). Replacing paper newspapers with a mobile app has
allowed KLM to save 750 tonnes of CO2 per year (KLM, 2017). Future improvement potential exists for example in
replacing current (and relatively heavy 58) in-flight entertainment systems with seat-back screens by systems that allow
passengers to utilise their own devices carried on board anyway, lighter cabin trolleys, lighter crew equipment, lowerweight seats 59, carbon brakes, ‘rightsizing’ water and supplies, helped by pre-ordering of meals and retail purchases
(Gubisch, 2011; Reals, 2014; Schäfer, Evans, Reynolds, & Dray, 2015; Becken & Pant, 2020; Cirium, 2020). Although
some of these changes require OEM or regulatory approval, they can be applied to aircraft already in operation (for
example during larger maintenance work) and thereby realise savings earlier than the introduction of an entirely new
aircraft would. Noting that the full potential might not be reached due to regulatory or cost constraints, and realising
that not all weight savings are applicable to all aircraft (many short-haul aircraft currently already fly without seat55 Some improvement potential still remains, however, as the amount of fuel taken on board an aircraft is determined by the filed flight plan. If that flight plan distance

can be reduced (by either 0.4% or further, if even shorter shortest constrained routes would be made available by ANSPs), fuel uptake is limited. Even though that fuel
might not be used, this can save other fuel that is used for transporting the redundant fuel (cost of weight, also discussed in Section 4.2.2). Last, as further discussed in
Section 4.3.1, it is emphasised that the shortest constrained route might not be the most fuel efficient one due to e.g. weather (wind) effects.
56 With better flight planning, the improvement potential of better flight management systems is likely to be reduced, just as is the case vice versa.
57 Total benefits are estimated at 3 to 4%, and if 2% of improvement is already realised earlier on, 1 to 2% remains. A conservative value of 1% is assumed here.
58 The Canadian airline WestJet indicated saving approximately 550 kilogrammes per aircraft by removing seat-back screens (The Economist, 2012). Based on Bakx
(2015), these numbers are likely to correspond to Boeing 737 aircraft, of which WestJet operates multiple versions (Airfleets, 2020). Assuming typical 2-class
configurations and averaging seat count based on number of aircraft in the fleet (13 × 108-seat 737-600, 52 × 128-seat 737-700, 39 × 160-seat 737-800) yields an average
of 137.5 seats per aircraft. This translates into a weight saving of 4 kilogrammes per seat. Ferro (2014), citing Bachman (2012), notes a weight of 13 pounds or 5.9
kilogrammes.
59 Gubish (2011), Reals (2014) and Schäfer, Evans, Reynolds & Dray (2015) cite various industry parties which estimate weight savings of 15 to 30% per seat, reducing the
weight of seats from approximately 16 to 12 kilogrammes for long-haul aircraft and from 12 to 5 kilogrammes for short-haul aircraft.

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back screens, for example), a weight saving potential of 10 kilogrammes per seat is assumed. This corresponds well
with the average cabin weight reduction potential estimated by Schäfer, Evans, Reynolds & Dray (2015).
Besides equipment, weight savings can be realised by reducing the amount of fuel taken on board. Although
regulations require particular amounts of reserve and additional fuel for reasons of safety, some aircraft carry more
fuel than necessary to conduct the flight. Reducing this is assumed to unlock a potential saving of 0.25%. More
significantly, EUROCONTROL (2019a) estimated 15% of ECAC flights perform tankering. Bringing along some fuel for
the next flight, airlines reduce operating cost when flying to airports where fuel prices are substantially higher –
sometimes up to 55%. While saving 265 million Euros annually, CO2 emissions are at the same time increased by
901,000 tonnes, equivalent to roughly 0.5%.
Summarising the potential improvements discussed above, a carbon emissions reduction of 0.75% is assumed, in
addition to a weight reduction of 10 kilogrammes per seat, applicable to 75% of the flights in order to take into
account airlines already having made above-average efforts. This translates into emissions savings by assuming a 3.5%
hourly cost-of-weight factor (ICAO, 2014b) 60. Both (one-time) efficiency improvements are assumed with respect to
the baseline year and are modelled to materialise between 2020 and 2030. Weight reductions after 2030 are realised
through fleet replacement and as such are part of Chapter 3. Similarly, weight reductions following from advances in
the field of condition-based or predictive maintenance are included as improvements in technology.

4.2.3

Aircraft condition monitoring and maintenance

Improving the airframe condition also has beneficial effects on fuel consumption. Cleaning the engines more often, for
example, is estimated to save between 0.5 and 1.2% of CO2 emissions (Schäfer, Evans, Reynolds, & Dray, 2015; ATAG,
2015) – although water consumption is likely to increase. Reduced exterior skin quality through dents or dirt
decreases the aerodynamic efficiency and thereby increases fuel consumption, as does improper control surface
rigging. The International Civil Aviation Organisation notes that “over a period of 5 years, engine and airframe
deterioration may increase the drag of the aircraft by up to 2 per cent” (ICAO, 2014b, p. x). Noting the “up to” clauses
in the previous statements, reality is likely to be much less dire. As such, and largely consistent with similar works
published previously (Sustainable Aviation UK, 2016; Sustainable Aviation UK, 2012), a fuel efficiency improvement of
0.2% is assumed, delivered between 2020 and 2050.

4.2.4

Potential impact overview

Table 14 provides an overview of potential impacts of the aircraft operational improvements discussed in this section.
Weight savings listed in the column ‘potential CO2 emissions reduction’, for example as a result of lighter cabin
equipment or reduced fuel load, are translated into fuel savings on a flight-by-flight basis using a cost-of-weight
computation (further explained in Section 4.2.2, specifically footnote 60 on page 56).

60 This means that for transporting 10 fewer kilogrammes, 0.035 × 10 = 0.35 kilogrammes of fuel are saved per block hour. For a single aisle aircraft with 200 seats
operating a flight of 4 block hours, the fuel reduction would add up to 280 kilogrammes, equivalent to almost 900 kilogrammes of CO2. For 1000 flights per year (a little
under three flights per day), this entails a CO2 saving of 900 tonnes.

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Table 14: Potential CO2 emissions reductions to be delivered by airline operational improvements per flight
Measure
Improved flight planning
Flight management system updates
Weight reduction
Airframe condition and maintenance

4.3

Potential CO2
emissions reduction
2% × 0.75 = 1.5%
1%
10 kg / seat, 75% of
flights
0.2%

Starting
year
2020
2025

Delivered
by
2025
2035

2020

2030

2020

2050

Remarks

Modelled using 3.5% cost
of weight

Airspace and air traffic management

Airspace is part of the infrastructure in which aviation activity takes place. Air traffic management (ATM) – often
subdivided into air traffic services, air traffic flow management and airspace management – aims to ensure safe and
efficient flights, to balance demand for flights and airspace capacity available and to provide aeronautical information
to airspace users. The improvements grouped in this category therefore mainly concern the design and use of airspace
in which airlines conduct their flights. Traffic management at the airport itself (from the gate to the runway and vice
versa) is partially included. Improvements that for example prevent aircraft to wait in a queue with running engines
are part of this section; opportunities with regard to electric taxi or operational towing are dealt with in Section 4.4.
The section is subdivided as follows. Section 4.3.1 first discusses the Single European Sky and SESAR. Then, Section
4.3.2 pays attention to non-European ATM efficiency improvements and Section 4.3.3 specifically discusses improved
flight efficiency over the North-Atlantic. Wake energy retrieval, an innovative concept also known as extended
formation flight, is treated in Section 4.3.4. It is included in the present section rather than in the previous one to
emphasise the airspace and ATM-related actions required to ensure its implementation. Again, Section 4.3.5
concludes this section and summarises CO2 emissions reduction potential.

4.3.1

Single European Sky and SESAR

A major improvement potential in Europe in terms of air traffic management is the realisation of the Single European
Sky (SES). As this programme encompasses changes to European ATM at system-level, it has a potential impact on the
entire flight – from gate to gate. The dedicated underlying research programme SES ATM Research (SESAR) is regarded
as a crucial enabler for realising the contribution the SES can make to lowering CO2 reductions.
Background
Agreed upon in the International Convention on Civil Aviation (colloquially known as the Chicago Convention), states
have “complete and exclusive sovereignty over the airspace above its territory” (ICAO, 2006). As such, it is no surprise
that airspace and air traffic management have historically been national affairs. As air traffic is however inherently
international, aviation growth signified the limitations of the national perspective on air traffic management. Among
other things, this resulted in heavy delays at the end of the 1990s, with up to 20% of flights seeing average delays of
25 minutes (EC, 2000). In order to solve these problems, the SES was conceived, following a report of the high level
group on SES noting that “airspace is a common resource and should be treated as a single European sky” (EC, 2000, p.
35). The European Commission formally launched the programme in 2004 and set a number of High-Level Goals for
2020: increasing capacity (× 3), reducing delays, improving safety (× 10), reducing environmental impact (- 10%) and
reducing cost (- 50%) (SESAR JU, 2019f). The aforementioned SESAR programme was set up in 2007 as “the
mechanism which coordinates and concentrates all EU research and development (R&D) activities in ATM” (SESAR JU,
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2019c). In 2014, the SESAR Deployment Manager was created to coordinate synchronised deployment of SESAR
solutions to maximise their benefit to the network. The European Air Traffic Management Master Plan (EU ATM MP),
then, “defines the development and deployment priorities needed to deliver” the vision as set out by SESAR (SESAR
JU, 2019d, p. V). Implementing Regulations on common projects (such as Regulation 716/2014) help to more
concretely operationalise the high-level Master Plan vision.
Regulatory and administrative outline
In SES, as it was envisioned in the beginning of the century, a major objective was to defragment European airspace
and increase collaboration between ANSPs. In order to achieve this goal, so-called functional airspace blocks (FABs)
were introduced. These would allow airspace to be managed based on operational requirements rather than state
boundaries, enable economies of scale, and increase air navigation service provision across country borders. This
would also increase competition, drive down costs, stimulate innovation and reduce environmental impact. The SES II
regulation, approved in 2009, then introduced a performance scheme, setting binding performance targets on safety,
environment (horizontal en-route flight efficiency), capacity (delays) and cost-efficiency (EC, 2019a). This compels
ANSPs to deliver increased service at lower cost, even in case market mechanisms (which would otherwise yield such
an incentive for service improvement and cost reduction) are limited or lacking and in an industry where
“monopolistic service provision” often applies (ECA, 2017, p. 8). SES II also introduced the Network Manager (NM; a
function currently fulfilled by EUROCONTROL) to “co-ordinate certain actions at network level” and refocussed the
FABs towards service provision rather than airspace design (EC, 2020h). In 2013, the European Commission proposed
an update to the SES II framework, called SES II+, aimed to accelerate the implementation of the SES vision (EC, 2013b;
EC, 2013a). Among other aspects, it aims to strengthen the performance scheme, increase the flexibility and
performance-focus of FABs and reinforce the role of the NM. Despite the fact that seven years have passed since it
was proposed, SES II+ has not been agreed on. To pick up the work again the European Commission has published a
revised proposal for SESII+ based on a recent staff working document (EC, 2020a).
This historical background may form the basis for concrete and tangible solutions that in turn realise the various goals.
A prime operational shift that builds upon these wider trends in ATM harmonisation and collaboration efforts is 4D
(space and time) trajectory management or Trajectory Based Operations (TBO). By sharing information about the
current and future positions of aircraft, TBO continues the paradigm shift which in the past realised the step from
procedural (estimating positions based on flight plans) to radar-based (‘measuring’ positions) navigation and
surveillance (Da Silva, 2012). Because it improves predictability of aircraft trajectories, potential problems or
possibilities for efficiency improvements can be identified further in advance and acted upon. Rather than having to
put an aircraft in a (fuel- and emission-intensive) holding pattern when it arrives at an airport earlier than expected,
this longer planning horizon allows for solving this problem by a slight reduction of cruise speed 61. Furthermore, the
fact that flight trajectories are dynamically negotiated between airspace users and ANSPs enables trajectories to be
optimised from the system perspective rather than that of the individual airspace user. This can improve ATM
performance in a wide range of areas – from capacity and safety as well as from an environmental point of view. In
order to further increase predictability, better data sharing and interoperability are key.
Solutions and improvements
Whereas the previous paragraphs treated largely conceptual aspects, the current illustrates a number of concrete
solutions these can deliver. A clear example is Free Route Airspace (FRA), in which airline crews enjoy more freedom
in selecting a particular – more fuel-efficient – trajectory. Implementation of FRA depends not only on ATM, but also
on political will by governments to make the necessary compromises regarding organisation of airspace. Flexible Use
of Airspace (FUA, now Advanced Flexible Use of Airspace or AFUA (EUROCONTROL, n.d.)), in which airspace is no
longer designated as either military or civil but is allocated based on current operational requirements. The potential
61 Cross-border arrival management, implemented in various airports in Europe, is a SESAR solution that helps achieve this.

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environmental benefits of both are clear, as they allow shorter and/or wind optimal routes. A third example –
extended arrival management and cross-border arrival management (Extended AMAN and XMAN) – mainly indicates
the benefits of collaboration with other ANSPs in increasing the arrival management planning horizon, such that
potential inefficiencies during approach can be resolved in the cruise part of the flight. This way, aircraft can be
instructed to fly slightly slower to prevent arriving early and having to wait in a (fuel inefficient) holding pattern. Even
though this does not change airspace boundaries, it reduces fragmentation from a service-provision point of view.
Better and more comprehensive information sharing and interoperability between parties (through system-wide
information management or SWIM) and collaborative decision making (CDM) can further reduce the time aircraft
spend waiting in queues – burning fuel in the process – and thereby also contributes to environmental objectives in
terms of operations and ATM. Last, numerous innovations aim to improve surface navigation accuracy in low-visibility
conditions, benefit both safety and environment.
Current status
Even though the SES vision was to be fully implemented by 2020, these objectives have regrettably not been met.
Recent reviews stress current airspace inefficiencies are unacceptable (Wise Persons Group on the Future of the Single
European Sky, 2019) and note that only “lacklustre quantitative results” (ECA, 2017, p. 43, talking about the
performance scheme) have been achieved.
According to the 2020 EU ATM Master Plan, 37% of SESAR solutions have been delivered (of which 70% have a
regulated or non-regulated deployment decision and 30% are awaiting such a decision), 31% are under development,
and 32% are expected to be covered in future R&D (SESAR JU, 2019d, p. 94; SESAR JU, 2019g). That means that of all
SESAR solutions, approximately 26% have been deployed 62. Substantial differences, however, exist between the
implementation progress of individual solutions, with some (such as direct routing and continuous descent
operations) reported to be implemented by over 80% airports or States and others (e.g. time-based separation) not
having passed 10% (SESAR, 2019).
A number of recent reports, such as by the European Court of Auditors (2017), a Wise Persons Group established by
the Directorate-General of Mobility and Transport (DG MOVE) to make recommendations for the future of SES (2019)
and the Industry Consultation Body SES Vision 2035 (ICB, 2019), reviewed the current status of SES and indicated
reasons why 2020 implementation objectives are not met. Relevant outcomes and recommendations of those studies
are addressed in greater detail in Sections 4.5 and 4.6, but two aspects are already briefly discussed here:
•

Despite “substantial efforts undertaken for their implementation”, objectives of reducing defragmentation
through the use of FABs have not been met (ECA, 2017, p. 30; Integra A/S; ECORYS Nederland BV; Winsland
Consulting & Combitech, 2017). Initially envisioned as a way to provide “integrated management”, “FABs
were gradually transformed” into “enhanced” “cooperation mechanisms” (ECA, 2017, pp. 28-29; EP & CEU,
2009). As indicated in the title of the ECA review (“Single European Sky: a changed culture but not a single
sky”), the SES work so far has instilled a more efficiency-focussed culture in ATM, but has not managed to
create a single European sky. Whereas national sovereignty interests might stand in the way of treating
airspace as a “common resource” (EC, 2000, p. 35), cooperation within sovereignty boundaries has not
resolved interoperability issues to the maximum extent possible 63.

62 The SESAR Deployment Manager (SESAR DM, 2020) states that 155 out of 343 projects (approximately 45%) are in operation bringing benefits to passengers.

Deployment is completed or in progress of 75% of the Pilot Common Project (PCP).

63 EUROCONTROL’s 2016 ATM Cost-Effectiveness benchmark, for example, notes that throughout Europe, flight data processing systems from at least 10 different

suppliers are used. ‘At least’ is used, because bespoke systems are not individually indicated, making it impossible to access whether each bespoke FIR is a separate
system, or whether multiple FIRs share the same bespoke system. The former seems most likely.

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•

Aspirational goals rather than targets were set, which were based on projections of demand growth 64 and
associated capacity requirement and benefits of economies of scale that did not come true (ECA, 2017).
Furthermore, the original goals – in addition to addressing safety – seemed to prioritise capacity, efficiency
and cost over environment – which is quite different from the realities of today (Wise Persons Group on the
Future of the Single European Sky, 2019), where environmental aspects are deemed much more important
than before 65. This was also acknowledged recently by the Commission, noting “a decreased emphasis on
cost reduction and an increased emphasis on delays and the environment” in its Staff Working Document on
SES2+ (EC, 2020a, p. 4).

Interdependencies
The different topics addressed in the SES goals and the previously discussed shift in priorities of those goals also draw
attention to the complexity of the air traffic management system – aiming to cater to a wide array of often conflicting
and varying demands from a large number of stakeholders – and the interdependencies that cause that complexity,
further discussed in e.g. Sustainable Aviation (2017) and EUROCONTROL (2018c). Although not limited to it, this
complexity is especially seen in the airport vicinity. While a particular departure procedure may have a beneficial
effect on the noise exposure to surrounding communities 66, that same departure procedure might not be most fuel
efficient – or vice versa. The same is true for flying approach routes in which aircraft navigate around populated areas,
but which come at a price of increased flight distance and fuel consumption, or having to choose between continuous
climb versus descent operations. Trade-offs between CO2 and other emissions (such as NOX) affecting local air quality
further complicate the matter, as well as the lack of (quantified) knowledge about the effects of various
interdependencies (BLUE MED, G.A.R.S, Universita di Bologna, & FABEC, 2020).
Whereas noise is of limited concern during cruise flight, other interdependencies play a role. Guaranteeing separation
limits in highly demanded airspace results in congestion and capacity shortages, which in turn might require aircraft to
be distributed over a wider set of routes – reducing horizontal flight efficiency and increasing CO2 emissions. Similarly,
increasing the number of air traffic control operators available might alleviate queues, enable closer flight monitoring
and suggestions to reduce environmental impact, but on the other hand increases cost.
Lastly, and although climate effects beyond CO2 emissions are not considered in this research (as indicated in Section
1.4), opting to fly a longer route can have a (net) beneficial effect on global warming, as it might make optimal use of
strong tailwinds (reducing fuel consumption) or circumvent climate sensitive areas of atmosphere (where contrails,
which have a warming effect, more easily form) (Grewe, et al., 2017). Especially in terms of non-CO2 effects, such as
contrail cirrus and NOX emissions, numerous research efforts and projects are underway that examine the feasibility of
tactically rerouting aircraft around regions where persistent contrails are likely to form and produce long lived cirrus
cloud. This can help minimise the climate impact of these flights. Despite this potential, interdependencies with other
performance indicators (such as noise and cost) must be taken into account in such assessments.
In some cases, the specific trade-off examples discussed in the previous paragraphs can be readily generalised to the
SES Performance Scheme (EC, 2019a) of safety, environment, capacity and cost-efficiency. This is for instance the case
in the example of congested airspace, resulting in interdependencies between safety, capacity and environment.

64 A cost/benefit-analysis for SES from 2005 assumed 2.9% annual growth rates from 2005 to 2035, whereas growth rates of only 1.1% per year were realised between
2005 and 2016 (ECA, 2017). The current study predicts a year-on-year growth from 2005 to 2035 equal to about 1.5%.
65 “From the very beginning the [Wise Persons] Group was clear that safety, security and environmental elements have the highest priority, whatever recommendations
it makes to increase the capacity and improve the efficiency, including the cost efficiency, of the ATM system. These elements must also have priority when the
recommendations are implemented.” (Wise Persons Group on the Future of the Single European Sky, 2019, p. 4)
66 Which might, due to the reduction of noise, also reduce adverse health effects.

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Potential impact
As emissions are not reported for different flight phases, data indicating the impact of specific parts of the SES
framework is difficult to acquire. Similarly, fuel or emission estimates on the level of all individual SESAR solutions is
not publicly available. As such, the impact estimate shown in this section considers the effect of ATM-related
improvements 67 on a gate-to-gate level. Nevertheless, a breakdown is used to split these potential impact estimates
over airport, climb/descent and cruise in order to account for the aforementioned interdependencies. It is emphasised
that opportunities such as e-taxi – that are mostly concerned with how ground operations are carried out – are not
part of the current section.
In 2005, the Commission envisaged SES would deliver a 10% reduction in CO2 emissions by 2020, compared to levels
observed in 2005 (SESAR JU, 2019f; IATA; AEA & ERA, 2013), although this did not form any base for the SES legal
framework. In recent communications by the European Commission on the European Green Deal, the environmental
impact of an improved ATM system in the EU is now represented as “up to 10%” (EC, 2019h) – a likely consequence of
the fact that the European Commission has acknowledged that the initial goals were “to be seen as aspirations rather
than targets” (ECA, 2017, p. 18).
The 2020 European ATM Master Plan 68, based on the same flight forecast as the current study 69, does list targets: a
reduction of gate-to-gate emissions by 5 to 10% compared to 2012 should be realised by 2035. This is for an average
flight consuming 5,280 kilogrammes of fuel. This saving is equivalent to a reduction in fuel consumption of 250 to 500
kilogrammes and an associated reduction in CO2 emissions of 0.8 to 1.6 tonnes 70 (SESAR JU, 2019d, p. 37).
Another study from the SESAR Joint Undertaking, on the potential benefits of a Single European Airspace System,
indicates a potential of “between 240 and 450 kg of CO2 saved on an average flight due to optimisation of trajectories”
(SESAR JU, 2019a, p. 67) to be obtained by 2035 compared to 2019 – equivalent to a total reduction in CO2 of 30 to 60
million tonnes. These reductions in CO2 emissions would follow from a reduction in flight distance between 7 to 13
nautical miles in 2035. Although the Single European Airspace System is different from the SES legal framework (it is
described as ''an evolution of the European airspace architecture'', SESAR JU, 2019a, p. 3), its focus on collaboration,
harmonisation and data sharing demonstrate it being consistent with SES ideas.
Besides estimates from the SESAR Joint Undertaking, various other parties have published similar data.
EUROCONTROL (2019b, p. 11) shows 2018 excess gate-to-gate emissions at approximately 6.1%, predominantly
caused by horizontal en-route flight inefficiency, horizontal arrival flight inefficiency, and vertical cruise flight
inefficiency. Noting that inefficiencies cannot and should not be reduced to zero 71, EUROCONTROL (2019b) cites the
2015 European ATM Master Plan in the ambition of reducing these excess emissions to 2.3% by 2035 – a reduction of
3.8 ppt (percentage point). A note preceding the policy debate on the future of the SES 72, too, states the number of
“around 6%”, but describes those as “avoidable emissions” (Presidency of the Council of the European Union, 2019).
Although no timelines are mentioned in that document, it is assumed this 6% too holds for 2035 with respect to 2018.
Estimates provided by industry experts interviewed for the current study are somewhat more extreme – on both ends
of the scale. One representative expected essentially no environmental benefits from ATM, stating that airspace users
should be happy if performance remains at the current level as air traffic continues to grow. Indeed, these worries are

67 Thereby excluding the impact of reduced engine taxi, operational towing or e-taxi, discussed in Section 4.4.

68 The fuel consumption reductions reported in the 2020 EU ATM Master Plan comprises “additional ATM-related gate-to-gate fuel burn per flight”, on top of “the ability

of accommodate traffic increases safely and simultaneously and ensuring the achievement of punctuality objectives of airspace users” (SESAR JU, 2019e, p. 14)
69 EUROCONTROL Challenges of Growth 2018, ‘Regulation and Growth’-scenario. Further details can be found in Chapter 0.
70 Although computed values differ slightly (5 to 10% of 5.280 equals 264 to 528 kilogrammes of fuel, equivalent to 832 to 1664 kilogrammes of CO emissions), the
2
rounded values used in the cited documents are used.
71 Some elements that strongly contribute to aviation safety, such as separation minima and navigation around adverse weather, reduce flight inefficiency. This is due to
the fact that these conditions are not reflected in the KPIs.
72 Part of the 3734th Council meeting on Transport, Telecommunications and Energy, Brussels, December 2-4, 2019.

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shared by numerous parties. EUROCONTROL (2019c, p. 7), for example, notes it “may be challenging in itself to
maintain efficiencies as traffic grows” and Sustainable Aviation (2020a, p. 49) states “increased traffic growth can
erode or nullify ATM efficiency gains”. Increased concerns about interdependencies – most notably noise – has
furthermore made the UK ANSP NATS re-phase their emission reduction commitments (Sustainable Aviation, 2020a,
p. 48), also indicating the difficulty of meeting emission reduction targets. On the other end of the spectrum, another
representative estimated SES would deliver fuel consumption reductions of 12 to 14%, due to for example more direct
routings, reduced altitude restrictions and increased continuous climb and descent operations. The wide range in
industry estimates clearly illustrates the uncertainty associated with the SES benefit pool. The differences might,
however, also be caused by some stakeholders promoting their goals over those of the network whereas others do
not.
The impact assessments are combined as follows. Starting with the total impact potential of 5 to 10% listed in the
2020 EU ATM Master Plan, this is reduced to 3.7 to 7.4% by taking into account that 26% of SESAR solutions has been
deployed 73, yielding a single value of 5.6% reduction potential by 2035 with respect to 2018. Following the most
ambitious of the two rollout timelines published 74, realisation of the full SESAR vision by 2040 is expected viable – if
necessary actions and policy measures are taken (SESAR JU, 2019d). As that vision goes beyond the environmental
performance improvements discussed here, these are expected to be realised by 2035.
Then, this is combined with the estimates of excess gate-to-gate emissions. According to EUROCONTROL and the
European Council, this varies between 3.8% and 6.1% (for 2035 with respect to 2018). The benefit pool noted by FAA
and EUROCONTROL (2019), expressed in relative terms 75, is 6.4%. The fact that this is a higher value is consistent with
its classification as a theoretical maximum 76, which cannot be completely achieved due to safety concerns introducing
some inefficiencies. Regardless of that theoretical status, it indicates the validity of the two earlier values. As neither
one was determined to be more accurate or more truthful, these figures are combined to yield an average of 5.0%.
Combining this with the 5.6% found previously – again using an averaging operation – results in a figure of 5.3% 77.
As not all flights are part of the scope of the present study (further detailed in Section 1.4, more specifically in Section
1.4.3), the potential improvement of 5.3% is split up over various flight phases 78. Information for that exercise comes
from two sources: the SESAR Joint Undertaking website (2019) and the 2020 European ATM Master Plan (SESAR JU,
2019d) and its Companion Document (SESAR JU, 2019e). Furthermore, following interdependencies between noise
and CO2 in the TMA, it is assumed that only 75% 79 of the potential in the TMA (excluding the holding phase) can be
realised. Table 15 summarises the results and shows:


For the EU ATM MP2020 estimate, what share is delivered by what elements. For example, airport
operations (12.6% improvement potential) is composed of taxi-in (4.4%) and taxi-out (8.2%). These individual
components hence make up 4.4 / 12.6 = 35% and 8.2 / 12.6 = 65% of the total improvement in terms of
airport operations.

73 Lacking emission impact estimates at solution level, as indicated, this assumes that each solution contributes an equal amount of the CO emission reduction potential.
2
74 A less ambitious rollout option sees full SESAR implementation by 2050. Given the ambition level displayed in the European Green Deal as well as in this study, the

2040-timeline is deemed realistic.

75 The benefit pool is estimated to be a fuel burn reduction of 259 kilogrammes for a 450 nm flight operated by a standard aircraft (Airbus A320). In the model used for

this study, flights operated using A320-family aircraft on distances between 350 and 550 nm consume an average of 4032 kilogrammes (over an average flight distance
of 447 nm). 259 / 4032 × 100% = 6.42%.
76 Nevertheless, Ryerson, Hansen and Bonn (2014, p. 297) argue that an earlier version of the FAA/EUROCONTROL-report “may be too conservative”, seeing a
“substantially greater” benefit pool associated with improved terminal efficiency in their research results than reported by the FAA and EUROCONTROL. On the other
hand, the Ryerson-study is limited to the US. As such, its argument of conservatism need not apply to the European situation.
77 Figures relating to the environmental efficiency of current air traffic presented in the recent SES2+ Staff Working Document (EC, 2020a) have not been used in this
study, as it refers to the EUROCONTROL-analyses also referred to in the SWD. In addition, the “several % points of additional emissions” referred to in the SWD are linked
to “the congestion and necessary re-routing of many flights” in recent years. Interpreting this as a reference to the 2019 capacity crunch, these additional emissions
would not be part of this study anyway, as it uses 2018 as a baseline.
78 The total CO emissions reduction potential identified by both sources varied from the number derived from literature in this report. Lacking more detailed
2
information, it is assumed here that the relative contributions of different flight phases do not change with a higher or lower overall improvement potential.
79 Rather than choosing 0 or 50%, a value of 75% is selected because of the fact that there are also synergistic effects – measures that reduce both CO emissions as well
2
as noise. Continuous descent operations (or rather: optimised descent profiles) are a prime example.

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

An average value combining the two sources. Contributions from the more detailed elements listed in the
ATM Master Plan are computed by splitting the average according to the ratio determined using the Master
Plan. For example, given an averaged potential improvement of 13.8% for airport operations, 65% × 13.8% =
9.0% is contributed by taxi-out and 35% × 13.8% = 4.8% is delivered by taxi-in.



The potential improvement per flight phase. This is found by multiplying the average share of the total
SES(AR) improvement potential by the total SES(AR) improvement potential, determined previously as 5.3%.



The applicability of the different potential improvements to different types of flight considered within the
scope of the present study. For intercontinental flights (i.e., extra-EU+), it is assumed that 50% of the enroute distance travelled is within airspace covered in the SES programme.

Table 15: Breakdown of the total quantified SES(AR) improvement potential of 5.3% over different flight phases (SESAR
JU, 2019b; SESAR JU, 2019d; SESAR JU, 2019e)
Share of quantified potential SES(AR) improvement
Website
EU ATM MP2020 80
Average
75 / 500 = 15% 23 / 182 = 12.6%
13.8%
15 / 182 = 8.2% (65%)
9.0%
8 / 182 = 4.4% (35%)
4.8%

Potential CO2
reduction

325 / 500 = 65%

67 / 182 = 36.8%

50.9%

2.70%

100 / 500 = 20%

2 / 182 = 1.1% ( 3%)
21 / 182 = 11.5% (31%)
44 / 182 = 24.2% (66%)
92 / 182 = 50.6%

1.5%
16.0%
33.4%
35.3%

0.08%
0.85%
1.77%
1.87%

Horizontal
efficiency

55 / 182 = 30.2% (60%)

21.1%

1.12%

Vertical
efficiency

37 / 182 = 20.4% (40%)

14.2%

0.75%

Flight phase
Airport operations
Taxi-out
Taxi-in
Climb/descent
(TMA)
Climb
Descent
Holding
En-route

0.73%
0.48%
0.25%

Applicability
All
Intra-EU+

All, 75%
Intra-EU+, 75%
Intra-EU+
100% intra-EU+;
50% extra-EU+,
dep. only
100% intra-EU+;
50% extra-EU+,
dep. only

Table 15 shows the total quantified improvement potential of 5.1% 81 is fully applicable to intra-EU+ flights. For
departing extra-EU+ flights, this value is reduced to 1.5% 82. An additional improvement potential of 3.6% 83 for arriving
extra-EU+ flights is noted, but (given the selected scope, as documented in Section 1.4.3) not modelled. Similarly, an
additional en-route improvement potential of 1.9% is noted – but again not modelled – for flights that either not
depart from or not arrive at a European airport.
EFFECTS OF TRAFFIC GROWTH ON ACHIEVABLE EFFICIENCY
Even though concerns to that extent are shared by various stakeholders, no discounts are applied to compensate for the
potentially negative impacts of traffic growth on efficiency. This is because no sources could be found that quantify that
impact. Furthermore, it is noted that original SES goals targeted simultaneous efficiency improvement and a three-fold
capacity increase. When the SES programme was launched in 2004, there were approximately 9 million IFR movements
(EUROCONTROL, 2018b), leading to a goal of 27 million movements after SES implementation. In the present report, a 1.4%
annual growth in the number of flights is anticipated (Figure 5) relative to 2018. Given 11 million flights in 2018
(EUROCONTROL, 2019b), this yields approximately 13.6 and 17 million flights in 2035 and 2050 84, respectively. For 2035,
this is below the ambition value of 15.7 million flights expressed in the 2020 European ATM Master Plan (SESAR JU, 2019d),

80 The cited document states breaking down 173 kilogrammes of additional fuel burn, but component values add up to 182 kgs. This is a consequence of the fact that in

the 173 kilogrammes estimate, discounts are applied for arrivals and/or departures outside the ECAC area (SESAR JU, 2019e, p. 17). As such, factors are based on the
182 kilogramme total.

81 Summing the contributions from airport operations, climb/descent and en-route: 0.73% + (0.08% × 75% + 0.85% × 75% + 1.77%) + 1.87% = 5.1%.
82 Again, summing the contributions from airport operations, climb/descent and en-route: 0.48% + (0.08% × 75%) + (1.87% × 50%) = 1.5%.
83 Computed by taking the difference from 5.1% and 1.5%.

84 This number is different from the figure reported in Section 2.3.1 (12.4 million in 2050), as that is limited to flights departing EU airports.

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which is presented in concert with environmental improvements. Also, the aforementioned Master Plan takes into account
the growth projections from EUROCONTROL (2018b) that underlie the present study (SESAR JU, 2019e, p. 8).

Further CO2 emissions reduction potential
A number of recent analyses and reports suggests that the CO2 reduction potential derived and quantified in the
foregoing pages does not capture the full decarbonisation potential that exists. EUROCONTROL (Vranjkovic & Brain,
2020), for example, suggests that “further inefficiencies exist” which might only be demonstrated by “indicators that
are directly based on CO2 emissions”.
A more detailed EUROCONTROL study (2020a) utilising a different metric for assessing fuel inefficiency also shows
significantly higher reduction potential than the excess gate-to-gate emissions noted in other publications (such as the
PRR; EUROCONTROL, 2019b). Rather than distance-based current regulatory metrics as KEP (based on last filed flight
plan) and KEA (based on actual route), EUROCONTROL used the 10th percentile fuel-burn observed for each
combination of airport pair and aircraft type as benchmark for determining the excess fuel burn (and subsequent CO2
emissions) of the remaining 90% of flights. Contrary to distance-based metrics, this new metric is likely to capture – at
least to some extent – favourable operating conditions, such as beneficial tailwinds or avoidance of headwinds, even
though distances flown may be longer. Indeed, and as noted in Section 4.2.1, the shortest route may not be the most
fuel- and thereby CO2-efficient route. ICAO (2014a) lists numerous examples and this concept is also applied on flights
between Europe and North-America, the Middle East and Australia, and in Asia where airlines and ANSPs work
together to plan their daily operations taking account of forecast metrological conditions. Such route optimisation can
also have a beneficial effect on non-CO2 effects, such as contrail cirrus.
Last, it could not be definitively determined to what extent the improvement potential quantified earlier might be
constrained by inefficiencies that are accepted as given in the ‘optimum reference’ of studies referred to, whereas
such inefficiencies might actually be (partially or fully) resolved by the EU wide implementation of solutions developed
in SESAR – creating a truly seamless and digital single European sky.
Detailed system-level assessments on the impact of optimising for CO2 emissions are presently unknown to the
authors of this study. The further inefficiencies discussed are estimated to lie between 0 and 4% by Vranjkovic & Brain
(2020). Due to the significant uncertainty, and as Vranjkovic & Brain (2020) also refer to new concepts (such as wake
energy retrieval, discussed in Section 4.3.4) as a way to reducing these excess emissions, the potential is modelled in
this study as 2%, applicable to all flights within the scope. That means that the total SES(AR) CO2 emissions reduction
potential grows to 7.1% for intra-EU+ flights and to 3.5% for departing extra-EU+ flights. Due to the uncertainties
associated to the additional 2% improvement potential, that impact is modelled five years later (delivery between
2025 and 2040) than the previously identified 1.5 to 5.1%.

4.3.2

Non-European ATM efficiency improvement

In addition to the ATM modernisation and efficiency improvements underway in Europe as part of the Single
European Sky initiative (discussed in greater detail in Section 4.3.1), similar goals are pursued elsewhere around the
world. Even though European policymakers can only aim to indirectly influence such efforts, notable improvements
are anticipated that do directly influence the fuel consumption and associated CO2 emissions of flights departing
European airports 85.

85 Further elaborated in Section 1.4.3, all emissions of flights departing from EU+ airports are considered in the scope of this study.

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Potential impact
The size of the anticipated improvement is based on studies conducted previously. CANSO (2012) 86 set global ATM
efficiency goals for 2020 (between 93 and 95%) and 2050 (95 – 98%), compared to a baseline in 2005 (92 – 94%). The
2020-goal aligns well with estimates on the current EU+ ATM efficiency (approximately 6%; further discussed in
Section 4.3.1). Efficiency numbers from 2017, analysed and presented in the 2019 ICAO Environmental Report are
slightly higher (between 94 and 98%, 95% when averaged based on 2018 traffic volumes from ICAO, 2018b), but only
include horizontal en-route flight efficiency (Brain & Voorbach, 2019). In contrast, the CANSO-study investigated the
complete trip as well as vertical flight efficiency, and thereby is found to provide a more realistic assessment of the
available improvement potential. The total non-European ATM efficiency improvement is therefore estimated at 3%.
This is slightly above the 2.5% mentioned by the 2016-version of the Sustainable Aviation UK roadmap (Sustainable
Aviation UK, 2016), but in the lower half of the range presented in the 2020-version (being 0 to 8%; Sustainable
Aviation, 2020a). Given the fact that ICAO CAEP has set a 92 to 96% efficiency goal for 2026 (Brain & Voorbach, 2019)
and SES(AR) implementation is foreseen by 2035, the 2050-timeline anticipated by CANSO (2012) and Sustainable
Aviation (2020a) are shortened by ten years. This means the CO2 reduction potential is to be delivered by 2040.
In order to avoid double-counting with the anticipated CO2 reductions delivered by SES(AR), the improvement
potential identified here is only applied to flights that depart to a non-EU+ destination. Nevertheless, it is additional to
the 1.5% identified in Section 4.3.1. Based on the previously computed 3.6% of noted but unmodelled emissions
reduction potential in Section 4.3.1 (below Table 15), the value of 3% is reduced to 2.1% 87. This corrects for the fact
that even for flights to non-EU+ destination, a SES(AR)-based savings potential due to improvements during taxi-out,
climb-out and 50% of the cruise phase (per Table 15) was identified. Also, consistent with Section 4.3.1, this correction
takes into account that only 75% of the CO2 emissions reduction potential in the TMA can be realised due to
interdependencies between noise and CO2.

4.3.3

Improved North-Atlantic flight efficiency

A large portion of aircraft flying between Europe and (North-)America currently cross the Atlantic Ocean using the socalled North-Atlantic Tracks (officially the North-Atlantic Organised Track System, abbreviated to NAT-OTS). Lacking
the means to accurately track the position of aircraft in this area, these routes were designed in the 1960s to enable
safe oceanic crossings.
Overview
The working principle behind NAT-OTS is straightforward. The system consists of a number of fixed routes, which
change twice a day depending on weather conditions. These routes are designed to exploit beneficial tailwinds flying
East and prevent adverse headwinds flying West. Based on airline preferences indicated earlier, the final routes are
published in advance in order to allow airlines to file their flight plan. Oceanic controllers then assign a particular track
(and altitude) to a flight, thereby effectively defining a tunnel through which the flight has to be operated. Given the
fact that speeds are also fixed, the position of aircraft can be predicted during the crossing. If an aircraft is detected at
a particular waypoint (either at the start of the tracks or at an intermediate checkpoint), multiplication of time and
velocity allows computing the distance travelled – and thereby determining the current location.

86 Even though this report is based on older data, more recent updates could not be found. Also, the CANSO-report is still referred to in other much more recent reports
(ATAG, 2020b).
87 3% × (3.6 / 5.1) = 3% × 0.71 = 2.1%.

