Annual Report 2010-2011 Q6:Annual Report 2005-2006.qxd...Annual Report 2010-2011 3 Jonathon Counsell of BA called for UNFCCC regulation to enforce the goal of a 50% cut in net emissions

Air Travel – Greener by DesignAnnual Report 2010-2011

DESIGNbyGreener

GREENER BY DESIGN

Executive Committee Mr Simon Luxmoore Chief Executive Royal Aeronautical SocietyMrs Ros Howell Aviation Strategist West Sussex County CouncilProf Hugh Somerville Visiting Professor University of SurreyMr Geoff Maynard Managing Director Altra Capital LtdDr John Green Consultant Chief Scientist Aircraft Research AssociationMr Robert Whitfield Managing Director EnvirostratMr Charles Miller Principal Policy Analysis GroupProf Jeff Jupp Visiting Professor University of BathProf Ian Poll Technical Director Cranfield AerospaceProf Peter Bearman Senior Research Investigator Imperial College, LondonMr Roger Wiltshire Former Secretary-General British Air Transport Association

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Annual Report 2010-2011

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CHAIRMAN’S INTRODUCTION

Welcome to this 2010-2011 Annual Report from ‘Air Travel — Greener by Design’, or ‘GBD’ in short. GBD has now entered its second decade by being fully

incorporated within the governance of the Royal Aeronautical Society but with a guarantee of being able follow its primary purposes of providing independent

objective information and advice, and promoting balanced debate on the environmental sustainability of civil aviation.

Significant progress continued through 2010 towards achieving the ACARE 2020 environmental goals, although with some realism setting in that although the goals

are technically achievable and indeed could be exceeded, it will almost certainly take longer than 2020 and much determination by world authorities to get there.

ACARE has recently gone through a new visioning exercise (‘Flightpath 2050’) looking further ahead to yet more demanding goals to drive continued research in

Europe. Significant progress is being made on the powerplant front and we heard something about the major current research programmes in the GBD Annual

Conference in October 2010, summarised later in this report. It was, however, a mixed year on actually seeing step change improvements coming into service. Boeing’s

problems on the 787 have been well publicised and it now looks as though it may be into 2012 before it enters service with the significant improvements in fuel

burn and emissions that it will offer. Airbus is now in the detailed design phase with manufacturing starting on the A350 XWB project which offers similar

improvements, but are again facing the problems of introducing major technology improvements into the product and with the likelihood of a late 2013 entry into

service.

It is salutary to remember that all aircraft in service today were initially designed and optimised in an era when fuel prices were at or below $1 per US gallon.

With oil currently yo-yoing above $100 a barrel, aviation fuel costs are in the region $2.5-$3 per US gallon, that is three times the previous cost! As it is highly

unlikely that fuel costs will reduce significantly, particularly with the almost certain addition of an environmental levy in some way, the effect on optimisation of an

aircraft design will be dramatic and thankfully fully in line with the objective of reducing carbon dioxide emissions! In the 150-seater arena, Airbus has been first off

the mark in announcing its A320neo with new powerplants offering up to 15% reduction in fuel burn. With the announced increase in aircraft/powerplant price, this

development would almost certainly have proved uneconomic for the airlines at the earlier fuel cost but gives an advantage at current and future likely costs.

Biofuels have continued to attract significant attention and research investment (more in this report). Certification of a ‘drop-in’ 50-50 blend with fossil kerosene is

close to being achieved and full certification of a 100% drop-in fossil kerosene replacement is no longer a stopper. The emphasis is now very much on sustainable

feedstock which will not detract from fresh water resources or food production. However, the likely costs of production remain an issue and so the pressure on

airframe and powerplant research as well as operational improvements to reduce fuel burn very much remains the way to go.

Another welcome recent development has been the publication of several academic reports from the USA on the impact of Aviation on Climate Change, some being

referenced in this report.

In October 2010, GBD held a very successful ‘Round Table’ discussion on economic instruments and identified the need for further examination of the effects of

taxation and other instruments on the habits of the travelling public and as incentives to introduce new more fuel efficient aircraft. One conclusion was that

regulatory instruments were likely to be the more appropriate way of driving the necessary fleet replacements rather than taxation. There is also still support for an

open Emissions Trading Scheme and ICAO is slowly working towards world-wide agreement on some way to encompass aviation. However for the time being attention

is on the introduction of Aviation into the European Union ETS, with it really starting to affect the airlines this year with the first reporting of their ‘baseline’

emission levels. There will be some progress on this by the time of the GBD 2011 Annual Conference to be held on 18 October. This occasion is being designed as a

brief overview and update on all aspects of the effect of Aviation on Climate Change and to allow good time for panel discussion and comments from the floor —

which often seemed to be squeezed out of the agenda by presentation over-runs in my experience! We look forward to seeing you there!

Jeff Jupp

Acting Chairman

Jeff JuppActing ChairmanAir Travel Greener by Design

Published by the Royal Aeronautical Society, May 2011

Cover photo: Above: Airbus concept art of A320neo, Below: Boeing X-48B blended wing demonstrator in flight (NASA photo).

Air Travel – Greener by Design

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2010 CONFERENCE: GREENING OF AIRCRAFT PROPULSION

Instead of hosting its own annual conference, GBD was last year invited by the Propulsion Specialist Group ofRAeS jointly to organise an event focusing on propulsion technologies. Each group led two segments, with GBDdeciding to use a new format in which speakers were invited to give very short presentations, with detail beingadded in moderated group discussions.

The Propulsion Group’s segments focused on a review of progress in two major EC-funded technologydemonstrator programmes. The first, DREAM (valiDation of Radical Engine Architecture systeMs), is a three-yearEC Framework 7 programme with 44 partners. Uwe Fuss of Rolls-Royce gave an overview of the programmewhich has five major work packages, including open rotor technologies (see Fig 1) and alternative fuels. Progresshas been impressive with a large number of components built and tested and a number of the more complexrigs built and ready to begin their test campaigns.