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Developments and improvement potential
Since its inception, the NAT-OTS has seen numerous improvements. Fairly recently, vertical as well as lateral
separation minima were reduced (RVSM and RLAT), increasing capacity of the tracks. This allows more flights to use
their preferred – fuel-burn optimised – track.
A more significant change – and according to some “the beginning of the end of the OTS” 88 – is formed by the
introduction of Automatic Dependent Surveillance - Broadcast (ADS-B) coverage over the North-Atlantic, enabled by
using space-based receivers which relay their signals to ANSPs on both sides of the Atlantic. ADS-B equipment will be
mandatory for aircraft used in United States, European and Canadian airspace from January 2020, December 2020 and
February 2021 onwards, respectively (Learmount, 2019a; United States Government Publishing Office, 2011; FAA,
2020; EC, 2014; Learmount, 2019b; SESAR DM, 2020). This requirement means the advantages of this technology over
the North-Atlantic airspace can be fully exploited, as the ATM system no longer needs to support older equipment. In
addition to further reductions in separation minima and associated capacity advantages from November 2020
onwards, ADS-B is expected to enable aircraft to fly optimal – rather than fixed – speeds (Learmount, 2019a; Osborne,
2019), possibly allowing for further improvements.
Potential impact
According to NATS-estimates, increased use of ADS-B over the North-Atlantic is expected to result in a fuel saving of
400 to 650 kilogrammes per crossing (Learmount, 2019a; Osborne, 2019), equivalent to approximately 1,250 to 2,050
kilogrammes of CO2. In an earlier study, Sridhar et al. (2015) 89 computed a savings potential of 3 to 5%, equivalent to
420 to 970 kilogrammes of fuel for a Boeing 767-300 90. For the same routes, the model used in the present study
(described in Section 2.1) shows the absolute fuel burn reduction is equivalent to 1.1 to 2.6%. As it cannot be
established what model offers the best approximation, an averaged range of 2 to 3.8% is used. Combining these
numbers, a savings potential of 2.9% is estimated. As not all traffic uses the OTS, the savings potential is applied to
45% of flights over the period 2020 to 2027 91.

4.3.4

Wake energy retrieval

A more disruptive improvement potential under renewed attention is wake-energy retrieval, also known as
cooperative trajectories or extended formation flight (Warwick, 2020; Flanzer, Bieniawski, & Brown, 2020). In this
operational concept, aircraft fly closer together than usual (reducing separation to approximately one nautical mile).
Most relevant to long-haul operations, academic studies estimate formation-level reductions in fuel burn between 2
and 12%, depending on cruise Mach number (Bergmans & den Boer, 2012; Voskuijl, 2017). Recently, this idea has also
received increased attention from the industry. Boeing showed a 10% fuel burn benefit (5% at formation level) in
flight tests in 2018 with two Boeing 777 Freighter aircraft (Norris, 2019), and Airbus announced similar plans, targeting
5 to 10% better fuel economy and expecting entry into service in the first half of this decade (Airbus, 2019a; 2019d).
Flanzer, Bieniawski & Brown (2020) estimate that the potential is 3% for each aircraft part of a formation – taking into
account that wake-energy retrieval will only be possible in the cruise phase of the flight and splitting the savings
equally over both aircraft. Dahlmann et al. (2020) observed a larger reduction potential and noted especially
88 Osborne (2019), citing Andy Smith of UK ANSP NATS.

89 Sridhar et al. (2015, p. 1) have examined “the benefits of a wind-optimal trajectory concept with a strategic de-confliction component compared to the current flight
planning using the North Atlantic Tracks”, enabled by the “availability of Automated Dependent Surveillance-Broadcast”.
90 The difference between these figures and the NATS-estimate are most likely caused by fleet renewal over the years between the assessments (Sridhar et al. use data
from 2012; the NATS-estimates were made in 2019) and a limitation in city pair coverage (Sridhar et al. have only considered transatlantic flights between the United
States and Europe).
91 EUROCONTROL (2017) estimated in August 2017 that 50% of flights used the OTS; Osborne (2019) estimated in September 2019 that this number had reduced to 38%,
a reduction of 12% in 25 months, approximately equivalent to a reduction of 0.5% per month. Taking 50% in August 2017, this rate yields an estimated OTS use of 48% in
January 2018 (the reference year used in this study) and 42% in December 2018 – averaging 45%. At the current rate, this will reach zero in 90 months or 7.5 years from
January 2019.

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significant non-CO2 effects. This study follows Flanzer, Bieniawski & Brown (2020) and models a 3% fuel efficiency
savings for flights using wake-energy retrieval.
Notwithstanding the potential, the concept is not yet mature and requires substantial work – not only from an air
traffic management perspective, but also from the side of manufacturers and operators. Many questions on
operational application for example still exist: how can safety be guaranteed, how will the costs and benefits be
shared, what routes are suitable, how will airline schedules be affected?
Following airline operational flight tests in the next few years (Sustainable Aviation, 2020a), implementation is
estimated to be able to start from 2025 on flights between Europe and North-America (Dumont, 2020). Full adoption
is anticipated in 2032. From 2030 to 2040, the scope is expanded to include other routes such that by 2040, these
benefits are obtained for 50% of flights. It is assumed that cost savings associated to realising reductions in fuel burn
offset any expenditures following these improvement programmes (Flanzer, Bieniawski, & Brown, 2020).

4.3.5

Potential impact overview

Table 16 provides an overview of potential impacts of airspace and ATM-related improvements discussed in this
section. With the exception of the non-European ATM efficiency improvement and part of the CO2 emissions
reduction delivered by improved NAT-efficiency and the introduction of wake energy retrieval, all improvements
concern EU+ airspace.
Table 16: Potential CO2 emissions reductions to be delivered by airspace and ATM-related improvements per flight
Measure
Single European Sky / SESAR – intraEU+
Single European Sky / SESAR – extraEU+
Single European Sky / SESAR – further
CO2 emissions reduction potential
Non-European ATM efficiency
improvement
Improved North-Atlantic flightefficiency
Wake energy retrieval

4.4

Potential CO2
emissions reduction

Starting
year

Delivered
by

5.1%

2020

2035

1.5%

2020

2035

2%

2025

2040

2.1%

2020

2040

2.9% × 0.45 = 1.3%

2020

2027

2025

2032

2030

2040

3%

Remarks

Intercontinental
departures only
Intercontinental
departures only
Flights from Europe to
North-America
Flights from Europe to
North-America
Other flights, up to 50%
combined

Ground operations at airports

This section considers ground operations. As indicated in Section 1.4, the present study is limited to emissions from
aircraft operations, here further limited to emissions while parked at the gate or stand, and associated to movement
between the gate and runway. As such, this section does not consider emissions generated by for example ground
support equipment (GSE). Also, emission reductions following from (improved) information sharing and collaborative
decision making, as considered within the SESAR programme, are assumed to be included in the potential
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improvement numbers listed in Section 4.2.4. For the present section, this leaves two main items of interest: reduced
emission taxi and reduced APU usage. These are treated in Sections 4.4.1 and 4.4.2, respectively. Section 4.4.3
provides an overview of potential impacts.
It is relevant to note that besides reducing CO2 emissions, the measures listed in this section often also reduce noise
and other emissions and thereby contribute to improving local air quality. Furthermore, following ACI EUROPE’s
commitment for net zero carbon emissions by 2050 (ACI Europe, 2019) and an accelerated clean energy transition in
the European Union, it is assumed that by 2050 at the latest, ground-based energy supplies at airports that are used
to replace aircraft-based power generation are completely renewable.

4.4.1

Reducing taxi emissions

At the start and end of every flight mission, the aircraft needs to move from the apron to the runway and vice versa. In
case the aircraft does so using its own power, this is called taxiing. In case another vehicle is used, this is called towing.
For departing flights, taxiing or towing is generally preceded by push-back using a push-back truck. Even though the
amount of fuel burnt during the transport between apron and runway is limited compared to the fuel burnt during
flight, there are various ways in which this consumption can be further reduced 92.
An option available and regularly applied today is reduced engine taxi, in which one or more of the aircrafts’ engines
are shut down during taxiing. Various analyses have shown this can reduce taxi fuel consumption by 20 to 40% for
arriving and 20 to 45% for departing flights (AviationPros, 2011; Koudis, Hu, Majumdar, Ochieng, & Stettler, 2018;
Fleuti & Maraini, 2017; Ithnan, Selderbeek, Beelaerts van Blokland, & Lodewijks, 2013; Deonandan & Balakrishnan,
2010). Figures for departing flights are slightly higher, for instance because of longer taxi-out times (due to aircraft
sequencing, possible de-icing, etc.) and the higher aircraft weight at that time, and below 50% due to engine warm-up
requirements for the non-operational engine(s) 93. Combining these numbers, an improvement potential of 30% is
estimated for each arriving and 35% for each departing aircraft that moves from all-engine taxi to reduced engine taxi.
Opportunities to further reduce emissions during taxiing are electric taxi and operational towing – the latter using a
tow tractor powered by fossil fuels, bio-fuels or electricity. As industry development of solutions integrating an
electric motor in the aircraft gear were recently abandoned (Dubois, 2019), the remainder of the text is focussed on
operational towing 94, for which certified systems currently only exist for use on some single aisle aircraft. In this
procedure, the aircraft engines can remain switched off during the majority of ground operations. The emission
savings depend on the energy used by the tow tractor, noting it has to return to the apron (or runway) after towing
the aircraft. For various alternatives powered by bio-fuels, estimates range from 25% to 75% compared to aircraft
taxiing with all engines running (Deonandan & Balakrishnan, 2010; Ithnan, Selderbeek, Beelaerts van Blokland, &
Lodewijks, 2013). If an electric tow truck is used, potential savings increase to 85% of taxi emissions (Srivastava, 2018;
EEA, EASA & EUROCONTROL, 2019). Taking into account that aircraft power would have to be sourced from the APU if
the engines are not running, the effective savings are assumed to be 75%. Other potential benefits of autonomous
tow vehicles or systems include reduced noise (if electric) and other gaseous emissions.

92 In order to avoid double counting of potential emissions reduction with SES(AR), discussed in Section 4.3.1, benefits to be delivered through e.g. (support systems for)
surface movement planning, System-Wide Information Management (SWIM), etc.
93 Deonandan and Balakrishhnan (2010) estimated warm-up time to be between 2 and 5 minutes. Hemmerdinger (2016) notes an industry standard of “less than 1”
minute.
94 Nevertheless, e-taxi solutions might receive renewed interest (Airbus, 2013). Savings potential is estimated to be similar, although the aircraft weight increase due to
the e-taxi system is a key challenge to overcome.

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There is little public information about the amount of fuel that is used during taxiing operations compared to the total
amount of fuel consumed during a flight. Lacking a more recent reference that takes a broader perspective than one
airport, airline or aircraft type, generic estimates are sourced from a standard work on aircraft design. This states that
after having taxied to the runway, a departing aircraft has lost 1% of the weight it had as it begun the taxi phase due
to burning fuel (Roskam, 1985). Upon arrival, the weight decrease is approximately 0.5% for landing, taxi and
shutdown 95. Assuming some 35% of the starting weight of long-haul aircraft is fuel, a 1% weight decrease corresponds
to 3.5% of fuel consumed during taxi-out. For taxi-in, 0.5% of the weight of the aircraft and passengers can be
translated to approximately 1% of the original fuel weight 96. Adding these together results in 4.5%. However, fuel
consumption has reduced since the aforementioned source was published. Using the 1968 to 2014 compounded
annual rate of fuel burn reduction of 1.3% per year (Kharina & Rutherford, 2015), the 4.5% is decreased to 3%. For
single aisle aircraft, generally used on short haul routes, more information is available. Lawson (2016) approximates
that 6% of fuel is burnt on the ground. With 1% for ground APU usage (based on Department for Transport (2017)),
this leaves 5% for taxi fuel, which is consistent with assumptions by Schäfer, Evans, Reynolds & Dray (2015) and results
by Turgut et al. (2014) and Fleuti & Maraini (2017).
From 2020 up to 2025, the adoption of reduced engine taxi is here assumed to increase from a currently estimated 40
to 80%, yielding a reduction in mission-level fuel consumption of 0.2 to 0.4% for arriving and departing short haul
flights and 0.1 to 0.3% for arriving and departing long haul flights 97. A 80% limit is set to take into account operational
circumstances where reduced engine taxi might not be safe, for instance due to increased single-engine jet blast. The
split between short haul and long haul aircraft is set at 3500 kilometres. From 2025 up to 2035 commercial application
of electric taxi or electrified operational towing solutions is anticipated. Compared to reduced engine taxi, this has the
potential of delivering an additional benefit of 0.8% to 1.2% for short haul and 0.3% to 0.9% for long haul flights 98. Due
to the scope of the present study, benefits for arriving aircraft are only taken into account for intra-EU+ flights. As
operational towing also relieves the aircraft of the need to carry taxi fuel, an additional weight saving of 175 to 600
kilogrammes is estimated 99 – to be translated into an additional fuel saving using a cost of weight factor of 3.5% per
flight hour (the same as used in Section 4.2.2). This only considers taxi-in fuel, as taxi-out fuel is not carried along over
the flight.
In addition to the aforementioned changes to the energy source used for transporting the aircraft between apron and
runway and vice versa, it is relevant to qualitatively address the influence of airport design as well. Small distances
between the runway and terminal of course reduce taxi emissions, but there are other less straightforward measures
that can have a positive effect. Examples include high-speed runway exits and associated high-speed taxiway turns,
multiple taxiway-runway connections allowing for intersection take-offs and taxiways that allow aircraft to taxi around
active runways, preventing them from waiting and idling (Fala, Uday, Le, & Marais, 2014). Although improvement
potential is likely to exist, a lack of quantitative input data makes that these measures are not included in the model.

95 As most almost all of the fuel will be burnt during the flight, the weight upon arrival is notably lower than on departure – even more so for long-range aircraft.
96 (1 – 0.35) / 0.35 × 0.5% = 1.85 × 0.5% ≈ 1%

97 Taxi fuel savings of 30% to 35% × 3% to 5% of total emissions × (80 – 40)% application.

98 In case all engines are used, taxi accounts for 3 to 5% of total fuel burn. If reduced engine taxi is used – yielding 30 to 35% reductions – in 80% of cases, taxi emissions

reduce to 2.6% (taxi-in) and 1.8% (taxi-out) for short haul flights and 0.6% (taxi-in) and 2% (taxi-out) for long haul flights. This assumes a 40:60 split over taxi-in and -out
for short haul flights and a 2:7 split for long haul flights, following footnote 96. Electric operational towing reduces taxi emissions to 2% for short haul flights and 1.2% for
long haul flights in total. (In that case, mission fuel consumption of short haul flights would be reduced by 3 ppt, largely consistent with performance estimates of
(recently shelved) e-taxi solutions incorporating electric nose gears (Airbus, 2013; Air Transport Action Group, 2015; Dubois, 2019).) The remaining difference hence
becomes 0.8 to 1.2 ppt for arriving and departing short haul flights and 0.3 to 0.9 ppt for arriving and departing long haul flights.
99 For long haul aircraft, it was found using Roskam (1985) that the fuel required for taxi-out is approximately 3.5% of the total fuel weight. For taxi-in, this was
estimated to be 1% - or 2/9th of the total fuel used for taxiing. Applying the fuel burn improvement since the publication of Roskam lowers the taxi fuel amount to 3%,
without changing the ratio. As such, it is estimated that 2/9 × 3% = 0.667% of the fuel weight for long haul aircraft is consumed using taxi-in. Assuming 35% of the takeoff weight of such an aircraft is fuel, the taxi-in fuel weight is 0.667% × 35% = 0.233% of the take-off weight. Given a typical long haul take off weight of 250 tonnes, this
translates into 582.5 kilogrammes. For short haul aircraft, the taxi fuel was found to be 5% of total fuel. Applying the same ratio to split this number between taxi-out
and taxi-in and assuming fuel weight now only makes up 20% of the take-off weight, 5% × 2/9 × 20% = 0.222% of the take-off weight is estimated to be taxi-in fuel. Given
a typical short haul take off weight of 80 tonnes, this translates into 177.6 kilogrammes.

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4.4.2

Reduced APU usage

According to the UK Department for Transport (2017, p. 109), 1% of the emissions of a flight is associated with the use
of the auxiliary power unit (APU), which is used to power on-board systems. Feeding aircraft with electrical groundpower from a fixed (FEGP) or mobile source (e-GPU) and/or using fixed or mobile pre-conditioned air (PCA) enables a
reduction in APU usage. Based on data from Heathrow, Zurich and Barcelona El Prat airports, a fuel saving potential of
0.4% per flight is assumed (ATAG, 2015). Given the fact that various airports already apply these practices, this
number is reduced to 0.3% to be realised between 2020 and 2025. A fairly long implementation period is anticipated
as the full emission reduction potential can only be realised when renewable energy is used. In newer aircraft, this
reduction might also be realised by fuel-cell powered APUs, discussed in Section 3.3.1.

4.4.3

Potential impact overview

Table 17 provides an overview of potential impacts of the ground-related operational improvements at airports
discussed in this section. ‘SH’ indicates short haul flights (below 3500 kilometres); LH indicates long haul flights (3500
kilometres and up). Weight savings listed in the column ‘potential CO2 emissions reduction’, for example as a result of
lighter cabin equipment or reduced fuel load, are translated into fuel savings on a flight-by-flight basis using a cost-ofweight computation (further explained in Section 4.2.2, specifically footnote 60 on page 56).
Table 17: Potential CO2 emissions reduction to be delivered by ground-related operational improvements at airports
per flight
Measure
Reduced engine taxi – SH
Reduced engine taxi – LH
Reduced engine taxi – SH
Reduced engine taxi – LH
Electric taxi / operational towing – SH
Electric taxi / operational towing – LH
Electric taxi / operational towing – SH
Electric taxi / operational towing – LH
Reduced APU usage

4.5

Potential CO2
emissions reduction
0.2%
0.1%
0.4%
0.3%
0.8%
0.3%
1.2% + 175 kg weight
reduction
0.9% + 600 kg weight
reduction
0.3%

Starting
year
2020
2020
2020
2020
2025
2025

Delivered
by
2025
2025
2025
2025
2035
2035

2025

2035

2025

2035

2020

2025

Remarks
Intra-EU+ arrivals only
Departures only
Intra-EU+ arrivals only
Departures only, weight
saving modelled using
3.5% cost of weight per
block hour

Drivers and barriers

The previous section already showed and discussed the substantial amount of complexities associated with ATM and
aircraft operations. The current section specifically discusses drivers and barriers – elements inspiring or speeding up
fuel burn improvement and aspects hindering or slowing the realisation of potential emissions savings.

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4.5.1

Drivers

Besides the all-encompassing and ever-increasing political, governmental and societal push towards reducing CO2
emissions, various specific developments and trends drive the implementation of the ATM and operational measures
described in this chapter. It is stressed that these developments are drivers: they directly or indirectly contribute to a
particular effect, but need not necessarily be the most effective agents for change.
As holds for the other chapters, this section describes what the authors of this report have determined to be the most
important drivers, rather than presenting an exhaustive listing. Nevertheless, especially given the attention this
chapter pays to emissions around airports, it is acknowledged that CO2 reductions often yield benefits in terms of
improved air quality and reduced noise emissions in the landing and take-off (LTO) cycle. Similarly, measures designed
to reduce these environmental impacts can result in reductions in CO2. On the other hand, there are also situations
where trade-offs are necessary.
Current and short-term: reducing cost, automation and improving CNS accuracy and performance
Already at present, reducing fuel consumption and CO2 emissions is often in line with reducing direct operating cost.
This provides airline business with a clear economic incentive to reduce their environmental impact. In case the share
of fuel(-related) costs in the total direct operating cost increases, this driver is strengthened. This might for instance
be the result of an increase in oil price, or a reduction in ATM charges or crew cost.
As relevant for the aviation sector as for many other sectors, increasing computational power, (big) data availability
and artificial intelligence (AI) present opportunities in airspace and flight modelling, simulation, prediction and
optimisation. This is relevant for almost all aspects treated in this chapter. Examples include improving weather
predictions, taking more parameters into account in flight (re-)planning efforts, predicting future aircraft trajectories
and associated separation distances, and improving revenue management systems to realise higher load factors.
Further towards 2050, these developments are crucial in further ATM automation.
Related to the previous item, increasing accuracy and performance of communication, navigation and surveillance
(CNS) equipment, such as ADS-B and ground- or space-based augmentation systems, enable more precise positioning
and navigation. This is absolutely necessary for effective wake energy retrieval (discussed in Section 4.3.4), but also
enables reduced separation minima. This in turn might increase available airspace capacity, such that more aircraft
can achieve their optimum flight path and profile in both a horizontal and vertical dimension. For such potential
benefits to be captured in a safe manner, a much higher predictability of traffic mentioned in the previous paragraph
is one of the many requirements that must be met.
Medium and long-term: accommodation of other airspace users, further automation and personnel changes
Although their environmental impact is not considered in this report, the introduction of drones and urban air
mobility systems undoubtably presents challenges to the current ATM system and drives ATM innovation. Closely
coupled to AI and increased automation, techniques initially developed to file and check flight plans of automated
flight systems (which lack a pilot to communicate through) might someday be applied to larger commercial aircraft as
well. Combined with improved flight planning software and flight management systems, this could enable real-time
changes to flight trajectories in order to make use of favourable weather conditions.
An additional driver for automation is formed by (anticipated) changes in personnel duties. Air traffic control officers
are likely to shift towards a more supervisory position and single pilot cockpits are foreseen in the next decades.
Possible personnel shortages can further strengthen this driver. In the shorter term, increased automation can be
used to support air traffic control officers in their duties and improve their efficiency.
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4.5.2

Barriers

In addition to the drivers identified in Section 4.5.1, numerous developments or industry characteristics make it more
difficult to realise the improvements laid out in this chapter. An overall barrier, also applicable to other pillars
considered in this report, is formed by the substantial (financial) risks associated with most – if not all – potential
improvements that are outlined.
Further discussing barriers, it is relevant to re-emphasize the complexity identified at the beginning of this chapter.
Although in all cases encapsulated in a regulatory environment, airlines can fairly independently carry out some
weight reductions (e.g. reducing supplies), whereas OEMs need to be involved in cases that might influence the
functioning of the aircraft. Similarly, reducing CO2 emissions en-route requires a joint effort by airlines as well as
ANSPs – who also have to take into account other (possibly military) airspace users. Last, ground handlers influence
efforts towards reducing APU and taxi emissions.
Interdependencies and lack of alignment
This complexity is not a barrier per se, although it generally requires a lot of discussion and negotiation to actually
enable change. Different actors have different interests and ANSPs and airport operators face dilemmas in trading off
between reductions in noise and reductions in emissions. Airports are scored based on departure punctuality – even
though making sure one flight departs on time might require an incoming aircraft to deviate from its optimised
descent profile 100. Airlines have to balance environmental efforts to maintaining competitive cost levels. And at a
regulatory and political level, national interests and lack of political willingness are often cited as barriers to progress
in the realisation of the Single European Sky that (as seen in Section 4.3.1) can substantially contribute to lowering CO2
emissions. In general, different priorities and the requirement to balance the numerous interdependent factors (e.g.
CO2 emissions, noise and local air quality, as well as non-environmental aspects) hamper progress towards lowering
the environmental impact of aircraft operations.
Traffic growth and fragmentation
In addition to the aforementioned shortage of and focus on specific and clearly-defined common goals (by both
industry as well as governmental or regulatory organisations), some more specific barriers can be mentioned. A
primary challenge is ensuring a sustainable COVID-recovery, followed by accommodating the post-COVID long-term
traffic growth that is anticipated – also in this report. As indicated in Section 4.3.1, a number of organisations and
individual industry experts are worried that the improvement potential in ATM is reduced by an increasing number of
flights 101. A lack of standardised ways of exchanging data between parties (ANSPs amongst each other, but also with
other parties) and limited interoperability make for a fragmented ATM system, hindering faster and more universal
implementation of new procedures. Besides, some actors have for instance cited a lack of competition amongst ANSPs
as hurdle towards innovation. Notwithstanding the fact that other mechanisms – such as customer satisfaction and
feedback, the ANSP Performance and Charging Scheme and changing legislation – are (put) in place to stimulate
innovation, it is true that competition can act as a catalyst for change.
New entrants
Despite its listing as a driver, the increasing variety (and number) of airspace users comes with disadvantages as well.
Rather than being able to design the airspace system for only commercial aircraft of a certain weight class, other types
of vehicles – with different operational limitations – have to be integrated into the system. This might result in a
situation where compromises have to be made. Another barrier closely related to a driver is that the aviation sector
100 ACI EUROPE has embraced the shift towards arrival management and punctuality, even though station management of airlines is not seldomly assessed on departure
punctuality.
101 As a concrete example: if safety concerns require the current separation standards, and traffic between A and B in a particular period of time is increased, some of
that additional traffic might have to take a detour through less congested parts of airspace – even though this increases fuel burn and CO2 emissions.

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for a variety of reasons is not the easiest to new entrants – although entrepreneurial spirits might exactly be the ones
best suited for introducing step-change innovations, for example in terms of artificial intelligence.
Regulation, certification and authorisation
Last, it is noted that time- and cost-intensive regulation, certification and authorisation processes are a barrier to
realising change rapidly. The international context, and the need for rules and regulations to be consistent around
large parts of the globe, makes this a difficult problem to solve. Industry experts spoken to in the context of this study
further indicated that constraints on personnel availability for non-operational tasks sometimes make it more difficult
to achieve progress quickly.

4.6

Policies and actions

Having identified a substantial list of potential improvements with respect to ATM and aircraft operations in the
previous sections, it is stressed again that these will not realise themselves on their own. Policies and actions from
governments as well as industry are necessary to realise the full potential and impact of the solutions discussed. They
are often directly related to the drivers and barriers discussed in Section 4.5.
Given the fact that many of the possible improvements can be implemented in the short- to medium-term, decisive
and quick actions are necessary. This holds as much for the development and implementation of policies as for efforts
to be taken by sector parties.
The remainder of this section treats policies (Section 4.6.1) and actions (Section 4.6.2) in greater detail. Although
overlap does exist, policies are mostly related to government or regulatory bodies, whereas actions are largely aimed
at the aviation industry.

4.6.1

Policies

The present section provides an overview of policies that are deemed necessary to unlock the potential improvements
in ATM and aircraft operations discussed in this chapter. These are derived from literature as well as expert input
gathered in the development of Destination 2050.
More specifically, many of the policy recommendations on European ATM stem from or are inspired by fairly recent
and still highly relevant reports on the possible future of the SES (ECA, 2017; Wise Persons Group on the Future of the
Single European Sky, 2019; SESAR JU, 2019a; ICB, 2019). Given the sheer size and impact of this program, the majority
of the present section is dedicated to SES. In reference to the aforementioned studies, it is stressed that whereas
these take a broader look at realising the full set of anticipated benefits of the SES (including safety, capacity and costefficiency), the present report is limited to potential improvements reducing the environmental impact of aviation.
Irrespective of the exact policy measure, it is stressed in general that long-term, consistent and widely applicable
policies are key. This is essential to reducing uncertainty and risk to manageable levels, allowing businesses to plan,
invest and prepare for change.
Single European Sky: towards a network-centric and digital ATM system, with regulation and R&D to match
The most important task to realise the environmental improvement potential associated with SES is to replace the
rather fragmented system of today with a coherent, network-centric and collaborative ATM system. Defragmentation,
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enhanced collaboration and a mindset-shift focused on balancing local interests with network interests, should deliver
the results that European citizens have been waiting for far too long 102, rather than prioritise the requirements or
preferences of any individual ANSP or airspace user. Indeed, as outlined in the communication on the Green Deal,
“work on adopting the Commission’s proposal on a truly Single European Sky will need to restart, as this will help
achieve significant reductions in aviation emissions” (EC, 2019i, p. 10). At the most strategic level, this first requires
agreement upon and complete commitment, also by the Member States as shareholders in their ANSPs and by air
traffic controllers as the crucial operators, to these shared specific, measurable, achievable, realistic and time-bound
objectives 103. Second, it requires the realisation of concrete milestones – starting now. The following paragraphs
outline a number of these, which together help cut CO2 emissions across European airspace. Even though the present
section primarily addresses governmental or regulatory bodies, the required involvement and participation of industry
partners is stressed: results cannot be achieved without a joint effort.
Consistent with observations in the aforementioned reports, the conclusion that the FABs as originally intended are
not likely to deliver their anticipated benefits is reaffirmed. Therefore, other ways to achieve those same benefits
have to be – and are – found 104. Ever-increasing computational power and networking opportunities were previously
listed as important drivers. They enable real-time collaboration, data sharing and virtualisation – moving towards a
situation in which airspace boundaries and national sovereignty considerations can be respected, but no longer
negatively impact ATM environmental performance (and by extension: Europe’s climate neutrality ambitions) as they
presently do. This increases possibilities for solutions such as cross border arrival management (XMAN), which reduces
the need for aircraft to be placed in holding patterns prior to landing. As a complete and real-time flow of information
between stakeholders (ANSPs and airspace users, possibly others) is essential, standardisation of data formats and
protocols is required 105. Relevant stakeholders should be consulted in the development of such standards, in order to
guarantee a future-proof foundation. Newly-created ATM Data Service Providers 106 might play a role in supporting a
data exchange infrastructure or in effectively collecting and re-distributing relevant information. The development
and distribution of consistent near-term traffic flow predictions, made possible by processing all relevant data, is a
closely related task. All of this could eventually bring us to a collaboratively operated ATM based on shared goals –
including goals with respect to environmental performance and sustainability.
Although efforts to realise this collaborative, cooperatively operated network should start sooner rather than later, it
is noted that such changes will take years to fully materialise. In the shorter term, a stronger coordinating role for the
Network Manager 107 (as proposed in SES II+ regulation) can be a first step towards a more network-centric view of
European ATM. Proposals for airspace re-configuration and redesign of airspace sectors 108 or the creation of a
seamless European upper airspace system 109 are also noted as tangible opportunities. Especially the latter measure
further advances the ideas of Free Route Airspace and (Advanced) Flexible Use of Airspace. Reducing the differences
between unit rates, for example through the introduction of a common upper airspace route charge 110, might (wilfully
or not) disincentivise airline operators from using possibly more fuel consuming routes, although possible negative

102 Following recommendation 2 by the European Court of Auditors (2017), recommendation 2 from the Airspace Architecture Study (SESAR JU, 2019a) and
recommendations 1 to 3 by the Wise Persons Group on the Future of the Single European Sky (2019).
103 Following recommendation 1 by the European Court of Auditors (2017) and paragraph 77 of its report.
104 Following recommendation 2 by the European Court of Auditors (2017) and recommendation 2 from the Airspace Architecture Study (SESAR JU, 2019a).
105 Following recommendation 3 by the Wise Persons Group on the Future of the Single European Sky (2019).
106 Following recommendation 2 from the Airspace Architecture Study (SESAR JU, 2019a) and recommendation 4 by the Wise Persons Group on the Future of the Single
European Sky (2019).
107 Following recommendation 1 by the Wise Persons Group on the Future of the Single European Sky (2019).
108 Following recommendation 1 from the Airspace Architecture Study (SESAR JU, 2019a).
109 Following recommendation 9 by the Wise Persons Group on the Future of the Single European Sky (2019).
110 Following recommendation 9 by the Wise Persons Group on the Future of the Single European Sky (2019), and also discussed in the SES2+ Staff Working Document
(EC, 2020a).

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consequences should not be overlooked. Financial or other incentives might additionally be used to stimulate more
environmentally-friendly flight paths or equipage 111.
In order to guarantee the implementation and application of (technical developments driving) the aforementioned
measures, regulatory frameworks should be aligned. Among other things, this means that key performance indicators
in the SES Performance and Charging Scheme should be (re-)designed – with input from industry – in such a way that
adequate accountability is guaranteed 112. An updated environmental KPI, for instance, might consist of one part
targeted at ANSP performance and one part targeted at airspace user performance. In case in-flight rerouting enables
a reduction of flight distance even below the SCR 113, the efforts by both ANSPs and operators should be acknowledged
– for example as ‘bonus’ that can be used to compensate for lower performance elsewhere in the system. In order to
take into account that the shortest route might not be most fuel-optimal 114, it should be investigated whether it is
possible to objectively determine the most fuel-optimal route and use that distance (or fuel burn metric) – rather than
the shortest distance (or fuel burn metric) – in aforementioned environmental KPIs. Such KPIs should take the
interdependencies between different (environmental or other) performance areas into account, possibly by defining a
particular altitude below which noise is prioritised, and above which CO2 emissions are focussed on (Ministry of
Infrastructure and Water Management, 2020b, pp. 78-79). Reiterating that the Performance and Charging Scheme
aims to mitigate negative effects of the monopolistic status of numerous ANSPs, liberalisation might be actively
stimulated (e.g. in data and tower service provision) and should in any case not be hampered 115.
In assigning accountability and ownership, the SESAR Joint Undertaking should be held more strictly accountable to
the delivery of SESAR Solutions 116 – with the NM or ANSPs subsequently assessed or (financially) stimulated based on
the time between delivery and implementation in the operational environment 117. Such stimuli should strike a balance
between rewarding first-movers and preventing unsynchronised deployment, for those cases where synchronisation is
required to deliver benefits. National Supervisory Authorities (NSAs) should be able to independently and effectively
supervise the ANSPs in their Member State 118. Given sometimes different local or national priorities, for example in
the trade-off between emissions and noise nuisance, it is proposed to investigate how these interdependencies can be
accurately reflected in performance targets or requirements. Using separate KPIs for en-route and TMA performance
might be one of the available options – although this would contradict efforts increasing harmonisation.
In further support of technology and procedure research and development, the public R&D funding scheme should be
reviewed. Whereas current EU ATM R&D efforts are limited in time to 2024, a structure (SESAR JU or other) should be
created to address the longer-term R&D effort 119. This should be fully aligned with the relevant timelines and
specifically promote realising innovations that significantly reduce the environmental impact of aviation and thereby
improve the situation for the European public at large 120. Work has already started in this area, in the form of the
proposed SESAR 3 Joint Undertaking, clearly focused towards making a contribution to the CO2 emissions reductions
modelled in this study. This will not only strengthen ATM research and innovation capacity in the EU, but explicitly
aims “to develop and accelerate the market uptake of innovative solutions to establish the Single European Sky
airspace as the most efficient and environmentally friendly sky to fly in the world” (SESAR 3 JU, 2020). In order not to

111 Following recommendation 5 by the Wise Persons Group on the Future of the Single European Sky (2019), as well as EC (2020a)
112 Following recommendation 6 by the European Court of Auditors (2017).
113 A possibility clearly observed in EUROCONTROL (2019b).

114 Or climate optimal, as for example researched in the Horizon 2020 ClimOP-project (cf. https://cordis.europa.eu/project/id/875503).
115 Following recommendations 4 and 10 by the Wise Persons Group on the Future of the Single European Sky (2019).
116 Following recommendation 8 by the European Court of Auditors (2017).

117 Although formulated more broadly in this report, this policy recommendation aligns well with recommendation 5 by the Wise Persons Group on the Future of the
Single European Sky (2019).
118 Following recommendation 3 by the European Court of Auditors (2017), and also discussed in the SES2+ Staff Working Document (EC, 2020a).
119 Following recommendation 7 by the European Court of Auditors (2017).
120 Following recommendations 5 and 7 by the European Court of Auditors (2017).

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endanger deployment of currently developed SESAR solutions – bringing proven sustainability and environmental
benefits – by the impacts of the COVID-19 pandemic, full public funding for that deployment might be considered.
Last, policies should be put in place to ensure steady progress on delivering the benefits of SES. Although some
progress has been made in the previous 15 years and some of the complications during that time have provided
relevant insights that support the present recommendations put forward in this section, a repetition of steps would be
highly unfortunate. In case new insights in three, five or ten years’ time indicate the pathway outlined in this report is
not the best way forward, swift action should be taken to adapt plans and meet the agreed-upon goals. Further delays
in delivering the potential improvements of a more network-oriented and digitalised ATM system to the European
public cannot be afforded.
Quantifying – but most importantly: realising – the further CO2 emissions reduction potential that might be captured
by fuel and CO2 optimised trajectories and resolving possible persistent inefficiencies should receive notable policy
attention. As noted in Section 4.3.1, detailed system-level assessments on the potential impact of optimising for CO2
emissions seem to be lacking – but as EUROCONTROL (2020a) suggests, might indicate very worthwhile improvement
potential. Following such assessments, current regulations or stimuli focused on reducing distance flown might show
to be an impediment to achieving more fuel optimal routes, and should be altered.
Speeding up communication, navigation and surveillance innovation
Although relevant to the context of the Single European Sky, but certainly not limited to it, financial or other
incentives should be considered as a means to increase technology uptake at the side of airspace users. Examples
might be a ‘most capable, best served’ scheme, or using a framework rewarding early movers, for instance through
financial incentives or a modulated route charge 121. In any case, procedures should reflect modern technology and
realise the improvements contained within rather than maintaining ‘backwards compatibility’ for a small number of
airspace users. Policy measures contributing to the operational use of technology that is currently available can
provide quick wins and should be implemented as soon as possible. This also means that – although instantaneous
implementation cannot be expected or required from operators – implementation and transition periods should be
kept relatively short.
Even beyond readily available technology, improved CNS accuracy and performance – and regulatory changes
capitalising on these technology improvements – are essential to delivering some of the other benefits noted in this
chapter, and to do so in a safe manner. Wake energy retrieval most certainly is one of those concepts for which
regulatory changes with respect to separation minima will be necessary. Given the ambitious timelines proposed in
the present study, it should be investigated sooner rather than later how safe implementation can be guaranteed. The
knowledge and evidence-base gained this way might – in a longer term – contribute to more widespread application
of reduced separation minima. Although such measures have not been considered in detail in this report, it is noted
that this can be one way to resolve the current and future capacity shortages – leading to substantial amounts of
additional CO2 emissions.
Beyond the Single European Sky
Although European policymakers have no direct influence on airspace design and ATM elsewhere around the world,
they should do their utmost to stimulate regions and States around the world to improve ATM efficiency. This can, for
example, be done through international structures as ICAO, international cooperation with other important ATM
operators and perhaps also through provisions included in bi- or multilateral air service agreements.

121 Following recommendation 3 from the Airspace Architecture Study (SESAR JU, 2019a) and recommendation 5 by the Wise Persons Group on the Future of the Single
European Sky (2019).

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Guaranteeing environmentally friendly ground operations
Focusing on improvements to airport operation beyond those addressed in the SESAR-programme, incentives or
regulations should be put in place to guarantee environmentally friendly ground operations. This should consider
incentives (e.g. allowing accelerated depreciation) for replacing fossil-fuel based ground support equipment by biofuel or electrically powered alternatives. Similarly, options to require newly constructed or renovated gates or remote
stands to be equipped with electrical ground power (FEGP or using an e-GPU) and/or pre-conditioned air can
contribute to making sure infrastructure constraints do not limit a reduction in APU usage. Rather than only applying
such requirements to new developments, another option would be to set minimum equipment levels airport-wide. If
such measures are contemplated, technical enablers, including sufficient renewable electrical capacity, should be
made available. Furthermore, the recovery of associated costs by airport operators has to be taken into account. In
case of replacement of current infrastructure, the aforementioned idea of accelerated depreciation might be used. In
addition to having these more sustainable installations in place, their use has to be guaranteed – through either coststimuli or enforceable mandates.
Enabling electrification and other alternative energy sources
With numerous potential improvements relying on a substantial supply of renewable electricity (e.g. electrical ground
power, electrical operational towing; possibly extended by electric aircraft in the longer term), policies to further drive
and accelerate the clean energy transition are required. This also holds for possible infrastructural changes related to
other sustainable energy sources, most notably hydrogen (further discussed in Section 3.3 and Chapter 5).

4.6.2

Actions

Whereas Section 4.6.1 was mostly aimed toward governments and regulatory bodies, the current section describes
what actions from the aviation industry are necessary to unlock the potential in reducing CO2 emissions in the ways
described in this chapter. Given the fact that many different actors might be involved in realising a particular
improvement the actions are listed per (group of) improvement measure following the structure of this chapter rather
than per actor. The section ends with a number of overall actions that apply to the industry as a whole.
Aircraft operations: improving flight planning, reducing weight and optimizing aircraft condition
Although it might not come easy, the necessary industry actions to realise the improvement potential listed in Section
4.2 are relatively straightforward. Aircraft operators should further increase their efforts towards:


improving flight planning, using the latest available software solutions;



reducing weight, by starting up or continuing weight reduction programmes, and by reducing or altogether
putting an end to tankering operations; and



improving aircraft surface and engine condition.

The potential improvements described in Section 4.2, widely available best practices and knowledge exchange
between different aircraft operators can help identify the most suitable and cost-effective measures to realise
aforementioned benefits (ATAG, 2015; ICAO, 2014b; Becken & Pant, 2020). Especially for SMEs developing solutions to
enable such benefits might benefit from in-kind support and/or direct financial investment from established parties.
In case new flight management systems are introduced into the market, aircraft operators should be quick to upgrade
their fleets. Although this will require a not insignificant investment, savings associated with fuel cost (as well as cost
for carbon offsetting, carbon capture and/or emissions allowances) will allow operators to recuperate that investment
in a reduction of operating cost. OEMs, equipment manufacturers and MRO providers should fully support and
actively promote retrofitting aircraft in service.