Fuss also covered DREAM’s alternative fuels work package, demonstrating the detail needed to qualify fuels foruse in aircraft and discussing some of the characteristics of the fuels being trialled. Rigs have been designedand used to assess the potential impact on aircraft and engine fuel systems in addition to their combustioncharacteristics. The results shown during the presentation indicate that both of the alternative fuels under testare acceptable alternatives to standard kerosene but the problems of a sustainable supply of such fuels arestill a real issue.

We then turned to the 40 partner Framework 6 NEWAC project, concentrating on innovative engine coretechnologies. An overview was given by Jörg Sieber of MTU. Although longer-standing than DREAM, it works atlower Technology Readiness Levels and so the concepts could be seen as more futuristic. The second presentation,given by Andrew Rolt of Rolls-Royce, compared the different core technologies within the project. From themodelling and test work that has been completed he was able to show which had met the fuel burn targetsthey had been assigned. One of the key technologies that needs further work is that of high performance heatexchangers.

The intercooled recuperative engine (see Fig 2), covered by Stefan Donnerhack of MTU, is perhaps the mostambitious of the concepts considered in NEWAC. The promise of this technology for reducing fuel burn is high,and progress is promising.

The first GBD segment covered biofuels, with five presentations covering a comparison of environmental impactsof different biomass and algal fuels; current and projected production costs and the timeline for achieving cost-effectiveness; the path to the optimal biofuel; and whether biofuels will be seen as the industry’s environmentalpanacea, diverting manufacturers from accelerating development of next generation technologies.

In the first session, Dr Ausilio Bauen of E4Tech explained that they had advised the UK Climate ChangeCommittee that biofuels could meet 35-100% of global jet fuel demand in 2050 (Fig 3) with the potential forhigh greenhouse gas savings (Fig 4) if land use change from feedstock production is avoided, but that theramp up may be slower than other projections: ~1.6% by 2020. He compared the land use:emissions ratiosof a number of feedstocks (Fig 5), contrasting the negative lifecycle impact of palm oil with the positive outlookfor fuel using wheat.

Jeff Gazzard of the Aviation Environment Federation offered a contrasting view, pointing out that the CCC tooka more conservative view, projecting 10% use of biofuels by 2050. He referred to a recent OPEC forecast thateven with current trends of fuel intensity improvements by the aviation industry, fuel demand could increasefrom the current 5m barrels/day to 7.7m by 2030, suggesting that manufacturers of algal fuels lack the scaleto satisfy any more than a tiny fraction of demand. On a biomass-to-liquid fuel basis, forecast demand wouldrequire 254m hectares of woody energy crops. Providing it all by jatropha growing would require 477m ha or34% of the world’s total current current arable area and ,if satisfied by algae production, it would requirearound 31,000 algae plants of 1,000 ha each, taking up 31m ha or 2% of the world’s total current arablearea.

Greg Elders of EQ2 offered an outlook for commercialisation to 2025 (Fig 6) that, while more optimistic thanGazzard’s, nonetheless projected the biofuel sector’s ability to satisfy no more than 2% of demand. He offeredan analysis of production costs to 2030 (Fig 7), with the prospect of a price premium if sustained jet fuelprices in excess of $130/barrel are achieved.

Figure 1. Open rotor engine.

Figure 2. Intercooled reuperative engine.

Figure 3.

Figure 4.


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Jonathon Counsell of BA called for UNFCCC regulation to enforce the goal of a 50% cut in net emissions by2050. He believed that the global carbon price will be the key signal and that the greatest risk would be adrop in the avgas price for sustained periods.

Dr James Kinder of Boeing concluded the segment, outlining three production methods that are being tested:upgrading of pyrolysis oil from biomass; alcohols to jet fuel; and microbial hydrocarbon production.

The second GBD segment looked at incentivising accelerated development of NextGen technologies, with sessionscovering their anticipated climate change impact, the future of ACARE, and incentives. Dr John Green of GBDexplained the 20-25% limit for potential efficiency improvement in the Joule-cycle turbofan and set out someof the options, concluding that open rotors offer the most promising prospect for reducing CO2, with the externalnoise issues being manageable if passengers will accept lower cruising speeds and higher cabin noise. Dr RayKingcombe of BIS explained that the ACARE goals are around 65% on the way to completion by 2020,highlighting the importance of regulatory standards in incentivising improvement. Finally, a revealing presentationby George Dimitroff of ASCEND set out the significance of fuel price in driving new technology and the powerof leasing companies in determining its pace — they will, for example, consider maintenance cost to be almostas important as fuel burn.

At the time of publication, it is planned that the 2011 GBD conference will cover ‘Climate and environmentalchallenges — the way ahead’.

SUSTAINABLE AVIATION

Established in 2005, Sustainable Aviation is a coalition of UK airlines, airports, aerospace manufacturers and airnavigation service providers that work together to address the future sustainability of the aviation industry.SA’s third progress report, published in March 2011, can be found at www.sustainableaviation.co.uk along withspecific reports on work accomplished over the reporting period and other relevant information. SA bringstogether experts in their fields to help lead specialist work packages that address major sustainability challengesfacing the aviation industry in the UK. Recognising the long-term nature of the challenge, the SA approach isto concentrate on those areas where a co-operative approach can be most effective at the current time. Thisis designed to complement advances made within individual companies and sectors.

SA’s GoalsThese relate to the economic, environmental and social aspects of aviation and have been updated over thelast reporting period, without substantial change to the long term vision.

Goal 1: Social and EconomicA competitive aviation industry making a positive contribution to the UK economy, and meeting the needs ofsociety for air transport, while maintaining constructive relationships with stakeholders.

Goal 2: Climate Change Aviation incorporated into a robust global policy framework that achieves stabilisation of greenhouse gasconcentrations in the atmosphere at a level that would prevent dangerous man-made interference with theclimate system.

Goal 3: Noise Limit and, where possible, reduce the impact of aircraft noise.

Goal 4: Local Air QualityIndustry to play its full part in improving air quality around airports.

Goal 5: Surface Access Industry playing its full part in an efficient, sustainable multi-modal UK transport system.