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Air traffic management: putting the latest technology in operation
Requiring cooperation with OEMs, equipment suppliers and MRO providers, airlines should make sure their aircraft
are equipped with state-of-the-art communication, navigation and surveillance equipment. Following the supportive
policies proposed in Section 4.6.1, the systemwide ATM-benefits unlocked by this new technology will be translated
into benefits for the operator. Furthermore, savings in fuel(-related) cost are anticipated to offset one-time
expenditures. Additionally, policies rewarding first movers (as proposed in Section 4.6.1) can be used to make such
investments even more worthwhile.
The above action holds true for ANSPs as well. The system-wide data and information sharing, discussed at length in
Section 4.6.1, should be supported throughout Europe. As indicated there, data exchange formats and protocols
should be standardised, but ANSPs might also opt to replace their bespoke systems by commercial-off-the-shelf
applications, or commission the development of a shared system for use throughout Europe. Stimulated by
regulations or incentives, ANSPs should implement delivered SESAR innovations in a consistent and rapid manner –
such that the environmental benefits they allow can be enjoyed without delay.
Specifically for wake energy retrieval, a concept of operations (CONOPS) should be developed by industry and
regulators collaboratively. This must first of all concern safety aspects, which are of paramount importance. In
addition, airlines should work out how costs and benefits are to be distributed between the two aircraft in a pair. This
is easier to implement when both aircraft are operated by the same airline and can be considered part of a
(transatlantic) joint venture in case two airlines have such a partnership, but is expected to require more thought in
case airlines are unrelated – or might even directly compete with each other on a particular route. Although the
competitive airline environment is respected and valued, it should not stand in the way of achieving reductions in
aircraft emissions. Given its role in clearing inter-airline debt as well as its international standing, IATA might play a
role in this.
Ground operations: reducing emissions from aircraft taxi and APU usage
In the quest of reducing ground emissions from aircraft, numerous actions are to be taken. First of all, the various
stakeholders involved in taxi operations should work to further adopt and standardise reduced engine taxi
procedures. Special attention should go out to applying this widely for departing flights, as these show the largest
potential, yet face particular specific challenges. In addition to developing procedures to do so safely and efficiently,
airlines should make sure to stimulate or instruct their cockpit crews to indeed apply these measures. In a slightly
longer term, a joint and industry-wide effort should be made to enable electric taxi or (electric) operational towing.
Specifically, this includes the following tasks:


For OEMs to aid (or directly collaborate with) tractor manufacturers in their development of the necessary
equipment, for example by assisting with testing and certification, and – if necessary – developing upgrades
to the nose landing gear in order to support this new load case. In any case, OEMs should make sure their
(future) products are fully compatible with operational towing. Furthermore, appreciating the larger
(absolute) impact of electrical operational towing on long-haul aircraft, systems suitable for widebody
aircraft should be developed.



For airports and tractor manufacturers, with input from ANSPs and airlines, to determine the best way of
implementing operational towing, balancing e.g. environmental sustainability, reliability and costeffectiveness. Such considerations might drive the tractor design (speed, power, energy capacity), as well as
infrastructure requirements (charging stations, possible additional airside service roads for tractor
movement).



For ANSPs to work together with airports, tractor manufacturers and airlines to develop a concept of
operations for autonomous towing, as well as the supporting infrastructure, on-board hardware and
software to support such a concept.
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Given the complex, highly regulated and capital-intensive nature of the industry (as outlined in Sections 1.1 and 4.5.2)
in-kind or capital investment by established organisations in new entrants developing such solutions might be
considered to speed up innovation – and thereby speed up delivery of the associated benefits.
Fitting with electric taxi and electrical operational towing, but not strictly limited to it, airport operators should futureproof their electricity systems. In the medium term, that entails ensuring support for charging electrically powered
equipment (ranging from ground support equipment to complete hybrid- or battery-electric aircraft). Starting now,
this includes making sure to offer airlines electrical ground power at both gates as well as remote stands (through
FEGP or e-GPU-systems) and pre-conditioned air, the latter somewhat dependent on the local climate observed at the
airport. This holds for the construction of new aircraft stands, but should also be taken up in the modernisation efforts
of existing infrastructure. Policies that incentivise the acquisition of environmentally friendly equipment (as proposed
in Section 4.6.1) ease the capital expenditure burden on airports and/or handling agents. Besides such stimuli, parties
should also appreciate – and take into account in their business plans – the generally lower operating and
maintenance cost associated to electrical rather than fossil-fuel powered equipment. Of course, (further) efforts to
lower and ultimately eliminate the carbon content of electricity used should be pursued. This can take the form of
equipping terminal buildings with solar panels, for example, but also to exclusively procure renewable electricity from
power suppliers.
In addition to aforementioned efforts, airports should uphold best practices when it comes to runway and taxiway
design – including, for instance, high-speed runway exits and preventing aircraft from having to (wait in order to) cross
other active runways. As for aforementioned infrastructure investment, these considerations should be taken into
account in new developments, but might also be applied in an effort to improve existing infrastructure. When
combined with larger maintenance works, the impact on the operation can be limited as much as possible. Similarly,
but with a reduced need for infrastructure adjustments, improvements can be realised by implementing SESARsolutions focused on ground operations.
Last, airlines and airports should include sustainability requirements in tenders for handling services and ground
service equipment. This way, other companies in the value chain are stimulated to take their responsibility when it
comes to reducing CO2 emissions. For existing contracts, handling agents should be promoted to work sustainably.
Even though emissions savings associated to limiting unnecessary use of ground service equipment is considered
outside the scope of the present project, stimulating sustainable behaviour now can contribute to a changed mindset
urgently required in the years to come.
Overall: a truly collaborative effort in decarbonisation
Highlighted previously in Section 4.5.2 and exemplified in numerous actions earlier in this section, it is stressed here
once again that a collaborative industry effort is urgently required to effectively address the decarbonisation challenge
facing commercial aviation. Respecting of course the responsibilities and authority of various stakeholders over
different parts of the operational process, actors should not limit their sustainability efforts to the elements they
directly control. A renewed balance between local and network-level optima should be strived for by all relevant
actors. Replacing a profit-first mindset (having cost-efficiency as a boundary condition, and optimising for
sustainability) by a sustainability-first attitude (the other way around) might be a stimulating fresh perspective.
This joint approach – of which the recent Aviation Round Table Report as well as the joint commissioning of this study
might be seen as major examples – gives rise to a number of more concrete actions. Aligning goals is one; further
sharing knowledge and best practices is another. Data sharing and tackling operational inefficiencies from multiple
perspectives at once would be a next. Airlines which share fuel consumption data with ANSPs, for example, might help
quantify further CO2 emissions reduction potential or assist air traffic control officers in helping to drive down the
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environmental impact of flights by providing them with more information on the consequences of their instructions in
terms of fuel consumption and CO2 emissions 122.
Finally, increasing sustainability efforts on a corporate or industry-wide level also requires increasing awareness of the
importance of sustainability and fuel efficiency with operational employees: pilots, ATCOs, handling agents,
maintenance personnel and airport employees. It also means that organisations should provide adequate time and
resources for their staff to work on sustainability initiatives – rather than asking them to do it ‘on the side’.

122 If one of two aircraft has to be rerouted, for instance, such data could be used to determine the most environmentally friendly detour – also taking into account
possible additional fuel burn required to make up time during the rerouting.

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5

Sustainable aviation fuels
Eight pathways have been ASTM approved as alternative drop-in fuels to make aviation more
sustainable. Towards 2050 additional pathways are expected to get certified including extending
the blending limit to 100%. The sustainability of the fuel is considered in terms of life-cycle emission
reductions including the effect of land use change and socio-economic impacts. The sustainability
criteria in the EU are defined by the RED II framework mainly based on life-cycle emission reductions
and caps on high ILUC-risk feedstocks. The analysis therefore considers ‘advanced feedstocks’ made
from non-food crops, residues and renewable electricity. Production of these fuels mainly takes
place in the EU based on regional supply chains. For e-fuels also the import of hydrogen is
considered from regions outside the EU such as North Africa and Middle East.
Based on the announced production facilities, announced or implemented national blending
obligations and EU hydrogen production and imports, the SAF potential in 2030 is estimated at 3.2
Mt (equivalent to 6% of total fuel consumption). SAF contribution in 2030 may be increased if a
strong political support is given to SAF development. The life-cycle CO2 savings are estimated
according to the RED II GHG savings thresholds. The SAF potential in 2050 is based on the
comparison with other roadmaps taking into account multiple sectors of the economy. In 2050 the
SAF amount is estimated at 32 Mt, equivalent to 83% of total kerosene consumption. The value is
based on scenarios and verified against feedstock availability predictions. In 2050 CO2 savings over
the life-cycle are estimated at 95% for biofuels and 100% for power to liquid fuels. Scenarios for
the deployment of SAF are closely connected and influenced by assumptions on the policy
framework, as such this analysis presents a possible pathway for the uptake of SAF in 2030 and
2050.
The policies and actions towards 2030 define the basis for a coherent long term policy framework
which enables upscaling of production. This includes diversifying the mix of feedstocks and
production processes, and setting up a monitoring and accounting framework. To create a stable
market different types of incentives are considered to bridge the price gap with fossil fuels such as
carbon pricing. Towards 2050 the policies focus on the division of sustainable feedstocks between
different sectors, taking into account that aviation will continue to rely on liquid fuels. To ensure a
minimum uptake of sustainable fuels an EU wide blending obligation is considered.

5.1

Introduction

In the last 15 years the aviation industry has focused on developing alternative “drop-in” fuels to reduce the
environmental impact of aviation. Drop-in fuels can be blended with conventional kerosene (up to a certain
percentage) and are certified for use in the existing fleet and therefore require no changes to the aircraft, engine or
infrastructure. The boundaries of the current certification blending limits may be extended in the future, requiring
changes to either the current engines and fuel systems or the chemical composition of the fuel, to reach larger shares
of sustainable aviation fuels. More recently, research has also focused on the use of power to liquid fuels.
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Sustainable aviation fuels (SAFs) have a major potential in reducing the climate impact of the aviation industry as the
net CO2 emissions over the life-cycle can currently be reduced up to 80% and in the future up to 100%. Especially in
the short term using sustainable drop-in fuels presents a major opportunity to achieve in-sector emission reductions
while using the existing fleet. Development of the SAF market can lead to regional business opportunities, job creation
and might position the European Union as a frontrunner in this upcoming industry.
Despite the many benefits, major challenges remain for a successful deployment of SAF. Stringent sustainability
criteria should form the basis of the policy framework and the industry actions. The development and the application
of these criteria are essential for airlines, fuel producers, states and international organisations like ICAO. These
criteria aim to achieve carbon reductions combined with positive socio-economic impact while avoiding competition
with food and feed supply and negative ecological impacts such as deforestation. The main economic barriers are
related to the higher cost compared to fossil kerosene and the investment risks associated with a new market.
Development and deployment of SAF is also influenced by political decisions such as the recently announced
European Green Deal. Europe’s energy transition towards full decarbonisation affects the availability of renewable
energy for all sectors of the economy including aviation.
This chapter gives an overview of ASTM certified fuels and other potentially interesting fuels, the available feedstocks
and the related production processes, and finally the potential deployment of SAF in 2030 and 2050. The analysis
includes the main drivers and barriers that influence the future deployment of SAF and that define the level of
uncertainty. The successful deployment of SAF is directly connected to a long term policy framework in combination
with industry ambitions and political focus. The chapter therefore ends with an overview of industry and government
actions.

5.2

Sustainability

The definition of sustainability in the context of SAF is defined by ATAG as “something that can be continually and
repeatedly resourced in a manner consistent with economic, social and environmental aims, specifically something
that conserves an ecological balance by avoiding depletion of natural resources and does not contribute to climate
change” (ATAG, 2017). Sustainability is therefore not limited to GHG reductions but also takes into account land use
change (LUC) and socio-economic impacts. Some feedstocks for the production of biofuels are typically grown on
cropland which can also be used for the production of food or feed. It is important to ensure that the production does
not compete with these primary resources. LUC takes place when biofuels cause modifications in the use of the land
(e.g. from forest to crop) either in the same cropland the biofuel is grown (Direct LUC) or elsewhere (Indirect LUC) due
to, for example, supply and demand constraints. This may cause eventually indirect emissions due to the loss of CO2
capture by photosynthesis by former trees or due to the release of CO2 stored in trees or soils resulting from the
clearance of high carbon stock land like forests for the production of biofuel crops. One major way to mitigate the risk
of land use change is to use residues, waste materials and by-products for the production of sustainable fuels
(Sustainable Aviation, 2020b).
Sustainability criteria
These criteria should evaluate the sustainability of the fuel over the entire life-cycle, from feedstock production and
conversion to fuel production and distribution including usage on-board of the aircraft, while taking into account the
geographical location and thereby the local social economic context. Stringent sustainability criteria are the most
important aspect when considering the deployment of SAF as they directly determine to which extent the alternative
fuels are truly sustainable. They are an essential element in the policy framework aiming to guarantee true
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sustainability. It is therefore important to work towards a worldwide robust set of sustainability criteria that applies to
all policies and regulations worldwide. A number of standards have been developed that include social, economic and
environmental sustainability criteria. Several of these standards for identifying criteria for sustainability assessment
are described more in detail in the following paragraph.
Sustainability standards
The Roundtable on Sustainable Biomaterials (RSB) Standard is seen as a strong and trusted sustainability standard
according to World Wildlife Fund (WWF), International Union for Conservation of Nature (IUCN), and Natural
Resources Defence Council (NRDC) (ICAO, 2019 Environmental Report, 2019a). It is based on 12 principles that ensure
lasting solutions without creating social and environmental challenges: legality; planning, monitoring and continuous
improvement; greenhouse gas emissions; human and labour rights; rural and social development; local food security;
conservation; soil; water; air quality; use of technology, inputs, and management of waste; and land rights (ICAO,
2019 Environmental Report, 2019a). Other internationally recognized standards have also been developed such as the
International Sustainability and Carbon Certification (ISCC). This scheme certifies biomass over the entire supply chain
from origin to the final market. The scheme is based on six principles: protection of biodiverse and carbon rich areas;
good agricultural practice; safe working conditions; compliance with human, labour and land rights; compliance with
laws and international treaties; and good management practices and continuous improvement.
Renewable Energy Directive
In Europe, the Renewable Energy Directive (RED) and its recast towards 2030 (called RED II) specify the sustainability
criteria for the fuel and the feedstocks to be eligible under the scheme (EC, 2019b; EC, Renewable Energy – Recast to
2030 (RED II), 2020g). Further details on European policy are given in Section 5.3. Key elements of the RED II include:
•

Minimum level of GHG emission saving;

•

Areas of high carbon stock (wetland, forest and peat land) should not be used for fuel production;

•

Land with high biodiversity should not be used for biofuels production.

The minimum level of GHG savings for the fuels to be eligible under the framework is shown in Table 18.
Table 18: GHG savings thresholds according to RED II framework
Plant operation start date

Transport biofuels

Before October 2015
After October 2015
After January 2021
After January 2026

50%
60%
65%
65%

Transport renewable fuels of
non-biological origin
70%
70%

Electricity, heating and
cooling
70%
80%

One major concern is that the EU policy framework still partially allows feed and food crops for the production of
fuels. In the recast towards 2030 (RED II) the framework sets limits on high ILUC-risk biofuels which will gradually
decrease to zero by 2030. These limits consist of a freeze at 2019 levels for the period 2021-2023, gradually
decreasing from the end of 2023 to zero by 2030 (EC, 2019c). Member states are not able to count the volumes
covered by these limits towards their renewable energy target.
Voluntary standards approved in the EU
For biofuels the EU has approved a list of voluntary sustainability standards (including RSB and ISCC) that meet the EU
sustainability criteria (EC, 2020k). By selecting a voluntary scheme, the aviation sector can apply more stringent
criteria then the existing Renewable Energy Directive. Leading airlines have indicated that they prefer to use strong
and trusted sustainability standards that aim for the highest sustainability levels.

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Life-cycle GHG emissions - analysis and methodology
The life-cycle GHG reductions that can be obtained with SAF compared to fossil fuels mostly vary between 25-95%.
Life–cycle emissions refer to the emissions produced during feedstock production and transport, conversion to fuel,
fuel transport and distribution, including the final use in the aircraft engine. By adding up all the emissions of the
individual steps the total GHG emissions of the fuel are obtained. This approach is called a life-cycle assessment (LCA).
The assessment of the life-cycle emissions is most accurate when individual regional supply chains are analysed.
Nevertheless, reference values for different conversion processes and feedstocks give a good indication of the
difference between pathways and geographical locations. As an example this report shows the default values and the
methodology used by ICAO for CORSIA eligible fuels.
In June 2019, ICAO published the analysis and methodology to calculate the life-cycle GHG emissions for CORSIA
eligible fuels including the effect of indirect land use change (ICAO, CORSIA Eligible Fuels, 2019). The life-cycle
assessment methodology calculates the carbon dioxide equivalent (CO2e) emissions of CO2, CH4 and N2O from well-topump activities (WTP) and CO2 emissions from well-to-wake (WTWa) fuel combustion. The default core life-cycle
values (without taking into account land use change) are given in Table 19.
Table 19: Default core LCA values for CORSIA eligible fuels without taking into account ILUC effects (ICAO, 2019). The
values are compared with a fossil baseline to show the reduction percentage.
Conversion process

Fischer-Tropsch (FT)

Hydro-processed
esters and fatty acids
(HEFA)

Synthesized
IsoParaffins (SIP)

Iso-butanol Alcoholto-jet (ATJ)

Feedstock

LCA gCO2e/MJ

Agricultural residues

7.7

% emissions savings compared to
fossil-kerosene baseline of 89 g
CO2eq/MJ
91%

Forestry residues
Municipal Solid Waste (MSW),
0% NBC
MSW, NBC as % of total C

8.3

91%

5.2

94%

Short-rotation woody crops

12.2

86%

Herbaceous energy crops

10.4

88%

Tallow

22.5

75%

Used cooking oil

13.9

84%

Palm fatty acid distillate

20.7

77%

Corn oil

17.2

81%

Soybean oil

40.4

55%

Rapeseed oil

47.4

47%

Camelina

42

53%

Palm oil - closed pond

37.4

58%

Palm oil - open pond

60

33%

Brassica carinata

34.4

61%

Sugarcane

32.8

63%

Sugarbeet

32.4

64%

Sugarcane

24

73%

Agricultural residues

29.3

67%

Forestry residues

23.8

73%

Corn grain

55.8

37%

Herbaceous energy crops

43.4

51%

Molasses

27

70%

NBC × 170.5 + 5.2

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Conversion process

Feedstock

LCA gCO2e/MJ

Ethanol Alcohol-tojet (ATJ)

Sugarcane

24.1

% emissions savings compared to
fossil-kerosene baseline of 89 g
CO2eq/MJ
73%

Corn grain

65.7

26%

The ILUC analysis, performed by ICAO for CORSIA eligible fuels, uses two different economic equilibrium models and
then compares the results. The models take into account emissions due to changes in vegetative living biomass carbon
stock, emissions due to changes in soil carbon stock, and emissions debt equivalent to forgone carbon sequestration
(ICAO, CORSIA Eligible Fuels, 2019). This analysis can serve as a reference to compare and understand the
environmental impact of different fuels. The default ILUC emissions under CORSIA are shown in Table 20. Negative
modelling values suggest that high soil carbon sequestration and biomass carbon from producing cellulosic crops will
be larger overall than associated emissions from land use change.
Table 20: Default ILUC emission values for SAF pathways, in g CO2e/MJ (2019)
Region

Feedstock

Conversion process

Default ILUC value

USA

Corn

Alcohol (isobutanol) to jet (ATJ)

22.1

USA

Corn

Alcohol (ethanol) to jet (ATJ)

25.1

Brazil

Sugarcane

Alcohol (isobutanol) to jet (ATJ)

7.3

Brazil

Sugarcane

Alcohol (ethanol) to jet (ATJ)

8.7

Brazil

Sugarcane

Synthesized iso-paraffins (SIP)

11.3

EU

Sugar beet

Synthesized iso-paraffins (SIP)

20.2

USA

Soy oil

Hydroprocessed esters and fatty acids (HEFA)

24.5

Brazil

Soy oil

Hydroprocessed esters and fatty acids (HEFA)

27

EU

Hydroprocessed esters and fatty acids (HEFA)

24.1

Hydroprocessed esters and fatty acids (HEFA)

39.1

USA

Rapeseed oil
Palm oil
(open/close pond)
Miscanthus

Fischer-Tropsch (FT)

-32.9

USA

Miscanthus

Miscanthus Alcohol (isobutanol) to jet (ATJ)

-54.1

USA

Switchgrass

Fischer-Tropsch (FT)

- 3.8

USA

Switchgrass

Alcohol (isobutanol) to jet (ATJ)

-14.5

USA

Poplar

Fischer-Tropsch (FT)

- 5.2

EU

Miscanthus

Fischer-Tropsch (FT)

-22

EU

Miscanthus

Alcohol (isobutanol) to jet (ATJ)

-31

Malaysia & Indonesia

Additional benefits of SAF
The use of sustainable aviation fuels has a positive effect on other GHG emissions and air quality emissions which are
out of the scope of this work. Current drop-in SAFs (that are blended with conventional kerosene) significantly reduce
SOx and PM emissions; furthermore, these SAFs generally also reduce CO and UHC emissions, whereas a minimal
reduction to no effect is found for NOX emissions (Booz Allen Hamilton, 2018). A reduction in these emissions
contributes to improving the air quality around airports.
A lower aromatic and sulphur content also lead to differences in contrail and cirrus formation. Contrails form as the
water vapour emitted by the engine at high altitudes condenses into droplets or ice crystals. Particles, such as soot
and sulphur, influence the formation of contrails (Lee, et al., 2010). A lot of research is currently performed to assess
the overall climate impact of various types of SAF blends including 100% synthetic fuels. According to the recently
published study on hydrogen powered aviation, using a 100% synthetic fuel may reduce the overall climate impact by
30% to 60%, assuming a fully carbon neutral production process (McKinsey & Company, 2020). This is mainly due to
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reduced formation of contrail and cirrus clouds. These non-CO2-effects are, as mentioned in the introduction, outside
the scope of this roadmap.

5.3

Current EU policy framework

The overall policy framework in the EU for the production and promotion of energy from renewable sources is the
Renewable Energy Directive (RED) 2009/28/EC. The European Commission states that this directive is “aimed at
keeping the EU a global leader in renewables and, more broadly, helping the EU to meet its emissions reduction
commitments under the Paris Agreement” (EC, 2019b).
Under the recast to 2030 (called RED II) the EU established renewable energy targets and translated these targets in a
climate and energy framework. In 2030 a binding target of 32% of renewable energy has been set with a possible
revision by 2023 (EC, 2019b). Under this general target, a specific target for road and rail transport fuels has been set
at 14% renewable energy by 2030 (EC, 2019d).
Within this policy framework, sustainable aviation fuels can opt in to contribute to the 14% transport target but are
not subject to an obligation (EC, 2019d). This means that when sustainable aviation fuels are deployed in a Member
State, that Member State is allowed to count these fuels towards its national renewable energy target. For aviation
fuels the system includes a multiplier of 1.2. This multiplier allows fuel suppliers to count the contribution of non-food
renewable fuels 1.2 times their energy content towards the targets. For comparison, multipliers have also been
applied to renewable electricity production for use by electric road or train transport with a factor of 4 and 1.5,
respectively. Inclusion of these options in national regulations depends on political decisions in the transposition
processes.
As mentioned previously, the RED and RED II define the sustainability criteria for the fuels. This includes minimum
GHG reductions and incorporates a cap on high ILUC-risk feedstocks. The RED II framework is based on a list of
feedstocks. It should be noted, however, that the list is not exhaustive; some feedstocks may therefore not be
included in the list. In Annex IX the feedstocks are divided into advanced feedstocks in Part A and capped feedstocks in
Part B. The RED II poses a cap on feedstocks in Part B as these feedstocks have a high ILUC-risk. To promote innovation
the obligation includes a specific sub-quota for advanced biofuels coming from feedstocks listed in Annex IX, Part A,
increasing from 0.5% in 2021 to at least 3.6% in 2030 (ICCT, The European Commission's renewable energy proposal
for 2030, 2017).
Under the EU Emissions Trading System (EU-ETS) airlines can purchase SAF instead of purchasing ETS allowances. If
the fuel complies with the sustainability criteria defined in the RED, it is attributed zero emissions under the scheme
(EEA, EASA & EUROCONTROL, 2019). If the price of EU-ETS allowances is higher than the cost of SAF, this may form a
direct incentive for airlines to purchase SAF.

5.4

Feedstocks and production processes

The aviation industry will move towards a variety of renewable biomass feedstocks and renewable electricity sources.
These feedstocks include used cooking oil, agricultural residues, forestry residues, municipal solid waste, some types

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of energy crops 123 (crops whose primary target is the production of end-use energy carriers). For each feedstock
different conversion processes can be used to reach a fuel that meets current jet fuel specifications. Most of these
pathways are currently under development, with only Hydro-processed Esters and Fatty Acid (HEFA) currently
commercially available – although in very limited amounts.
An overview of the feedstocks and production processes is given in this section. In terms of biofuels, this report
focuses on so called ‘advanced biofuels’, namely biofuels produced from non-food crops or residues and biofuels
produced with advanced processes from non-food feedstocks.

5.4.1

Feedstocks

Feedstocks are often categorized into biomass feedstocks and renewable electricity. Biomass feedstocks can be
divided into forest biomass, agricultural residues, energy crops and already processed biomass. Biomass can be
converted to liquid biofuels. Renewable electricity can be produced by a variety of renewable sources such as wind,
solar and hydro. Renewable electricity can be used directly to power hybrid/electric aircraft or it can be converted to
sustainable liquid fuels such as hydrogen and synthetic kerosene. For the production of synthetic fuels renewable
electricity can be used to capture carbon from the air thereby creating a fuel based solely on renewable electricity
input (and water for the production of hydrogen).
Forestry biomass is currently an important source of renewable energy accounting for around half of the EU’s total
renewable energy consumption (Khawaja & Janssen, 2014). Until now it has mainly been used to support material
demand, but the demand for energy purposes is expected to take over in the future (Bentsen & Felby, 2012).
Agricultural residues are often categorized in primary and secondary agricultural residues. Both types can be used for
energy production. Primary residues are the result of primary agricultural operations (such as straw from grass
species), whereas secondary agricultural residues are produced during the processing of crops into food or other
products (Khawaja & Janssen, 2014). Europe has a large cereal production; therefore these residues originate mainly
from wheat, maize, barley and rye production (Bentsen & Felby, 2012).
Already processed biomass includes for example sewage sludge, municipal solid waste and manure. These types of
biomass have different properties and are collected in many different ways.
Energy crops are often categorized in two types: perennial herbaceous crops (such as miscanthus and switchgrass)
and woody crops known as short rotation coppice (SRC) (such as willow and poplar). The s2biom project defines these
non-food lignocellulosic crops as “crops that are unsuitable for human or animal food consumption and are grown
exclusively or primarily for the purpose of producing biomass for energy and/or material purposes in an agricultural
rather than a forestry context” (Khawaja & Janssen, 2014). The project also identifies that these crops can be
converted to energy following two pathways: the production of biofuels or the production of heat and power; noting
that the latter option is more common at the moment.

123 Only energy crops which do not compete with food and feed are considered for this roadmap.

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5.4.2

Production processes

This section gives a short overview of the types of production processes with their technology readiness level in
combination with selected feedstocks. Only a number of these production processes have been certified for the use in
aviation as further detailed in the next section 5.5.
Hydro-processed Esters and Fatty Acids (HEFA)
HEFA is the most mature SAF pathway currently commercially available with technology readiness level 8-9 (de Jong,
et al., 2017). It is very similar to the Hydrotreated Vegetable Oil (HVO) process for making road transport fuels with
the addition of further hydrocracking. The main feedstocks are waste and vegetable oils. For the future other
feedstocks like oil-bearing algae are being investigated. These feedstocks undergo a deoxygenation reaction followed
by the addition of hydrogen in order to break down the compounds into hydrocarbons (Pavlenko, Searle, &
Christensen, 2019). Further refining steps are used to obtain a mix of fuels including kerosene.
Synthesis gas Fischer-Tropsch (FT)
This process mainly uses lignocellulosic biomass of municipal solid waste to produce a mix of road and aviation fuels.
Conversion to fuel is achieved through gasification of feedstocks into synthesis gas (a mix of carbon monoxide and
hydrogen) (Pavlenko, Searle, & Christensen, 2019). Using biomass the technology readiness level is approaching TRL 78 (E4tech (UK) Ltd & studio Gear Up, 2019).
Power to liquid (PtL) Fischer-Tropsch
This process creates synthesis gas by using hydrogen and CO2 either from industrial facilities or captured from the air.
In a largely decarbonized system the CO2 source will eventually come from Direct Air Capture (DAC) technology. DAC
technology is currently estimated at TRL 6 (Schmidt & Weindorf, 2016).
Direct Sugars to Hydrocarbons (DSHC)
This pathways uses genetically modified microorganisms (like yeasts or bacteria) to convert sugar into hydrocarbons
or lipids (E4tech (UK) Ltd & studio Gear Up, 2019). One specific example is Synthesized Isoparaffins (SIP). This route
converts sugary feedstocks (currently sugar cane) through fermentation and upgrading into farnesane. Depending on
the feedstock DSHC has TRL 7-8 for sugar feedstocks and TRL 5 for cellulosic feedstocks (E4tech (UK) Ltd & studio Gear
Up, 2019).
Alcohol-to-jet (AtJ)
As the name also mentions, this process turns alcohol into jet fuel. Through fermentation sugars, starches, or
hydrolysed cellulose are converted into alcohol (isobutanol or ethanol), then processed and upgraded into fuels
(Pavlenko, Searle, & Christensen, 2019). AtJ pathway is currently at TRL 6-7 (E4tech (UK) Ltd & studio Gear Up, 2019).
Hydrotreated Depolymerized Cellulosic Jet (HDCJ)
This pathway includes liquefaction technologies like pyrolysis and Hydrothermal Liquefaction (HTL). Pyrolysis
transforms lignocellulosic biomass or solid waste into bio-crude oil which can be upgraded to jet fuel (E4tech (UK) Ltd
& studio Gear Up, 2019). The production of jet fuel through pyrolysis is at maximum TRL 6 (E4tech (UK) Ltd & studio
Gear Up, 2019). This process is undergoing certification for qualification as jet fuel. HTL uses water and biomass at
high temperatures and pressures to produce bio-crude which can be upgraded to jet fuel (E4tech (UK) Ltd & studio
Gear Up, 2019). HTL is being demonstrated at small scale, its TRL is estimated at 5-6 (E4tech (UK) Ltd & studio Gear
Up, 2019). This process may in the future undergo certification for use in aviation.
Aqueous Phase Reforming (APR)
This process converts biomass-derived oxygenated compounds with a catalyst into a mix of hydrocarbons (E4tech (UK)
Ltd & studio Gear Up, 2019). Using conventional sugar feedstocks the process has TRL 5-6, with lignocellulosic
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feedstocks it is still at lab scale with TRL 3-4 (E4tech (UK) Ltd & studio Gear Up, 2019). This process is undergoing
certification for the qualification as jet fuel.
Product slate
The production processes presented in the previous sector can produce many fuel types including kerosene and
diesel. Therefore production facilities can choose to optimize the process for different outputs. If the jet fuel output is
maximized the amount of kerosene produced will become much larger than the diesel percentage. An overview of the
percentage of jet fuel as a percentage of total fuel output from the plant is given in Table 21. The table presents two
scenario’s in which jet output is maximized and in which other fuels output is maximised.
Table 21: Product slate depending on process optimization as percentage of jet fuel compared to total fuel output
(Sustainable Aviation, 2020b)
Pathway
HEFA
FT (gasification & power to liquid)
Aerobic fermentation
AtJ catalysis
Pyrolysis (with catalytic upgrading)
HTL (with catalytic upgrading)
APR (with catalytic upgrading)

5.5

Jet % when optimized for other
fuels output
14%
20%
0%
25%
20%
20%
20%

Jet % when optimized for jet
output
70%
50%
100%
90%
60%
60%
60%

ASTM certification

Each combination of feedstock and production process needs to be certified by the ASTM, the American Society for
Testing and Materials, to ensure the safe operation of flights with current aircraft and engine technologies. The fuel
should meet the ASTM specifications in order to qualify for use in the existing fleet. Currently, eight conversion
processes have been certified for use in commercial aviation. Currently all fuels approved under ASTM D7566 have
been certified to a maximum blending limit ranging between 10% to 50%, with most fuels meeting the 50% limit.
Furthermore, co-processing of renewable feedstocks with crude oil-derived middle distillates in petroleum refineries
has been added to Annex A1 of ASTM D1655. An overview of currently certified pathways and pathways under
approval by ASTM is given in Table 22.
Table 22: Approved pathways and pathways under approval under ASTM (CAAFI, 2020)
ASTM Certification
status
Approved under
ASTM D7566

Pathway

Feedstocks

Fischer-Tropsch Synthetic
Paraffinic Kerosene (FT-SPK)

Approved under
ASTM D7566

Hydroprocessed Esters and
Fatty Acids Synthetic
Paraffinic Kerosene (HEFASPK)
Hydroprocessed Fermented
Sugars to Synthetic
Isoparaffins (HFS-SIP)
Fischer-Tropsch Synthetic
Paraffinic Kerosene with
Aromatics (FT-SPK/A)

Biomass such as municipal solid waste
(MSW), agricultural and forest wastes,
and wood and energy crops.
Plant and animal fats, oils and greases
(FOGs)

Approved under
ASTM D7566
Approved under
ASTM D7566

Blending limit by
volume
50%
50%

Sugars

10%

Biomass such as MSW, agricultural
and forest wastes, and wood and
energy crops.

50%

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ASTM Certification
status
Approved under
ASTM D7566
Approved under
Annex A1 of ASTM
D1655
Approved under
ASTM D7566

Approved under
ASTM D7566

Phase 2 Testing
Phase 2 Testing
Phase 1 OEM
Review
Phase 1 Research
Report
Phase 1 Testing

Pathway

Feedstocks

Alcohol to Jet Synthetic
Paraffinic Kerosene (ATJ-SPK)
Co-processing of renewable
feedstocks with crude oilderived middle distillates in
petroleum refineries.
Hydroprocessed
Hydrocarbons, Esters and
Fatty Acids Synthetic
Paraffinic Kerosene (HHC-SPK
or HC-HEFA-SPK)
Catalytic Hydrothermolysis
Synthesized Kerosene (CH-SK,
or CHJ)

Starches, sugars, cellulosic biomass

Hydro-deoxygenation
Synthetic Kerosene (HDO-SK)
Hydro-deoxygenation
Synthetic Aromatic Kerosene
(HDO-SAK)
High Freeze Point
Hydroprocessed Esters and
Fatty Acids Synthetic
Kerosene (HFP HEFA-SK)
Integrated Hydropyrolysis
and Hydroconversion (IH2)
Alcohol-to-Jet Synthetic
Kerosene with Aromatics
(ATJ-SKA)

Blending limit by
volume
50%

Renewable lipids (plant and animal
fats)

5%

Bio-derived hydrocarbons(tri-terpenes
produced by the Botryococcus
braunii species of algae), fatty acid
esters, and free fatty acids

10%

Fatty acids and fatty acid esters, or
more generally various lipids that
come from plant and animal fats, oils
and greases (FOGs)
Sugars and cellulosics

50%

Sugars and cellulosics
Renewable plant and animal fats, oils
and greases
Multiple
Sugars and lignocellulosics

To be determined
To be determined
To be determined

To be determined
To be determined

Aircraft and engine manufacturers are currently investigating the effect of increasing the blending limit to 100% for
some pathways. The main difference in fuel composition is the amount of sulphur and aromatics contained in the fuel
and the viscosity of the fuel. Safety needs to be ensured over the entire lifetime of the engine, the fuel system and the
airframe. The amount of aromatic compounds has an effect on the volume and mass of sealings immersed in the fuel
(Zschocke, Scheuermann, & Ortner, 2012). This could be solved by using a different type of sealings or by adding
additives to the fuel to meet certain chemical specifications.
Industry experts do not expect major hurdles in increasing the blending limits for their newest engines to operate on
fully synthetic fuel, but this has yet to be demonstrated. Industry experts highlight that it may also have positive
effects on engine maintenance over the life-time, but no references can be given yet as this is currently being
investigated.

5.6

Production cost

This section shows that even the cheapest technologies, like HEFA, are still more expensive than the fossil jet fuel.
Policy support options to deploy these sustainable fuels on the market are discussed in section 5.10. The costs for SAF
are estimated by IATA between two and seven times the cost of fossil kerosene (IATA, IATA Sustainable Aviation Fuel
Roadmap, 2015). ICCT estimates the cost between two to eight times the cost of fossil kerosene (Pavlenko, Searle, &
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Christensen, 2019). The cost is influenced by many factors such as equipment and installation costs and feedstock
costs. The costs mentioned in this section are referenced from literature. These costs refer to the minimum viable
selling price which may differ from the final sales price that fuel suppliers ask on the market. To select the most
promising fuels, CO2 emission reductions over the life-cycle in combination with the minimum selling price should be
considered. This analysis can be performed by calculating the CO2 abatement costs.
HEFA
The best understood production process is HEFA. This is the only process commercially available today. The costs of
this route can therefore be estimated with the most certainty. The minimum viable price is estimated in the EU
between 1.9 to 2.8 times the costs of fossil jet fuel (given a Jet-A1 price of € 0.39 per litre) as shown in Table 23. These
costs are primarily dependent on the feedstock costs (such as used cooking oil), which are not expected to go down
due to increased competition with other sectors (Pavlenko, Searle, & Christensen, 2019). The price of HEFA based jet
fuel is therefore not expected to decrease over time.
Table 23: Overview of minimum viable price estimates for HEFA in the EU per litre and per tonne, with the density of
kerosene equal to 0.8 kg/l.
Pathways

Feedstocks

€/litre

€/tonne

Source

HEFA

Soy oil, palm oil,
Palm fatty acid
distillate and used
cooking oil

Compared with fossil
at 0.39 €/litre 124

0.88-1.09

1100-1363

2.3-2.8

Pavlenko, Searle &
Christensen (2019)

HEFA

Used cooking oil

0.76-0.84

950-1015

1.9-2.2

HEFA

Used cooking oil

±1

± 1,300

2.6

EASA, EEA &
EUROCONTROL (2019)
de Jong et al. (2017)

By putting a price on carbon, the fuel price no longer only depends on its quantity, but also on the CO2 reductions
compared to fossil jet fuel. It is therefore important to take the CO2 reductions into account when comparing the cost
of fossil jet fuel with sustainable fuels. For illustrative purposes, the CO2 abatement costs are given in Table 24
depending on carbon savings between 60% and 100% with respect to Jet-A1. The minimum selling price for HEFA
(1176 €/tonne) is estimated at 2.4 times the reference Jet-A1 price in 2018 (490 €/tonne).
Table 24: HEFA CO2 abatement costs depending on GHG reduction levels assuming a HEFA price of 1176 €/tonne
compared to 2018 jet fuel prices.
Assumed life-cycle CO2 reductions
60%
75%
100%

Illustrative CO2 abatement cost (€/tonne) 125
362
289
217

Other pathways
In general, costs are expected to decrease with technological improvement, learning and the effects of economies of
scale. The costs for first-of-a-kind facilities are expected to be higher than subsequent production facilities.
For new pathways the costs are often estimated using models because data from commercial operations is not
available. These models use chemical and efficiency data of existing pilot facilities to estimate operational and capital
costs for larger facilities. Especially the equipment and installation costs are often difficult to predict; capital costs are
the most uncertain for processes at an early stage of development (Pavlenko, Searle, & Christensen, 2019).

124 Jet-A1 price in 2018

125 Calculated as (SAF price – Jet A1 price) / (CO2 saving × Jet A1 emission factor). Jet A1 emission factor = 3.16.

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Cost estimates for bio-based fuels in the EU have been analysed by De Jong et al. The minimum selling prices for
lignocellulosic feedstock are shown in Table 25. These costs already take into account technological learning. For firstof-a-kind facilities the costs are expected to be higher. For pioneering plants the cost can increase by 40% to 80%. If
solely the price is considered without taking into account the life-cycle GHG reductions, the most promising routes
according to this analysis are HTL and Pyrolysis followed by FT and AtJ. The costs for these pathways range between
2.7 and 7.1 times the price of fossil jet fuel. DHSC is the most expensive pathway with costs around 9.4 to 12.7 times
the price of fossil jet fuel.
Table 25: Overview of minimum viable price estimates of SAF pathways in the EU according to de Jong et al. based on
2000 t dry biomass input per day (de Jong, et al., 2017). Prices for forestry residues and wheat straw assumed to be
190 and 730 €/tonne dry matter respectively.
Pathway
Fischer-Tropsch
Fischer-Tropsch
Hydrothermal Liquefaction
Hydrothermal Liquefaction
Pyrolysis
Pyrolysis
Alcohol-to-Jet
Alcohol-to-Jet
DSHC
DSHC

Feedstocks
Forestry residues
Wheat straw
Forestry residues
Wheat straw
Forestry residues
Wheat straw
Forestry residues
Wheat straw
Forestry residues
Wheat straw

€/tonne
1670
2445
930
1300
1335
1780
2300
3445
4595
6185

€/litre 126
1.34
1.96
0.74
1.04
1.07
1.42
1.84
2.76
3.68
4.95

Compared with fossil at 0.39 €/litre 127
3.4
5.0
1.9
2.7
2.7
3.7
4.7
7.1
9.4
12.7

ICCT analysed the costs of various production pathways in the EU including the CO2-equivalent abatement costs.
These costs are shown in Table 26. After HEFA, the lowest CO2-equivalent abatement costs are calculated for the FT
pathways (between € 400 – € 800 per tonne) and AtJ pathway depending on the type of feedstock used (€ 800 per
tonne in the least expensive case). The assumed GHG reductions are different per pathway and feedstock type.
Table 26: Overview of minimum viable price estimates of SAF pathways in the EU according to ICCT including cost of
carbon abatement (Pavlenko, Searle, & Christensen, 2019). Density of kerosene assumed equal to 0.8 kg/l.
Pathway

Feedstocks

€/tonne

€/litre

FT
gasification

Compared with fossil
at 0.39 €/litre127

CO2e abatement
cost 128 €/tonne

MSW

1675-2338

1.34-1.87

3.4-4.8

± 400-500

2000-3125

1.60-2.50

4.1-6.4

± 800-4500

5000

4.00

10.3

± 2500

3125

2.50

6.4

± 800

AtJ
SIP
FT power to
liquid

Corn, sugarcane,
agricultural residues and
energy crops
Sugar cane molasses
Renewable electricity and
CO2 point sources

The main characteristics of the costs shown in Table 26 are (Pavlenko, Searle, & Christensen, 2019):
•

FT-gasification: very low feedstock costs; capital costs account for 80% of cost on per litre basis; second
cheapest pathway after HEFA; GHG savings of around 85%.

•

AtJ: costs largely depend of the type of feedstocks used; using corn and sugarcane results in lower prices than
using agricultural residues or energy crops; GHG savings vary per feedstock type ranging from 10% to 80%.

126 Density of kerosene assumed equal to 0.8 kg/l
127 Jet-A1 price in 2018

128 The carbon abatement costs are calculated as the difference between the levelized costs and a fossil jet fuel price of €0.39 per litre and dividing by the carbon
reductions for a litre of fuel. Carbon reductions are based on CO2 equivalent emissions (gCO2e/MJ). Numbers have been estimated based on Figure 6 page 15.

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•

SIP: high feedstock costs combined with low efficiency lead to high costs compared to other pathways; costs
are very dependent on the capital expenditure; GHG savings of around 50%.

•

Power to liquid: costs are mainly influenced by the price of electricity; GHG savings of around 85%.

Power to liquid
The development of power to liquid fuels is expected to grow on the long term. On overview of the minimum selling
prices in the EU is given in Table 27. DAC technology increases the cost compared to using CO2 from existing industrial
applications due to the lower technological maturity level and the lower efficiency of the process. Technological
maturity and efficiency are expected to improve with large scale deployment. Overall price estimates for power to
liquid fuels range from 2.3 to 6.4 times the price of fossil jet fuel. Assumptions on renewable electricity prices have a
major impact on the predicted costs. The renewable electricity should come for additional installations specifically
built to supply fuel factories.
For illustrative purposes, the CO2 abatement costs for the minimum selling price estimates given in Table 27 can be
calculated assuming carbon savings of 85% and a jet fuel price of € 0.39 per litre. The abatement costs would range
between approximately € 245 and € 980 per tonne.
Table 27: Minimum viable prices for power to liquid jet fuel in the EU according to different sources. Density of
kerosene assumed equal to 0.8 kg/l.
Pathway
PtL FT
PtL FT
PtL FT
PtL FT
(2030)
PtL FT
(2050)

Feedstocks
Renewable electricity
and DAC
Renewable electricity
and CO2 point sources
Renewable electricity
and CO2 point sources
Renewable electricity
and DAC
Renewable electricity
and DAC

€/litre

€/tonne

Compared with
fossil at 0.39
€/litre 129

1.3

1675

3.4

0.9

1144

2.3

2.5

3125

6.4

1.9

2338

4.8

McKinsey & Company (2020)

1.2

1530

3.1

McKinsey & Company (2020)

Source
German Environment Agency
(2016)
German Environment Agency
(2016)
Pavlenko, Searle & Christensen
(2019)

For 2050 two additional sources have been found which estimate the minimum selling prices outside the EU. The
McKinsey report estimates prices based on imports from Middle East whereas the IEA report estimates a global
average price. These values are given in Table 28.
Table 28: Minimum viable prices for power to liquid jet fuel specifically for 2050. McKinsey estimated is based on
imports from and IEA is a global average. Density of kerosene assumed equal to 0.8 kg/l.
Year
2050
2050

Feedstocks
Import from Middle East
- Renewable electricity
and DAC
Global average Renewable electricity
and DAC

€/litre

€/tonne

Compared with
fossil at 0.39
€/litre129

Source

0.8

935

1.9

McKinsey & Company
(2020)

1.3

1658

3.4

International Energy
Agency (2020)

129 Jet-A1 price in 2018

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5.7

Supply potential in 2030

ICAO collected data during the 2019 ICAO Stocktaking Seminar which show that worldwide production capacity of SAF
was 0.005 Mt 130 per year between 2016 and 2018. This is far less than 1% of total jet fuel demand in that period.
Nevertheless, it is a major step towards commercialization and growth in this sector (ICAO, 2019 Environmental
Report, 2019a).
Until now the most significant volumes were produced by the World Energy Paramount facility in California, USA using
the HEFA technology. In recent years the market has expanded and multiple companies worldwide have announced
plans for the production of SAF: SkyNRG, Fulcrum, LanzaTech, Neste, Velocys, UPM, Red Rock (ICAO, 2019
Environmental Report, 2019a). The increasing level of focus and upfront commitment of different stakeholders in the
supply chain shows that this sector can continue to grow in the future.
Since 2009, SAF volumes were regularly supplied at six airports worldwide (ICAO, 2019 Environmental Report, 2019a).
In Europe, SAF is commingled in the fuel system at a regular basis at Oslo Airport and Stockholm Arlanda airport. Most
of this SAF is coming from the World Energy facility in California and being transported to Europe. The following
paragraph analyses the future SAF uptake and production of SAF in the EU.
Availability of biomass in the EU
Total fuel consumption from flights departing Europe in 2030 is estimated around 67 Mt. Assuming a biomass to fuel
efficiency factor of 55%, this would require 120 Mt (4.8 EJ 131) of biomass feedstocks. For the year 2030 the EU project
S2Biom conducted in 2014 estimated a biomass potential between 10.9 and 22.7 EJ (Khawaja & Janssen, 2014). Within
the same range the study “Scenarios and Preconditions for Renewable Jet Fuel Deployment towards 2030” utilises a
potential supply of 11.2 EJ per year in 2030 (de Jong, et al., 2017). It is important to note that multiple sectors of the
economy rely on this biomass to transition to renewable energy sources. It is likely that only a portion of the potential
supply will be delivered to the transport sector of which a portion will be used for aviation. De Jong et al. estimate
that the projected demand from electricity production, heat and road transport remains below the supply reaching a
level of 60% in 2030, which would be equal to 6.7 EJ (de Jong, et al., 2017) 132. The remaining feedstocks (4.5 EJ) could
potentially be used for other sectors such as aviation. However, not all feedstocks are equally suitable for the
production of fuels and some require more processing steps than others. Waste oils, for example, can be easily
transformed into fuels for transport and are allowed to count twice towards the renewable energy target of EU
Member States (de Jong, et al., 2017). This combination causes an increase in demand and an increase in competition
for these feedstocks between sectors.
Cellulosic wastes and residues collected in the EU are another example of a promising feedstock with limited supply.
The study Wasted found that if all this material were converted to biofuels it would lead to 36.7 Mtoe per year for all
transport modes (Harrison, et al., 2014). In 2014, when the study was conducted, this was equivalent to 12% of road
fuel consumption in the EU. In 2030 the study estimated this amount could supply 16% of road fuel demand. This
shows that the supply of these feedstocks is limited and that competition with road transport will potentially increase
in the 2030 timeframe.
Import of biomass
Import of biomass from outside the EU will remain very limited as shown in two recent studies. According to the EC
communication “In-depth analysis in support of the COM (2018) 773”, 10 Mtoe of biomass imports are expected in
130 6.45 million litres = 0.00516 Mt
131 Conversion factor = 0.04 EJ/Mt

132 The study “Scenarios and Preconditions for Renewable Jet Fuel Deployment towards 2030” does not take into account the target for advanced biofuels under the RED
II, which may lead to a higher utilisation of waste and lignocellulosic feedstocks.

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2030 and 2050 (EC, 2018c). When looking more specifically at advanced biomass the PwC study “Sustainable and
optimal use of biomass for energy in the EU beyond 2020 (BioSustain)”, estimates these will remain as low as
1-2 Mtoe per year. Of this biomass, not all will be suitable for producing biofuels and more specifically biokerosene.
Furthermore, only a portion will be used for aviation. As they represent such a small portion of total biomass
availability in the EU, imports of biomass are not further considered for this roadmap.
Announced SAF production in the EU
Accompanying the political and social focus many companies have announced plans for opening production facilities
in the EU. The following plans have been publicly announced:
•

SkyNRG has recently announced the opening of the first dedicated production facility for SAF in the EU based
on the HEFA technology. The DSL-01 plant will be operational starting in 2022 and produce 100,000 metric
tonnes of SAF in 2030 (ICAO, 2019 Environmental Report, 2019a).

•

Neste has announced they can produce up to 100,000 tonnes per year of sustainable jet fuel (worldwide). It
is looking for further expansion of their existing facilities in the Netherlands and Finland.

•

Altalto Immingham Limited, a collaboration between Velocys, British Airways and Shell, plans to open a

•

Total La Mède in France converted a former oil refinery to a biorefinery with a maximum capacity of 500,000

commercial waste to fuel plant in the UK. The plant is expected to be operational starting in 2024.
tonnes of fuel (for both road transport and aviation).
•

As part of a broad project consortium, the renewable energy company Ørsted and Copenhagen Airport aim
to develop a hydrogen and sustainable transport fuel facility. The project has the potential to displace 5% of
fossil fuels at Copenhagen Airport by 2027 and 30% by 2030.

•

Pilot facilities have also been announced:
o

Quantafuel facility in eastern Norway based on forestry residue feedstocks supported by the

o

Rotterdam The Hague Airport synthetic fuel facility with green hydrogen and direct air capture;

o

Norwegian airport operator Avinor;
Heide refinery announced future production of synthetic kerosene through the use of surplus wind
energy generated locally which will be purchased by Lufthansa. Hamburg Airport is also involved in
the collaboration.

Some existing facilities in the EU which currently produce biodiesel for road transport could also be used for the
production of jet fuel as the product slate can be adjusted. Facilities that produce biodiesel based on HEFA or FT
technology can be tuned to produce larger portions of kerosene, making kerosene their primary product instead of a
co-product. The product slate of HEFA plants can be tilted up to 70% jet fuel production as shown in Table 21.
Goals and blending obligations in the EU
Many EU countries are developing or considering their own regulations for the mandatory blending of SAF as shown in
Table 29. These countries thereby take a leading role in the deployment of SAF while international agreements are
being discussed. The ambitions of the industry and the ongoing discussions at EU Member State level will be used to
estimate the amount of SAF in 2030 in combination with the announced production facilities.
Table 29: Overview of industry goals, government ambitions, regulations and ongoing discussions for a blending
obligation
Country
Norway
Sweden

Blending level 133
0.5% in 2020
1% in 2021
5% in 2025
30% in 2030

Type of target
Mandate

Status
Implemented

Source
Norwegian Government (2019)

Mandate

Ongoing discussion

Greenair Communications (2019)

133 These percentages most likely refer to fuel volume, but this has not always been specified by the sources found.

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Country

Blending level 133

Germany (Aireg)

10% in 2025

Netherlands

France
Spain
Finland
UK

Type of target
Aspirational
industry goal

Status

Source

-

IATA (2015)

starting 2023

Mandate

Ongoing discussion

14% in 2030
1% in 2022
2% in 2025
5% in 2030
50% in 2050
2% in 2025
30% in 2030
32% in 2050

Aspirational goal
Mandate

Ongoing discussion

Ministry of Infrastructure and
Water Management (2020a)
Royal Schiphol Group et al. (2018)
Squadrin & Schmit (2020)

Aspirational goal

-

Greenair Communications (2020)

Mandate
Mandate
Aspirational goal

Ongoing discussion
Ongoing discussion

Martinez (2018)
Biofuel International (2019)
Sustainable Aviation (2020b)

SAF supply
The total SAF supply is estimated at 3.2 Mt in 2030, approximately equal to 6% of European aviation fuel consumption
in 2030. This estimate falls within the range of the recently published report “Joint Policy Proposal to Accelerate the
Deployment of Sustainable Aviation Fuels in Europe” which estimates European-based SAF production between 1.5
and 7 Mt per year by 2030 (World Economic Forum, 2020). SAF contribution in 2030 may be increased if a strong
political support is given to SAF development. From a global perspective Europe would realise a frontrunner position.
The ICAO Environmental report 2019 estimates global SAF production may reach up to 6.5 Mt (8 billion litres) per year
in 2032. This would imply that Europe would account for 50% of global SAF production.
Model assumptions biofuel
Based on announced production facilities in the EU in combination with announced or considered national blending
obligations and industry goals, the amount of biofuels produced for aviation is estimated at 2 Mt in 2030. It is
assumed that the SAF is produced in the EU with mainly regional supply chains. The estimated SAF supply of 2 Mt
requires roughly 1% of the available biomass in the EU in 2030 assuming a total potential of 11.2 EJ and conversion
efficiency of 55%.
Industry goals and national mandates set before 2030 will likely be met with HEFA technology and HEFA compatible
feedstocks unless specified otherwise. Building new facilities and scaling up production requires several years. It is
therefore likely that most production facilities in 2030 will be based on the commercially available HEFA technology.
E4Tech estimates that the global mix of production pathways in 2030 will consist for 60 to 70% HEFA in a road and
aviation optimized scenario respectively (E4tech (UK) Ltd & studio Gear Up, 2019). An even higher percentage is
estimated by de Jong et al., predicting a share of 90% HEFA technologies in 2030 based on a gradual SAF integration
scenario (de Jong, et al., 2017). This study stresses that a sub-target for lignocellulosic biofuels could increase the
share of other pathways and feedstocks up to 50% within the 2030 timeframe.
De Jong et al. identify a risk for a lock in effect on the long term if the focus remains on the HEFA pathway. Advanced
pathways, such as Fischer-Tropsch, Alcohol-to-Jet and Pyrolysis, diversify the mix of feedstocks leading to higher
supply potential and larger GHG reductions. Advanced fuels would fail to develop if the short term efforts are focused
on the more cost effective HEFA technology (de Jong, et al., 2017).
To increase the available biomass potential and to avoid competing with other sectors, multiple studies recommend
diversifying the mix of feedstocks and to focus on advanced feedstocks that remain largely unexploited, such as
agricultural and forestry residues and non-food lignocellulosic crops (de Jong, et al., 2017; Searle, Pavlenko, Kharina, &
Giuntoli, 2019).
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Hydrogen
As hydrogen aircraft are only foreseen to enter the fleet from 2035 onwards (as shown in section 3.3.3.1), by 2030
hydrogen available to the aviation sector will be used either in the production process for biofuels or renewable fuels
of non-biological origin (such as power to liquid kerosene). The amount of hydrogen available for aviation was
calculated in chapter equal to 0.65 Mt in 2030.
Based on announced production facilities, it was assumed that 2 Mt of SAF are produced, of which 70% based on the
HEFA technology and the remaining based on advanced biofuel production pathways. The HEFA pathway requires
approximately 4% of hydrogen by mass of feedstock (Karatzos, McMillan, & Saddler, 2014). Other production
processes with lignocellulosic feedstocks require more hydrogen, and are therefore estimated at 10% by mass of
feedstock. The hydrogen required for the production of HEFA would therefore be equal to 0.1 Mt and the amount
required for other production processes with bio-feedstocks also 0.1 Mt. In total 0.2 Mt of hydrogen will be used to
supply the announced production facilities. This leaves approximately 0.4 Mt of hydrogen which can be used for the
production of power to liquid fuels for aviation, for example by using the Fischer-Tropsch process.
From a mass balance perspective, 0.4 Mt of hydrogen will lead to 1.2 Mt of PtL-kerosene via Fischer-Tropsch (Shell,
2018). It should be noted that when converting hydrogen to synthetic fuel, 15% to 30% of additional energy will be
required either to capture CO2 from point sources or to capture CO2 from the air, and to synthesize hydrocarbon fuels
(McKinsey & Company, 2020; International Energy Agency, 2020).
The minimum life-cycle GHG savings threshold for power to liquid fuels is 70% to fall under the RED II requirements.
This report considers only renewable hydrogen as feedstock. To large extent it is also assumed that renewable
electricity will be used, therefore the average GHG savings are increased to 85% over the life-cycle.
Model assumptions
The SAF uptake in 2030 is modelled based on three parameters: pathway type, CO2 savings and cost. An overview of
model assumptions is given in Table 30:
•

HEFA is assumed to make up 44% of the SAF mix. The total HEFA production in the EU is estimated at 1.4 Mt
in 2030. The minimum selling price for HEFA in the EU is estimated at € 1170 per tonne (2.4 times the price of
Jet-A1 in 2018).

•

Other biofuel pathways are estimated to make up 19% of the SAF mix. The production costs for the most
promising pathways are estimated by various sources to be on average € 2765 per tonne (4 times the price of
Jet-A1 in 2018) as many first-of-a-kind facilities need to be built. These costs are assumed 40% higher than
average due to the use of pioneering plants which require technological learning and upscaling.

•

Power to liquid fuels are estimated to make up 37% of the SAF mix. The levelized costs are assumed to be on
average 4 times the price of Jet-A1 in 2018 as many first-of-a-kind facilities need to be built. These costs are
assumed 40% higher than average due to the use of pioneering plants which require technological learning
and upscaling.

•

The price of fossil kerosene is expected to increase to € 600 per tonne in 2030 excluding carbon pricing.

•

The life-cycle CO2 savings for biofuels (including the effects of land use change) are estimated based on the
RED II GHG savings threshold. This leads to CO2 abatement costs around € 280 per tonne for HEFA, € 1050 per
tonne for the other bio-based pathways.

•

The life-cycle savings of 85% are assumed for power to liquid fuels based on renewable hydrogen as a
feedstock. This leads to CO2 abatement costs around € 860 per tonne.

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NLR-CR-2020-510 | February 2021

Table 30: Overview of SAF model assumptions for 2030. Total SAF supply is estimated at 3.2 Mt, equal to 6% of
European aviation fuel consumption in 2030.
Pathway and
feedstocks
HEFA pathways
with various
waste and
residue
feedstocks
Advanced
feedstocks
combined with
FT, ATJ, SIP
Power to Liquid
FT
Total / average

5.8

SAF amount

Percentage of
SAF fuel mix

Life-cycle CO2
saving

Minimum selling
price (€/tonne)

CO2 abatement
costs (€/tonne) 134

1.4 Mt

44%

65%

1170

280

0.6 Mt

19%

65%

2765

1050

1.2 Mt

37%

85%

2900

860

3.2 Mt

100%

72%

2274

640

Supply potential in 2050

For 2050 the estimate of the SAF amount has an even higher degree of uncertainty than for 2030. The main factors
that influence this uncertainty are:
•

economic capacity of the fuel industry to invest in new production facilities;

•

ambition of the industry;

•

political focus;

•

regulatory support;

•

energy transition pathways for other sectors; and

•

(Europe’s) decarbonisation strategy.

The analysis for the SAF amount is 2050 is based on a comparison between different scenarios from various
publications. The SAF amount presented in these publications is used to give an ambitious, but at the same time
realistic, target for the SAF amount taking into account feedstock availability, costs and industry ramp-up within the
context of a European energy transition.

5.8.1

Feedstock availability

In recent years more research has been conducted on the feasibility of a 100% renewable energy system worldwide.
Most publications have found this is technically feasible and economically viable with a sector-coupled integrated
system (Hansen, Breyer, & Lund, 2019). Despite being potentially unlimited, global energy transition pathways
developed by IRENA, IPCC, Shell and Teske estimate a share of renewable energy between 43-93% in 2050 to limit
global temperature rise to well below two degrees (IRENA, 2019). This sections looks more specifically at the biomass
and renewable electricity availability in the EU in the 2050 timeframe.
Biomass
For all sectors of the economy the worldwide biomass potential is estimated by various energy transition scenarios
between 67-160 EJ. The EU biomass potential has been analysed in different studies. A Joint Research Centre report
134 Calculated as (SAF price – jet fuel price in 2030) / (CO saving × Jet A1 emission factor). Jet A1 emission factor = 3.16. Jet fuel price in 2030 = 600 €/tonne.
2

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from 2015 estimates the potential between 8-21 EJ in 2050. A recent study by CE Delft estimates the potential in 2050
between 17-31 EJ per year (Leguijt, et al., 2020). The main sources of biomass analysed in the studies are forest
biomass, agricultural residues, energy crops and already processed biomass such as sewage sludge, municipal solid
waste and manure. Results presented by different studies vary substantially whether the theoretical, technical,
economic or sustainable potential are considered. This is clearly illustrated in the paper by Bentsen and Felby from
2012 that estimates the biomass potential between 8-75 EJ per year in 2050 (Bentsen & Felby, 2012). By comparing all
kinds of studies with variations in sustainability constraints and geographic scope (only EU27 or including Balkan and
former Soviet states) the potential range and uncertainty become very large.
In general, most studies agree on the lower end of the range which is estimated around 8 EJ per year. The median
value according to Bentsen and Felby of 24 EJ per year is consistent with the average value identified by the recent CE
Delft study. The value of 24 EJ lies just above the maximum identified by the JRC study.
The main growth potential is identified for energy crops, whereas residues from agriculture and forestry are not
expected to increase significantly (Bentsen & Felby, 2012). Growth potential for energy crops however also has the
largest uncertainty. The main growth potential is found for non-food lignocellulosic energy crops whereas traditional
food crops (such as rape seed, sugar or starch crops) are not expected to increase by much. The sustainability of
lignocellulosic bioenergy crops depends on the type of land they are grown on. Displacing high-carbon stock lands
such as forests has a negative environmental and climate impact, whereas using low-carbon stock land such as
abandoned agricultural land can support biodiversity and has little or no carbon debt (ICCT, Sustainability challenges
of lignocellulosic bioenergy crops, 2018).
The available biomass can supply multiple sectors of the economy including heat, power, plastics, road, maritime and
aviation. It is difficult to predict how the biomass will be divided among sectors. This depends on multiple factors such
as the feasibility to switch to other forms of renewable energy such as solar and wind. Road transport could, for
example, shift to full electrification in the 2050 timeframe.
Renewable electricity
According the European Commission’s strategy “A Clean Planet for all” 80% of the electricity mix will come from
renewable sources (including nuclear) in 2050. The share of electricity in final energy demand in Europe is expected to
rise from approximately 23% in 2017 to 53% in 2050 (EC, 2018b; EEA, 2020).
A study commissioned by the European Parliament found that it will be cost-efficient to decarbonize the energy
system by converting surplus renewable electricity to fuel (van Nuffel, Gorenstein Dedecca, Smit, & Rademarkers,
2018). In a decarbonized energy system hydrogen and e-fuels act as a sink for electricity surpluses preventing wasting
harvested energy that is not used directly. This improves the flexibility of the network, making it possible to cope with
fluctuations in demand.
Despite aviation representing a limited portion of the total EU energy consumption, it remains difficult to predict how
the renewable electricity supply will be divided between different sectors of the economy and how fast it can be
scaled-up to meet demand.
SAF scenarios
Various reports have been compared to analyse the level of uncertainty associated with the expected amount of SAF
in 2050, an overview is given in Table 31. The most important distinction needs to be made between reports that take
100% SAF as a starting point (top-down analyses) compared to reports that estimate the amount of SAF that follows
from a sector-wide energy transition in combination with economic feasibility and a policy framework (bottom-up
analyses). It is important to realise that the overall fuel consumption depends on assumptions on fuel efficiency
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improvements and the demand for air travel. For a given SAF amount, lower overall fuel consumption leads to a
higher SAF percentage in 2050.
Table 31: Overview of reports that estimate SAF uptake in 2050
Scope

Worldwide

EU

UK

Report
Energy Transitions
Commission (2019),
Mission possible
Searle et al. (2019), ICCT –
Long term aviation fuel
decarbonisation
Uslu (2017), TNO –
Market Analysis
De Jong et al. (2017),
Renewable jet fuel in the
European Union
Baker et al. (2017), Ecorys
– Potential for Advanced
Biofuels in Europe
Sustainable Aviation
(2020b), UK sustainable
fuels roadmap

Total fuel
consumption

SAF percentage

SAF
amount

600 Mt
(26 EJ)

100%

600 Mt

654 Mt 135

21% 136

139 Mt

55 Mt
48 Mt

57% (1.5TECH)
55% (1.5LIFE)
36% (Delayed
action)
77% (Full adoption)
44% (Medium)

31 Mt
26 Mt

52% (High)

29 Mt

32%

4.5 Mt

112 Mt
110 Mt
56 Mt
14 Mt

Remarks
Total fuel
consumption based
on ICAO estimates
Literature results
given in barrels of
oil equivalent 137
Literature results
given in Mtoe 138

40 Mt
85 Mt
25 Mt

Literature results
given in Mtoe138

Global scenarios
The worldwide scenarios show a very high level of uncertainty, mainly depending on the division of sustainable
feedstocks between different sectors of the economy. Increasing SAF production is considered viable only if sufficient
sustainable feedstocks (biomass and renewable electricity) are available from a sector-wide perspective.
ICCT expects heat, power, plastics and road vehicles to use 83% of the available biomass with 9% being delivered to
the aviation sector (Searle, Pavlenko, Kharina, & Giuntoli, 2019). Specifically in Europe the study identifies a strong use
of biomass in the power sector. Increasing the percentage used by transportation would require a major shift of the
European power sector to solar and wind.
The Mission Possible report estimates 45 EJ of biomass input would be required to meet the entire energy demand
from aviation in 2050, leading to 45-60% of (worldwide) available biomass going to the aviation sector (Energy
Transitions Commission, 2019).
Even if it would be technically possible to allocate large amounts of sustainable feedstocks to the aviation industry as
opposed to other current users, the fuel industry has to be able to ramp-up production significantly faster than
historic ramp-up of ethanol and biodiesel for road transport. ICAO estimates it would require approximately 170 new
large bio-refineries to be built every year from 2020 to 2050 to achieve complete replacement of fossil kerosene with
SAF (ICAO, 2019 Environmental Report, 2019a).
Furthermore, 100% SAF may not be the most cost-effective solution in a global framework for carbon pricing and
emissions reduction. As shown in the next chapter on economic measures, carbon abatement costs for SAF will
remain more expensive than achieving emission reductions in other sectors worldwide. Within Europe, however, EU-

135 Estimate based on figure 1 in ICCT publication: total jet fuel demand in 2050 13 million barrels oil equivalent per day.
136 Estimate based on figure 1 in ICCT publication.

137 Value in Mt is calculated based on the following conversion factors: 1 tonne of Jet A1 = 44,196 MJ and 1 million barrels of oil equivalent = 0.00611932395 EJ.
138 Value in Mt is calculated based on the following conversion factor: 1 Mt of Jet A1 = 1.0556 Mtoe.

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ETS prices are expected to increase to similar levels as the carbon abatement costs for SAF (further explained in
section 6.4), creating a direct incentive to increase the SAF uptake.
European scenarios
All EU scenarios presented in Table 31 predict a lower SAF uptake compared to total fuel consumption. These
scenarios have different assumptions in terms of fuel consumption, ambition level and type of sustainable fuels used.
The 1.5TECH and 1.5LIFE scenarios analysed by TNO cover all sectors of the economy and aim to reach net zero GHG
emissions by 2050 and thus pursuing efforts to limit global temperature increase to 1.5°C. The 1.5TECH scenario is
more driven by technology whereas the 1.5LIFE scenario is more driven by business and consumption patterns. The
1.5LIFE and 1.5TECH scenarios indicate that the supply to the aviation sector will not cover the entire fuel
consumption in 2050 being limited to around 55-57% SAF, equivalent to 26-31 Mt. The 1.5LIFE and 1.5TECH scenarios
estimate that e-fuels could provide 10% and 34% (respectively) of aviation’s energy demand in 2050 while direct use
of renewable electricity is estimated to remain low (1%); biofuel consumption is expected to remain the major source
of sustainable fuels accounting for 23% to 45% of the mix (Uslu, 2017).
The Ecorys report considers the uptake of advanced biofuels which is estimated around 25-29 Mt (Baker, et al., 2017).
With advanced biofuels the study refers to biofuels produced from lignocellulosic feedstocks (such as agricultural and
forestry residues), non-food crops (such as grasses, miscanthus and algae), or industrial waste and residue streams.
The feedstocks considered are selected based on having low CO2 emissions and reaching zero or low ILUC impact. The
overall biofuel uptake lies close to the overall SAF uptake estimated by the 1.5LIFE and 1.5TECH scenarios. Both
reports also have consistent estimates for the overall fuel consumption around 50-55 Mt.
The scenarios presented by De Jong et al. assume higher overall fuel consumption around 110 Mt and higher SAF
amounts. The ‘delayed action’ scenario predicts 40 Mt of SAF, equivalent to 36% of total fuel consumption. The ‘full
adoption’ scenario predicts up to 85 Mt, equivalent to 77%. In this context ‘full adoption’ refers to SAF being used to
cover the emission gap up to the industry goal of -50% net emissions in 2050 compared to 2005 emission levels. This
publication highlights that the ‘full adoption’ scenario requires an extremely high rate of feedstock and capacity
deployment. In particular a high deployment of lignocellulosic biofuel production capacity which increases from nearly
zero to 26 Mt per year over the course of 15 years (de Jong, et al., 2017).

5.8.2

SAF supply

For this roadmap 32 Mt of sustainable aviation fuels is assumed in 2050, equivalent to 83% of total kerosene
consumption. This amount is based on the 1.5TECH scenarios presented in Table 31 in combination with the European
hydrogen strategy and predicted hydrogen demand for the production of power to liquid fuels.
European SAF production is seen as an integral part of Europe’s energy transition towards full decarbonisation and
energy independence, therefore the majority of the production capacity is assumed to be built in Europe based on
locally resourced feedstocks. Production capacity will vary per region. Regional supply chains are envisioned to
achieve the highest level of sustainability.
Biofuels for aviation
The 1.5TECH scenario is the closest to the analysis performed in this roadmap, in terms of ambition level (net zero
emissions by 2050), technology focus and overall fuel consumption. Furthermore, the 1.5TECH scenario considers a

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mix of biofuels and e-fuels which is also consistent with the scope of this roadmap. This scenario estimates that the
amount of biofuels for aviation will be 13 Mt in 2050.
The required feedstock input would be equivalent to 24 Mt assuming a conversion factor of 55%. These 24 Mt of
biomass feedstock would be approximately equal to an energy content of roughly 1 EJ (by taking a conversion factor
of 0.04 EJ/Mt). A conservative analysis can be done by taking the lower-end value of biomass availability, equivalent to
an energy content of 8 EJ per year in 2050, to identify the percentage of these feedstocks required for aviation. This
would require 12% of biomass availability in the EU. Taking a more optimistic value for the total biomass availability of
24 EJ, the percentage required by aviation to power the fleet on biofuels would be 4%. The share of biomass
attributed to aviation is therefore considered both realistic and feasible in a sector wide context. Therefore it is
considered technically feasible to produce aviation biofuels based on European resources only.
It is envisioned that production pathways such as FT, AtJ and DSHC will be further developed for the conversion of
advanced feedstocks. The mix of pathways and feedstock is difficult to predict for the 2050 timeframe. The CO2 lifecycle savings are expected to increase to 95% as advanced feedstocks are increasingly being used and the entire
supply chain for sustainable fuels is further optimized in line with the circular economy strategy of the EU.
Power to liquid fuels
In chapter 3.3.3.2 the amount of hydrogen available for the aviation sector was estimated at 12.3 Mt. Given the
introduction of hydrogen aircraft in 2035, by 2050 a large portion of the single aisle fleet within Europe will use liquid
hydrogen to directly power the aircraft. Based on the energy efficiency of these aircraft as defined in the technology
chapter, the amount of hydrogen consumed by these aircraft is estimated at 3.7 Mt in 2050. Any additional hydrogen
will be used as feedstock to produce power to liquid fuels and for the production process of biofuels 139. This leaves
8.6 Mt of hydrogen for the production of power to liquid fuels and as feedstock in the production processes of
biofuels.
Biofuel production processes are estimated to require approximately 7% of hydrogen by mass of feedstock. The
hydrogen required for the production of biofuels (13 Mt) would therefore be equal to 1.8 Mt. This leaves around
6.8 Mt of hydrogen which can be used for the production of power to liquid fuels for aviation, for example by using
the Fischer-Tropsch process. From a mass balance perspective, 6.8 Mt of hydrogen will lead to 19 Mt of PtL-kerosene
via FT (Shell, 2018). The 19 Mt estimate is used as model assumption for the amount of power to liquid fuels in 2050.
This estimate also lies close to the 1.5TECH scenario which considers the amount of e-fuels to be 18 Mt in 2050 (Uslu,
2017).
Model assumptions
In 2050 the fuel mix will consist of 13 Mt of biofuels, 19 Mt of synthetic fuels, in total equal to 32 Mt of sustainable
fuels. An overview of model assumptions is given in Table 32.
The most promising bio-based routes in terms of cost in combination with CO2 emission reductions were found to be
HEFA, FT, AtJ and pyrolysis. The minimum selling prices for these pathways were presented in section 5.6 for a variety
of different feedstocks. These prices vary depending of the type of production process, the type of feedstocks, the
demand for these feedstocks and the improvement in process efficiency and technological learning. The average
minimum selling price of all these combinations (production process + feedstock) is estimated at approximately €1790
per tonne in 2050. Assuming life-cycle reductions of 95% the CO2 abatement costs are estimated at €366 per tonne.

139 Additional energy is required to go from gas to liquid hydrogen. This additional energy should also be generated using sustainable sources. This amount of energy is
not calculated in the report.

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The minimum selling prices for power to liquid fuels have been estimated for EU production based on the average
values presented in Table 27 and for imports based on the average values presented in Table 28. Assuming 15% will be
imported from outside the EU, the average price is estimated at €1557 per tonne. For the production of power to
liquid fuels, the CO2 life-cycle savings are expected to increase to 100%. This results in CO2 abatement costs of
€274 per tonne.
Table 32: Overview of model assumptions for 2050
Fuel type

Amount

Percentage
of fuel mix

Biofuel
Power to liquid
Fossil
Total kerosene
Total SAF

13 Mt
19 Mt
6 Mt
38 Mt
32 Mt

34%
49%
17%
100%
83%

Average minimum
selling price
(€/tonne)
1790
1557
690
-

Average life-cycle
CO2 reductions
95%
100%
n/a
-

Average CO2
abatement costs
(€/tonne) 140
366
274
n/a
-

Division between intra-EEA and extra-EEA
For 2050, the Roadmap foresees that the CO2 abatement costs of SAFs become equivalent to the compliance costs of
EU-ETS and significantly higher than the compliance costs of global carbon credits at €160 per tCO2 (for price
developments see Section 6.4). Hence, it is likely that airlines will purchase SAFs on flights with the highest costs for
alternative CO2 abatement: intra-EEA flights. Therefore, the SAF uptake on intra-EEA flights is assumed 100%. Any
remaining SAF is used on extra-EEA flights. In 2050, this implies a SAF uptake of 78% on extra-EEA flights.
Increased blending level
An advantage of drop-in SAF is the use of existing aircraft engines and existing fuel supply infrastructure at airports.
However, from a technical perspective the certification barrier of 50% (for most pathways) needs to be overcome to
reach a 83% overall SAF uptake. Safety of the engine and the aircraft need to be guaranteed and therefore sound
testing will be required. Increasing the blending range up to 100% to include fuels with lower aromatic content is
deemed technically feasible within the 2050 timeframe. This may however create additional costs for retrofitting
aircraft which are not taken into account in the modelling.
Accounting system (book & claim system)
To achieve the lowest cost and highest efficiency an accounting framework similar to the framework for renewable
electricity might be needed: airlines should be able to purchase SAF attributes (similar to Guarantees of Origin for
renewable electricity) and only airlines that have purchased such SAF attributes can claim the associated emission
reductions. These attributes should be issued for uplifted SAF, but any airline, regardless of whether it effectively
tanks SAF or not, should be able to buy them. SAF production facilities may not be distributed evenly in Europe. Some
areas will have more feedstocks than others. To increase the use of regional supply chains, the production facilities
are likely to be built close to these regions. The SAF could then be distributed to the nearest airports, as long as this
does not require changes to the existing fuel supply infrastructure. The airport infrastructure will supply a given
amount of SAF through its fuel system, but only airlines that actually purchase the SAF attributes will be able to
account for it in the booking system. Airlines should be given the possibility to then decide on which flights to actually
account for the SAF. This prevents airlines from carrying extra fuel on-board if SAF is not available at a certain airport.
Airlines that aim for higher CO2 emission reductions will decide to buy a larger amount of SAF and distribute the SAF in
the most economic efficient way across the fleet. If the price of EU-ETS allowances remains higher than CORSIA
offsets, it is likely that airlines will decide to use the SAF on intra-European flights first, the remaining being taken into
account on international flights.
140 Calculated as (SAF price – jet fuel price in 2030) / (CO saving × Jet A1 emission factor). Jet A1 emission factor = 3.16. Jet fuel price in 2050 = 690 €/tonne.
2

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5.9

Drivers and barriers

The previous section showed and discussed the elements that influence the deployment of sustainable aviation fuels.
This section shows the main drivers and barriers that can speed up or slow down the deployment of SAF.

5.9.1

Drivers

The main driver for the use of SAF is its potential to decrease CO2 emissions within the aviation sector. It is therefore a
short to long term solution that can decarbonize all types of flights including long range flights. It is an energy
alternative that can also be used on the short term as many types of fuels have already been approved for the current
fleet and infrastructure. Drop-in fuels lead to direct benefits that are not limited by the time it takes for a new
technology to slowly propagate through an aviation fleet. On the long term additional non drop-in fuels such as
hydrogen are expected to be certified for the use on-board aircraft.
Technological alternatives in other sectors, like electric cars, are already available today and can be scaled up to fully
electrify the fleet. Speeding up the introduction of alternative technologies in other sectors will enable biomass
feedstocks to be used in sectors that are more difficult to electrify, such as aviation. Aviation can therefore be
considered a priority sector for the use of advanced biomass feedstocks. Furthermore, aviation can benefit from the
upscaling of renewable electricity production for other sectors, as it will lower the costs for the production of
hydrogen and power to liquid fuels.
The SAF market is expected to develop and grow offering many business and job opportunities in Europe. The
economic viability of SAF is expected to increase with higher carbon prices through EU ETS (see section 6.3), in
combination with complementary incentives (see section 5.10) that reduce the project risk and the minimum selling
price. As multiple sectors of the economy decarbonize, carbon allowances outside the sector are expected to become
increasingly rare and therefore more costly, making SAF a more viable investment. Furthermore, the price of SAF is
expected to decrease due to technological learning and upscaling of production. For the EU this new SAF market can
contribute to increasing its energy independence if locally resourced feedstocks and regional supply chains are
established.
The environmental benefits of SAF are not limited to GHG reductions but also contribute to better air quality around
airports due to lower sulphur and fine particle emissions. Potential health benefits due to lower emissions vary
depending on the fuel type and blending level. Less fine particle emissions also lead to lower contrail formation which
decreases the overall climate impact. Furthermore, a lower level of aromatic compounds in the fuels may lead to less
maintenance on engines and therefore lower maintenance costs.

5.9.2

Barriers

The overarching barriers that have been discussed extensively in this study are:
•

sustainability;

•

availability; and

•

price.

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These overarching barriers result from a series of more complex and detailed elements which largely relate to the
immature stage of the SAF market. Barriers can be divided into technological, socio-economic and policy barriers.
Technical barriers
New feedstocks and production processes need to be developed to increase the feedstock base. These technologies
currently have low TRL levels that need testing in pilot facilities before upscaling of production can take place. For
biofuels this includes technologies such as alcohol to jet and pyrolysis. In particular for hydrogen electrolyser
technology needs to be further developed and for power to liquid fuels the efficiency of direct air capture technology
needs to improve.
Biomass is a limited resource in the EU. Particular types of biomass, such as used cooking oil, are easily converted in
liquid fuels for transport. For these types of biomass, competition with the road sector is expected to increase on the
short term. New types of biomass feedstocks, such as non-food lignocellulosic crops and algae, need to be
investigated for the production of aviation fuels. These ‘advanced feedstocks’ need to be assessed in terms of
environmental and socio-economic impact to reach higher sustainability levels.
Renewable electricity production needs to be scaled-up in the EU. At the moment it is only a small part of the EU
electricity mix whereas the demand is expected to increase drastically towards 2050. This includes setting up the
required infrastructure and logistics. Additional renewable electricity installations are required for the production of
hydrogen and power to liquid fuels.
Engines and aircraft need to be tested, and if needed adapted, to assure the blending limit can be increased to 100%.
By increasing the blending limit, specific chemical properties of the fuel may change, such as a lower sulphur and
aromatic content. This process requires testing to ensure safety of the airframe and engine over the entire life-time of
the aircraft.
Research is required on the additional climate and health benefits of synthetic fuels and hydrogen. This includes the
effect of lower fine particle emissions in the formation of contrails and lower NOX emissions due to lower engine
combustion temperatures.
Economic barriers
A price gap exists between SAF and fossil kerosene. This price premium directly affects airline competitiveness and
revenues due to an increase in operational costs. Furthermore investors are faced with a multitude of issues that
contribute to a higher investment risk: lack of a long term policy framework; high upfront capital investments;
uncertain costs due to low technological maturity and future price developments. The production costs of SAF are
expected to decrease with technological learning and upscaling of production. Current market-based measures such
as EU-ETS and CORSIA are not sufficient to provide a direct incentive for SAF. The price of carbon within these
frameworks needs to increase to make SAF cost competitive. The affordability of SAF can be improved by using a
multitude of incentives, for example funding mechanisms in combination with an EU wide blending mandate. The
incentives should cause as little market distortions as possible, avoid carbon leakage and avoid additional cost
increase due to lack of market competition.
For new pathways additional investments are needed to get fuels through the certification process compared to road
transport fuels. The qualification process requires time as technical specifications need to be checked. Furthermore, a
stable market for road transport biofuels already exists including blending mandates. Tilting the product slate to
produce more jet fuel often increases costs for producers making it less attractive compared to the production of
biodiesel.