Goal 6: Natural ResourcesEnvironmental footprint of UK aviation's ground-based non-aircraft activities is contained through effectivemanagement and reduction measures.

Figure 5.

Figure 6.

Figure 7.


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Goal 7: ImplementationFull industry commitment to sustainable development and communicating fully the role of aviation in societyin order to support a better understanding of its contributions.

How SA worksSA works through a Council comprised of representatives from the four subsectors: manufacturing, airlines,airports and NATS. Reporting to the Council are two groups: the Communications Group, and the Working Group(SAWG). There are subsidiary groups within the SAWG dealing with specific work streams. Representatives ofkey external organisations have joined a Stakeholder Panel that meets regularly with the SA Council.

Work over the past two yearsSpecific work areas over the past two years include:

■ Working with SA and other service partners to tackle the complexities of aircraft waste management anddisposal (see Fig 1).

■ Examining ways in which to reduce the environmental impact of aircraft arrivals and departures includingthe innovative testing of the “Perfect Flight”

See http://www.youtube.com/watch?v=UbuBtSY3MUs&feature=player_embedded

■ Reducing emissions of CO2 from aircraft on the ground (see Fig 2)

■ Publication of a briefing paper on Sustainable Alternative Fuels indicating the potential of such fuels butalso reviewing the conditions that must be met for sustainability, as well as some of the other issuesinvolved in bringing them to market.

■ A paper, aimed at decision makers outlining the interdependencies between noise, emissions of CO2 andNOX. As aircraft technology develops important decisions must be made on noise, NOX reduction and fuelefficiency options. This paper reviews the key considerations to be taken into account (see Fig 3).

Prior to the 2009 Copenhagen Climate Summit, SA published a manifesto supporting a Global Sectoral Deal foraviation. The SA view continues to be that this is essential to the long term sustainability of the industry.

The SA Manifesto — key elements of a Global Sectoral Deal■ be based on global targets for CO2 emissions from aircraft, consistent with ICAO’s recommendation

■ be based on full and open emissions trading

■ incentivise airlines to purchase sustainable low-carbon aviation fuels that offer net carbon reductions overtheir full life cycle

■ replace local, national and/or regional measures with a single, global framework which will ensure thataviation emissions are accounted for only once, whether from domestic or international activities, with noduplicative measures

■ look to establish an appropriate internationally-recognised life-cycle carbon model and sustainabilitystandard, as well as monitoring, reporting and verification procedures to be established to acknowledgethe lower life-cycle carbon footprints of these fuels.

■ require Governments to establish the right legal and fiscal frameworks to facilitate and increase investmentin the research and development of new technology designs for aircraft and aircraft engines, developmentof low carbon sustainable alternative fuels, and longer term options such as improvements in airspacemanagement

■ ensure that any revenues from economic measures should be clearly earmarked for environmental purposes

■ give ICAO a clear mandate and timetable for developing and implementing the detail of such an approach

SA also publishes a periodic newsletter. Recent articles include a report on the prospective incorporation ofaviation within the EU Emissions Trading System.

For further details of Sustainable Aviation go to www.sustainableaviation.co.uk

Figure 1.

Figure 3. Noise margin.

Figure 1. Recyclable cabin waste chart.

Figure 2. HRW ground movements emissions.

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BIOFUELS

The move towards biofuels for aviation was very sudden. It was looked at in the early part of the last decadebut seen as having limitations. There was then the surge of biofuels for non-aviation purposes and peoplestarted to reassess the potential of biofuels in aviation. They started to challenge the received opinion andadopt a more of a can-do approach.

A major hurdle was fuel certification. However certification of 50/50 BTL blend (50% biomass to liquid / 50%kerosene) was achieved in 2009 and ASTM, responsible for aviation fuel certification, is currently addressing thecertification of a 50/50 Bio-SPK (50% Bio-SPK or Hydrotreated Renewable Jet, and 50% kerosene) blend. Thishad been expected in 2010 but is now not expected before mid or late 2011 however. ASTM is now underfire from some impatient airlines but this delay and frustration needs to be seen against the fact that in 2008the expectation of fuel experts was that it might take ten years before biojet would be certified.

To take a horse racing analogy, certification might constitute the horses being put under starters’ orders. Thecontestants are different biofuels but they are all a combination of feedstocks and conversion processes (horses andriders?).

The biofuels currently in the lead, with commercial deals including volumes and start dates announced are theoil seed plants. These are camelina, an energy crop that grows in rotation with wheat and other cereal crops,and jatropha a perennial that can grow on poor land. The conversion processes involved are hydrogenation andFischer Tropsch. The projects announced to date are summarised in the chart in Fig 1).

This shows a build up to a production of 2.1bn gallons per year by 2020, representing 1.6% of global aviationfuel. Richard Altman from the Commercial Aviation Alternative Fuels Initiative (CAAFI), considers that 2011 willbe ‘a critical year for initial investment in production programmes’. This remains to be seen. But the race hasonly just started and there is a long way to go. There are many other horses in the race, including some witha lot of money running on them — and some are still in the stables.

The potential market is very large but the cost of fuel has historically been very low — compared with saya pint of milk or a bottle of water. The commercial challenge is therefore to develop biofuel feedstocks andconversion processes that can produce biojet at low cost, in large volumes and sustainably.

The one thing that the different biofuels have in common is that they start with living matter. The initial focuswas on lipids and this has led to a wide variety of feedstocks ranging from waste fat to oil seed annuals toalgae. While lipids have a significant future in biojet production, attention has not been limited to them, buthas also focused on sugars and now even protein.

Processes range from primarily physical processes such as pyrolysis, to fermentation to biochemical, genomicand microbial processes.

SustainabilitySustainability proved a fundamental weakness with first generation biofuels that were launched with little heedfor the carbon benefit. The widespread reaction to this approach spawned a variety of different initiativesregarding sustainability standards, one of the most respected of which is the Round Table for Sustainable Biofuels(RSB). In April 2011, the RSB is setting up a separate entity to start sustainability certification for specificbiofuels. A current weakness of the RSB standard however is that it does not yet address Indirect Land UseChange in a quantified manner since it does not consider that the science is yet available to support suchquantification.

What is needed, in terms of sustainability standards, is either one global standard or at least one coherentsuite of global standards. There are currently international feedstock specific initiatives such as the Roundtableon Sustainable Palm Oil (RSPO), the Better Sugarcane Initiative (BSI) and the Round Table on Sustainable SoyAssociation (RTRS). There are many national and supranational initiatives such as the Renewable Energy Directive(RED) in the EU, the Renewable Transport Fuel Obligation (RTFO) in the UK and the Social Fuel Stamp inBrazil. And there are international non-feedstock specific initiatives such as the Global Bioenergy Partnership(GBEP), the Green Gold Label, the IEA Task Force 40: FairBiotrade, the Sustainable Agriculture Network and theRound Table on Sustainable Biofuels (RSB). The RSB is establishing a robust, usable meta-standard andimplementation system for biofuel sustainability. It is supported by the Sustainable Aviation Fuel Users Group(SAFUG) and it currently seems to offer the best chance to provide that international standard that is sonecessary.


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The RSB latest version (Version 2.0) of its 12 principles and criteria for Sustainable Biofuel Production highlightsthe challenge faced in terms of key factors such as water, land and fertiliser. Each of the second generation/ advanced biofuels has their own approach to these challenges. With algae, the emphasis is on high landproductivity, with many algae companies focusing their attention on salt-water algae to avoid the impact onfreshwater. Halophytic plants are not as productive as algae but they do not require freshwater. They enablelarge areas of land to become productive, providing sustainable jobs in developing countries.

Where rapid growth rates occur, nutrients will need to be provided. Currently fertiliser represents one of thelargest fossil fuel components in the life cycle analysis of agricultural products and this will prove a challengefor many biofuel feedstocks. There is some scope for a systems approach however, producing the nutrients aspart of the system and this is being pursued by a number of companies.

AvailabilityThe availability of cost-effective feedstocks and fuels is the key, meeting the necessary sustainability criteria ata competitive cost.

■ Jatropha and particularly camelina are the feedstocks that are available today in some volume andproviding the bulk of the fuel for demo flights and other large volume testing. There have been someproblems relating to jatropha’s implementation and yield expectations; sustainable methods of productionare starting to emerge but water is likely to remain an issue.

■ Halophytes have offered near-term promise of sustainable biofuel though the realisation of that promisehas been somewhat delayed. Masdar Institute of Science and Technology (MI), and its partners Boeing,Etihad Airways, and Honeywell's UOP announced the completion in January of a Sustainability Assessmentof the Integrated Seawater Agriculture System (ISAS) for production of aviation biofuels and otherbioresources. In addition, a 20,000 hectare ISAS project has been proposed by New Nile Co on the RedSea coast.

■ Algae offer the greatest potential for sustainable biojet in terms of production per hectare. The keychallenge remains cost effective dewatering, and though progress is being made, commercial viabilityremains some years away. It is noteworthy that the technology that PetroAlgae appears to be successfullylicensing relates to the production and processing of diatoms (much larger than microalgae) rather thanmicroalgae themselves.

■ While the near-term focus of the above feedstocks relates to their oil content, they are all also sourcesof biomass. There is indeed a multitude of sources of biomass, ranging from specific biomass crops tofarm waste. British Airways is tapping one such source with Solena, namely municipal waste, benefitingfrom the very low (negative) feedstock cost. More broadly, there are sustainability and cost issues withbiomass but they tend to be focused more on factors such as transport costs and processing technology.There is a particular focus on the processing into biojet of the pyrolysis oil that can be obtained frombiomass.

It is notable that many of the biofuel companies are emphasising their co-products. This is in order to maximisethe overall revenue from the production process and thereby reduce the cost allocated to the aviation fuel. Asvolumes increase, there is a question as to whether the demand for those co-products increases at the samerate as that for the biofuel. If not, co-product revenues must be expected to fall as a percentage of totalrevenue, but hopefully by then the total production costs will be low enough for that not to be a major issue.

The debate continues as to when each feedstock will provide biojet that is competitive with kerosene. E4Techproduced a feedstock by feedstock analysis for the UK Committee on Climate Change but this ignores thepossible impact of Government intervention.

GovernmentsGovernments are heavily involved in biofuels. For instance, the EU’s Renewable Energy Directive requires thateach Member State shall ensure that the share of energy from renewable sources in all forms of transport in2020 is at least 10% of the final consumption of energy in transport in that Member State. This should bea powerful driver but it is not yet considered to have made a major impact. If the build up to the 10%threshold does not progress more rapidly than the current rate, care will need to be taken towards 2020 toensure that the sustainability criteria are not ignored in the surge to meet the deadline.

One significant area where Governments in Europe need to act is in relation to the relative incentives forbiofuel to go to road transportation versus aviation. Both transport sectors have the same 10% target by 2020,but ground transportation has electric cars as one option while aviation has no such sustainable alternativeBo

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available to it. Ground transportation’s need for biofuel is correspondingly reduced. It is Government’sresponsibility to ensure that the net effect of regulation, taxation and Emissions Trading takes due account ofthis need for rebalancing.

There remains the issue of whether regulation in relation to biojet fuel should be at the national, regional orglobal level. Many countries argue rightly that, as aviation is a global industry, so the regulation of an aspectaffecting competition such as biofuel should be regulated at the global level. In the past, however, sucharguments have often been with the implicit aim of no action being taken at all, given the difficulty in achievingconsensus on such issues within ICAO. ICAO acknowledges that if the use of alternative fuels is to be part ofa comprehensive strategy for minimizing the effects of aviation on the global climate, then regulatory andfinancial frameworks need to be established to ensure that sufficient quantities of alternative fuels are madeavailable to aviation. ICAO’s failure, at its triennial meeting last Autumn, to make any substantive move in thethree areas where it had set itself a target, was not encouraging. Nevertheless the SWAFEA report, a feasibilityand impact assessment due to be published in April 2011, that was trailed in a stakeholders meeting in Toulousein February, will apparently continue to stress this need for agreement at the global level (to avoid distortion),despite the reports strong emphasis on the need for action.