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Policy barriers
Investments in production facilities and projects in the energy sector often have a lifetime of 15 to 20 years. A policy
framework with a similar timeframe provides investors with more certainty thereby lowering the project risk. A long
term vision towards 2050 helps to direct investments into renewable energy projects such as the production of
sustainable liquid fuels. The current RED II framework has a limited timeframe until 2030. A proper long term EU
framework with clear, transparent and robust sustainability criteria and a challenging, but realistic ambition would
make it possible to deliver impact without level playing field distortions.
With the current framework a price gap exists between fossil kerosene and sustainable aviation fuels. To reduce the
price gap and create a stable market various types of incentives should be considered in the policy framework: ranging
from strengthening the current EU-ETS framework for carbon pricing to introducing additional incentives such as
funding mechanisms and blending mandates. These policy measures thereby support the development of new
production processes and advanced feedstocks. Additional elements of the policy framework are discussed more in
detail in Section 5.10.1.

5.10

Policies and actions

Having identified a substantial emission reduction potential from the use of sustainable aviation fuels, it is stressed
again that these will not realise themselves without supporting measures. Policies and actions from both governments
(including international organisations such as ICAO) as well as the aviation sector are necessary to realise the full
potential and impact of the solutions discussed.
Although overlap does exist, policies are mostly related to government or regulatory, whereas actions are largely
aimed at the aviation industry.

5.10.1

Policies

To increase the supply and demand for SAF a long term policy framework at EU level will be essential to reduce
aviation’s carbon footprint. Based on the barriers and enablers identified in the previous section elements of the
policy framework are specified.
This section starts with the overarching elements of the policy framework including an overview of possible incentives.
Then it specifies which form the basis for specific elements which are relevant in the 2030 and 2050 timeframe.
Policy framework
This section includes policy recommendations for the development of a European policy framework for SAF in
collaboration with governments. The high-level objectives include:
•

Establish a long term policy framework (>15 years);

•

Include stringent sustainability criteria in policy framework;

•

Ensure a uniform and coherent framework for level-playing field at EU level and regional level;

•

Coordinate and promote action at European level;

•

Enable and increase the deployment of SAF in the EU;

•

Include incentives based on EU financial funding mechanisms to reduce the price difference with fossil fuels;

•

Create a European platform gathering all the actors in the value chain as a way to foster route to ambition.
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To reach these objectives elements of the policy framework have been further elaborated for 2030 and 2050 in the
next sections.
Incentives
To increase the SAF uptake, different mechanisms can be considered to reach cost parity. The preferred type of
incentive depends on the goal of the policy framework. Besides carbon pricing, governments can use multiple funding
mechanisms to lower the price gap and/or reduce the project risk for investors. These include input or output
subsidies, capital grants, auctioning mechanisms and contracts for difference. The EU has multiple options for
providing funding by using new or existing financial instruments. Depending of the technology readiness level, the
availability of feedstocks, the required capital investment and the project lifetime the most appropriate funding
mechanism can be selected. At the moment not enough literature is available to specify exactly which type of funding
mechanism is preferred in which context. Additional research should be done on this subject as soon as possible. This
has also been highlighted in the recent inception impact assessment within the EU project ReFuelEU Aviation.
The following type of incentives can be used:
•

Carbon pricing: directly incentivizes the best performing fuels proportionally to the life-cycle carbon

•

Blending obligation (mandate): impose a minimum share of SAF over a certain time period to be supplied to

reductions (including ILUC effects).
airlines or used by airlines. The blending obligation may include sub-quotas or additional specifications, such
as the minimum level of CO2 reductions compared to fossil jet fuel. This reduces the investment risk.
•

Voluntary offtake agreements: the buyer commits to buying a certain amount of the product for a certain
price over specified time. This reduces the project risk.

•

Funding mechanism: the EU can channel funds through EU financial instruments or regulations (e.g., EU
emissions trading scheme, EU-ETS Innovation Fund). Member States could also fund SAF projects taking into
account restrictions from State aid rules. Financial instruments may for example be:
o

Capital grant: the producer receives a subsidy for the construction of the facility. This is often used

o

Input subsidy: this is seen as a reduction in feedstock costs.

o

o

for first-of-a-kind large demonstration facilities.
Output subsidy: the producer receives a subsidy per quantity of production. This reduces the
minimum selling price.
Loan guarantee: loans used to run/build the facility will be paid back. This mainly decreases the
project risk, reduces cost of capital and attracts other funding. Usually loan guarantees are provided
by States.

o

Contract for difference: implementing a guaranteed price floor by means of a reverse auction. If the
fuel drops below the price floor, the government will pay the difference to the value of the price
floor for the duration of the contract (Searle, Pavlenko, Kharina, & Giuntoli, 2019). This decreases
the project risk.

•

Central auctioning mechanism: SAF producers would be invited by a central auctioning authority to bid at
the lowest price to supply a certain volume of SAF to the aviation market over a certain period (EC, ReFuelEU
Aviation - Inception impact assessment, 2020f).

Incentives for SAF may influence the cost of fuels for other sectors like road transport and the other way round. Two
studies are presented here with two different points of view. ICCT highlights that it would be more cost effective to
support advanced fuels for the road sector in the near-term (Searle, Pavlenko, Kharina, & Giuntoli, 2019). Tilting the
product slate to jet fuel is costly for some technologies; therefore, producing larger volumes of road fuels during
technological development would decrease the cost. The study suggests incentivising the entire product slate
regardless of end-use sector. Jet fuel would initially be a co-product of the process, but it would increase in volume as
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the road sector electrifies. The Energy Transitions Commission suggests using both or either a “green fuel” mandate
specifically for aviation preferably at global level starting with regional level and carbon pricing. It highlights that
incentives to replace fossil kerosene are a priority and should be taken despite the higher cost of sustainable aviation
fuels (Energy Transitions Commission, 2019).
Policy strategy towards 2030
Given that currently very limited SAF production takes place, the policy framework should focus on increasing the SAF
production capacity in Europe based on feedstocks sourced primarily in the EU. This can be achieved by strengthening
the existing policy framework and setting the basis for a future long-term policy framework.
In the coming years, the policy framework should consider a combination of the following elements:
1.

Diversify the mix of pathways and increase the feedstock pool given the limited availability of sustainable
feedstocks:
a.

Perform R&D on new feedstocks and new production processes;

b.

Set-up pilot plants and first-of a kind facilities.

c.

Incentivize new technologies to prevent a lock-in effect on commercially available technologies:
i. Define specific (complementary) support for R&D;
ii. Define specific (complementary) support for pilot plants and first-of-a-kind facilities;
iii. Define specific (complementary) support for new production pathways.

2.

Scale-up commercially available technologies to increase the total EU SAF production and create a mature
market:
a.

Incentivize pathways proportionally to the CO2 emission reductions over the life-cycle (including
ILUC effects) to reduce the price gap with fossil fuels

b.

Strengthen the RED II policy framework
i. Enable EU production and regional supply chains
ii. Revise the multiplier for aviation
iii. Strengthen the sustainability requirements

c.

Strengthen the EU-ETS carbon pricing system

3.

Introduce an EU blending mandate based on careful analysis of timing and conditions

4.

Set-up a monitoring scheme for the use of SAF and share knowledge between stakeholders

5.

Set-up an accounting framework for the use of SAF

1. Increasing the feedstock pool and developing new technologies
Given the limited availability of sustainable feedstocks (both biomass and renewable electricity) in the EU the policy
framework should focus on diversifying the mix of feedstocks to increase the feedstock base. This can be achieved by
investing in research and development of new feedstocks and new production processes. The most promising
technologies can be further investigated in terms of pilot plants followed by first-of-a kind facilities. Supporting new
pathways increases technological learning and increases the process efficiency which lowers the production costs of
future facilities. Defining specific incentives for new pathways therefore enables scale-up of production in the long
term. These incentives should take into account that new pathways are often capital intensive and therefore require
large upfront investments. This can be done, for example, by offering capital grants for first-of-a kind facilities. Capital
grants decrease the project risk by offering investors a predefined amount of money. This grant is therefore not
dependent on the duration of the policy framework and not dependent on the lifetime of the production facility.
Incentives per litre of SAF are often met by using the cheapest pathways which are already commercially available,
unless additional eligibility criteria are specified (for example subtargets for specific SAF types or GHG reduction
thresholds). If commercially available fuels use the bulk of the subsidies, it creates a lock-in effect on these
commercially available fuels instead of increasing the mix of SAF types.
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2. Scale-up of commercially available fuels
The policy framework should also aim to increase the total SAF production by using already commercially available
technologies such as HEFA. This can be done by further improving the existing RED framework and EU-ETS.
The RED (and RED II) framework should increase the focus on life-cycle GHG reductions instead of limiting the fuel
selection to a list of feedstocks. A life-cycle analysis of the fuels could be performed in a similar way to the analysis
done for ICAO CORSIA eligible fuels including core GHG emissions and ILUC impact. Furthermore, the RED II does not
guarantee that production takes place in the EU. The system could be improved to incentivize regional supply chains
that aim to achieve the highest possible life-cycle reductions by limiting transport and distribution of feedstocks.
Furthermore, a revision of the current 1.2 multiplier for aviation could enable higher production levels. Revising the
multiplier should however not divert renewable energy supply from other users but enable the overall renewable
energy production in the EU to increase.
The most effective way to directly incentivize the best performing SAFs is carbon pricing. This measure and its related
policy actions are described in the section on economic measures. On the short term, the carbon price within EU-ETS
and CORSIA is expected to be much lower than the carbon abatement costs for SAF. Carbon pricing within EU-ETS is
expected to increase as a result of the declining emission cap. In the 2030 timeframe however the EU-ETS price is not
expected to cover the price gap. Therefore, additional forms of incentives are needed complementary to carbon
pricing. Complementary incentives can focus on reducing the project risk, reducing the minimum selling price or both
as explained in Section 5.10.1. Currently not enough information is available to select the exact combination of
incentives. Many elements influence the type of incentives needed such as project lifetime, capital investment,
regional socio-economic conditions and technological maturity. Additional research should be done to define the most
effective type of incentives on top of carbon pricing mechanisms. These incentives should be coordinated at EU level
by using an EU financial funding mechanism.
3. EU blending obligation
To increase the SAF uptake a policy option would be to introduce an EU wide blending obligation. A variety of policy
options should be taken into account when designing the mandate. The ReFuelEU Aviation initiative is currently
analysing the conditions needed for the implementation of a mandate such as sustainability criteria, timing and
amount. In general, the following principles can be used as requirements for the design of the mandate:
•

Ensure stringent sustainability criteria are met;

•

Stimulate the most cost efficient technologies;

•

Cause as little market distortions as possible;

•

Avoid carbon leakage;

•

Avoid additional cost increase due to lack of market competition.

The advantage of using a mandate is that the EU has more certainty that a minimum level of SAF is supplied to
aviation. Furthermore, it directly influences CO2 emissions from flights departing or within the EU. The risk of
introducing a mandate while the market is not mature is the lack of competition between producers leading to an
unnecessary increase in SAF prices. If a mandate is introduced in a very short timeframe and without strict
sustainability criteria, it will likely be met by lower sustainability fuels as these are cheaper and more easily available.
It is therefore recommended to announce the introduction of a mandate at least a couple of years in advance such
that investments can be made and production of highly sustainable pathways can be scaled-up in time. The mandate
for aviation should contribute to increasing the overall renewable energy use and production in the EU (without
diverting existing resources from other users). Therefore, an increasing mandate for aviation fuels can be
accompanied by a decreasing mandate for the road sector as the amount of electric cars increases and the road sector
moves away from liquid fuels.
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An EU wide mandate increases the level playing field. In general, most parties believe a mandate at EU level is
preferable over a variety of national mandates to avoid level playing field distortions. Many EU countries are already
considering of have already implemented a blending obligation. Norway has introduced a blending obligation on the
supplier of 0.5% with advanced feedstocks starting in 2020. Furthermore, the Netherlands has announced a blending
obligation starting in 2023 if no European agreement is reached beforehand. The following countries are also in the
process of introducing a mandate: France, Spain, Sweden and Finland. These proactive actions taken by countries may
distort the level playing field, therefore coordination at EU level is preferred.
4. Facilitation and monitoring
Exchanging knowledge between stakeholders along the entire value chain can facilitate the uptake of SAF. Aviation
stakeholders (such as manufacturers, airlines and airports) can exchange information with fuel producers and
government representatives to identify common goals and to discuss barriers and enablers to increase SAF uptake.
For example, to speed-up the introduction of new pathways, technological support can be provided to producers
along the certification process. Another topic may focus on sharing best practices between airlines to increase the
efficiency of setting-up offtake agreements (taking into account the boundaries of competition law). Furthermore, the
SAF uptake has to be monitored to understand if the established policy mechanisms have the desired effect and
whether these mechanisms need to be adjusted.
5. Accounting framework
An accounting framework similar to the framework for renewable electricity should be developed in the EU. The
framework should take into account that SAF production may not be distributed evenly across Europe. Production
facilities are likely to be built close to the available sustainable feedstock sources. Fuel supply to airports will then
need to be organised in the most cost-effective manner, using existing infrastructure. This should also reduce the lifecycle GHG emissions of the fuel as transport and distribution are minimized. The accounting framework should give
airlines the possibility to claim the use of SAF in the most economically efficient way across the fleet, regardless of
where SAF has been physically uplifted. For example, airlines may decide to redistribute the SAF claims to intraEuropean flights if the price of EU-ETS allowances remains higher than CORSIA carbon credits. This prevents airlines
from carrying extra fuel on-board if SAF is not available at a certain airport.
Policy strategy towards 2050
Long term policy framework should:
1.

Increase renewable energy production in the EU for all sectors and focus on energy efficiency improvements

2.

Allocate sustainable feedstocks between sectors based on technological alternatives to fossil fuels:

in all sectors;
o

3.

Ensure that a minimum amount of sustainable feedstocks (biomass and renewable electricity) is
available to the aviation sector by taking into account that aviation strongly relies on liquid fuels;

o

Ensure that technological developments in other sectors benefit from new technologies developed

o

Speed-up the introduction of alternative technologies in sectors that have these alternatives (such

for aviation and the other way round;
as electric cars, electric ground vehicles and electric aircraft for short ranges).

Increase sustainability of the fuels from an environmental and socio-economic perspective:
o

Increase life-cycle CO2 savings including the impact of land use change;

o

Ensure sustainability criteria are constantly assessed.

o

Introduce a more stringent EU mandate.

o

Strengthen EU-ETS framework to make SAF price competitive on the long term.

4.

Ensure a minimum amount of SAF is used on all flights:

5.

Incentivise all pathways proportionally to the CO2 reductions over the life-cycle:

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6.

Incentivise the use of SAF on international flights that are covered by worldwide offsetting programs:
o

Strengthen CORSIA framework to make SAF price competitive on the long term.

On the long term the main question to be answered by the policy framework is the division of sustainable feedstock
between various sectors of the economy. Current studies predict that EU renewable energy production will not be
able to meet the entire demand in the 2050 timeframe, but that it can be scaled-up eventually to meet demand from
all sectors. It is therefore of upmost importance to focus on energy efficiency improvements in all sectors.
Aviation will remain dependent on liquid fuels even in the long term. Full electrification of aviation using batteries is
deemed technologically feasible only for short range flights. Furthermore, from 2035 onwards, hydrogen is expected
to be used on intra-European flights up to 2000 km (per Section 3.3.3). Nevertheless, it is important to allocate
feedstocks to aviation for the production of power to liquid fuels and biofuels. For sectors that have technological
alternatives like the road sector, the policy framework should help to speed-up the introduction of these new
technologies. That also holds for aviation market segments in which alternative energy sources can play a notable
role.
Sustainability criteria for the fuels should form the basis of the policy framework. These criteria should therefore be
constantly assessed and whenever necessary improved. This includes both environmental and socio-economic
assessments. The framework should aim to increase the GHG reductions over time by using advanced feedstocks and
by creating regional supply chains. Technologies that are potentially carbon free such as the production of hydrogen
and power-to-liquid fuels with direct air capture are therefore promising technologies on the long term.
Towards 2050 this report estimates that carbon pricing under EU-ETS will be more expensive than using sustainable
aviation fuels. This will create a direct incentive for airlines to purchase SAF instead of fossil kerosene on intra-EU
flights. For international aviation however, carbon abatement costs for SAF are expected to be 2 times higher than the
carbon costs under CORSIA. SAF produced in Europe would thereby not be able to compete with the price of global
carbon credits. For international aviation complementary policy measures will be needed to ensure a minimum SAF
uptake is reached on international flights departing Europe. This can be achieved by using a blending obligation in
combination with complementary incentives to make SAF more affordable. The mandate is expected to increase
gradually by taking into account total fuel demand and efficiency improvements. The mandate should stimulate the
use of carbon reduction technologies in a cost-effective way and ensure stringent sustainability criteria are met, while
avoiding carbon leakage and distortion of competition. The gradually increasing mandate for aviation should also take
into account the technological development of other sectors. As the road sector is expected to gradually electrify and
move away from liquid fuels, these sustainable liquid fuels can be used in aviation.

5.10.2

Actions

The policies described in the previous section are accompanied by actions. Given a common goal, the actions will
focus on the elements the stakeholders can directly influence.
Aircraft manufacturers
For manufacturers the actions focus on designing and testing equipment to increase the blending level of SAF up to
100% and to get new pathways certified in ASTM. Manufactures design and test the aircraft, the engine and the
individual components to be compatible with current fuel specifications and future energy sources. For synthetic fuels
the equipment needs to be certified for fuels with lower aromatic content up to no aromatic content. For hydrogen
the engine and aircraft require substantial design changes which need certification and testing. For new pathways
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manufacturers provide technological support throughout the certification process. The required design changes will
depend on the chemical composition of the fuel. Communication and information sharing will improve efficiency and
collaboration with other stakeholders. In particular, manufacturers can support policy makers and standard making
bodies.
To increase the SAF uptake manufactures can play a role by setting up offtake agreements for engine testing, flight
testing and deliveries. Furthermore, they can invest in new production processes and feedstocks to increase
technological learning and to increase the overall uptake.
Airports
The actions for airports focus on providing the relevant infrastructure. Infrastructure for SAF can vary depending on
the geographical location of the airport. In some cases, fuel suppliers might set up production facilities directly on-site
or SAF produced elsewhere can be transported by trucks or pipelines to the airport. It is critical that airports receive
already blended SAF, which can be treated as Jet-A1, without any adjustments in the existing infrastructure. On-site
blending would require separate infrastructure, in particular for recertification to Jet-A1. This would not be a costeffective option. In some cases, dedicated storage facilities might be set up for biofuels and synthetic fuels and
liquefaction facilities are needed for the storage of liquid hydrogen. They can be located either on- or off-site the
airport; the most cost-effective option will depend on local circumstances. For hydrogen in particular, new distribution
networks will be required, as contrary to drop-in SAF, it will not be possible to use the same pipelines as those
supplying fossil kerosene.
To increase the SAF uptake airports can contribute by supporting and facilitating purchase agreements between
stakeholders in the value chain. Furthermore, they can invest in new production processes and feedstocks to increase
technological learning and to increase the overall uptake. Related initiatives are being implemented by Royal Schiphol
Group in collaboration with KLM and other companies, aiming to establish a production plant for SAF based on waste
such as used cooking oil, and Copenhagen Airport, which recently partnered with SAS and several other Danish
companies to set-up a production facility for power-to-liquid fuels.
To promote the use of SAF, if deemed desirable at the local level, airports can investigate modulating airport charges
based on the amount/percentage of SAF used by airlines or based on their CO2 emissions. Modulating airport charges
based on SAF would strengthen the environmental component of the charges as it addresses both climate related
emissions and air quality improvements. Some airports are also using other types of financial incentives to support the
deployment of SAF. For instance, through its Sustainable Aviation Fuel Programme, Swedavia offers to cover up to
50% of the SAF cost premium to airlines uplifting SAF at one of its airports.
Airlines
Airlines have a major role to play in the deployment of SAF. The commitment of an airline to purchase a certain
amount of SAF over a defined time period from a supplier has a valuable role in project risk mitigation and improves
the chances of financing the production facility. These off-take agreements are often negotiated before the
production facility is constructed. Airlines are very sensitive to fuel price variations and therefore off-take agreements
usually include a form of risk pricing, such as a price floor and a price ceiling (IATA, IATA Sustainable Aviation Fuel
Roadmap, 2015). The risk mitigation may be done together with intermediaries such as large investment banks.
Purchase agreements allowed the first European projects to be financed. For example, KLM has committed to an offtake of 75,000 tonnes per year which has enabled the first dedicated European SAF plant to be constructed in The
Netherlands. To increase the feedstock base and develop new technologies, airlines can also contribute to
investments in new feedstocks and new production processes. For example, Transavia invested into a pilot facility for
the production of power to liquid kerosene at Rotterdam airport.
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Airlines also have a major role to play towards customers. Airlines can offer special programs to costumers to
purchase SAF, thereby inviting customers to play an active role in the transition towards sustainable fuels in aviation.
For example, Lufthansa offers passengers a personal book-and-claim system called Compensaid (Compensaid, 2020).
SAS offers customers the option to purchase 20 minutes of flight time powered by biofuel (Kaminski-Morrow, 2019).
This biofuel will be used to replace fossil jet fuel within SAS’s operations (not necessarily on that specific flight). KLM
offers corporate customers the opportunity to be a part of the KLM Corporate Biofuel Program. The investments are
then used to bridge the price gap between fossil fuel and SAF. Furthermore, the airline can actively communicate
about the projects and activities in which it is currently investing. This includes the airlines ambition and current
involvement in financing SAF production facilities.
To increase SAF uptake airlines can support and collaborate with policy and standard making bodies. For example, by
sharing information to define the most suitable incentives to bridge the price gap with fossil fuels making SAF more
affordable, or by defining the type of accounting and monitoring framework in the EU.

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6

Economic measures
Economic measures assign a price to greenhouse gas emissions, ensuring that producers take the
climate costs of their emissions explicitly into account in their business decisions. This
internalisation of climate costs is increasingly recognised as a key mechanism to reduce emissions.
Emissions can be priced through levies as well as emission trading and offsetting schemes. Emission
trading and offsetting schemes reduce emissions in a more cost-effective way than levies and
ensure that a specific emission target is reached (provided that quality criteria are met).
This study therefore focuses on trading and offsetting schemes. Since 2012, EU ETS covers
emissions from intra-EEA flights. CORSIA has a global reach and shall be introduced in 2021 for
international flights. The schemes differ in approach, geographical coverage, applicability and
ambition level. It is yet unclear how both measures will develop and co-exist in the future. One
global measure is preferred to prevent market distortion and carbon leakage. However we consider
it likely that multiple schemes remain in place.
The prices of allowances and carbon credits shall increase over time, as the most cost-effective
measures are taken first. This will eventually lead to a price whereby carbon removal projects
become economically attractive to investors. Any remaining emissions in 2050 can therefore be
compensated by allowances and carbon credits stemming from carbon removal projects. This
allows the aviation industry to reach net zero CO2 emissions by 2050.

6.1

Introduction

For a long time, greenhouse gas emissions (GHGs) have remained unpriced. This allowed companies to emit GHGs at
no cost. As a result products were priced below the social optimum, which led to levels of supply and demand above
the social optimum. Economic measures assign a monetary value to emissions. This internalisation of emission costs
ensures that producers explicitly take these costs into account in their business decisions. It incentivises producers to
reduce their emissions.
The pricing of greenhouse gas emissions (GHG) is increasingly recognised as a key mechanism to reach the Paris
climate goals (CDP, 2017; World Bank Group, 2019; IMF, 2019a). In 2019, 57 carbon pricing initiatives were
implemented or in preparation 141. More initiatives are expected as countries seek cost-effective ways to reach their
climate goals. Out of the 185 Parties that submitted their Nationally Determined Contributions (NDCs) to the Paris
Agreement, 96 Parties (representing 55 percent of global GHG emissions) have stated that they are planning or
considering carbon pricing as a tool to meet their commitments (World Bank Group, 2019).
Although carbon pricing is seen as a key component to decarbonise, literature indicates that it needs to be
complemented with a mix of other policies to drive the required changes in a 1.5° C scenario (IPCC, 2018a). The large
scale transformation of sectors also requires policies that for instance support research and development. Such
141 Prices differ significantly between jurisdictions. Most are still too low to incentivise investments at the scale needed to reach the Paris climate goals (OECD, 2018a;
UNEP, 2018; World Bank Group, 2019). The IPCC, International Monetary Fund (IMF) and the OECD all pushed for strengthening and accelerating carbon pricing.

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complementary policies mean that the reduction goals can be achieved with a lower carbon price (CDP, 2017). This
study suggest a combination of measures and policies.
This chapter focuses on economic measures. Section 6.2 introduces various types of pricing mechanisms and discusses
their effectiveness. Section 6.3 describes the measures in more detail and indicates how these measures and carbon
prices may develop until 2050. The relevant drivers and barriers are discussed in Section 6.5. Required policies and
actions are presented in Section 6.6.

6.2

Types of pricing mechanisms

Carbon emissions can be priced through levies (taxes and government charges), emission trading and offsetting
schemes (ICAO, 2015). 142 Each can be used to internalise the cost of emissions, leading to more socially optimal levels
of supply and demand and incentivising producers to reduce their emissions. However, there are important
differences in terms of administrative costs, efficiency, risk of market distortion and assurance that a specific emission
target is being met:
•

Administrative costs: The administrative costs of levies might be lower than those of emission trading and
offsetting. Taxes and government charges are levied on passengers and/or flights (CE Delft & SEO Amsterdam
Economics, 2019). This leads to limited administrative costs to airlines. Emissions trading and offsetting require
airlines to respectively obtain emission allowances and carbon credits to cover their emissions. Airlines therefore
need to estimate their future emissions, report their actual emissions, determine an optimal strategy to gather
the required allowances or carbon credits and finally to obtain them in the market. This is a more complicated
process which leads to higher administrative costs. However it should be noted that part of these costs are made
regardless by airlines for instance to determine optimal fleet renewal pathways and fuel hedging strategies and to
inform investors on their sustainability efforts;

•

Efficiency: Emissions trading and offsetting are more effective in reducing emissions than levies for a number of
reasons. First, the former incentivise airlines to reduce their emissions as the number of allowances or carbon
credits needed is directly related to their emissions. Levies on passengers or flights which show no relationship to
emissions do not stimulate airlines to reduce their emissions. Levies can however be designed in a way that they
do incentivise airlines to reduce their emissions. Secondly, the trading of allowances and carbon credits between
sectors and states ensures that emissions are reduced where this can be achieved at the lowest cost. Put
differently: each invested euro leads to the largest emission reduction. Levies only allow for in-sector reductions,
whereas out-of-sector reductions might be much more cost-effective. Thirdly, the revenues of auctioned emission
allowances are (partly) invested in reducing carbon emissions. Globally, an estimated 70 percent of ETS revenues
is used for environmental spending. For carbon taxes this is only 15 percent (IMF, 2019a);

•

Risk of market distortion / carbon leakage: The cost-effectiveness of emission trading and offsetting schemes
increases with the size of the market for allowances or carbon credits. The larger the market in terms of sectoral
and geographical coverage, the broader the scope for emission reduction projects. This ensures that investments
flow to the most cost-effective emission reduction projects, increasing the effectiveness of the market-based
measure. Taxes and government charges are levied on a national or airport level which may lead to market
distortions, negatively affecting the competitive position of based airlines. The Irish, German and Dutch ticket
taxes have shown that airlines reduce capacity and/or cancel planned expansions after the introduction of these
taxes (KiM, 2011). Moving capacity to other airports is however only possible for airlines that operate from
multiple bases. Airlines operating from one base, do not have any outside options. To avoid the tax, passengers

142 The focus of this chapter is on measures that price carbon emissions. Measures that increase the cost of emissions in an indirect way, for instance by abolishing fuel
subsidies and excise duty exemptions are left out of the analysis. Such measures may however be implemented when additional emissions reductions are necessary.

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might divert to more distant airports. Studies on the Dutch ticket tax have shown this effect (SEO Amsterdam
Economics, 2009; SEO Amsterdam Economics, 2019). Diverting to more distant departure airports leads to an
increase in emissions of surface transport. This means that national taxes are ineffective in reducing carbon
emissions and may reduce national welfare (CPB & PBL, 2016). The same holds true, albeit to a lesser extent for
multilateral levies or emission trading and offsetting schemes. Global economic measures are therefore preferred
over local measures;
•

Certainty on reaching emission target: well-designed emission trading and offsetting schemes allow governments
to cap future net emissions at a level which corresponds to an emission target. This ensures that the emissions
target is being met. A levy does not cap emissions and it remains unsure to what extent emissions will eventually
be reduced. When the levy is set at a level that is too low, the emissions target will not be met. Consequently, this
may mean that the levy needs to be adjusted. In case the levy is too high, it may depress demand and emissions
to levels that are socially not optimal. Emissions targets are therefore met with more certainty by emission
trading and offsetting schemes than with levies (IMF, 2019a).

6.3

Smart economic measures

Emission trading and offsetting reduce carbon emissions most efficiently and at the same time ensure that emission
targets or climate goals are being met. Such measures are therefore referred to as ‘smart’ economic measures and are
to be preferred over levies. In this study we therefore assume that carbon emissions from flights departing from
European airports are priced through a smart economic measure. The next section describes emission trading and
offsetting schemes in more detail.
•

Emission trading: Emission trading schemes or cap-and-trade schemes require producers to cover their emissions
through emission allowances. Allowances are certificates that allow the holder to emit one unit of a particular
pollutant, such as a tonne of CO2. The number of available allowances is capped at a level which corresponds to
the emissions target. This ensures that the target will be met. Producers can either reduce their emissions or buy
allowances on the market (trade). Governments can either sell allowances or give them away for free. Allowances
sold at auctions generate revenues for the government that can be used to support innovations or reduce existing
taxes. In 2019, 20 emission trading systems were in force spanning 27 jurisdictions and covering around 8 percent
of global GHG emissions (ERCST, et al., 2019). The systems in the EU and South Korea are the only ones that
include the aviation sector (World Bank Group, 2019). Over the next five years six more jurisdictions are putting in
place emission trading systems, including China and Mexico. The Chinese system initially only covers the power
sector; later it shall be expanded to other sectors including aviation. Another 12 jurisdictions are considering a
system as part of their climate policy (ERCST, et al., 2019);

•

Offsetting: Offsetting schemes require producers to offset emissions that exceed a certain threshold through
carbon credits. A carbon credit represents the certification that a tonne of CO2 has been reduced or avoided
compared to a scenario without the offsetting scheme. The overall threshold is translated in thresholds for
individual producers. When producers want to increase their output, they shall either have to reduce their
emissions to the threshold level and/or buy credits on the market to offset any emissions over and above the
threshold.

In both systems producers shall reduce their emissions when the cost of doing so is lower than the cost of acquiring
allowances or carbon credits on the market. When emission targets become more ambitious, the price of allowances

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and carbon credits increase. Consequently, more emission reduction projects become economically viable. Smart
economic measures therefore ensure that the most cost-effective measures are taken first 143.
The effectiveness of smart economic measures depends on their design. First, compliance should be high to ensure
that the majority of emissions is covered and producers cannot evade the system and undermine its working. Second,
when an airline buys an allowance or carbon credit, this should respectively reduce the right to emit of its seller or
represent actual emission reductions realised by a project which would not have taken place without the scheme.
Third, the market for allowances or carbon should be sufficiently large. The market is broadened when more sectors
and countries take part in the measure.

6.3.1

EU Emissions Trading Scheme (ETS)

ETS is the cornerstone of EU’s policy to combat climate change and its key tool to reduce GHG emissions in a costeffective way. At present it is the world largest carbon market.
Initially the ETS only covered the power industry and heavy industry. Since 2012, aviation also falls under the EU-ETS
and is still the only transport mode included in the scheme 144. Originally it was designed to cover the emissions of all
flights from, to and within the EEA 145 (full scope). In 2013, the scope was reduced to intra-EEA flights through the
‘stop-the-clock’ decision after strong opposition from various countries outside the EU. 146 With the ‘stop-the-clock’
decision the EU also allowed the International Civil Aviation Organization (ICAO) to develop a global measure (CORSIA,
see below). Airlines active in the European Economic Area (EEA) need to monitor, report and verify their emissions
and surrender allowances for those emissions. The reduced scope shall remain in place until the end of 2023, after
which it reverts to its full scope unless there will be a revision in light of CORSIA.

Trading of
emission
allowances
Cap on
emission
allowances

Figure 11: Illustration of cap-and-trade scheme

143 In a well-functioning system, prices tends towards the marginal abatement cost of carbon (Synapse Energy, 2016).

144 EU-ETS covers CO2-emissions from the power and heavy industry as well as aviation. In addition it covers N2O-emissions from the production of various acids and
glyoxal and perfluorocarbons (PFCs) from aluminium production. For aviation EU-ETS only covers CO2-emissions.
145 The EEA includes the EU Member States plus Iceland, Liechtenstein and Norway.
146 The United States for instance adopted the ‘EU ETS Prohibition Act’ which would allow its authorities to forbid airlines based in the United States to comply with the
system.

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Two types of emission allowances exist within the EU-ETS system. General allowances (EUAs) and aviation allowances
(EUAAs). Fixed installations (power and heavy industries) need to cover their emissions through general allowances.
Airlines can use both the general and aviation allowances for compliance. In the next trading period (2021-2030) fixed
installations are also allowed to use aviation allowances.
In the current trading period (2013-2020) operators are also allowed to use international offset credits from the Clean
Development Mechanism (CDM). 147 According to the provisions in the revised EU ETS Directive, international credits
can no longer be used for compliance in the next trading period (2021-2030) as the EU has a domestic emissions
reduction target (UNFCCC, 2017; Carbon Tracker, 2018; EC, 2018a).
Cap
The number of available allowances is capped and is reduced each year to ensure that the climate targets of the EU
will be met. Over the current trading period (2013-2020) the number of general allowances issued is reduced by a
linear reduction factor of 1.74 percent per year (of the average quantity of allowances over the 2008-2012 period).
This should result in an emission reduction of 5 percent by the end of the trading period, compared to the average
emissions in the 2004-2006 period. The number of aviation allowances is not reduced over the current trading period.
The number of allowances put into circulation decreased by 37 million or 1.8 percent per year on average since 2013
(see Figure 12). Although CO2-emissions from aviation increased, total CO2-emissions of all sectors included in the EU
ETS declined by 43 Mt CO2e over the same period (2.3 percent per year on average see Table 34). This shows that the

ETS allowances put into circulation (mln)

EU-ETS brings about real emission reductions, first in those sectors where abatement costs are lowest.

2,400

2,100

1,800

1,500

1,200

2013

2014

2015
EUAs

2016

2017

2018

EUAAs

Figure 12: Number of allowances put into circulation (source: European Commission (2018a), analysis by authors)
As mentioned above a cap-and-trade system only works when compliance is high. In the EU ETS system 99 percent of
emissions are covered by allowances. For the aviation sector the compliance rate was 98 percent. In the past various
airlines have paid fines of over € 1 million each for non-compliance with the EU-ETS. These airlines later complied with
the system (EC, 2018a; EC, 2017).

147 The credits are no longer surrendered directly, but may be exchanged for allowances at any time during the calendar year.

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Over the next trading period (2021-2030) both the general cap and the aviation cap are reduced by 2.2 percent per
year to reach ETS specific reduction target of 43 percent (compared to 2005 levels) by 2030 148. The European Green
Deal contains more ambitious goals, and recently, the European Commission clarified these with a proposed target of
reducing emissions by 55 percent by 2030, compared to 1990 levels. This may lead to a stronger reduction target for
the sectors covered by the EU-ETS and thus a larger linear reduction factor. For 2050 the Green Deal aims for net zero
GHG emissions.
CARBON REMOVAL
In order to limit the temperature rise to 1.5C by the end of the century, CO2-emissions should be reduced by 45 percent in
2030 (compared to 2010 levels) and reach net zero in 2050. According to the IPCC (2018b) these targets can only be met by
deep emission reductions in all sectors in combination with Carbon Dioxide Removal (CDR) from the atmosphere. CDR is
needed to compensate for any residual emissions that cannot be mitigated by 2050.
Modelling assessments by the European Commission have also shown that technological innovations and the use of
alternative fuels are not sufficient to reduce emissions to zero. The EC framework to achieve climate-neutrality recognised
the need for greenhouse gas removals to compensate for any remaining emissions from sectors that cannot be fully
decarbonised (EC, 2020d). The European Green Deal contains a 90 percent reduction target for the transport sector,
indicating that the transport sector is seen as one of the sectors in which emissions cannot be completely reduced to zero in
2050.
It is therefore likely that carbon removal projects lead to the issuance of ETS allowances and/or dedicated carbon credits
which can be used by the aviation sector to compensate for a part of its emissions that cannot be mitigated by 2050. This
means that even under a net zero target, there may still be allowances and carbon credits made available through carbon
removal projects in the EU. The price of the allowances and/or carbon credits equals the cost of removing carbon emissions
from the atmosphere. This means that the price of allowances and carbon credits cannot exceed the cost of carbon
removal.
There are various ways to remove CO2 from the atmosphere, such as afforestation and reforestation (planting trees),
Bioenergy with Carbon Capture and Storage (BECCS) and Direct Air Carbon Capture and Storage (DACCS). Afforestation and
reforestation rely on purpose-grown tree to removes CO2 from the air as part of the photosynthesis process. BECCS relies
on purpose-grown biomass (plants and tree) to capture CO2. The biomass is subsequently harvested and combusted to
produce power. The CO2 that is released during the combustion process is captured and stored. DACCS removes CO2
directly from ambient air by placing large volumes of air in contact with chemicals known as sorbents.
The various options differ widely in terms of maturity, potential, costs and risks (IPCC, 2018b). According to a recent study
by the IEA (2020) afforestation/reforestation and BECCS are the most cost-effective options, with cost estimates ranging
between $5 and $85 per tCO2 removed. However, their main disadvantage is that they require vast amounts of land and
water which limits their potential.
DACCS is more expensive mainly due to the low concentration of CO2 in ambient air 149. Compared to
afforestation/reforestation and BECCS it does not require much land and water and therefore has the potential to remove
large amounts of CO2 from the atmosphere. 150 However, the separation process requires significant amounts of
(renewable) energy and heat (Gambhir, 2019; Realmonte, 2019). Cost estimations range between € 30 (Breyer, 2019) and $
1,000 (House, 2011) per tCO2 removed, with most estimations lying in the € 100 to € 500 range. 151 The UK Committee on
Climate Change (2019) assumed a price of 300 pounds per tCO2 for DACCS in 2050.
For carbon removal within Europe we base our price estimation on the cost of Direct Air Capture as afforestation
/reforestation and BECCS require vast amounts of land which might not be available. Based on the literature we therefore
assume a value of € 315 tCO2 for carbon removals within Europe. For carbon removal projects outside Europe we expect
the average costs of carbon removal to be lower. First, because of the larger potential for afforestation /reforestation and
BECCS projects due to greater land availability. Second, because DACCS might be less costly in regions with a large supply of
(renewable) energy and heat. For carbon removal projects outside Europe we therefore assume the middle value as
published by the IEA (around $175 or € 160 per tCO2 removed). This is in line with the estimated cost of carbon credits in
2050 (see below), indicating that carbon removal projects over time become cost-effective alternatives to carbon avoidance
projects. It is therefore fair to assume that in 2050 carbon credits may be issued from carbon removal projects for € 160 per
tCO2.
148 For the sectors not covered by the ETS, such as transport, construction, agriculture and waste, separate reduction targets are defined. When the agreed EU legislation
is fully implemented, total greenhouse gas reductions are estimated to reach around 45% in 2030 (compared to 1990 levels). The policies put in place today have a
continued impact after 2030 and with projected emissions of around 60% by 2050 (EC, 2018b).
149 The CO concentration from a point source such as a coal-powered power plants is around 12 percent, which is approximately 300 times higher than in ambient air
2
(0.04 percent) (House, 2011).
150 The atmosphere effectively disperses CO quickly and evenly, which means that processing plants can be located anywhere (Broehm et al., 2015).
2
151 Estimations for the longer-term are generally smaller than those for the short-term due to economies of scale and learning by doing. However, energy requirements
are likely to remain high in the future (Breyer, 2019).