In the medium to long term, airlines are unlikely to wish to be seen as major polluters and biofuels offer theprospect of avoiding that charge. In the shorter term, there is some marketing advantage for airlines but thequestion is whether the airlines will be prepared to pay the price for this short-term marketing advantage.The projects will come but there may need to be more Government intervention to help pull them through,to help with the risk and enable suppliers to move down the learning curve. In terms of which feedstocks andprocesses will win out in the end, it is likely that there will be a diversity of winners, each responding to localconditions in terms of climate, location, labour availability and technological sophistication. This diversity willenable a number of countries to move towards fuel security, and this will provide an additional incentive.

SCIENCE AND TECHNOLOGY

Atmospheric ScienceIn its Report in 2005, the Science and Technology Sub-Group concluded ‘There is no higher priority in this fieldthan research into the impact of aviation on the atmosphere and climate’. It followed this with what it saw,from the perspectives of the aircraft and engine designer and the operator as three key questions:

■ How important relative to CO2 are the contributions of contrails, primary and secondary cirrus?

■ How important is the contribution of NOX emission, and how does its effect vary with altitude, latitudeand season?

■ What is the most appropriate measure of climate impact to guide the industry in its future designdecisions?

Last year’s Annual Report discussed at length some of the advances in this field in recent years, notably theprogress made in the EC FP6 Specific Support Action ATTICA. At the GBD Conference in October 2008, ProfessorKeith Shine of Reading University, in discussing the impact of NOX, offered the view that, if the aviationcommunity formulated a well-posed question, the scientific community would be able to provide an answer withappropriate error bars. There has been further progress this year and we appear to be nearing the point wherea balanced view of climate impact can be taken and can be a factor in future design decisions. With the keydecisions on the next generation of short and medium haul aircraft, the replacements for the A320 and B737families, not many years away, we believe there is an urgent need to sharpen our response to the threequestions above.

Metrics for the climate impact of aviationCurrent understanding can be illustrated by reference to two recent publications by Emily Dallara and colleaguesfrom Stanford University and MIT. The first paper, Metric for Comparing Lifetime Average Impact of Aircraft(1)addresses the third question. It is a substantial paper which discusses a range of possible metrics before puttingforward average temperature response (ATR) as its preferred candidate. ATR is the average temperature increaseat the surface of the Earth caused by the emissions of an aircraft or a fleet of aircraft over its operatinglifetime. The measure combines integrated temporal change with the possibility of temporal weighting. Itsvariation over time is illustrated in Fig 1. This shows the variation with time of the increase in the mean

Figure 1. Temperature change due to 30 years operation of a fleet of narrowbodyaircraft (no discounting of solid curves, 3% pa discounting of broken curves).


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surface temperature of the Earth due to the operation of a fleet of narrowbody aircraft operating over a 30-year period with an assumed utilisation of three million flights per year on an average route length of 1,000nautical miles.

The individual effects of the main greenhouse contributors are shown. ‘Net NOX’ is the effect of ozone createddirectly by NOX emission offset by the effect of methane depletion caused by the NOX and of the consequentialreduction in ozone formation by methane. ‘AIC’ is aviation-induced cloudiness and includes both linear contrailsand cirrus. The combined effect of emissions of water, sulphates and soot is shown to be relatively small.

The fleet is assumed to operate for 30 years and then cease but its impact on surface temperature lingerson. The metric allows the impact in future years to be discounted and Fig 1 illustrates two possibilities. Thesolid lines show the effect on temperature over 160 years with no discounting. The impact of the non-CO2emissions after the fleet ceases to operate is seen to decay away to near zero over the next 50 years, as theoceans and Earth slowly give up the heat absorbed during the time the fleet was in operation. The impact ofthe CO2, however, remains high with a value about one third of the temperature peak over the past 120 yearsshown on the figure. The broken lines show the impact in future years discounted at a rate of 3% per annumfrom the time the fleet ceased operation. In their paper on the use of the ATR metric in aircraft design(2), theauthors use two weighting options, the integral under the total temperature curve with 3% discounting andthe integral under the total undiscounted curve over a span of 500 years.

The calculation of ATR proceeds from a knowledge of fleet emissions as a function of time to a calculation ofradiative forcing (RF) and then of temperature response as functions of time. An important proposal in Ref. 1is that the effect of cruise altitude should be included in the calculation of RF. Figure 2 shows the variationwith cruise altitude of the radiative forcing factor s for the short-lived emissions, AIC and NOX (creating ozoneO3S and depleting methane and hence ozone, CH4 & O3L), where s is defined as the radiative forcing peremission at a particular altitude normalised with respect to the world fleet average radiative forcing. The linesin Fig 2 are derived from currently available data using atmospheric models with some simplifying assumptionsand are subject to significant uncertainties, as discussed in Ref. 1. Nevertheless, Figs 1 and 2 provide a rationalframework for assessing the climate impact of future aircraft designs, as discussed below under technology.

NOX, Contrails and CirrusOf the first two questions noted above, that on the impact of NOX remains subject to great uncertainty. Thewarming effect of the short-term generation of ozone by NOX is believed to outweigh the cooling effect ofmethane reduction but, when the long-term effect of ozone reduction as a consequence of the methane reductionis taken into account, the net radiative forcing by NOX emission appears to be substantially less than that ofCO2. However, the fact that the RF from the short-term creation of ozone is localised to the main flight corridorswhile the effect of the long-lived methane and ozone reductions are spread globally is a significant complication.The aviation community needs a better understanding of the effects of NOX at altitude before it can adoptmetrics such as that developed at Stanford(1) with real confidence.

That said, the impact of linear contrails and cirrus together — AIC — remains the most pressing question.In the 1999 IPCC Report the estimated radiative forcing from contrails alone, for the year 1992, exceeded theestimated RF from CO2. Later assessments based on climate models reduced the estimated contrail RFsubstantially but showed significant differences, mainly due to the large uncertainty in contrail optical depth.A recent study(3) has revised these estimates upwards, using a microphysical cloud-scale model to adjust theclimate model results and to capture more realistically the statistical variation of optical thickness. The resultis an increase in the estimated contrail RF by a factor of 3.3, bringing the authors’ estimate of RF in 1992to 11.6mW/m2 compared with the IPCC 1999 estimates of 18mW/m2 for CO2 and 20mW/m2 for contrails.

In 2010 Schumann(4) made a presentation to an ICAO colloquium in which he discussed recent progress inunderstanding and predicting the occurrence and evolution of contrail-cirrus. There is no doubt that progressis rapid, even though uncertainties remain high. Schumann’s estimate for the RF from contrail-cirrus was40mW/m2 with an uncertainty range of 20 to 70mW/m2. Given that these figures do not include linearcontrails, the total estimate of RF from AIC is well in excess of the RF from CO2, estimated as 25.3mW/m2 in2005(5). In Schumann’s words to ICAO, contrail cirrus contributes a large fraction to the aviation-induced climateimpact (comparable to 50 years of aviation CO2)

†.

Another DLR paper to the colloquium(6) discussed the critical dependence of persistent contrail formation oncruise altitude relative to the thin layers of supersaturated air in which they form and hence the potential ofavoiding contrail formation by adjusting flight altitude upwards or downwards depending on local conditions.

† In the April 2011 issue of Nature Climate Change, Burkhardt and Kärcher of DLR have published a paper entitled ‘Global radiative forcingfrom contrail cirrus’ in which, using air traffic data from the AERO2k inventory for the year 2000, they calculate a net radiative forcing fromcontrails and contrail-cirrus, including the consequential reduction of natural cirrus, of 31mWm–2.

Figure 2. Radiative forcing factor for NOX impacts and AIC.


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The paper proposed optimised flight planning to take account of current meteorological conditions — how toavoid being in the wrong place at the wrong time — which is something that has come up regularly at GBDconferences and was advocated in the 2005 GBD S&T report. A first test version of climate-optimised flightplanning, considering only contrails and CO2 (UFO), is already implemented within the Lufthansa Systems toolsand a more comprehensive solution (REACT4C) is to be tested during the next few years.

TechnologyA near-term advanceTwo new medium-sized high bypass ratio engines that have been in development over the past several yearsand have now found launch customers will begin to make a worthwhile contribution to the fuel efficiency ofshort and medium haul operations from 2016 onwards. The Pratt and Whitney PW1100 geared turbofan hasfeatured in earlier GBD Annual Reports, is the engine for the Bombardier CSeries aircraft due to make its firstflight in 2012 and in its PW1100G form will be one of the launch engines on the Airbus 320neo (new engineoption). The other engine offered on the A320neo is the CFM International LEAP-X, which is also the launchengine on the Chinese Comac C919 aircraft, due to enter service in 2016.

The A320neo (Fig 3) will be heavier than the current A320 and will have large winglets (Sharklets) to increaseits effective span and improve fuel efficiency by an estimated 3.5%. The new engines will be around 15% morefuel efficient than the current A320 engines but, being higher bypass ratio and therefore having larger diameters,they will entail a weight and drag penalty that will offset part of the gain from the engines. Nevertheless,Airbus is projecting a 15% reduction in fuel burn compared with the present A320 and, in addition, a significantreduction in noise.

Clean SkyThe build up of activity in the €1.6bn, seven-year EC Clean Sky Joint Technology Initiative has continued, withthe eighth call for proposals, the biggest yet at a total value of €32m, published in February 2011. Clean Skyis made up of six Integrated Technology Demonstrators (ITDs), of which the two with the widest potential toreduce climate impact are SFWA (Smart Fixed Wing Aircraft) and SAGE (Sustainable and Green Engines), bothof which involve substantial flight demonstrator programmes, mostly flown on Airbus test aircraft.

The main flight demonstrators will be flown in the period from 2013 to 2015. Even so, the first flight test campaignin the SFWA ITD began in September 2010. It involved the A380 MSN001 test aircraft with one of its enginessubstantially modified to incorporate an ‘Advanced Lip Extended Acoustic Panel’ (ALEAP), Fig 4. The purpose of thetests was to demonstrate in flight the acoustic and aerodynamic benefits already established in ground tests.

The most important flight demonstration in the SFWA ITD will entail the replacement of the wing sections onan A340-300, outboard of the outer engines, with full-scale natural laminar flow control (NLFC) wing sections.These will have aerofoil sections designed to achieve laminar flow over the forward upper surface of theoutboard wing without the use of leading-edge suction. The sweep of the outer wings will be reduced so asto avoid leading-edge transition caused by crossflow instability. Wings of this kind would be candidates forincorporation into a new aircraft design to succeed the A320 family in the time frame 2020–2025. No predicteddrag reductions have been published but a new wing of increased span and incorporating NLFC would constitutea major step towards achieving the ACARE target of a 50% reduction in fuel burn. Figure 5 shows a conceptaircraft to which NLFC would be applicable.

The other key ITD is SAGE, the two main components of which (SAGE 1 and SAGE 2) entail building and testingfull-scale counter-rotating open rotor (CROR) engines. SAGE is portrayed as the Clean Sky flagship ITD — agame-changing technology. Originally, two contrasting CROR architectures were to have been demonstrated inSAGE. The engine in SAGE 1, led by Rolls-Royce, Fig 6, will have contra-rotating rotors driven through an epicyclicgearbox, as on the P&W Allison 578DX demonstrator engine that flew on an MD-81 aircraft in 1989. The enginein SAGE 2, led by Safran (Snecma) was initially intended to have the same architecture as the GE36 engine— the original unducted fan (UDF) that first flew on a Boeing 727 testbed in 1986 and then on an MD-81in the following year, in which form it appeared, and created much interest, at the 1988 Farnborough air show.The UDF architecture avoids a gearbox by mounting the rotors directly on the casings of the counter-rotatingpower turbines. This has the attraction of simplicity and proved to be a viable architecture on the GE36.However, because of the mismatch between the optimal rotational speeds of the open rotors and the powerturbines, the UDF is rather less efficient aerodynamically than a geared arrangement where both rotors andturbines can rotate at optimum speeds. As a result the Safran plan has now been changed and SAGE 2 willalso be a geared engine.