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Trade
Although the total CO2-emissions under EU ETS declined by 2.3 percent per year on average since 2013, the emissions
from intra-EEA aviation increased by 4.5 percent per year (see Table 29). This indicates that the aviation sector is a net
buyer of emission allowances. The power sector is the main seller of emission allowances. For power generators it is
currently more cost-effective to reduce their own emissions and sell abundant allowances to other sectors where
abatement costs are higher. By purchasing allowances from the power sector, the aviation sector contributes to the
decarbonisation of the power sector. This shows that money flows to those investment projects that reduce emissions
in the most cost-effective way.
Table 33: Verified emissions (mln CO2e) (source: European Commission (2018a), analysis by authors)
2013

2014

2015

2016

2017

2018

Y-o-Y change

Fixed installations

1,908

1,814

1,803

1,751

1,754

1,681

-2.5%

Aviation

54

55

57

62

64

67

4.5%

Total

1,962

1,869

1,860

1,813

1,818

1,748

-2.3%

In 2017, 41 percent of aviation emissions within the EEA was covered by EUAs purchased from the other sectors (see
Figure 13). The remainder of the aviation emissions is covered by the aviation allowances (EUAAs). The majority of the
EUAAs, 82 percent, was allocated for free to airlines over the 2013-2017 period (see Figure 13) 152. Free allocation was
introduced to limit the risk of market distortions and carbon leakage. This risk is highest for sectors that are exposed
to international competition. Therefore the aviation sector obtains a relatively large share of its allowances for free.
The system of free allocation remains in place during the next trading period. The remainder of the EUAAs,
18 percent, was auctioned or reserved for fast-growing airlines and new entrants.
70.0

Number of allowances (mln)

60.0
50.0
40.0
30.0
20.0
10.0
0.0

2013

2014

Free allowances (EUAAs)

2015
Auctioned allowances (EUAAs)

2016

2017

Purchase of EUAs

Figure 13: Aviation emissions covered by EUAAs and EUAs (source: European Commission (2018), analysis by authors)

152 The European Commission estimates that 57 percent of allowances are auctioned over the 2013-2020 trading period. Power generators in principle do not receive any
free allowances under the current trading period, although Article 10c of the ETS Directive allows for free allocation to modernise the power sectors in lower-income
Member States. The heavy industry received around 80 percent of the allowances for free at the beginning of the trading period, which has been gradually decreased to
30 percent in 2020.

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The auctioning revenues accrue to the Member States. 153 Member States report that they spend 80 percent of
auctioning revenues on climate and energy purposes (ERCST, et al., 2019) 154. Most of the revenues go to national and
EU purposes, while a smaller share goes to international purposes (EC, 2019g). Data on the spending of the revenues
is provided by the individual Member States. It is not clear to what extent the expenditures are additional and to what
extent they lead to actual CO2 reductions.
Member States can compensate producers for part of the costs incurred to a maximum of 25 percent of the
auctioning revenues. The amount of compensation paid is partial and regressive and subject to state-aid guidelines. In
2018 producers could be compensated for 80 percent of their costs, this was reduced to 75 percent in 2019. In 2017, a
total of € 694 million was paid out in compensation by ten Member States (EC, 2018a).
Several funding mechanisms are linked to the EU ETS to stimulate investments in low-carbon technologies (EC, 2019g):
•

Innovation fund: The innovation fund supports the development of innovative technologies and
breakthrough innovation in sectors covered by the EU ETS. The fund was established by the revised ETS
directive. The amount of funding available corresponds to the market value of at least 450 million allowances.
Depending on the allowance price the fund may amount to € 10 billion. The fund will be supplemented by
any unused budget from the New Entrants Reserve (NER) 300 155 and up to 50 million allowances when these
are not needed for free allocation (EC, 2018a);

•

Modernisation fund: The modernisation fund supports low-carbon investments in the energy systems of 10
low-income Member States. The fund will be sourced with allowances corresponding to 2 percent of the total
quantity in phase 4. At a carbon price of € 20 tCO2, around € 14 billion will be available over the coming
decade.

Historic price development
The 2008 economic crisis and the widespread use of international credits in the second and third trading periods led
to a surplus of emission allowances. As a short-term measure the European Commission postponed the auctioning of
part of the allowances in 2014. This back-loading did not reduce the total number of allowances available during the
third trading period, but only the timing at which new allowances became available. The introduction of the Market
Stability Reserve (MSR) in January 2019 addressed the surplus of allowances in a more structural way. It makes the
system more resilient to shocks by adjusting the supply of auctionable allowances 156.
The price of EUA allowances peaked at almost €30 per tCO2e just before the economic crisis hit in 2008. The surplus of
allowances that followed depressed the price to less than €5 per tCO2e in 2013. The back-loading of allowances led to
a modest price increase, but prices on average remained relatively low. In 2017 EUA prices averaged €5.80 per tCO2
and the allowance costs represented around 0.3% of total operating costs for airlines within the scope of the ETS (EEA,
EASA & EUROCONTROL, 2019). Since 2018 prices have risen sharply as market participants anticipated on the supply
squeeze of the MSR and the post-2020 reforms that would come into effect from 2021. In 2019 EUA prices averaged
almost €25 per tCO2 (see Figure 14). The corona crisis had a sharp, but short-lived impact on the EUA price, which is
currently back on the pre-crisis level. The EUAA prices showed a similar development.

153 Two auctioning platforms are in place. The European Energy Exchange (EEX) is used by most participating countries. The ICE Futures Europe (ICE) acts as the platform
for the United Kingdom. In 2017, the EEX-platform auctioned 89 percent of the total volume on behalf of 27 Member States. The ICE-platform was responsible for the
remainder 11 percent (EC, 2018a).
154 Article 10 of the EU-ETS Directive requires that at least 50 percent of the auctioning revenues are used by Member States for climate and energy related purposes.
155 The NER 300 is one of the world’s largest funding programme for innovative low-carbon energy demonstration projects. It is funded from the revenues of 300 million
EU ETS emission allowances.
156 Between 2019 and 2023, the amount of allowances put in the reserve will double to 24% of the allowances in circulation. The regular feeding rate of 12% will be
restored as of 2024. As a long-term measure to improve the functioning of the EU-ETS, and unless otherwise decided in the first review of the MSR in 2021, from 2023
onwards the number of allowances held in the reserve will be limited to the auction volume of the previous year. Holdings above that amount will lose their validity.

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35

EUA price (euro per tCO2)

30
25
20
15
10
5

Oct-20

Jan-20
Apr-20
Jul-20

Oct-19

Jan-19
Apr-19
Jul-19

Oct-18

Jan-18
Apr-18
Jul-18

Oct-17

Jan-17
Apr-17
Jul-17

Oct-16

Jan-16
Apr-16
Jul-16

Oct-15

Jan-15
Apr-15
Jul-15

Oct-14

Jan-14
Apr-14
Jul-14

Oct-13

Jan-13
Apr-13
Jul-13

0

Figure 14: Development of ETS allowance prices in Phase 3 (EEX, n.d., analysis by authors)
The price increases lead to higher auctioning revenues for Member States. Figure 15 shows that the revenues from
auctioning EUA and EUAA allowances increased from almost €4 billion in 2013 to over €16 billion in 2019. The
additional revenues allow Member States to increase funding for climate and energy purposes as mentioned above.
Over the 2013-2019 period, an estimated € 52 billion was raised by the auctioning of emission allowances. Almost
€ 0.5 billion was paid for by the aviation sector through the auctioning of aviation allowances 157.
18

Revenue (bln euro per year)

16
14
12
10
8
6
4
2
0

2013

2014

2015

2016

2017

2018p

2019p

Figure 15: Development of ETS auctioning revenues in Phase 3 (analysis by authors). Note: Revenues are based on the
allowance prices at the largest exchange platform, the European Energy Exchange (EEX). The number of auctioned
allowances has not yet been officially published by the European Commission for 2018 and 2019. We predicted these
numbers (indicated by 2018p and 2019p) based on the growth in auctioned allowances on the EEX-platform since
2017.

157 In addition the aviation sector purchased allowances from the power and industrial sectors. The total cost of these purchases could not be calculated due to missing
data for 2018 and 2019. However data for the 2013-2017 period suggests that these costs are significantly higher than the costs of the auctioned allowances. Also these
costs are expected to increase more rapidly as an increasing share of allowances shall be purchased by the aviation industry.

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6.3.2

CORSIA

The Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) is an offsetting scheme. This global
market-based measure was agreed upon at the 2016 ICAO Assembly to address CO2-emissions from international
aviation.
CORSIA aims to stabilize net CO2-emissions from international flights from 2020 onwards. CORSIA requires airlines to
offset any emissions above the 2019 threshold by purchasing carbon credits generated by projects that reduce
emissions in other sectors. This should ensure that the ICAO target of carbon-neutral growth from 2020 onwards
(CNG2020) is being met. No further targets have been specified for the period after 2020.
International carbon credits are financial instruments that represent a tonne of CO2 reduced or removed from the
atmosphere as a result of an emissions reduction project. The credits are generated by emission reduction projects
and are available through various offsetting programs. The Kyoto Protocol set the basis for two of such programs, the
Clean Development Mechanism (CDM) and the Joint Implementation (JI) in 1997. The most widely used programs
today are the Verified Carbon Standard (VCS) and the Gold Standard. 158
In October 2020, 88 states (including all EU Member States) representing 77 percent of international aviation activity
applied to voluntarily participate in the pilot phase (2021-2023) and first phase (2024-2046) of CORSIA. The second
phase (2027-2035) is mandatory, although exemptions exist for states with a small aviation industry, Least Developed
Countries (LDCs), Small Island Developing States (SIDS) and Landlocked Developing Countries (LLDCs). These states
may however still participate on a voluntary basis.
Initially the price of carbon credits developed in line with the price of EU-ETS allowances, as they could be used for
compliance within the EU-ETS system. Prices plummeted after the financial crisis. But where the EU-ETS prices
recovered when the oversupply of allowances was addressed, the prices of credits remained low due to oversupply
and the fact that they could only be used to a limited extent during the third trading period of the EU-ETS (20132020). In early February 2020, carbon credits were traded for as little as € 0.23, roughly 100 times less than the price
of EU-ETS allowances. Projects that adhere to higher quality standards regarding environmental and social integrity
generate more expensive credits and could trade at up to $ 70 per tCO2e (Energies Nouvelles, 2017). However, around
half of the credits is sold below $ 1 per tCO2e (World Bank Group, 2019). CORSIA might lead to a large increase in
demand for carbon credits. The more stringent the criteria for the credits, the more expensive these credits will
eventually be.
QUALITY OF OFFSET CREDITS
There is a general consensus that offset programs may in principle generate credible credits. The major offsetting programs
follow equivalent, if not the same, procedures and methodologies. Therefore the environmental and social integrity of the
carbon credits mainly depends on the type of projects that are being offered through the programs.
The quality of carbon credits is generally measured by the following criteria:
˗
Additionality: credits generated by a project represent greenhouse gas reductions or carbon sequestration or
removals that would not have occurred without the project;
˗
Measurable: greenhouse gas reductions should be measurable to confirm that they are real;
˗
Permanence: credits should represent greenhouse gas reductions or removals that are permanent, i.e. have a low
risk that the reductions or removals are reversed;
˗
No leakage: the projects generating credits should not lead to increased emissions elsewhere;
˗
Prevent double counting: the greenhouse gas reductions or removals may only be counted once;
158
Offset credits may also be used by companies and organisations to voluntarily offset (part of) their carbon footprint. The size of the voluntary carbon market is much
smaller than the compliance markets. Over the 2005-2018 period around 2,000 projects worldwide had issued over 430 MtCO2e of voluntary credits. This is relatively
modest compared to the 11 GtCO2 covered each year by emission trading schemes and carbon taxes (Energies Nouvelles, 2017).

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NLR-CR-2020-510 | February 2021

˗

Do no net harm: the projects generating credits should not cause any negative environmental or social
externalities.

Several studies suggest that claims made by projects regarding environmental integrity often appear unrealistic and
exaggerated. The majority of available carbon credits on the market is therefore of questionable quality with respect to
their environmental integrity. A study commissioned by the European Commission concluded that 85% of the CDM projects
and 73% of the credits issued under the mechanism had a low likelihood that emission reductions were actually additional
and were not overestimated. Only 2% of the projects and 7% of the credits had a high likelihood of additionality and low
likelihood of overestimation (Ökö-Institut e.V., 2016). Despite the fact that CDM standards have been improved, the
performance of the scheme has not improved due to a shift in the project portfolio to more questionable project types.
Furthermore, the low prices of carbon credits generally does not reflect the actual cost of avoiding or reducing a tonne of
CO2. The projects often receive additional funding such as grants or subsidies from NGOs and governments. This means that
the buyer of the credits is not fully responsible for the emission reductions achieved. When both the buyer and the NGO
and/or government claim the same emission reduction, there is a risk of double counting the same reduction.
This suggests that there are many credits available in the market that might not actually represent additional, permanent
and real emission reductions. Companies may however only rightfully claim emission reductions from projects that adhere
to high standards regarding the environmental and social integrity.

In 2018 the ICAO Council adopted standards and recommended practices (SARPs) for CORSIA. In 2019 ICAO invited
offsetting programmes to apply for assessment by the Technical Advisory Body (TAB) based on its eligibility criteria
(ICAO, 2019c). It received 14 responses, which included the aforementioned Clean Development Mechanism (CDM),
Verified Carbon Standard (VCS) and the Gold Standard. Although the Ökö-Institut e.V. (2019) concluded that many
programs did not guarantee environmental integrity, 6 out of the 14 programs were approved in March 2020.
The implementation of the scheme is ongoing and not yet complete. Uncertainties remain regarding its coverage,
robustness and compliance policy. Certain countries with a large aviation industry might not participate or delay the
implementation of CORSIA into national law.
As mentioned above, carbon removal projects may lead to the issuance of allowances or carbon credits which can be
used by the aviation sector to compensate for a part of its emissions that cannot be mitigated before 2050. This
means that even under a net zero target, there may still be allowances and credits available stemming from carbon
removal projects.

6.3.3

Comparison

The previous sections detailed EU-ETS and CORSIA. Table 34 summarizes the main differences between the two
schemes. These relate to:
•

Ambition level: EU-ETS aims to reduce absolute GHG emissions by 43 percent (compared to 2005) levels in 2030
for the sectors covered by the system (power generation, heavy industry and aviation). The European Green Deal
may lead to a more ambitious target. CORSIA is less ambitious as it aims to stabilize net CO2-emissions at the 2019
level;

•

Certainty on reaching emission target: In EU-ETS the number of available allowances (cap) is fixed and
corresponds to the target. This ensures that the target is met under full compliance. As mentioned before
compliance levels are high due to the fact that the system is legally binding and penalties apply in case of noncompliance. For CORSIA much is still uncertain. The quality of the carbon credits greatly determines its efficiency.
Furthermore, the system is not legally binding until countries have implemented it into national law. If CORSIA is
not implemented in all countries at the same time, this could lead to market distortions (EC, 2017). Also it is yet
unclear how compliance will eventually be enforced;

•

Geographic coverage and timing: EU-ETS covers CO2-emissions from intra-EEA flights until the end of 2023, after
which it reverts to its full scope unless there will be a revision in light of CORSIA. CORSIA has a global reach and
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NLR-CR-2020-510 | February 2021

covers the growth in CO2-emissions of international flights between participating states after 2020. The global
scope of CORSIA limits the risk of market distortions and carbon leakage. However, emissions from domestic
flights are not covered by CORSIA. 159 This allows airlines with a large domestic network to pass-through part of
the costs to their domestic routes. This gives them a competitive advantage on international routes. The same
holds for airlines that serve international markets through indirect flights whereby one of the flights is domestic.
This means that they only need to offset their emissions for the non-domestic flight leg, whereas competitors that
operate direct need to offset emissions on the entire route. This introduces new risks of market distortions and
carbon leakage. Both systems are in place at least during the 2021-2023 period. Over these years the growth in
CO2-emissions of intra-EEA flights between two EEA states is covered by both systems, unless the EU ETS is being
revised. However, CO2-emissions from the EEA states to states not participating in CORSIA (and vice versa) are
neither covered by ETS nor CORSIA;
•

Use of international credits: EU-ETS is based on emission allowances that can be traded among sectors in the EU.
The system only allows operators to cover a small part of their obligations through the use of international credits
until 2020. Thereafter such credits are no longer allowed. This means that as of 2021, all of the emission
reductions achieved will occur within the EU. The offsetting under CORSIA is based on international credits. These
credits will to a large extent stem from projects outside the EU. This means that CORSIA mainly offsets emissions
through reductions outside the EU and thus has only a limited potential to contribute to the EU GHG reduction
targets.

•

Exceptions for SAF: The EU-ETS attributes zero emissions to SAFs that comply with the sustainability criteria
defined in the RED. The purchase of SAF thereby reduces an aircraft operator’s reported emissions, and the
number of ETS allowances required (EEA, EASA & EUROCONTROL, 2019). Under CORSIA airlines can reduce their
offsetting requirements by claiming emissions reductions from the use of CORSIA eligible fuels (CEF) 160. The
emission reduction that can be claimed depends on the life-cycle emissions of the specific SAFs used compared to
the life-cycle emissions of conventional fuels. When the life-cycle emissions of a SAF are for instance 70 percent
lower than those of conventional fuels, airlines only need to offset the remaining 30 percent of the emissions
resulting from the combustion of the SAF through CORSIA. Excluding emissions from the combustion of SAFs
partly or completely acts as a financial incentive for airlines to use SAF (EEA, EASA & EUROCONTROL, 2019).

Table 34: Main differences between EU-ETS and CORSIA
Scheme

Applicability

Target

Certainty on
reaching
target

Cap and trade

EU-ETS

Caps the level of emissions. Operators reduce their
emissions or buy EU Allowances in the market (trade).
International credits (CERs and ERUs) can be used to offset
up to 1.5% of emissions (until 2020)

Offsetting

CORSIA

Operators buy international carbon credits to offset their
emissions above 2020 levels. Conditions apply to offsetting
programs.

’12-‘23

‘21-’26 (voluntary), ‘27-’35 (mandatory)

2020: -5% compared to ‘04-’06
2030: -43% compared to ‘05

Carbon-neutral growth from 2020 (CNG2020)

Reverts to full-scope in ’24 unless there is a revision in light
of CORSIA

From 2021-2030 general and aviation caps are reduced by
2.2% each year

Cap remains fixed at 2019 level

Available allowances (cap) correspond to target,
ensuring that target is met under full compliance

Depends on the quality of the carbon credits
and compliance level

Legally binding system, penalties in case of non-compliance

Only legally binding when implemented in national law.
Uncertain how compliance is enforced

159 Reducing these emissions is a responsibility of individual states. Domestic emissions are covered by the Nationally Determined Contributions (NDCs) that States have
to meet under the Paris Agreement. The ambition levels of the NDCs differs per state and are not legally binding. Around two thirds of all flights is domestic and 40
percent of aviation emissions can be attributed to domestic flights (ICCT, 2019).
160 Specific certification processes determine whether a SAF meets the CORSIA eligibility criteria.

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NLR-CR-2020-510 | February 2021

Coverage

EU-ETS
Intra-EEA flights and within Outermost Regions
Initially all flights to and from EEA airports. ‘Stop the clock
decision’ limited the scope in 2013 to give ICAO time to
develop a global MBM (CORSIA). Reverts to full-scope in ’24
unless there is a revision in light of CORSIA

SAFs

SAF are attributed zero emissions if matching
RED requirements

6.4

Approach

CORSIA
International flights between participating states
In June 2019, 80 states representing 76.63% of RTKs,
announced their intention to participate from the outset .
Exemptions apply for domestic flights, least developed
countries, small island states, landlocked developing
countries, small operators and aircraft, flights with public
purpose

Reduced offsetting obligation for ‘eligible fuels’
depending on life-cycle emissions

This section describes what is assumed regarding the development of market-based measures and associated prices in
the report.
Development of carbon prices
The impacts of market-based measures on traffic and CO2 emissions depend to a large extent on the price
development of emission allowances and/or carbon credits. Future carbon prices depend on a range of factors, such
as (1) economic growth, (2) international climate targets, (3) exceptions and freely allocated emission rights, (4)
improvements in energy efficiency in different sectors, (5) availability of lower carbon-intensive generation capacity,
(6) development of commodity prices, (7) coal phase-outs regulation, (8) timing of investments (9) linking of marketbased measures 161 and (10) whether prices are based on damage costs or prevention costs (Carbon Tracker, 2018;
ICIS, 2019; IPCC, 2018a; IMF, 2019a). This makes it difficult to predict how prices develop over time.
Based on recent literature we make a reasoned assumption on how market prices 162 may develop over time. The
literature provides a large range of values, reflecting the uncertainty in the estimations (see box). According to the
High-Level Commission on Carbon Prices, studies predicting relatively low prices assume a large reliance on
complementary measures, whereas higher prices make pessimistic assumptions regarding technological change,
supportive policies and mitigation through complementary measures. Although complementary measures have a
reducing impact on the price, it is not always clear to what extent such measures have been taken into account in the
various studies.
LITERATURE ON MARKET PRICES FOR CARBON 163
The UK Department for Business, Energy & Industrial Strategy (2019) projected the prices of EU-ETS emission allowances in
a high, central and low economic growth scenarios. Prices are determined based on trends in futures prices, projected
emissions, abatement costs and the EU-ETS emissions target in 2030. In the central scenario prices increase from €15.64
(13.84 pounds) per tCO2e in 2020 to €48.21 (42.66 pounds) per tCO2e in 2030. Prices increase at a slower pace until 2025 as
it is assumed that there will still be a surplus of allowances. From 2025 onwards the MSR has addressed the surplus and
prices rise faster.
IHS Markit (2017) estimated that the EU-ETS price would increase from around €8 per tCO2 in 2020 to €32 per tCO2 in 2030
and €47 per tCO2 in 2040.

161 The more systems are linked, the more emission reduction projects are available and the more cost-effective emission reduction becomes. This shall also reduce the
risk of market distortion and carbon leakage. However, uniform pricing may give rise to equity concerns, especially with respect to emerging and developing economies.
These can be solved by international transfers, although these may be politically difficult or infeasible at a large scale (Guivarch, 2017).
162 Market prices should not be confused with the social cost of carbon. Market prices reflect the marginal abatement costs of mitigating emissions, whereas the social
cost of carbon reflect the societal costs of allowing emissions to continue. The societal costs from damages caused by sea-level rise, food insecurity, loss of ecosystems et
cetera are very difficult to predict (Synapse Energy, 2016).
163 All prices found in the literature have been converted to the same currency (euro) and price level (2018) to make them comparable.

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Thomson Reuters (2014) considered various price scenarios which differ in terms of the design of the MSR and emission
targets. In the scenario that most closely resembles the MSR and the EU reduction target for 2030, the price of ETS
allowances increases from around €18 per tCO2 in 2020 to €52 per tCO2 in 2030.
In 2018 Carbon Tracker expected that the supply squeeze caused by the MSR over the 2019-2023 period would create a
significant gap for the power and aviation sectors. Fuel-switching from coal to gas in the power sector is considered the
most cost-effective short and medium term solution to reduce emissions in the ETS. Therefore it is assumed that carbon
prices rise to fuel-switching levels. Carbon Tracker (2018) forecasted that prices would reach to € 25 per tCO2 in 2018 as
producers and speculators anticipated the upcoming MSR supply squeeze. Thereafter prices would increase to fuelswitching levels: €35 per tCO2 in 2019 and €40 per tCO2 in 2020 and 2021. For 2022 prices were estimated to return to €35
per tCO2 as the impact of the MSR on auctioning volumes would soften. 164 Over the longer term the emissions of the power
sector are expected to decline as the cost of renewable and energy-storage technologies falls and coal plants are phasedout. The aviation sector shall become an increasingly important source of demand for allowances.
ICIS (2019) predicts that the EU-ETS allowances prices increase to more than €40 tCO2 in 2023 to 2025 as a result of the
introduction of the MSR and the post-2020 reforms. Over the short term prices are expected to remain relatively stable.
Global carbon prices under a Paris climate scenario
EDF (2018) estimated the price of emission reduction units in CORSIA using a modelling framework which explicitly takes
competing demand from other sectors into account. Various scenarios were analysed including a scenario which is
consistent with a 2°C scenario in which credits from Reduced Emissions from Deforestation and forest Degradation (REDD+)
are eligible. The prices in this scenario increase by 5 percent per year from €28.7 ($33.9) per tCO2e in 2020 to €59.7 ($70.4)
per tCO2e in 2035.
The High-Level Commission on Carbon Prices 165 (2017) was tasked with identifying price corridors that, combined with
other policies and international collaboration could deliver on the Paris target. Based on evidence from the literature,
industry and policy experience and taking into account the limitations of the various information sources, the Commission
concluded that the explicit carbon price should be at least €36-72 ($40-80) per tCO2 in 2020 and €45-90 ($50-100) per tCO2
in 2030 to deliver the temperature objective of the Paris Agreement, provided that pricing policy is complemented with
target actions and a supportive investment climate. In the absence of these elements, the carbon price range is likely
higher. The prices suggested by the High-Level Commission are used by various organisations such as the International
Finance Cooperation (IFC) of the World Bank and the European Bank for Reconstruction and Development (EBRD).
The IPCC (2018a) provides ranges for carbon prices under a 2° C and a 1.5° C scenario based on different models. In a 2° C
scenario, prices per tCO2e range between €13-185 ($15-220) in 2030 and €38-881 ($45-1,050) in 2050. In a 1.5° C scenario,
the prices range between €113-5,078 ($135-6,050) in 2030 and €206-12,003 ($245-14,300) in 2050. The wide range of
values is explained by differences in methodologies, and assumptions on fuel prices and technological developments.
Models that allow more flexibility regarding mitigation options and assume perfect foresight in prices lead to lower carbon
prices. Models that do not assume other ambitious measures lead to higher prices (World Bank Group, 2019). Also, the
timing of investments is relevant. Delayed action increases mitigation costs and corresponding carbon prices, because more
action is needed later to counterbalance the higher emissions in the short-term.
Implicit carbon prices
Companies and investors increasingly incorporate the future costs of climate related policies into their decision making. The
costs are proxied by assuming an (implicit) future carbon price (Synapse Energy, 2016). EDF (2018) asked market players in
the power sector which carbon prices were needed to meet the 2° C scenario in the Paris Agreement. For 2020 the carbon
price runs from $24-39 per tCO2e, increasing to $30-60 tCO2e in 2025 and $30-100 tCO2e in 2030.

2030
EU-ETS allowance prices are expected to range between €20-100 per tCO2 in 2030 with most estimations ranging
between €30-60 per tCO2. The Thomson Reuters (2014) forecast, although the least recent, has been most accurate in
predicting the EU-ETS allowance prices over the past years. This forecast estimates an allowance price of almost € 60
per tCO2 for 2030, slightly higher than the central estimation of the UK Department for Business, Energy & Industrial
Strategy (2019).
Global market prices for carbon might be a better proxy for credits used in CORSIA. EDF (2018) estimates a carbon
price of just under €50 per tCO2 in a 2° C scenario in 2030, which falls in the lower ends of the bandwidths provided by
CDP (2017), the High-Level Commission on Carbon Prices (2017) and the 2° C scenario of the IPCC (2018a). A higher
164 Although allowances prices might trade up to €50 tCO2 for limited time periods, Carbon Tracker (2018) expects that such levels are politically difficult to sustain over
longer periods. In such circumstance the EU might increase the supply of allowances (under Articles 29a and 10c of the EU-ETS Directive) to depress the price.
165 The Commission was initiated in 2016 at the 22nd Conference of the Parties of the United Nations Framework Convention on Climate Change (UNFCCC) and is chaired
by Joseph Stiglitz, a Nobel Laureate in Economics.

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price therefore corresponds better with these bandwidths and a more ambitious net zero target. We consider the
estimates from the High-level Commission on Carbon Prices most appropriate as these prices are based on delivering
the temperature objective of the Paris Agreement and explicitly take the impacts of complementary measures into
account.
As mentioned above, the cost-effectiveness of market-based increases with the size of the market both in terms of
sectoral and geographical coverage. The larger the market, the broader the scope for emission reduction projects. This
ensures that investments flow to the most cost-effective emission reduction projects. Prices in a global scheme (such
as CORSIA) are therefore unlikely to be higher than under a regional scheme (such as EU ETS).

2013
200

2018

2023

2028
Historic ETS price
UK BEIS (2019): ETS price (high)
UK BEIS (2019): ETS price (central)
UK BEIS (2019): ETS price (low)
EDF (2018): CORSIA price (2C scenario)

Euro per tCO2 (real 2018)

150

IHS Markit (2017): ETS price
Thomson Reuters (2014): ETS price (Early MSR + backloads
to MSR)
Carbon Tracker (2018): ETS price
ICIS (2019): ETS price

100

CDP (2017): Power sector price (2C scenario low)
CDP (2017): Power sector price (2C scenario high)
IPCC (2018): Carbon price (2C scenario low)
IPCC (2018): Carbon price (2C scenario high)

50

IPCC (2018): Carbon price (1.5C scenario low)
IPCC (2018): Carbon price (1.5C scenario high)
High-Level Commission (2017): Carbon price (low)
High-Level Commission (2017): Carbon price (high)

2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030

0

Figure 16: Estimated market prices for carbon emissions from the literature (Euros, real 2018). Note: The price
estimations have been converted to the same currency (Euros) and price level (2018) to make them comparable
2050
Few studies provide price estimates until 2050. Only the IPCC provides price estimates for 2050, ranging between €40
and €12,000. Due to the lack of literature and the large bandwidth in the IPCC forecast, the price developments over
the 2030-2050 period are based on the price developments over the 2020-2030 period. The studies forecasting EUETS allowance prices predict price increases ranging between 11-15 percent per year over the next decade, increasing
to 10-19 percent in the second half of the century when allowances become increasingly scarce (see Figure 17). Under
a net zero target, there will be very few allowances left when the EU-ETS remains in place. However, as mentioned
above, additional allowances may be issued by carbon removal projects to balance residual emissions in 2050.
The studies forecasting global carbon prices predict smaller price increases of 2-10 percent per year until 2030. This
supports our assumption that the prices of carbon credits will be lower than those of EU-ETS allowances. Apart from
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the fact that there is more potential for emission reduction on a global scale, not all countries outside of the EU may
pursue equally ambitious climate goals for 2030 and 2050, limiting the demand for credits in other parts of the world.
2013
450

2018

2023

2028
UK BEIS (2019): ETS price (high)

400
UK BEIS (2019): ETS price (central)

euro per tCO2 (index 2020=100)

350

EDF (2018): CORSIA price (2C scenario)

300

IHS Markit (2017): ETS price

250

Thomson Reuters (2014): ETS price (Early MSR +
backloads to MSR)
Carbon Tracker (2018): ETS price

200

ICIS (2019): ETS price

150

CDP (2017): Power sector price (2C scenario low)
CDP (2017): Power sector price (2C scenario high)

100

High-Level Commission (2017): Carbon price (low)

50
High-Level Commission (2017): Carbon price (high)

2030

2029

2028

2027

2026

2025

2024

2023

2022

2021

2020

0

Figure 17: Relative price increases between 2020 and 2030
Assumptions
Based on the previous analysis we assume a price of €60 per tCO2 for both the EU-ETS allowances and carbon credits
in 2030. For the 2030-2050 period we assume that the prices of allowances and credits increase by 15 percent and
5 percent per year respectively. This would result in an EU-ETS allowance price of almost €1,000 per tCO2 and a carbon
credit price of around €160 per tCO2 in 2050. However, under an efficient trading scheme the allowance prices cannot
exceed the price of the most cost-effective (set of) measure(s) to achieve a specific goal. This price is also known as
the efficient price. Hence, the allowance price cannot exceed the price of any of the other measures. We therefore
cap the allowance price at the price of carbon removal projects and SAFs: € 315 per tCO2 (see Figure 18).
The price for carbon credits is similar to the estimated price for carbon removals outside of Europe in 2050, i.e. € 160
per tCO2 (see above€ ). This indicates that over time carbon removal projects become attractive for investors. The
carbon credits issued by such projects can be used in CORSIA and represent actual carbon removals. Such credits are
therefore in line with the definition of net zero.
The reference scenario already assumes a moderate carbon price. When estimating the impacts of more ambitious
market-based measures we correct for the prices in the reference scenario.

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350
300

euro per tCO2 (real 2018)

250
200
150
100
50

2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050

0

Historic ETS price

EU ETS allowances

Carbon credits

Figure 18: Price scenario

6.4.1

Development of existing measures

As mentioned above, work at ICAO is ongoing to develop the implementation rules and tools for CORSIA. Within
12 months after its adoption, the European Commission shall assess its rules, tools, ambition and environmental
integrity. Based on the outcome of this assessment, the European Commission may revise the scope of EU ETS for
aviation, consistent with the EU climate targets (EU, 2017). In the absence of a new revision, EU-ETS would revert back
to its original full scope from 2024.
Although the EU favours a global measure, it is unlikely that it accepts CORSIA in its current form as the sole
mechanism to reduce aviation emissions in the EU. First, because of its lower ambition level and the exclusion of
domestic flights. With the European Green Deal the European Commission shows that it aims for more ambition
instead of less. This may lead to a reinforcing of EU ETS and a further reduction of free allowances, which will further
increase the difference in the level of ambition with CORSIA. Second, because of CORSIA’s reliance on international
credits which are generated in part by emission reduction projects outside the EU. For the EU the European ambition
is key. Policy is therefore aimed at reducing intra-EU and domestic emissions.
As it is yet unclear how both measures will develop and co-exist in the future, we assume that all CO2-emissions from
intra-EEA flights are covered by some sort of smart economic measure. 166 In line with the EU climate neutrality
166 A hybrid system is deemed most likely. Their coexistence however determines the cost to airlines, as EU allowances will be more expensive than carbon credits. In
case the EEA is considered a domestic market under CORSIA or when compliance with EU ETS also counts as compliance towards CORSIA, the EU ETS system may cover
all CO2-emissions of intra-EEA flights. As the prices of EUAs and EUAAs are likely higher than those of carbon credits, this will lead to higher costs than in a scenario in
which international flights in the EEA would be covered by CORSIA. For the modelling exercise we need to make an assumption on whether and how both systems
eventually co-exist.
We assume that all intra-EEA emissions are covered by EU ETS. We assume that number of issued aviation allowances (EUAAs) is reduced in line with the emission
targets of the EU. For the fourth trading period (2021-2030) this means a yearly reduction of 2.2 percent per year. Thereafter we assume a linear reduction factor to
reach net zero in 2050. The aviation sector likely needs more allowances to cover its emissions and therefore needs to acquire EUAs on the market as indicated.
Furthermore, we assume that the rate of free allocation of aviation allowances is reduced from 85 to 0 percent in 2030. This means that airlines need to buy an
increasing amount of allowances on the market, which increases the cost of compliance. Finally, it is also assumed that the auction revenues are invested in projects that
yield a net 50 percent CO2 reduction in 2030. These emission reductions are ascribed to the aviation industry.

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objective, it is assumed that any allowances/credits available to aircraft operators in 2050 are issued as a result of
DACCS based carbon removal projects in the EU.
For extra-EEA flights we assume that the growth in CO2-emissions from 2020 onwards is covered by CORSIA.
Furthermore we assume that all states will eventually participate in CORSIA and that it will be continued (or replaced
by an equivalent) scheme after 2035, with a heightened ambition level: net zero CO2-emissions in 2050. 167 Here we
also assume that any credits used by aircraft operators in 2050 stem from carbon removal projects.
In the modelling we therefore distinguish between:
•

Intra-EEA flights are fully covered by a market-based measure;

•

Extra-EEA flights are only covered by CORSIA. Until 2035 only the emissions of these flights above the 2019
threshold are covered. After 2035 the threshold is lowered in a linear way to net zero in 2050.

6.5

Drivers and barriers

This section describes the main drivers and barriers that determine the impact of market-based measures.

6.5.1

Drivers

Economic measures are increasingly recognised as a key tool to reduce carbon emissions. Well-designed market-based
measures reduce emissions in a cost-effective way and ensure that climate goals are actually being met. These
benefits contribute to their acceptance and adoption on a global scale. This is important, as the adoption of a global
measure yields the largest emission reduction at the lowest cost, while at the same time preventing market distortion
and carbon leakage.
Compared to the other measures described in this report, market-based measures are able to yield large emission
savings in the short term. Unlike the other measures, market-based measures do not require large upfront
investments. However, states need to agree on their details.

6.5.2

Barriers

CORSIA being a global measure has the largest potential for emission reduction. In its current form it however also has
some drawbacks . First, CORSIA’s CO2 target is less ambitious than that of EU ETS. Second, CORSIA depends on
international carbon credits, the quality of which is heavily debated. The majority of credits sold in the past did not
represent real emission savings. This can be solved through more stringent eligibility criteria. As shown above, the
price of carbon credits eventually reaches the cost of removal projects. This means that it becomes cost-effective to

CORSIA covers the extra-EEA emissions above the 2019 threshold until 2035 after which the threshold is linearly lowered to zero in 2050. Furthermore we assume that
the EU accepts the use of high quality offsets under CORSIA and that these contribute to the EU climate goals. The reason for this is that the EU signed and ratified the
Paris Agreement which recognises the importance of international carbon markets. More specifically, Article 6.2 of the Paris Agreement (United Nations, 2015) provides
for the use of ‘internationally transferred mitigation outcomes’ towards nationally determined contributions. Article 6.4 mentions a mitigation mechanism for
certification of emissions reductions for use towards the nationally determined contributions which shows similarities to CDM and JI (UNFCCC, 2017).
167 A raised ambition level for CORSIA after 2035 shall lead to an increased demand for carbon credits from the aviation industry. However, in a global market for offset
credits the impact on the price of offset credits is assumed to be limited as the share of offsets demanded by the aviation industry shall be limited. Therefore we do not
expect a large increase in the price for offset credits after 2035.

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invest in carbon removal projects. In 2050 carbon credits may therefore be issued from carbon removal projects.
These credits can be used to cover any residual emissions and attain the net zero CO2 emissions target.
Economic measures assign a price to emissions which increase airline costs. These costs increase over time as
allowances and carbon credits become increasingly scarce. This is especially the case when few other measures are
being taken. In a competitive market cost increases are passed on to the end-user. For some users, air travel may
become too expensive, which may translate into less demand for air travel. The compliance costs in combination with
a reduction in travel demand could however reduce airline’s ability to invest in new technology and SAFs.
National or multilateral economic measures may affect airline cost levels in different ways. This will distort
competition and might lead to carbon leakage. By increasing the geographical scope of an economic measure, this risk
is prevented. A global approach is preferred over a national or multilateral approach.
If CORSIA and EU ETS continue to co-exist after 2023, this may lead to a situation in which emissions from
international flights within the EEA that exceed the 2019 threshold are covered by both systems. This double counting
of the same emissions might be suboptimal and should be prevented. Also it will increase administrative costs to
airlines and might lead to a reduced acceptance.
The accounting of a state’s aviation emissions is generally based on the emissions of departing flights. Emission
reductions achieved through efficiency gains of arriving flights, such as Optimized Descent Profiles (ODPs), then do not
contribute towards the state’s climate targets. This may act as a disincentive for ANSPs to improve the efficiency of
arriving flights.
Although economic measures lead to cost-efficient emission reductions, they are sometimes opposed because they
lead to out-of-sector reductions. The aviation sector for instance shall remain a net buyer of emission allowances and
carbon credits. By doing so, the aviation sector invests in emission reductions in other sectors. This generates larger
overall emission savings than in a situation in which the sector would only be allowed to invest in its own assets and
processes.

6.6

Policies and actions

Aviation is a global industry which requires global solutions. National economic measures, such as aviation taxes often
lead to market distortions and carbon leakage. Ideally policy-makers and industry should work together towards one
global all-encompassing smart economic measure which yields actual emission savings. Such a global measure not
only has the largest scope for emission reduction, it will also ensure that emission reductions are achieved against the
lowest cost. Compared to a situation in which multiple systems co-exit, it has the added benefits of limited
administrative costs and a reduced risk of market distortion and carbon leakage. When all emissions from flights
departing from EU airports are covered by a smart economic measure, national economic measures need to be
reconsidered to prevent that the same external cost is priced twice.
Until an all-encompassing global measure is available, the EU should aim for a package of measures that covers the
emissions from all flights departing from EU airports in order to reach the EU climate goals. This might mean revising
EU ETS to complement CORSIA in such a way that ETS addresses all emissions which are not covered under CORSIA.
This would prevent double counting of the same emissions. Furthermore, while both systems co-exist, it is important
that the reporting mechanisms are aligned to the limit administrative costs for the airlines. When deciding on the way
in which ETS and CORSIA will interact, the risk of carbon leakage and distortion of competition has to be minimised.
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This will ensure the highest environmental effectiveness of the two systems, while also avoiding social and economic
disadvantages for European aviation.
The EU should also try to improve the existing measures. With respect to CORSIA this means (1) striving for an
ambition level that goes beyond carbon neutral growth from 2020 onwards, (2) urging third countries to also put in
place economic measures that cover their domestic emissions and (3) to agree on a high standard for carbon credits,
with all credits to be sourced from high-quality carbon removal projects by 2050.
There is also room for improvement regarding EU ETS. First, the number of allowances can be reduced to zero in 2050
to ensure climate neutrality is achieved. This should be complemented with a policy which allows any remaining
carbon emissions to be compensated by negative emissions. For instance by allowing carbon removal projects to lead
to the issuance of additional allowances. Second, to reduce the amount of freely allocated allowances. Third,
enhancing the cost-effectiveness of ETS by increasing its scope through the inclusion of more sectors and/or by linking
it to similar schemes elsewhere in the world. The latter might however lead to emission reductions outside the EU
financed by the European aviation sector. Fourth, by requiring that Member States to invest all proceeds of the
auctioned allowances in sustainability projects.
EU ETS has proven that it yields actual emissions reductions in a cost-effective way. Further improvements to the
scheme (lowering the cap and the number of free allowances) will help the EU to reach its 2050 climate goals.