Both engines will undergo full noise and performance evaluation on test beds and then one of them will beflight tested on an Airbus A340-600. In parallel, a low NOX combustor in-flight demonstrator could be addedto the Clean Sky programme in the near future.

Figure 3. Airbus A320neo.

Figure 4. Clean Sky Advanced Lip Extended Acoustic Panel (ALEAP) nacelle on anA380.

Figure 5. Clean Sky SFWA concept aircraft with natural laminar flow control.


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UTIAS workshopThe University of Toronto Institute of Aerospace Sciences (UTIAS) held its Second International Workshop onAviation and Climate Change in May 2010. This involved contributors from GBD, NASA, ICAO, IATA andrepresentatives from Government laboratories, Universities and the aviation and petroleum industries. There werefive papers on alternative fuels, papers reporting US work on laminar flow control (NASA), and US and Europeanwork on CROR (NASA with GE, DLR), and two papers from NASA reporting progress on the ERA (EnvironmentallyResponsible Aircraft) project, which has an annual budget of approximately $60m for the six years 2101 to2015, and the N+3 Advanced Transport Aircraft Concept Studies which is done within the $75m per annumNASA Fundamental Aeronautics Programme.

The NASA ERA Project(7) is in two phases, the first running through to the end of 2012 with overall completionin 2015. It does not entail such large-scale demonstrators as Clean Sky but has similar objectives in that it isaimed at aircraft that could enter service in 2025, involves participants from academia, industry and othergovernment agencies and aims to achieve substantial reductions in fuel burn, noise and NOX emissions. TheN+1 and N+2 objectives are defined respectively as Technology Readiness Level (TRL) 4-6 targets for 2015relative to a single aisle reference aircraft and for 2020 relative to a large twin-aisle reference aircraft. TheN+2 targets are very similar to the Vision 2020 goals of the ACARE Strategic Research Agenda, with the additionof a 50% reduction in field length requirement.

The key technologies investigated in the ERA project are similar to those in Clean Sky. The NASA presentationput considerable emphasis on PRSEUS (Pultruded Rod Stitched Efficient Unitized Structure), a technology whichis being developed in collaboration with Boeing and which appears to offer further weight reduction in an all-composite airframe. The reference aircraft for the N+2 studies is the Boeing 777-200LR. The advancedtube-and-wing design for 2025, which included hybrid laminar flow control on wings, tail surfaces and nacellesand riblets on the fuselage, was projected to reduce fuel burn by 42.5%. The hybrid wing body (HWB) design,which included hybrid laminar flow control on the outer wings and nacelles and riblets on the centrebody, wasprojected to reduce fuel burn by 48.1%. A later version of the HWB labelled 2025+, on which riblets werereplaced by laminar flow control by suction on the centrebody and which had embedded boundary-layer-ingesting engines, was projected to reduce fuel burn by 52.1%.

At present, the Boeing X-48B (Fig 7), an 8.5% scale model of a typical hybrid wing-body built by CranfieldAerospace, has successfully completed its 92-sortie investigation of the low-speed stability and control of thisconfiguration at NASA Dryden. The X-48C, a slightly modified version of the X-48B with its original threeturbojets replaced by two turbofans, is due to begin flight tests later in 2011 to investigate the noise shieldingprovided by a hybrid wing body.

The N+3 studies(8), which were aimed at TRL 4-6 by 2025 and had very ambitious targets for noise, NOX andfuel burn reduction, produced some highly imaginative proposals. Two typical configurations are shown in Figs8 and 9. The Boeing SUGAR Volt project, in which GE were partners, had a strut-braced wing of exceptionallyhigh aspect ratio. Its propulsion was a pair of ducted fans driven by hybrid gas-turbine/electric motors –assessed as a ‘game-changing’ technology. Of the four alternative concepts studied by Boeing, this offered thegreatest potential with a projected fuel burn reduction in the range 63-90% against the N+3 target of 70%.The projected fuel burn reduction for the MIT double-bubble medium-range configuration was 70.3%, ascompared with a 54% reduction projected for the hybrid wing-body long-range design in the MIT study.

The aircraft in Figs 8 and 9 are both slower than current aircraft, with cruise Mach numbers around 0.7. Theoptimum Mach number for a hybrid wing-body is significantly higher, making it commercially more attractivefor longhaul operations. NASA is therefore seeking to continue its work on this configuration and the idea ofa full-scale flight demonstrator, an ‘experimental vehicle testbed’ (XVT), Fig 10, is being promoted.

The reduction in fuel burn achieved by designing for a lower cruise Mach number is now becoming widelyrecognised. At the UTIAS workshop, Zingg and Martins(9) presented a paper on ‘High Fidelity Multi-DisciplinaryOptimisation for Future Aircraft Design’ which brought together advanced modelling of aerodynamics, structuresand propulsion systems in a multi-variate optimiser (see also Henderson et al (10)). The effect of the objectiveagainst which a narrowbody design is optimised is illustrated in Fig 11. The minimum fuel burn aircraft, withunswept wings and a lower cruise Mach number, is aerodynamically and structurally more efficient than theminimum-cost aircraft. Evidently, with progressively increasing fuel price, the shape of the minimum-cost aircraftwould evolve towards that for minimum fuel burn.

The minimum fuel burn aircraft has engines with high overall pressure ratio and turbine entry temperature,leading to NOX emissions in the landing and take-off (LTO) cycle more than four times those of the minimumLTO NOX aircraft. The minimum NOX aircraft has engines of appreciably lower pressure ratio and a rather largerwing, and burns approximately 15% more fuel than the minimum fuel burn aircraft. The Pareto trajectory of

Figure 6. Clean Sky SAGE 1 Geared counter-rotating open rotor.