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7

System changes and radical ideas

Having discussed the possible effects of technology, ATM and aircraft operations, sustainable aviation fuels and
economic measures, this chapter discusses a number of more radical and largely system-wide innovations.
These are not considered in the modelling and impact quantification for a number of reasons. First, some invalidate
the fundamental ideas of the forecast on which the present study is based (discussed in more detail in Chapter 2).
Second, some of the ideas listed here are not mutually compatible, or not compatible with measures that are part of
the modelling. Nevertheless, these ideas are presented here in a mostly qualitative sense in order to inspire further
thought and guide associated research.
Shorter flights with smaller aircraft
Probably the most all-encompassing of all ideas presented in this chapter is a radical return to smaller aircraft and
shorter stage lengths. As discussed in Section 3.3.1, electrification and hybridisation are most feasible for small and
regional aircraft travelling limited distances. A larger amount of flights might be used to transport the same amount of
passengers and longer distances can be traversed using one or more intermediate stops, at which batteries can be
charged or swapped. Following Figure 7 and assuming an average of 120 seats for each intra-European flight,
replacement with 30-seat battery-electric aircraft would yield a 4-fold increase in flights. Assuming passenger growth
factors are unaffected, this would result in 38.8 million intra-European flights in 2050, compared to 9.7 million in the
reference scenario. Lower aircraft utilisation due to necessary stopovers (a consequence of the limited range of
battery-electric aircraft) would require a fleet growth of more than the 4-fold-increase in flights. The same might also
occur with hydrogen-powered aircraft, until that technology possibly transitions to larger and longer-range aircraft.
Unsurprisingly, this yields a number of challenges. In the traffic growth forecast supporting the present research,
airport capacity is an important factor constraining growth, with EUROCONTROL (2018b) estimating some 160 million
unaccommodated passengers by 2040. Helped by their smaller size and likely lower environmental footprint, these
battery-electric aircraft might be welcomed by local or regional airports and shift part of the traffic that way. As such
airports are often located more closely to residential areas, local environmental concerns such as noise and thirdparty risk should be considered carefully. Also, whereas EUROCONTROL (2018b) does not assume constraints at
airspace level, this assumption might not hold in case of the massive increase in flights projected here. The additional
cockpit crews, ground handling personnel and air traffic control officers required means that cost to operators is likely
to increase – unless this can be compensated by increased automation and autonomy.
On the other hand of these difficulties, however, are substantial gains to be realised. In 2018, intra-European flights
were responsible for 45% of the emissions considered within the scope of this study, with 10% of that associated to
flights below 750 kilometres. Depending on the amount of electrification and available renewable energy, these
emissions might be partially or completely avoided.
Using larger aircraft will likely alleviate these issues – at least partially. On the other hand, the benefits are reduced as
well: larger aircraft are heavier, and following limitations of battery energy density, these are likely to require a
hybrid-electric (rather than a battery-electric) powertrain. Assuming a 70-seat aircraft with 50% lower emissions 168,
the number of intra-European flights would increase by about 70% to a total of 16.6 million in 2050, while reducing
CO2 emissions by 22.5% overall 169. Additional reductions in carbon dioxide emissions might be realised if such an

168 Based on the difference between fuel efficiency improvements assumed for regional versus single aisle aircraft, following Table 13.
169 50% × 45% = 22.5%.

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aircraft were to be specifically designed for a more limited range than what is currently offered in the single aisle
market.
Designing aircraft for reduced cruise speeds
Current (and anticipated future) aircraft are mostly designed for and operated at cruise speeds around Mach 0.8, with
turboprop-powered models flying at Mach numbers well below 0.7 a notable exception. Even with aircraft available
today, some fuel savings can be achieved by operating at reduced speeds. Estimates for the potential impact vary.
According to Brok, Hagstroem, Junior & Matthes (2010), a decrease in cruise Mach number yields fuel savings of 0.4 to
1.3%, consistent with Roberson, Root & Adams (2007) 170 and Edwards, Dixon-Hardy & Wadud (2015), noting that cost
index changes affect fuel burn by 1%. A simulation on 200.000 domestic flights in the United States validates these
numbers: full implementation of Long Range Cruise Mach numbers (LRC) would decrease CO2 emissions by 0.89% at a
negligible change in flight time 171; using the slower Maximum Range Cruise Mach Number (MRC), emissions would
decrease an additional 1.04% – at the cost of flight times 3.86% longer (Jensen, Hansman, Venuti, & Reynolds, 2013).
Although the majority of sources seems to indicate a limited savings potential, two publications stand out. Schäfer,
Evans, Reynolds & Dray (2015) cite studies noting benefits of 5.5% and a study by EMRC and AEA (2011) refers to work
supporting ICAO CAEPs Group of Independent Experts that shows a Mach number reduction from 0.86 to 0.74 (14%)
lowering fuel consumption by 11.4%. Internal NLR analyses at engine level are most consistent with Schäfer, Evans,
Reynolds & Dray (2015).
Additional benefits can be unlocked by specifically designing aircraft for these lower cruise speeds. These would then
require less power full engines, for example, which reduced engine weight and in turn allows for further decreasing
weight elsewhere in the structure. Similarly, lower cruise Mach numbers require less wing sweep (applied to prevent
drag increases found in the transonic regime), which too can save weight. These weight reductions might then
warrant another reduction in required engine thrust, and so on, and so forth.
As highlighted before, the reduction in fuel burn that is a consequence of lower cruise speeds comes at cost elsewhere
in the operation. The productivity (amount of passengers transported over a particular distance in a particular time) of
aircraft decreases, such that more aircraft are required for a given traffic demand. Due to longer flight times, crew
costs can also be expected to rise and passenger comfort might be (negatively) impacted. Overall, however, EMRC and
AEA (2011, p. 60) indicate “an 8% fuel saving from a 10% speed reduction [can be achieved], until diminishing returns
are reached”.
Intermediate stop operations
The amount of fuel consumed – and as such the amount of CO2 emitted – by long-distance flight is disproportionally
large compared to the share of such flight as part of total aviation traffic (also shown in Figure 9). This is a
consequence of the fact that the fuel required for the final flight phases has to be carried along the entire flight. This
increases the weight of the aircraft, which in turn increases the fuel consumption. This effect is also known as
‘transport loss’, ‘cost of weight’ or, more colloquially, the snowball effect.
Adding additional stop-overs might be a way in which the emissions associated to long-haul flights can be substantially
reduced. Indeed, this concept has been researched by numerous scholars. Without redesigning the aircraft for shorter
ranges, estimations for the potential savings of intermediate stop operations vary between 5 and 25% (Hartjes & Bos,
2015), with the majority being between 5 and 10% (Creemers & Slingerland, 2007; Brok, Hagstroem, Junior, &
Matthes, 2010; Lammering, Anton, Risse, & Franz, 2011; Bergmans & den Boer, 2012; Martinez-Val, Perez, Cuerno, &
Palacin, 2012; Hartjes & Bos, 2015; Linke, Grewe, & Gollnick, 2017). Most studies consider one stop-over and missions
170 This publication adheres to the definitions of Long-Range Cruise (LRC) and Maximum Range Cruise (MRC). The speed increase from MRC to LRC is approximately 3 to
5%, at the cost of a reduction in mileage (i.e., an increase in fuel burn) of 1%. 3 to 5% of an ordinary cruise Mach number of 0.8 is 0.024 to 0.04.
171 This improvement potential is considered to be part of the measures to improve flight planning and execution, described in Section 4.2.1.

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of 5000 to 7000 kilometres and above. At shorter distances, fuel consumption might actually increase due to the
larger ratio of fuel-intensive flight phases to cruise phase (Martinez-Val, Perez, Cuerno, & Palacin, 2012). Furthermore,
authors note the dependency on the location of the intermediate airport (primarily in terms of detour with respect to
the original great circle route, secondarily in terms of the ratio of lengths of the two flight legs). This is also shown by
Langhans, Linke, Nolte & Gollnick (2013), who, using a system-level analysis of all Airbus A330 and Boeing 777 flights
as operated in 2007, estimate a lower fuel-saving potential of 2.8%, likely due to non-ideal distributions of possible
intermediate airports.
In case the aircraft is redesigned for a shorter mission, potential CO2 reductions increase further. Langhans, Linke,
Nolte & Gollnick (2013) see the savings potential grow to just over 10% using a design range of approximately
5500 kilometres. Creemers & Slingerland (2007) estimate reductions of more than 25% for a reduced-range Boeing
747-400 derivative.
Despite these possible benefits, there are a number of disadvantages and complexities associated to intermediate
stop operations. Most obvious, flight times will increase and the number of take-offs and landings will grow. Given the
fact that these flight phases are most accident-prone, care should be taken to maintain present safety levels.
Furthermore, there should be airport capacity to meet the increased demand – up to 130 additional daily flights for
the ten airports most often used as stop-over location, such as at the East coast of the United States and Canada
(Langhans, Linke, Nolte, & Gollnick, 2013) – as well as ATC capacity related to these operations. Moreover, the stopovers will increase noise exposure for communities surrounding airports, as well as have an impact on local air quality.
On the other hand, the lower fuel weight reduces the take-off weight, which in turn reduces the required engine
thrust and associated emissions (Brok, Hagstroem, Junior, & Matthes, 2010). This is of course amplified if long-haul
aircraft are replaced by alternatives designed for shorter ranges.
The impact on cost was investigated by Creemers and Slinglerland (2007), Martinez-Val, Perez, Cuerno & Palacin
(2012) and Hartjes and Bos (2015). Even though maintenance costs are expected to go up and the production per
aircraft reduces, both publications show benefits in terms of direct operating cost. This is mainly due to the lower fuel
usage (especially when uplifted in locations where fuel prices are advantageous), but also due to reduced crew costs,
as there is less need for relief pilots. Depending on fuel efficiency of the aircraft use and overall flight length, savings
might be as much as 10% (Martinez-Val, Perez, Cuerno, & Palacin, 2012).
Air-to-air refuelling
Customary in military aviation, but unseen in commercial air traffic is air-to-air refuelling. In terms of fuel reduction,
the benefits of intermediate stop operations also apply to this concept. However, the impact on flight time, passenger
comfort and airport capacity (and the associated benefits and disadvantages) do not apply, or only do so to a more
limited extent. Langhans, Linke, Nolte & Gollnick (2013), however, anticipate a significant negative (rather than a
minor) impact on safety and requirements for automation. As such, it is not further considered here.

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8

Assumption and impact modelling

This study presents measures to reduce CO2 emissions from aviation across four types of measures: (i) improvements
in aircraft and engine technology (including hydrogen); (ii) improvements in ATM and aircraft operations; (iii) use of
drop-in SAF; and (iv) economic measures. This chapter outlines the approach that is used to assess the impacts of
these measures against the reference scenario.
The identified sustainability measures impact the total aviation emissions in two ways. Firstly, the amount of
emissions per flight is reduced, for example through the use of more fuel-efficient aircraft. This leads to less emissions
for an equal amount of flights. Secondly, some of the identified measures will incur higher costs with respect to the
reference scenario, which will be (partially) passed on to the passengers. These higher costs will reduce demand, as
some passengers will refrain from travelling if fares increase. Slower demand growth will result in fewer flights
compared to the reference scenario, which in turn results in lower total CO2 emissions from aviation. All cost increases
are assessed at the route level, where passengers may choose to use alternative (indirect) air routes, or choose to
refrain from using air travel.
Although demand reduction is inevitable if sustainability measures lead to higher costs for passengers, measures to
reach climate goals should not primarily be focused on reducing demand for air travel. Aviation supports international
connectivity, and enables international business activity and tourism, as also highlighted in Section 1.1. Measures
should be focused at reducing emissions from aviation, while sustaining its socio-economic benefits as much as
possible.
The following sections present if and how emission reductions and cost increases are estimated in each of the four
pillars. For improvements in technology and operations that yield emissions reductions, impacts of cost increases are
mostly assessed in a qualitative manner. For SAF, both the emissions and cost aspects are taken into account. These
impacts are based on a literature review, substantiated with interviews with experts from industry. For economic
measures, direct emissions impacts are only taken into account if the measure is designed to yield a one-to-one
reduction of CO2 emissions. Table 35 summarises how the aspects were taken into account in the modelling.
Table 35: Modelling of emission reduction and cost increases per pillar
Pillar

Emissions per flight modelled?

Improvements
in aircraft and
engine
technology

Yes

Reduction based on reported
/ estimated efficiency gain.

Improvements
in ATM and
aircraft
operations

Yes

Reduction based on reported
/ estimated efficiency gain.

Sustainable
aviation fuels

Yes

Emission reductions based on
literature; depend on type
and amount of SAF used.

Cost increase w.r.t. reference scenario modelled?
Costs associated to fleet renewal and
technology development of kerosenepowered aircraft are estimated to be offset
Limited
by reduced operational expenses. For
hydrogen-powered aircraft, cost increases
due to technology development and
hydrogen production are based on literature.
Cost implications are uncertain and difficult
to quantify. Cost increases for passengers
depend on way investments are funded.
No
Therefore, we assume that operational
improvements do not lead to cost increases
for passengers or airlines.
Yes

Cost increase based on literature study on
fuel cost.

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Pillar
Economic
measures

8.1

Emissions per flight modelled?
Emissions per flight only
reduce if receipts of the
Yes
measure are used to result in
/ no
a one-to-one CO2 reduction
elsewhere.

Cost increase w.r.t. reference scenario modelled?
Cost increase is directly related to the
proposed measure.

Yes

Improvements in aircraft and engine technology

Technological measures chiefly consider the use of more fuel-efficient aircraft and engines, that enter the market
through fleet replacement. Older aircraft types – that are still in use in the base year 2018 – will be replaced by newer
aircraft types, some of which are already on the market. Estimated emission reductions from such aircraft types are
derived from manufacturers’ publications, research projects and studies discussed in Chapter 3.
New generations of aircraft are modelled to be phased in linearly, and that over a period of 22.5 years starting from
the year a new aircraft enters service all older aircraft types will have been replaced. The average retirement age of
passenger aircraft is 25 years (Jiang, 2015; Forsberg, 2015). In financial reporting airlines tend to apply a linear
depreciation over a period of 20 to 25 years (KPMG & IBA, 2017). Figure 19 shows that the age of EU aircraft in service
is relatively evenly distributed. This supports the assumption of linear replacement of older aircraft types.

Share of total

100%

17%

80%

16%

60%

18%

40%
20%
0%

27%
21%
<5 years

5-10 years

10-15 years

15-20 years

>20 years

Age of aircraft registered in EU (2017)
Figure 19: Age of EU aircraft fleet (eurostat, 2019)
The impacts of fleet replacement depend on the specific aircraft type being replaced, which is modelled at the aircraft
type level for most aircraft. Table 36 provides an overview of the average improvement from upcoming technology,
per aircraft category. This takes into account both one-to-one (per Table 5) and class-averaged (Table 6) replacements
by upcoming aircraft (Section 3.2).
Table 36: Overview of average potential CO2 emissions reduction delivered by upcoming aircraft, expressed at aircraft
level (i.e., per flight) with respect to previous generation aircraft (based on Table 6). Fleet level CO2 emissions reduction
delivered by upcoming aircraft for 2030 and 2050 (i.e., taking into account fleet replacement duration)
Class
(abbreviation)
Regional (R)
Single aisle (SA)
Small/medium
twin aisle (SMTA)

Aircraft level CO2 emissions
reduction, at EIS, w.r.t.
previous generation aircraft
24.8%
14.8%
17.6%

Fleet level CO2 emissions
reduction, 2030

Fleet level CO2 emissions
reduction, 2050
13%
7%

24.8%
14.8%

6%

17.6%

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Class
(abbreviation)

Aircraft level CO2 emissions
reduction, at EIS, w.r.t.
previous generation aircraft

Large twin aisle
(LTA)

19.2%

Fleet level CO2 emissions
reduction, 2030

Fleet level CO2 emissions
reduction, 2050
8%

19.2%

Table 37 provides an overview of the CO2 emissions reduction potential of future technology, based on Section 3.3.
This lists both the CO2 emissions reduction at aircraft level, compared to its ‘upcoming’ predecessor, as well as the CO2
emissions reduction at fleet level. The latter takes into account the time required for fleet replacement. The effects of
drop-in SAF (i.e., lower carbon content per unit of fuel) is modelled in the SAF-pillar; the effects of hydrogen (i.e., zero
CO2 emissions) are included in the technology pillar.
Table 37: Overview of potential CO2 emissions reduction delivered by future aircraft, compared to ‘upcoming’ aircraft
expressed at aircraft level (i.e., per flight), and at fleet level (i.e., taking into account fleet replacement duration) for
2050
Class (abbreviation)

EIS

Aircraft level CO2 emissions
reduction, at EIS

Small (S)
Regional (R)
Single aisle (SA)
Hydrogen-powered single
aisle (Hydrogen-SA)
Small/medium twin aisle
(SMTA)
Large twin aisle (LTA)

2030
2035
2035

99%
50%, excluding effect of drop-in SAF
30%, excluding effect of drop-in SAF

Fleet level CO2 emissions reduction,
2050
88%
33.3%, excluding effect of drop-in SAF
20%, excluding effect of drop-in SAF

2035

100%

66.7%

2035

30%, excluding effect of drop-in SAF

20%, excluding effect of drop-in SAF

2040

30%, excluding effect of drop-in SAF

13.3%, excluding effect of drop-in SAF

The total fleet level CO2 emissions reduction delivered by upcoming and future aircraft for 2030 (only upcoming
aircraft) and 2050 is presented in Table 38.
Table 38: Overview of fleet level potential CO2 emissions reduction delivered by upcoming and future aircraft in 2030
and 2050, compared to the fleet in 2018
Class (abbreviation)
Small (S)
Regional (R)
Single aisle (SA)
Hydrogen-powered single
aisle (Hydrogen-SA)
Small/medium twin aisle
(SMTA)
Large twin aisle (LTA)

Fleet level CO2 emissions reduction,
2030
(not modelled)
13%, excluding effect of drop-in SAF
7%, excluding effect of drop-in SAF

Fleet level CO2 emissions reduction,
2050
88%
48%, excluding effect of drop-in SAF
31%, excluding effect of drop-in SAF
67%

6%, excluding effect of drop-in SAF

30%, excluding effect of drop-in SAF

8%, excluding effect of drop-in SAF

28%, excluding effect of drop-in SAF

The additional costs of fleet replacement of kerosene-powered aircraft are considered negligible with respect to the
reference scenario. This assumption is substantiated using Figure 20, which lists an investment of € 5,000 billion for
the acquisition of 26,000 new aircraft – meaning an average cost of € 192 million per aircraft. This is in line with recent
list prices, ranging from approximately €90 million for an SA-class aircraft, through €220 million for an SMTA-type to
over €300 million for an aircraft in the LTA category (Airbus, 2018a). Fleet replacement and aircraft acquisition or

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leasing is an important cost aspect for airlines, but these costs are also incurred in the reference scenario. Moreover,
technological innovation will also lead to lower operational costs for airlines.

Figure 20: Cost estimation of new aircraft technology (Clean Aviation Partnership, 2020, p. 23). Product development
cost based on Airbus Development (15 bn € per type); number of deliveries based on Airbus (2018b), assuming 50%
market share.
A cost change is however modelled for hydrogen-powered aircraft, introduced for intra-EU+ flights of 2000 kilometres
and below from 2035, as further detailed in Section 3.3.3.3. For one part, this is driven by cost increases that are a
result of the characteristics of a hydrogen-powered aircraft and for another, it is a consequence of cost changes
associated to the different energy carrier. Technology costs yield an increase in cost per ASK of 1.3 cents or 26% of
current levels; the cost for liquid hydrogen is modelled at € 2200 per tonne. The fact that hydrogen has a notably
higher (2.8 ×) energy density than kerosene suggests a rather high cost difference. Correcting for this, the energy
contained in one tonne of kerosene costs €790 in the form of liquid hydrogen. This cost increase is modelled to be
completely transferred to the passenger in the form of increased ticket prices.

8.2

Improvements in ATM and aircraft operations

Operational improvements lead to a general reduction in the emissions per flight, which are considered in the
sustainability scenario. Cost impacts are assessed qualitatively, but are not included in the model. The cost aspects
strongly depend on the exact measures defined and the way these costs impact demand for air travel in turn depends
on the way such investments are funded. In general, it is assumed that any increases in acquisition or R&D cost are
offset by decreases in other costs, such as fuel cost.
Table 39 provides an overview of the assumptions for the ATM and aircraft operations pillar. The underlying rationale
of the figures is provided in Chapter 4. The split between short-haul (SH) and long-haul (LH) is set at 3500 kilometres;
weight savings are translated into fuel burn reductions using a cost of weight factor of 3.5% per block hour, further
explained in Section 4.2.2 (specifically: footnote 60 on page 56).

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Table 39: Overview of potential CO2 emissions reduction delivered by improvements in ATM and aircraft operations,
compared to the reference scenario
Potential CO2
emissions reduction
2% × 0.75 = 1.5%
1%
10 kg / seat, 75% of
flights
0.2%

Starting
year
2020
2025

Delivered
by
2025
2035

2020

2030

2020

2050

5.1%

2020

2035

1.5%

2020

2035

2%

2025

2040

2.1%

2020

2040

Improved NAT-efficiency

2.9% × 0.45 = 1.3%

2020

2027

Wake energy retrieval

3%

2025

2032

2030

2040

Reduced engine taxi – SH
Reduced engine taxi – LH
Reduced engine taxi – SH
Reduced engine taxi – LH
Electric taxi / operational towing – SH
Electric taxi / operational towing – LH

0.2%
0.1%
0.4%
0.3%
0.8%
0.3%
1.2% + 175 kg weight
reduction
0.9% + 600 kg weight
reduction
0.3%

2020
2020
2020
2020
2025
2025

2025
2025
2025
2025
2035
2035

2025

2035

2025

2035

2020

2025

Measure
Improved flight planning
Flight management system updates
Weight reduction
Airframe condition and maintenance
Single European Sky / SESAR – intraEU+
Single European Sky / SESAR – extraEU+
Single European Sky / SESAR – further
CO2 emissions reduction potential
Non-European ATM efficiency
improvement

Electric taxi / operational towing – SH
Electric taxi / operational towing – LH
Reduced APU usage

8.3

Remarks

Modelled using 3.5% cost
of weight

Intercontinental
departures only
Intercontinental
departures only
Flights from Europe to
North-America
Flights from Europe to
North-America
Other flights, up to 50%
combined
Intra-EU+ arrivals only
Departures only
Intra-EU+ arrivals only
Departures only, weight
saving modelled using
3.5% cost of weight per
block hour

Sustainable aviation fuels

Increased use of SAFs will reduce CO2 emissions per flight, but at the same time result in higher fuel costs for airlines.
Both cost increases and emission reductions are taken into account in the model. The emission reductions of
increased SAF uptake are based on literature and depend on the type and amount of SAF used in the years in which
the sustainability scenario is evaluated.
The cost difference with respect to conventional jet fuel is sourced from literature discussed in Chapter 5. The cost
difference incurred by airlines is assumed to be passed through to the passenger. According to IATA (2019a), fuel costs
are on average 23% of the total airline costs in 2016. This is in line with the fuel cost share various large European
airlines state in their annual reports. A full pass-through of costs to passengers is likely with measures that affect all
competitors. However, if national or regional measures affect only part of the market it may lead to market
distortions. For the modelling a full pass-through ensures that the demand impacts are not underestimated. Carbon
pricing has an impact on the cost difference with conventional kerosene. Because SAF reduces carbon emissions, the

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cost difference decreases when the cost of carbon increases. This effect is taken into account when assessing cost
differences.
It should be noted that the price premium of SAF compared to fossil fuels has not been analysed in terms of the
business case for SAF producers. Likewise, the effects on airline business models have not been taken into account
and additional costs are applied to equally all operators. An overview of model assumptions is given in Table 40, with
Tables 41 and 42 detailing the situation in 2030 and 2050, respectively.
Table 40: Overall SAF percentages in 2030 and 2050
2030
Amount
Percentage of fuel mix
3.2 Mt
6%
51.8 Mt
94%
55 Mt
100%

Fuel type
SAF
Fossil Fuels
Total

2050
Amount
Percentage of fuel mix
32 Mt
83%
6 Mt
17%
38 Mt
100%

Table 41: Overview of model assumptions concerning SAF, 2030
Percentage of
SAF mix

Life-cycle CO2
saving

Minimum
selling price

CO2 abatement
costs

Pathway and feedstocks

Amount

HEFA pathways with various
waste and residue feedstocks

1.4 Mt

44%

65%

1170 €/tonne

280 €/tonne

Advanced feedstocks
combined with FT, ATJ, SIP

0.6 Mt

19%

65%

2765 €/tonne

1050 €/tonne

Power to Liquid FT
Total / average

1.2 Mt
3.2 Mt

37%
100%

85%
72%

2900 €/tonne
2274 €/tonne

860 €/tonne
640 €/tonne

Table 42: Overview of model assumptions concerning SAF, 2050
Amount

Percentage
of SAF mix

Average
life-cycle
CO2
reductions

Biofuel (various pathways)

13 Mt

41%

95%

Power to liquid

19 Mt

59%

100%

Total / average

32 Mt

100%

98%

SAF type

8.4

Average
minimum
selling
price
1790
€/tonne
1557
€/tonne
1650
€/tonne

Average
CO2
abatement
costs 172
366
€/tonne
274
€/tonne
312
€/tonne

Economic measures

Economic measures lead to higher costs for air passengers, and – depending on the measure – could also lead to
lower (net) emissions per flight.
The cost increases resulting from measures taken are assumed to be fully passed through to the passenger. This is
likely with global measures that affect all competitors. However, national or regional measures may only affect part of
the market which leads to market distortions. In such cases, airlines may not be able to pass the cost increases on to
172 Calculated as follows (SAF price – jet fuel price in 2030) / (CO2 saving × Jet A1 emission factor). Jet A1 emission factor = 3.16. Jet fuel price in 2050 = 690 €/tonne.

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their customers in full in the affected markets. However, due to the small profit margins in the aviation industry,
airlines shall need to recover the cost increases elsewhere in their networks. For the modelling exercise we therefore
assumed a full pass-through for all measures. This also ensures that the demand impacts are not underestimated.
Economic measures may result in in-sector and out-of-sector emission reduction. Out-of-sector reductions are
achieved through investing in other sectors. Through an economic measure, the aviation sector may for instance
invest in carbon removal projects. In theory, if all CO2 emissions from a flight are removed from the atmosphere, the
net CO2 impact of this flight is zero. The chapter on economic measures further elaborates on such measures and its
caveats.
Economic measures act as an incentive for technological development, operational improvement and SAF uptake.
It is yet unclear how CORSIA and ETS will develop and co-exist in the future. It is therefore assumed that all CO2emissions from intra-EEA flights are covered by some sort of smart economic measure, whereby a hybrid system is
considered most likely. For the impact modelling, the following assumptions have been made:
•

•

EU-ETS covers CO2-emissions from intra-EU+ flights, whereby:
o

The number of issued EU-ETS allowances is linearly reduced to zero in 2050 and freely allocated

o

Revenues of auctioned allowances are invested in sustainability projects which yield a 50% CO2
reduction in 2030;

CORSIA covers CO2-emissions from extra-EU+ flights:
o

•

allowances are gradually phased out (EC, 2020c);

o

From 2021-2035 airlines need to offset emissions above the 2019 threshold;
From 2035-2050 the threshold is gradually reduced to zero;

Carbon removal projects are assumed to lead to the issuance of additional allowances and carbon credits.

Table 43 summarises the model inputs on amounts and prices under the mechanisms in place.
Table 43: Overview of model assumptions concerning economic measures
Year

2030

2050

Amount
(MtCO2)

Price
(2018 €)

EU-ETS; auctioned allowances

28.3

€60

50%

EU-ETS allowances bought
from other sectors

40.7

€60

100%

CORSIA eligible carbon credits

0.0

€60

100%

EU-ETS; free allowances

0

€0

No CO2 saving

0.7

€315

100% (carbon removal projects)

21.2

€160

100% (carbon removal projects)

Type of measure

EU-ETS allowances bought
from other sectors
CORSIA eligible carbon credits

CO2 reduction

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9

Destination 2050
The European aviation industry can reach the net zero CO2 target outlined in the European Green
Deal and the European Climate Law by 2050 as part of the EU’s overall climate neutrality objective
by implementing the measures studied in this report. Improvements in aircraft and engine
technology, including the use of hydrogen-powered aircraft, contribute most to emissions
reduction, followed by drop-in sustainable aviation fuels, economic measures and improved
operations and ATM. Despite the fact that these measures increase the cost of air travel, passenger
traffic will still be able to grow by 1.4% per year until 2050.
In 2030, net CO2 emissions of the flights studied are reduced to 113 Mt, a reduction of 94 Mt
compared to the reference scenario. Economic measures realising carbon removal make the largest
contribution and ensure that the net emissions related to intra-EU+ flights are reduced to 13 Mt,
55% below their 1990 CO2 levels. Continuous fleet renewal, improvement in ATM and aircraft
operations as well as the use of 3.2 Mt of drop-in sustainable aviation fuels also help achieve this
reduction.
Besides the more specific policy and action recommendations elsewhere in this report, some crucial
characteristics of a long term vision for European sustainable aviation encompass this challenge in
its entirety. Collaboration between stakeholders is essential and a coherent long term policy
framework that reduces investment and innovation risk should be pursued. Furthermore,
stakeholders should work to ensure global commitment – and joint and collaborative action – to a
net zero carbon future for aviation.

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9.1

Introduction

This final chapter combines all the measures in the previous chapters into a plan for achieving substantial CO2
emissions reductions in 2030 and realising net zero CO2 emissions in 2050. The pathway is built on four pillars:
improvements in aircraft and engines (including the use of hydrogen-powered aircraft), improvements in air traffic
management and aircraft operations, sustainable aviation fuels and economic measures.
All flights departing the EU+ (i.e., EU, UK and EFTA) have been included in the analyses for 2030 and 2050. Results for
intermediate years are linearly interpolated and serve as a indicative pathway 173. For each of the two horizon years,
Section 9.2 present both the overall CO2 emission reductions as well as the contributions by the various pillars to the
grand total. Furthermore, the results are compared with relevant climate goals, notably the European Green Deal and
proposed European Climate Law, as well as long term industry decarbonisation targets. In support of that comparison,
the results for all departing flights are complemented by sub-analysis focused on flights inside and outside the EU+
region.
It is important to stress again here the status of this document, as was underlined in Chapter 0: this report shows a
path towards decarbonisation, written to take into account the latest insights available. Nevertheless, insights might
change during the timespan covered by this study. Anticipated benefits might not be realised fully, might exceed
expectations, or might manifest themselves through a different measure or in a different market segment. Also,
whereas the presented policies and actions for some pillars will focus on development and others on
implementations, these efforts might change in the future – as the innovation cycle progresses. In any case,
substantial joint and collaborative industry and government actions are required to realise the results presented here.
In addition to the policies and actions listed in the various chapters, Section 9.3 lists a number of policies and outlines
policy characteristics that apply to all aspects of this decarbonisation pathway.
Respecting on the one hand the uncertainties that are inherent to any study comparable to this, the consequences of
inaction can on the other hand not be neglected. Indeed, as noted in Section 1.1.4, the effects of climate change on
aviation and society in general are significant. As such, the results presented in the remainder of this chapter are
presented as a well-supported foundation for tackling the challenge of decarbonising aviation and guiding government
and industry action in the crucial following years to come.

9.2

CO2 reduction

This section describes the net CO2 reductions realised by 2030 and 2050. Section 9.2.1 presents and overview of the
emissions reduction pathway for all flights within and departing from the EU+ region, Sections 9.2.2 and 0 zoom in on
intra-EU+ flights and extra-EU+ flights. Last, Sections 9.2.4 and 9.2.5 detail the effects and the contributions of the
various pillars in 2030 and 2050. Also, these sections compare the results to relevant climate goals. A comparison with
the recently published ATAG-report Waypoint 2050 is included in Appendix E.

173 This linear interpolation however takes the specific year of entry into service of future aircraft into account. Hydrogen technology, for example, is expected to be
available from 2035 and accordingly, impacts are foreseen from 2035 onwards. Similarly, a

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9.2.1

Overall impact

Figure 21 shows the overall impacts on CO2 for 2030 and 2050. The dotted line shows the reference scenario,
discussed in Chapter 2. The various measures treated in Chapters 3 to 6 together form the sustainability scenario.
Based on these results, achieving net zero CO2 emissions from flights departing the EU+ region in 2050 is deemed
possible.

EU+ aviation net CO2 emissions (Mt)

300

All flights within and departing from the EU+ region

250

200

150

100

50

0

2018

2030
Hypothetical reference scenario
Improved aircraft and engine technology (kerosene)
Improved aircraft and engine technology (hydrogen)
Improved ATM and aircraft operations
Sustainable aviation fuels
Economic measures

2050
Net CO2 emissions
Effect of cost of hydrogen(-technology) on demand
Effect of cost of sustainable aviation fuels on demand
Effect of cost of economic measures on demand

Figure 21: Overall impacts on net CO2 emissions by flights within and departing from the EU+ region, modelled for 2030
and 2050. Linear interpolation between the years. Sustainability measures are not assessed year by year, as such
pathways and contributions of individual measures may differ from the linear interpolation shown in the graph.
The graph further highlights 2019 as the peak year of absolute CO2 emissions from EU+ aviation. Reliance on economic
measures is extensive in the period up to 2030, but this is significantly reduced towards 2050. This is consistent with
other projections and is caused by the fact that time is required before the most substantial emission reductions
measures, in the form of new technology and sustainable aviation fuel, materialise in the market. Higher ticket prices,
caused by additional costs related to sustainable aviation fuel, the introduction of hydrogen-powered aircraft and
economic measures, result in lower demand for air travel. Last, the figure shows the drastic impact that the COVID-19
pandemic has on passenger numbers – although CO2 reduction efforts are modelled to continue during the recovery
period.

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9.2.2

Flights within the EU+ region

Figure 22 shows how the various measures contribute to emissions reduction for intra-EU+ flights. In 2030, net CO2
emissions are reduced to 55% of 1990 levels. The reliance on economic measures gradually reduces (used to remove
the 1% CO2 emissions from intra-EU+ aviation that remain after in-sector reductions)as new technology becomes
available and SAFs become more widely available. In fact, hydrogen-powered aircraft contribute most to emission
reduction after 2030. Cost increases lead to a modest decline in demand compared to the reference scenario. This can
partly be explained by the lower carbon abatement cost of hydrogen, compared to that of drop-in SAF.

Intra EU+ aviation net CO2 emissions (Mt)

200

Flights within the EU+ region

180
160
140
120
100
80
60
40
20
0

2018

2030
Hypothetical reference scenario
Improved aircraft and engine technology (kerosene)
Improved aircraft and engine technology (hydrogen)
Improved ATM and aircraft operations
Sustainable aviation fuels
Economic measures

2050
Net CO2 emissions

-55% of 1990 CO2

Effect of cost of hydrogen(-technology) on demand
Effect of cost of sustainable aviation fuels on demand
Effect of cost of economic measures on demand

Figure 22: Impacts on net CO2 emissions by flights within the EU+ region, modelled for 2030 and 2050. Linear
interpolation between the years. Sustainability measures are not assessed year by year, as such pathways and
contributions of individual measures may differ from the linear interpolation shown in the graph.

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9.2.3

Flights departing from the EU+ region

Figure 23 shows the CO2 reduction pathway for flights departing the EU+. Here the largest contribution is expected
from the use of SAFs, followed by improvements in aircraft and engine technology. The higher cost of SAFs does lead
to a relatively large demand impact. Over the short-term the reliance on economic measures is limited. This is due to
the impact of COVID-19 on aviation demand in combination with the CORSIA 2019 baseline (ICAO, 2020d). It should be
noted however that CORSIA shall be an important instrument to limit CO2 emissions over the short-term in those parts
of the world where fewer technological and operational measures are taken. This means that CORSIA shall likely play a
more significant role for flights arriving in the EU, which were not included in the scope of the analysis, than for
departing flights. Contrary to the situation for intra-EU+ flights, the reliance on economic measures increases slightly
after 2030.
A significant share of CO2 emission reduction (88%, including demand effects) is achieved by in-sector measures.
Hydrogen-powered aircraft are not anticipated to operate on extra-EU+ routes and therefore do not contribute to CO2
emissions reductions for intercontinental air traffic.
200

Flights departing from the EU+ region

Extra EU+ aviation net CO2 emissions (Mt)

180
160
140
120
100
80
60
40
20
0

2018

2030
Hypothetical reference scenario
Improved aircraft and engine technology (kerosene)
Improved ATM and aircraft operations
Sustainable aviation fuels
Economic measures

2050
Net CO2 emissions
Effect of cost of sustainable aviation fuels on demand
Effect of cost of economic measures on demand

Figure 23: Impacts on net CO2 emissions by flights departing the EU+ region, modelled for 2030 and 2050. Linear
interpolation between the years. Sustainability measures are not assessed year by year, as such pathways and
contributions of individual measures may differ from the linear interpolation shown in the graph.

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9.2.4

2030

Table 44 shows the total and per-pillar impact on CO2 emissions modelled for 2030, relative to the reference scenario.
Overall, net CO2 emissions are reduced to 113 Mt. The majority (100 Mt) is emitted by flights to destinations outside
the EU+.
Table 44: Total and per-pillar CO2 emissions reduction, modelled for 2030, compared to the reference scenario
All

Change in CO2 emissions in 2030 compared to the reference
scenario

Mt

CO2 emissions in the reference scenario

207

%

Intra-EU+
Mt
%
87

Non-EU+
Mt
%
120

Sustainable aviation fuels-induced demand impacts
Economic measures-induced demand impacts

5
2

2%
1%

2
2

2%
2%

3
0

3%
0%

Total CO2 emissions reduction due to demand impacts

7

3%

4

4%

3

3%

14

7%

7

8%

7

6%

11
7
55

5%
3%
27%

5
3
55

5%
3%
63%

6
4
0

5%
4%
0%

Total CO2 emissions reduction due to sustainability measures

87

42%

70

79%

17

15%

Total combined CO2 emissions reduction

94

45%

74

83%

20

18%

CO2 emissions in the sustainability scenario

113

Improvements in aircraft and engine technology, kerosenepowered aircraft
Improvements in ATM and aircraft operations
Sustainable aviation fuels
Economic measures

13

100

Starting from the CO2 emissions in the reference scenario, discussed in Section 2.3.2, demand impacts are shown first.
These emissions reductions are the consequence of higher cost associated to the use of sustainable aviation fuels and
economic measures, which are modelled to increase ticket prices, and thereby suppress demand. In total, these
effects reduce CO2 emissions by 7 Mt or 3% (intra-EU+: 4 Mt or 4%; non-EU+: 3 Mt or 3%).
Improvements in aircraft and engine technology yields the largest reduction in CO2 emissions – 14 Mt or 7%. This
reduction is mainly a result of a newer generation of aircraft entering the market. As more revolutionary technological
improvements are expected to enter the market from 2030 onwards, the benefits delivered by these improvements
lie largely beyond 2030. As hydrogen-powered aircraft are modelled to enter into service in 2035, they do not affect
the results for 2030.
Improvements in ATM and aircraft operations yield a 11 Mt (5%) reduction in CO2 emissions in 2030. By 2030, most of
the foreseen measures have been implemented, or at least partially. It should be noted here that this analysis only
counts the CO2 emissions from flights departing from the EU+ (to avoid double counting), whereas some of the
benefits in this pillar yield benefits on arrivals or overflights. Such benefits are only counted for intra-EU+ flights, but
are out of scope for inbound intercontinental flights or en-route traffic.
The level of SAF uptake is still relatively limited in 2030, mainly due to its expected availability. Still, the efforts taken
to achieve the expected CO2 reduction of 7 Mt (3%) in 2030 are needed to yield much higher benefits of SAF beyond
2030, as production capacity will be increased and other production processes reach maturity.
Last, economic measures result in a CO2 emissions reduction of 55 Mt (27%) outside the sector. This means that in
2030, economic measures contribute most to the overall reduction of CO2 emissions by flights within and departing
from the EU.
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As 2019 was previously identified as the peak year for CO2 emissions, the industry target of carbon neutral growth
from 2020 onwards is achieved. Total CO2 emissions in the sustainability scenario accrue to 113 Mt, which is 36%
higher than the 83 Mt of CO2 emissions observed in 1990. As such, the proposed European target of reducing CO2
emissions across all sectors by 55% in 2030 compared to 1990-levels is not met for all flights considered in this study.
Focusing on intra-EU+ flights, alignment with that 55%-reduction goal is achieved. These flights emitted a total of
approximately 30 Mt of CO2 in 1990 and are foreseen to reduce that to 13 Mt in 2030.

9.2.5

2050

Table 45 shows the total and per-pillar impact on CO2 emissions modelled for 2050, compared to the reference
scenario. This shows that for all flights departing EU+ airports, net zero CO2 emissions are realised.
Table 45: Total and per-pillar CO2 emissions reduction, modelled for 2050, compared to the reference scenario
Change in CO2 emissions in 2050 compared
to the reference scenario
CO2 emissions in the reference scenario
Improvements in aircraft and engine
technology-induced demand impacts
(hydrogen-powered aircraft)
Sustainable aviation fuels-induced demand
impacts
Economic measures-induced demand impacts
Total CO2 emissions reduction due to demand
impacts
Improvements in aircraft and engine
technology, kerosene-powered or (hybrid)electric aircraft
Improvements in aircraft and engine
technology, hydrogen-powered aircraft
Improvements in ATM and aircraft operations
Sustainable aviation fuels
Economic measures
Total CO2 emissions reduction due to
sustainability measures

Mt

All

Intra-EU+
Mt
%

%

293

Non-EU+
Mt
%

115

178

2

1%

2

1%

0

0%

36

12%

8

7%

28

16%

5

2%

0

0%

5

3%

43

15%

10

8%

33

19%

51

17%

8

7%

43

24%

60

20%

60

52%

0

0%

18
99
22

6%
34%
8%

8
29
<1

7%
25%
1%

10
70
22

6%
39%
12%

250

85%

105

92%

145

81%

Total combined CO2 emissions reduction

293

100%

115

100%

178

100%

CO2 emissions in the sustainability scenario

0

0

0

Again, various demand impacts reduce CO2 emissions by 43 Mt (15%). In addition to the demand impact of sustainable
aviation fuels and economic measures, the results for 2050 include a demand impact associated to the introduction of
hydrogen-powered aircraft from 2035 onwards.
Of the sustainability measures, improvements in aircraft and engine technology, including the use of hydrogenpowered aircraft, yield the highest reduction of CO2 emissions. This is followed by application of drop-in sustainable
aviation fuel, economic measures realising out-of-sector carbon removals and improvements in ATM and aircraft
operations.
By 2050, aircraft and engine technology have developed such that (partially) kerosene-powered aircraft emit 51 Mt
(17%) less CO2 than currently is the case. This impact is mostly seen for intercontinental traffic, as hydrogen-powered
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aircraft are used for a large portion of intra-EU+ flights below 2,000 kilometres, reducing CO2 emissions by 60 Mt
(20%) while consuming a total of 3.7 Mt of hydrogen.
The further realisation of numerous improvements due to ATM and aircraft operations in the period between 2030
and 2050 result in a total contribution of CO2 reduction equal to 18 Mt, slightly increasing its share (from 5% in 2030
to 6% in 2050). Despite this reduction, as well as those realised by the energy efficiency improvements delivered by
kerosene-powered aircraft and the partial switch to hydrogen-powered aircraft, a demand for kerosene still exists in
2050. Due to upscaling of various production processes 83% of the jet fuel used is sustainable aviation fuel, reducing
CO2 emissions by 34% compared to the reference scenario. Following the introduction of hydrogen-powered aircraft
on intra-EU+ flights, SAF is primarily used for non-EU+ flights (23 Mt, versus 9.5 Mt intra-EU+).
Last, economic measures are used for removing 22 Mt of CO2 from the atmosphere, almost completely on flights
outside the EU+ region. The remaining emissions on intra-EU+ flights (0.7 Mt) result from the fact that not all SAF
pathways yield a 100% CO2 reduction. These emissions need to be removed through the EU-ETS scheme, at the price
of € 315 per tonne. For flights outside the EU+ regions, carbon credits are required for 22 Mt, at the price of € 160 per
tonne. This yields an average cost per tonne of CO2 of € 165.
Overall, Figure 24 shows that almost 90% of all energy used in aircraft operations in 2050 comes from a renewable
source. This includes both drop-in SAF as well as the use of liquid hydrogen, the CO2 savings of which are included in
the pillar ‘Improvement in aircraft and engine technology’.

Fossil kerosene
13%

Liquid hydrogen
21%

Bio-based kerosene
27%

SAF
66%

Power to liquid
kerosene
39%

Figure 24: Breakdown of total energy and SAF demand for 2050
As net zero CO2 is achieved for all flights within and departing from the EU+ region, these results show European
aviation operations to be aligned with the European Green Deal and the proposed European Climate Law in terms of
CO2 emissions. The currently set industry goal, reducing net aviation emissions by 50% in 2050 compared to 2005levels, is surpassed.

9.3

Overall policies and actions

In addition to the specific policies and actions described in the chapters dealing with the four pillars that this study
considers, a number of recommendations encompass the entire work. This section treats these, in two categories.
First, Section 9.3.1, highlights three characteristics that are considered crucial to the development of a successful
policy framework supporting European sustainable aviation. Second, Section 9.3.2, lists a number of much more
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concrete proposals for policies and actions, but which are nevertheless applicable to all areas of improvement
considered.

9.3.1

Characteristics of a long term vision for European sustainable
aviation

Three main items have been identified that are common to all pillars analysed in this study. These items form what
should be the main pillars supporting a common long term vision for European aviation: setting a long term goal in
combination with a coherent policy framework supported by strong collaboration between stakeholders.
Collaboration between stakeholders
A common item for all policies and actions presented in this report is collaboration and commitments between
stakeholders. ACI-EUROPE, ASD Europe, ERA, A4E and CANSO have jointly commissioned this study to highlight the
importance of a joint vision. The sustainability scenario requires action from all stakeholders, in the first place the five
organisations that jointly commissioned this study in collaboration with governments. Stakeholders – encompassing
both industry, government and non-governmental organisations – should strive for a truly collaborative effort to
effectively address the decarbonisation challenge facing commercial aviation. The EU Pact for Sustainable Aviation,
proposed in the recent Aviation Round Table Report on the Recovery of European Aviation (2020), that brings even
more aviation stakeholders together, is another key example of the collaboration required.
Coherent long term policy framework
Decarbonizing the aviation industry requires making large capital investments for a time period of 15 up to 25 years
ahead. This applies to improvements in aircraft, engines and sustainable aviation fuels. It is therefore essential for
investors to know well in advance which targets should be met and in which timeframe. The policy framework should
set a clear vision for the future to de-risk investment in sustainable aircraft, engine and fuels over the entire value
chain from R&D to commercial deployment. This requires long-term and consistent policies, reducing uncertainty as
much as possible.
Working towards global commitment to a net zero future for aviation
This study shows a pathway towards achieving net zero CO2 emissions from all flights within and departing form the
EU by 2050. Following the leadership position of the EU aviation industry and government, all should work towards
ensuring a global commitment to a net zero future for aviation, supported by effective policies and realised by joint
and collaborative action. This would align aviation worldwide to the Paris Agreement and the 1.5 °C scenario of the
IPCC, and thereby mitigate an important negative climate effect of aviation. The current ICAO work on defining a
global long term aspirational goal, which is anticipated to be set in 2022 (ICAO, n.d.), is a key opportunity to realising
this ambition. If a global net zero target cannot be agreed upon, global and European goals should at least be brought
closer together.

9.3.2

Cross-pillar policies and actions

The policies and actions described in the various chapters of this report address specific pillars. A number of policies
and actions, however, are shared between these pillars. As such, they are treated separately in this section.

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Enabling customers to make a sustainable choice
The policies and actions mentioned in this report are aimed at governments and industry stakeholders. Nevertheless,
customers can also play an important role in the sustainability transition. Providing consumers with information on
the sustainability of various travel options allows them to make sustainable choices. Various online calculators that
estimate CO2 emissions per flight exist, but show widely varying results, do not all accurately capture all factors that
contribute to a particular footprint and neglect airport sustainability efforts. Addressing these problems is one of the
possible ways that might help make aforementioned environmental decision making by consumers easier.
Increasing sustainability awareness across industry
A key point raised in various chapters, and reiterated in Section 9.3.1, is the need for the aviation community to work
together on the decarbonisation challenge ahead. Besides awareness at management and executive level, this
requires awareness with operational employees. Pilots and air traffic control officers are a straightforward example,
but maintenance personnel, ground handling agents, airport personnel and many others can each contribute.
Coupled to increasing awareness across the organisation comes the responsibility to recognise sustainability as a fullfledged part of the business. It should not be regarded as something different or extra – but part of the working
activities of all involved.
Nurturing and stimulating new and disruptive ideas – inside and outside
Also stressed earlier in this chapter, a study as this should be updated regularly to make sure the latest insights are
included. It is recommended to continuously gather these and to stimulate their development.
Idea generation contests, business accelerators and support for or participation in start-up programmes should be
considered to that effect. Such can be done within an organisation, but also cross-industry, or open to a more general
audience of possibly interested minds. Even though not all ideas might be mature enough to directly apply into
practice, they might provide a refreshing new perspective. Bringing together entrepreneurial spirits often found in
start-ups or spin-offs with seasoned aviation professionals is a not to be missed opportunity.

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Appendix A Abbreviations
ACRONYM

DESCRIPTION

/A

With aromatics

A4E

Airlines for Europe

ACARE

Advisory Council for Aviation Research and Innovation in Europe

ACI

Airports Council International

ADS-B

Automatic Dependent Surveillance - Broadcast

AFUA

Advanced flexible use of airspace

AI

Artificial intelligence

AIAA

American Institute of Aeronautics and Astronautics

AMAN

Arrival management

ANSP

Air navigation service provider

APR

Aqueous phase reforming

APU

Auxiliary power unit

AR

Aspect ratio

ASD Europe

AeroSpace and Defense Industries Association of Europe

ASK

Available seat kilometre

ASTM

American Society for Testing and Materials

ATAG

Air Transport Action Group

ATCO

Air traffic control officer

ATJ

Alcohol to jet

ATM

Air traffic management

BLI

Boundary layer ingestion

BPR

Bypass ratio

CAAFI

Commercial Aviation Alternative Fuels Initiative

CAEP

Committee on Aviation Environmental Protection

CANSO

Civil Air Navigation Services Organisation

CASK

Cost per ASK

CDM

Clean development mechanism

CER

Certified emission reduction

CfD

Contract for difference

CFRP

Carbon fibre reinforced plastics

CH

Catalytic hydrothermolysis

CNG

Carbon-neutral growth

CNG2020

Carbon-neutral growth at 2020 levels

CNS

Communication, navigation and surveillance

CO2

Carbon dioxide

CO2e

CO2 equivalent
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ACRONYM

DESCRIPTION

CoP

Conference of the Parties

CORSIA

Carbon Offsetting and Reduction Scheme for International Aviation

CROR

Contra-rotating open rotor

DAC

Direct air capture

DG MOVE

Directorate-General for Mobility and Transport

DSHC

Direct sugars to hydrocarbons

EASA

European Union Aviation Safety Agency

ECA

European Court of Auditors

ECAC

European Civil Aviation Conference

EEA

European Environment Agency

EEX

European Energy Exchange

EFTA

European Free Trade Association

e-GPU

Electrical ground power unit

EIS

Entry into service

EJ

Exajoule (1018 Joules)

ER

Extended range

ERA

European Regions Airline Association

ETC

Energy Transitions Committee

ETD

Energy Taxation Directive

ETS

Emissions Trading Scheme

EU, EU+

European Union
Unless explicitly stated otherwise, to be interpreted as EU + UK + EFTA, also
referred to as EU+.

EU ATM MP

European Air Traffic Management Master Plan

EUA

European Union Allowance

EUAA

European Union Aviation Allowance

FAA

Federal Aviation Administration

FAB

Functional airspace block

FEGP

Fixed electrical ground power

FMS

Flight management system

FOG

Fats, oils and greases

FQD

Fuel Quality Directive

FRA

Free route airspace

FT

Fischer-Tropsch

FUA

Flexible use of airspace

GDP

Gross domestic product

GHG

Greenhouse gases

GMF

Global Market Forecast
Airbus industry forecast

GPU

Ground power unit
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ACRONYM

DESCRIPTION

GSE

Ground service equipment

H2

Hydrogen

HDCJ

Hydrotreated depolymerised cellulosic jet

HEFA

Hydro-processed esters and fatty acids

HT

Horizontal tailplane

HTL

Hydrothermal liquefaction

HVO

Hydrotreated Vegetable Oil

IAG

International Airlines Group

IATA

International Air Transport Association

ICAO

International Civil Aviation Organisation

ICCT

International Council on Clean Transportation

ILUC

Indirect land use change

IMF

International Monetary Fund

IPCC

Intergovernmental Panel on Climate Change

IRENA

International Renewable Energy Agency

ISO

Intermediate stop operations

IUCN

International Union for Conservation of Nature

JI

Joint implementation

JU

Joint undertaking

KPI

Key performance indicator

LCA

Life-cycle assessment

LH2

Liquid hydrogen

LHV

Lower heating value

LR

Long range

LTA

Large twin aisle
Aircraft class

LULUCF

Land use, land use change and forestry

MEA

More electric aircraft

MFN

Mid-fuselage nacelle

MSR

Market Stability Reserve

MSW

Municipal solid waste

Mtoe

Mega-tonne oil equivalent

NASA

National Aeronautics and Space Administration

NAT

North-Atlantic tracks

NAT-OTS

North-Atlantic Organised Track System

NDC

Nationally determined contribution

NECP

National Energy & Climate Plan

neo

New engine option

NLR

Netherlands Aerospace Centre
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ACRONYM

DESCRIPTION

nm

Nautical mile (1.842 kilometres)

NOX

Oxides of nitrogen

NRDC

Natural Resources Defence Council

O&D

Origin and destination

OAG

Official Airlines Guide

ODP

Optimized Descent Profile
Formerly often referred to as Continuous Descent Operations (CDO) or
Continuous Descent Approach (CDA)

OECD

Organisation for Economic Co-operation and Development

OEM

Original equipment manufacturer

OPR

Overall pressure ratio

OTS

See: NAT-OTS

OWN

Over-wing nacelle

PCA

Pre-conditioned air

PCP

Pilot Common Project

PIP

Performance improvement package / programme

PPP

Public-private partnership

PtL

Power to liquid

R

Regional
Aircraft class

R&D

Research and development

R&I

Research and innovation

RDT&E

Research, development, testing and evaluation

RED

Renewable Energy Directive

REDD

Reduced Emissions from Deforestation and forest Degradation

RLAT

Reduced lateral separation minima

RPK

Revenue passenger kilometre

RSB

Roundtable on Sustainable Biomaterials

RSS

Relaxed static stability

RTK

Revenue tonne kilometre

RVSM

Reduced vertical separation minima

S
SA

Small
Aircraft class
Single aisle
Aircraft class

SAF

Sustainable aviation fuel

SAK

Synthetic aromatic kerosene

SCR

Shortest constrained route

SEO

SEO Amsterdam Economics

SES

Single European Sky

SESAR

Single European Sky ATM Research
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ACRONYM

DESCRIPTION

SESAR DM

SESAR Deployment Manager

SESAR JU

SESAR Joint Undertaking

SIP

Synthesised isoparaffins

SK

Synthetic kerosene

SKA

Synthetic kerosene with aromatics

SMTA

Small/medium twin aisle
Aircraft class

SPK

Synthetic paraffinic kerosene

SUGAR

Subsonic Ultra-Green Aircraft Research

SWD

Staff Working Document

TBO

Trajectory Based Operations

TE

Trailing edge

TMA

Terminal control area / terminal manoeuvring area

TR

Technology readiness

TRL

Technology readiness level

UHBR

Ultra-high bypass ratio

UN

United Nations

UNFCCC

United Nations Framework Convention on Climate Change

USD

United States dollar

VLA

Very large aircraft

VT

Vertical tailplane

WTP

Well to pump

WTWa

Well to wake

WWF

Worldwide Wildlife Fund

XMAN

Cross-border arrival management

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NLR-CR-2020-510 | February 2021

Appendix B Consulted parties
Throughout the process of developing Destination 2050, numerous industry and research parties provided valuable
input in interviews and workshops.
From Airports Council International – Europe
(ACI-EUROPE)

From Civil Air Navigation Services Organisation –
Europe (CANSO Europe)

•

Avinor

•

AustroControl

•

Groupe ADP

•

DFS

•

Heathrow Airport

•

ENAIRE

•

Manchester Airports Group

•

IAA

•

Royal Schiphol Group

•

NATS

•

Skeyes

•

Skyguide

From Airlines for Europe (A4E)
•

Air France

•

British Airways

•

easyJet

•

•

International Airlines Group

•

Neste

•

KLM – Royal Dutch Airlines

•

SkyNRG

Other
International Council on Clean Transportation

From European Regional Airlines Association (ERA)
•

Air Nostrum

•

Euroairlines

•

Widerøe

From AeroSpace and Defence Industries Association of
Europe (ASD)
•

Airbus

•

ATR

•

Avio Aero

•

DLR / German Aerospace Center

•

Honeywell

•

Leonardo

•

MTU Aero Engines

•

Rolls-Royce

•

Safran

•

Sustainable Aviation UK

176

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Appendix C Class-averaged improvement potential
of upcoming aircraft
Section 3.2 discusses the potential fuel efficiency improvements of upcoming aircraft. These aircraft are types that
have entered service recently (or are about to do so), but have not fully materialised in the European fleet. In some
cases, upcoming aircraft form a direct replacement of legacy aircraft and are replaced one-to-one. For legacy aircraft
types without a direct replacement, a class-averaged improvement potential is used. This appendix details how that
value – as presented in Table 6 – is computed for the various classes.
Table 5 specifies various upcoming aircraft in the regional, single aisle, small/medium twin aisle and large twin aisle
classes. Table 35 up to and including Table 49 repeat the relevant data, extended with the improvement per flight and
class-averaged values. These are subsequently used in Table 6 in Section 3.2.
Table 46: Improvement potential and entry into service of upcoming aircraft types in the regional class
Upcoming
Type
ATR72
Embraer E2
Embraer E2
Entire class

Subtype
E175-E2
E190-E2
Average

EIS
2011
2021
2018
2017

Reference
Type
CRJ700
E175
E190

EIS
2001
2005
2005
2004

Improvement
Per ASK
47.7%
16%
17.3%

Per flight
46.3%
10.7%
17.3%
24.8%

Given the much larger share of Boeing 737NG aircraft with winglets than without, a reference model with winglets is
assumed. Following Table 5, the Boeing 737MAX then realises a 14% improvement (assumed per flight, following
footnote 28 on page 29) over late Boeing 737NG models, which entered into service in 2004.
Table 47: Improvement potential and entry into service of upcoming aircraft types in the single aisle class
Upcoming
Type
A220
A220
Embraer E2
A320neo
A320neo
A320neo
A320neo
A320neo
B737MAX
B737MAX
B737MAX
B737MAX
Entire class

Subtype
A220-100
A220-300
E195-E2
A319neo
A320neo
A321neo
A321neoLR
A321neoXLR
B737MAX7
B737MAX8
B737MAX9
B737MAX10
Average

EIS
2016
2016
2021
2019
2016
2016
2018
2023
2021
2017
2018
2020
2018

Reference
Type
E190
E190
E195
A319
A320
A321
757-200
757-200

EIS
2005
2005
2006
1996
1988
1994
1983
1983

Improvement
Per ASK
20%
40%
25.4%
19%
20%
23%
30%
30%

737 NG

2004

14%

2003

14.8%

Per flight
6.8%
6.8%
5.4%
16.4%
15.0%
13.9%
27.0%
30.0%

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Table 48: Improvement potential and entry into service of upcoming aircraft types in the small/medium twin aisle class
Upcoming
Type
A330neo
A330neo
B787
B787
B787
Entire class

Subtype
A330-800
A330-900
B787-8
B787-9
B787-10
Average

EIS
2020
2018
2011
2014
2018
2016

Reference
Type
A330-200
A330-300
767-300ER
767-400ER
(est.)

EIS
1998
1994
1988
2000
1996

Improvement
Per ASK
14.2%
14%
20%
20%
25%
18.6%

Per flight
12.6%
12.6%
27.3%
22.0%
13.5%
17.6%

Table 49: Improvement potential and entry into service of upcoming aircraft types in the large twin aisle class
Upcoming
Type
A350
A350
B777X
B777X
B777X
Entire class

Subtype
A350-900
A350-1000
B777-8
B777-8
B777-9
Average

EIS
2015
2018
2023
2023
2021
2020

Reference
Type
777-200ER
777-300ER
777-200ER
777-200LR
777-300ER

EIS
1995
2004
1995
2006
2004
2001

Improvement
Per ASK
30%
25%
21.7%
20.8%
20%
23.5%

Per flight
25.7%
22.5%
27.0%
8.8%
11.8%
19.2%

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NLR-CR-2020-510 | February 2021

Appendix D Future aircraft concept studies
This appendix provides an overview of future concept aircraft studies, ranging from academic efforts to conceptual
studies presented by manufacturers. These studies show which technologies have been considered promising for
integration into an aircraft concept. As the fuel efficiency improvements published for such concepts are sometimes
criticised as “an unrealistically optimistic view of technological potential” (Graham, Hall, & Vera Morales, 2014, p. 34),
this appendix does not include such estimates.
The remainder of this appendix presents the results obtained from literature. Fitting the split made in Section 3.3, the
results distinguish between studies looking at aircraft powered by drop-in fuels (Appendix D.1) and non-drop-in fuels
(Appendix D.2).

Appendix D.1 Aircraft with drop-in fuels
Tables 50 up to and including 53 show concept studies of future aircraft using drop-in fuels, starting with the regional
class before moving on to the single aisle, small/medium twin aisle and large twin aisle classes.
Table 50: Future aircraft concept studies with drop-in fuels in the regional class showing main technologies
Name
T+W98-DD
OWN98-DD

Technology
Two under- (T+W) or over-wing (OWN) direct-drive turbofans, BPR
9.7, OPR 35. Hybrid laminar flow control (wing, HT, VT, nacelles),
riblets, stitched resin-infused composites, adaptive compliant TE,
winglets (T+W)

Source(s)
Nickol & Haller (2016)

Table 51: Future aircraft concept studies with drop-in fuels in the single aisle class showing main technologies
Name
CENTRELINE
CS SMR
D8.1
SD8.1
D8.5

SD8.5
DZYNE Ascent
1000
DZYNE BWB165
ESAero ECO150

Technology
Tube and wing with two CROR-engines between H-tails and natural
laminar flow wing.
Double-bubble lifting aluminium fuselage with twin T-tails and three
flush-mounted direct-drive turbofans with BPR 6 and centerbody BLI.
Straight wing with AR 17.3 (D8.1) or strut-braced wing with AR 25.9
(SD8.1). No LE slats. Minimal technology insertion.
Double-bubble lifting composite fuselage with twin T-tails and two
high-efficiency BLI fans (BPR 20) with advanced combustor, distortion
tolerant fan, variable area nozzle and advanced engine materials.
Natural laminar flow, reduced secondary structure weight, advanced
structural materials, health and usage monitoring, active load
alleviation. AR 24.85 (D8.5) or 33.92 with strut-braced wing (SD8.5).
Operational modifications w.r.t. cruise Mach number and altitude.
Advanced composite blended wing body (w/ aerodynamic and
structural advantages) with two upper-fuselage geared turbofans
(BPR 9) and hybrid-electric wake filling fans, reduced-size landing
gear, multifunctional wing movables (incl. load alleviation and stability
augmentation)
Two turbogenerators and 16 motor driven fans (all possibly
superconducting) in (relatively high AR) split wing with V-tail

Source(s)
CENTRELINE (2017)
Lafage, Aubry & Junior
(2016)

MIT (2010) and Drela
(2010)

Yang, Page & Smetak
(2018)
Madavan (2016)

179

NLR-CR-2020-510 | February 2021

Name
SELECT

Refined SUGAR

SUGAR High

SUGAR Ray

STARC-ABL
T+W160-GTF
OWN160-GTF
T+W216
HWB216

Technology
Two three shaft turbofans, ultra-high BPR 18, cooled cooling air
turbine, shape memory alloy nozzle, laminar flow, ultrahigh
performance fibre
Two under-wing two-spool turbofans, BPR 9.2, OPR 66 with a.o. an
advanced 3D aero composite fan ultra-high pressure recovery
compressor, advanced low-emissions combustor, integrated thrust
reverser/variable fan nozzle, CMC turbine blades/vanes, nextgeneration component aerodynamics and nacelle technology,
improved shaft material. Natural laminar flow wing, fuselage riblets,
multi-functional structures, gapless movables, c.g. control, RSS,
advanced composites. Incremental development of existing
technologies.
High-wing high-AR (23.1) truss-braced wing (High) or hybrid-wingbody (Ray) with two under-wing (High) or upper-fuselage (Ray) twospool turbofans, BPR 13, OPR 59, improved w.r.t. Refined SUGAR.
Natural and active laminar flow wing and VT (High), fuselage and wing
riblets, multi-functional structures, gapless movables, c.g. control,
RSS, advanced composites, advanced supercritical airfoil, adaptive
camber, spanload control, low drag nacelle and strut.
Two under-wing turbofans (BPR 6.4, OPR 58) and generators with a
rear fuselage axisymmetrical BLI-fan and propulsor (OPR 1.25).
Updated concept (2019) with smaller distributed rear fuselage BLI
fans.
Two under- (T+W) or over-wing (OWN) 2nd gen. geared turbofans,
ultra-high BPR 23.45, OPR 35. Hybrid laminar flow control (wing, HT,
VT, nacelles), riblets, stitched resin-infused composites, adaptive
compliant TE, winglets (T+W).
Tube and wing (T+W) or hybrid-wing-body (HWB) with two under
wing (T+W) or upper-fuselage (HWB) 2nd gen. geared turbofans, ultrahigh BPR 21.75, OPR 50. Hybrid laminar flow control (wing, HT [T+W
only], VT, nacelles), riblets, stitched resin-infused composites,
adaptive compliant TE (T+W), winglets (T+W)

Source(s)
Northrop Grumman
(2010)

Bradley & Droney
(2011) and Welstead &
Felder (2016)

Bradley & Droney
(2011)

Welstead & Felder
(2016), Warwick
(2019a) and Madavan
(2016)
Nickol & Haller (2016)

Nickol & Haller (2016)

Table 52: Future aircraft concept studies with drop-in fuels in the small/medium twin aisle class showing main
technologies
Name
2035R
PFC

DMFC
CS LR
Flying V
HWB301-DD
HWB301-GTF

Technology
Tube and wing (AR 12.4 – 12.6) with two advanced geared turbo fans
(BPR 18) and aft-fuselage propulsive fan using BLI (PFC), fully electric
subsystems (fuel-cell based APU), advanced wing (AR 12.6), shock
contour bumps, fuselage riblets, omnidirectional carbon fibres,
advanced bonding techniques.
Hybrid-wing-body (BPR 6.9) with six upper-fuselage mounted
distributed fans (BPR 20) using BLI, fully electric subsystems (fuel-cell
based APU), advanced wing (AR 12.6), shock contour bumps, fuselage
riblets, omnidirectional carbon fibres, advanced bonding techniques.
Tube and wing with two advanced three-shaft turbofan engines, new
FMS functions.
“Tailless, V-shaped flying wing with two cylindrical pressurized cabins
placed in the wing leading edge” with two over-wing turbofans.
Hybrid-wing-body with two upper-fuselage (HWB) or tube and wing
with mid-fuselage over-wing (MFN) direct-drive (-DD, BPR 12.85) or
2nd gen. geared turbofan (-GTF, BPR 17.65), OPR 60. Hybrid laminar

Source(s)

DisPURSAL (Outcome,
n.d.), Isikveren et al.
(2015) and Bijewitz,
Seitz, Hornung &
Isikveren (2017)

Lafage, Aubry & Junior
(2016)
Faggiano, Vos, Baan &
van Dijk (2017) and TU
Delft (Flying-V, n.d.)
Nickol & Haller (2016)

180

NLR-CR-2020-510 | February 2021

Name
MFN301-GTF
T+W301-DD
T+W301-GTF
N3-X

Technology
flow control (wing, HT [MFN only] VT, nacelles), riblets, stitched resininfused composites.

Source(s)

Tube and wing with two under wing direct-drive (-DD, BPR 14.65) or
2nd gen. geared turbofan (-GTF, BPR 20.6), OPR 60. Hybrid laminar
flow control (wing, HT, VT, nacelles), riblets, stitched resin-infused
composites, adaptive compliant TE.
Hybrid-wing-body with two highly efficient turbo-electric generators
(BPR 29, OPR 84) and distributed propulsion using superconducting
motors/generations and BLI.

Felder (2014) and
Berton & Haller (2014)

Table 53: Future aircraft concept studies with drop-in fuels in the large twin aisle class showing main technologies
Name
H3.2

HWB400

T+W400

Technology
Hybrid-wing-body with four advanced ultra-high BPR fans, distributed
propulsion, variable area nozzle, thrust vectoring, advanced
combustor and BLI. Lifting body with leading edge camber, no LE
movables, advanced materials, active load alleviation and health and
usage monitoring. Adjusted cruise altitude.
Hybrid-wing-body with three upper-fuselage 2nd gen. geared
turbofans, ultra-high BPR 17.6, OPR 60. Hybrid laminar flow control
(wing, VT, nacelles), riblets, stitched resin-infused composites.
Tube and wing with four under wing 2nd gen. geared turbofans, ultrahigh BPR 21.75, OPR 50. Hybrid laminar flow control (wing, HT, VT,
nacelles), riblets, stitched resin-infused composites, adaptive
compliant TE, winglets.

Source(s)
MIT (2010)

Nickol & Haller (2016),
Airliner World (2009)

Appendix D.2 Aircraft with non-drop-in fuels
Tables 54 up to and including 56 show concept studies of future aircraft using non-drop-in fuels, starting with the
regional class before moving on to the single aisle, small/medium twin aisle and large twin aisle classes.
Table 54: Future aircraft concept studies with non-drop-in fuels in the regional class showing main technologies
Name
Airbus ZEROe
Turboprop
PEGASUS

Technology
Hydrogen hybrid turboprop engines using liquid hydrogen, stored in
the rear of the fuselage.
Hybrid-electric (500Wh/kg) with high-wing and two turbine-electric
motors at wing tips, two underwing electric motors and one aftfuselage motor utilizing BLI, natural laminar flow, advanced
composites and lightweight electrical systems and cabin furnishings

S1

Hybrid-electric with high-wing and two underwing parallel motors
(conventional configuration), 1000Wh/kg (2948kg).

VoltAir

Fully electric (Li-air, 1000Wh/kg, approx. 10.000kg) with high-AR,
natural laminar flow wings, winglets, low slenderness ratio fuselage,
BLI and double counter-rotating aft-mounted fans.

Z1 – Parallel
Z1 – Parallel /
Series
Z1 – Series

Hybrid-electric (Li-air, 750Wh/kg) high-wing and two under-wing
thermal engines and zero (Parallel), four (Parallel/Series) or ten
(Series) under-wing electric motors. Savings for 500Wh/kg limited to
± 5%.

Source(s)
Airbus (2020d; 2020c)
Antcliff & Capristan
(2017) and Antcliff et al.
(2016)
Voskuijl, van Bogaert &
Rao (2017) and
Veldhuis & Voskuijl
(2016)
Stückl, van Toor &
Lobentanzer (2012)
Zamboni, Vos, Emeneth
& Schneegans (2019)

181

NLR-CR-2020-510 | February 2021

Table 55: Future aircraft concept studies with non-drop-in fuels in the single aisle class showing main technologies
Name
A320neo-HEP
Airbus ZEROe
Turbofan
Airbus ZEROe
Blended-Wing
Body
Bauhaus FBH
Bauhaus HER
Bauhaus HET

Ce-Liner

MIPH

Technology
Parallel hybrid-electric (2025: 500Wh/kg / 2045: 1000 Wh/kg),
downscaled turbofan (90%), electric taxiing, electrical architecture of
non-propulsive systems, fuel cell implementation (2025: 0.5kW/kg /
2045: 1kW/kg), photovoltaic exterior (2025: 0.5kW/kg / 2045:
0.9kW/kg)

Airbus (2020d; 2020c)

1500 Wh/kg (8.765kg) interchangeable batteries

Pornet, Kaiser, Isikveren
& Hornung (2014)

Hybrid-electric (940Wh/kg) tube-and-wing with two conventional
underwing engines and an electric tail-motor. 20% improvement at
1300nm with 1300Wh/kg.
Hybrid-electric (1000-1500Wh/kg, 11.740kg) tube-and-wing with two
underwing advanced geared turbofans and two underwing electrical
fans
Fully electric (2000Wh/kg, “aggressive assumptions”) open box-wing
(‘C-wing’) with two aft-fuselage mounted ducted fans powered by
high-temperature superconducting motors, self-trimming wing with
active poly-morphing capability, continuous GFRP window-belt
(rather than individual cut-outs), electric systems architecture.
Batteries in LD3-containers to enable quick turn-around.
Mechanically integrated parallel hybrid-electric (1000Wh/kg, 5.300kg)
turbofan
Parallel hybrid-electric propulsion system (600Wh/kg) as ‘retrofit’ on
A320, scaling down turboshaft engines to 90% / 80%

SUGAR Electric
Eel

Hybrid-electric Super Refined SUGAR (Table 51)

SUGAR Sting
Ray

ULTIMATE

Lammen & Vankan
(2019)

Hydrogen hybrid turbofan engines using liquid hydrogen, stored in
the rear of the fuselage (Turbofan) or underneath the wings (BlendedWing Body). Blended-Wing Body also utilises distributed propulsion.

S2

SUGAR Volt

Source(s)

Hybrid-electric (9405kg battery) high-wing high-AR (23.1) truss-braced
wing with two under-wing thermal electric engines, BPR 18 improved
w.r.t. Refined SUGAR. Natural and active laminar flow wing and VT,
fuselage and wing riblets, multi-functional structures, gapless
movables, c.g. control, RSS, advanced composites, advanced
supercritical airfoil, adaptive camber, spanload control, low drag
nacelle and strut. Hybrid-electric SUGAR High

Bauhaus Luftfahrt
(2017)
Pornet & Isikveren
(2015)

Hornung, Isikveren,
Cole & Sizmann (2013)
Seitz, Nickl, Stroh &
Vratny (2018)
Ang, Gangoli Rao,
Kanakis & Lammen
(2019) / Veldhuis &
Voskuijl (2016)

Bradley & Droney
(2011; 2015) and Wall
& Meyer (2017)

Hybrid-electric SUGAR Ray
Advanced high-AR tube-and-wing with two rear-fuselage mounted
open-rotor engines and T-tail, using active flow control, fuselage
riblets, natural laminar flow nacelle, hybrid laminar flow wing and tail,
manoeuvre and gust load alleviation, foldable wingtip, variable
camber, CFRP structures, fly-by-light, low-weight cabin, all electric
(fuel cell powered) subsystems, advanced propulsion component and
material efficiencies

Heinemann, et al.
(2017)

182

NLR-CR-2020-510 | February 2021

Table 56: Future aircraft concept studies with non-drop-in fuels in the small/medium twin-aisle class showing main
technologies
Name
AHEAD (LNG)
AHEAD (LH2)

ULTIMATE

Technology
Multi-fuel blended wing body with contra-rotating fans using BLI, dual
combustion chambers using cryogenic fuel, flameless combustion.
Advanced tube-and-wing with two underwing engines, using active
flow control, fuselage riblets, natural laminar flow nacelle, hybrid
laminar flow wing and tail, manoeuvre and gust load alleviation,
variable camber, CFRP structures, fly-by-light, low-weight cabin, all
electric (fuel cell powered) subsystems, advanced propulsion
component and material efficiencies

Source(s)
Gangoli Rao, Yin & van
Buijtenen (2014),
Grewe et al. (2016) and
Yin, Gangoli Rao, Bhat &
Chen (2018)
Heinemann, et al.
(2017)

183

NLR-CR-2020-510 | February 2021

Appendix E Comparison to Waypoint 2050
Stressing the relevance of the challenge treated in this study, numerous other reports have investigated
decarbonisation of aviation as well. This section briefly compares the results presented in this work to Waypoint 2050report published by ATAG (2020b), to clarify any potential differences and highlight similarities.
Approach
Published in September 2020, Waypoint 2050 (ATAG, 2020, p. 4) presents a view of “how the industry can accelerate
working together to contribute to the world’s climate action mission”. Much like Destination 2050, it looks at
improvements in aircraft and engine technology 174, operations and ATM 175, the use of sustainable aviation fuel and
economic measures 176. Both reports focus on CO2 emissions from flight operations. Waypoint 2050 takes global
aircraft emissions as its scope, whereas this study was limited to flights within and departing from the EU+ region
(further specified in Section 1.4).
Waypoint 2050 is focused on ways to meeting the current industry goal of reducing 2050 CO2 emissions by 50%
compared to levels in 2005. The Waypoint 2050 analysis suggests global aviation industry could be in a position to
reach net zero emissions by 2060/2065, without the significant use of economic measures. It notes that some regions
and individual companies could meet net zero earlier, but some parts of the world may need a little longer to reach
that point. Due to the leading role of the European Union in tackling climate change as presented in the Green Deal, it
is most likely that Europe reaches net zero before other regions. Destination 2050 is focused on assessing the
feasibility of net zero carbon emissions from European aviation in 2050. The higher ambition level presented in this
roadmap is aligned with the ATAG objective to encourage “all parts of the industry to focus on how they can play a
role in accelerating a decarbonisation pathway”.
Comparison between pathways
The anticipated contributions of the different pillars are similar to Waypoint 2050’s consolidated scenario 3, with the
exception of an explicit demand effect forecast by Destination 2050. Focussed on flights departing from the EU+
region, there is most agreement with Scenario 2 – although with a larger (but limited) reliance on economic measures
(or: “out-of-sector carbon reduction measures”).
Reference scenario and traffic forecast
Also published after the outbreak of the COVID-19 pandemic, the Waypoint 2050 forecast shows a 1.9% compound
annual growth rate up to 2050 for the European region in terms of revenue passenger kilometres; comparable to the
2.0% growth rate (in terms of passengers) modelled in Destination 2050.
Improvements in aircraft and engine technology
Waypoint 2050 has modelled multiple technology evolution scenarios, ranging from a baseline (that only includes
aircraft types indicated in this study as ‘upcoming’, described in Section 3.2 of this report) to an aspirational
technology scenario. This study balances these different visions, including both currently in production or recently
announced upcoming aircraft, as well as future tube and wing aircraft (“evolutionary technology”), such as the strutbraced wing or blended wing body; and open-rotor technology (“new configurations”), battery systems in lower seat
classes and hybridisation (“towards electrification”) and focused used of hydrogen-powered aircraft (“aspirational
technology”). Anticipated entry into service (indicated in Waypoint 2050 on page 48) is consistent within margins of

174 Grouped as “Innovating with aircraft technology”.
175 “Improvements in operations and infrastructure”.

176 “Investing in out-of-sector carbon reduction measures (offsetting)”.

184

NLR-CR-2020-510 | February 2021

plus or minus 5 years, but there may be differences in fleet integration (roll out of new models into the fleet) due to
aircraft size and ambition level following from aforementioned regional context.
Improvements in operations and ATM
Improvements in operations and ATM were modelled in more detail in Destination 2050, as more detailed information
was available for the region studied, compared with a global analysis. The 5 to 6% improvement potential noted here
fits between the ‘mid’ and ‘high’ improvement scenarios, leading to total CO2 emissions reductions of 3 to 6% for
2050. Also in terms of measures modelled, there is much overlap between Waypoint 2050 and Destination 2050 and
ATAG, too, notes operational and ATM-related improvement can make a notable benefit in the shorter term. The
Waypoint 2050 analysis also considered the incremental airline efficiency improvements from load factor as a
sustainability measure, whereas Destination 2050 includes it in both the reference and sustainability scenarios.
Sustainable aviation fuels
Waypoint 2050 has modelled four SAF scenarios, one baseline and three backcasting scenarios. The backcasting
scenarios show similar percentage ranging between 77-86% which is in line with the 83% share of SAF modelled in
Destination 2050.
Economic measures
Waypoint 2050 identified how much economic measures are needed to reach the 50% CO2 emissions reduction goal
after aircraft technology, operational measures and the use of sustainable aviation fuels have been implemented. It
notes that depending on the cost differential between SAF and the cost of offsetting, the use of SAF can be partly
replaced by out-of-sector carbon reduction. This might initially take the form of offsetting, but towards 2050 will be
based on carbon removal, using natural carbon sinks or dedicated technologies. The report does not specify which
part of emission reductions can be achieved by offsetting and carbon removal over the longer term: modelling such
economic forecasts at a global level and then individually for nearly 200 countries brings with it significant challenges
which were outside of the scope of Waypoint 2050. Destination 2050 makes an estimation of SAF supply until 2050.
The remainder of CO2 emissions are covered by economic measures to reach net zero in 2050.

185

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