Figure 7. NASA — Boeing X-48B 8.5% model of hybrid wing-body.

Figure 9. MIT Double-Bubble configuration for NASA N+3 study.

Figure 8. Boeing ‘Sugar Volt’ project for NASA N+3 study.


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fuel burn against NOX emission and the variation of the optimum configuration along this trajectory is shownin Fig 12. The optimum design evidently lies somewhere along this curve, where CO2 (fuel burn) is tradedagainst NOX to minimise climate impact, as discussed below under ‘cruise altitude’.

Design rangeFigure 13, taken from the Zingg and Martins presentation(9), shows the variation of payload fuel efficiency withdesign range for aircraft with two different design Mach numbers. It illustrates the fuel burn benefit of reducingcruise Mach number and also confirms, using a high fidelity multi-variate optimiser, the peak in fuel efficiencyat a medium design range that was derived in the first GBD technology report using an approximate parametricmodel. In that report, the potential fuel and cost saving of breaking long journeys into two or more stagesand using an aircraft designed for a range around that for peak fuel efficiency in Fig 12 were discussed. Thereport included in its conclusions the recommendation that a full system study be made of ‘the feasibility ofundertaking long-distance travel in stages not exceeding 7,500km’.

At the ICAS Congress in Nice in September 2010, Langhans et al of DLR(10) reported on just such a study. Itmade an analysis of all Airbus A330 and Boeing 777 scheduled flights in 2007 and considered how these routeswould be served by an A330-200 redesigned for shorter range, using existing airports for intermediate stopoperations (ISO). The report covered many issues that are beyond the scope of this report but its key findingswere:

■ An A330-200 type with design range reduced to 3,000nm would yield the highest global fuel savings,considering both ISO flights and shorter flights served in the conventional way;

■ Relative to operations with the current A330 and B777 fleets, the net present value of an ISO operationwith shorter-range aircraft, taking full account of all costs, would be about 8%;

■ A design range limit of 3,000nm would reduce fuel burn by 10.4% compared to the original directoperations mode, a saving of about 3.15m tons of fuel or 10m tons of CO2 per year.

In a longer version of the presentation by Zingg and Martins, which has been submitted to The AeronauticalJournal, Henderson et al (11) consider a 300-seat widebody aircraft design based on the A330-200 but optimisedfor a range of 1,500nm by reducing wing area, thrust, etc. The analysis suggests that, on a 1,500nm mission,it would be 13% more fuel efficient than the A330-200 and 5% more fuel efficient than two A320s on thesame mission. In another paper published in The Aeronautical Journal, Poll(12) analysed in detail the potentialsavings in fuel burn that follow from the snowball effect on aircraft weight of reducing design range. His workconfirms that, for travel over a distance of 15,000km, typical of the design ranges of the new generation oflonghaul aircraft, a maximum fuel saving of 28% could be achieved by a 5,000km design flying three equalstages. This would be with no change in the seating arrangement. Downgrading from three-class to two-classseating would increase fuel savings by a further 15% to give total savings in the range 40-45%. These are ofcourse idealised figures. The fact that the possible intermediate stops will not usually be on the great circlebetween the departure point and the destination, nor be equally spaced along the route, will result in gainsless the ideal. This is precisely what Langhans et al took into account in their study and the savings were stillsubstantial.

Informal discussion at the highest level indicates that the airlines and manufacturers are aware of both thefuel and cost savings that would result from a switch to a fleet of medium range aircraft and intermediatestop operations. They believe, however, that the travelling public, particularly the Business and First Classtravellers who generate most of the airline profits, will not accept intermediate stop operations. The fact thatneither Airbus nor Boeing currently offers a modern twin-aisle design with a maximum range of 3,000nm is afurther impediment. While it will be difficult to change the airlines’ business model in the foreseeable future,it is a fact that many routes shorter than 3,000nm are currently served by aircraft capable of at least twicethat range. The potential savings of serving these routes with a medium-range aircraft were noted in last year’sAnnual Report. The aircraft currently in service were designed when oil prices were around $35 a barrel. Itmight just be that the prospect of future oil prices sustained at a level of $100 a barrel or more could leadone or both of the major manufacturers to launch a medium range version of an existing aircraft. A fuselagestretch to allow passenger load to increase in exchange for reduced fuel load, at the same maximum take-offweight, might do it.

Cruise altitudeIn the conclusions of the original GBD technology report, another issue raised was the variation of climateimpact with cruise altitude. The scientific evidence indicated that climate impact could be reduced substantiallyby reducing cruise altitude, thereby reducing the impact of NOX emissions and possibly also of contrails andcirrus. However, re-optimising aircraft to cruise at lower altitudes and remain commercially competitive was aconsiderable design challenge and the atmospheric science at the time was not sufficiently robust to support

Figure 11. Narrowbody configurations optimised against different objectivefunctions.

Figure 13. Effect of cruise Mach number and range on fuel efficiency.

Figure 12. Pareto plot of fuel burn versus LTO NOX.

Figure 10. Image of proposed NASA Experimental Vehicle Testbed (XVT).


the case for it. Over the decade since the first GBD technology report was written there has been considerableprogress in the atmospheric science. Consequently, the paper on metrics cited above(1) has a companion byDallara and Kroo(2) which considers aircraft design to reduce climate impact; in this second paper cruise altitudeemerges as the key design variable.

The paper considers only aircraft equivalent to the Boeing 737-800 with the technology standard of an aircraftready to enter service in 2010. The method adopted was to use the ATR metric of Fig 1 together with thevariation with altitude of the forcing factor s, Fig 2, to perform a constrained design optimisation at a jet fuelprice of $2.25 a gallon ($94.5 a barrel). A set of 11 design constraints of the usual kind (range, field length,noise certification, etc.) were applied and optimum designs were generated that minimised the time-weighted ATRfor a fixed-cost penalty. Figure 14 shows the variation of ATR with operating cost penalty for two ATR discountrates, r = 0 corresponding to zero discounting and r = 3 corresponding to a 3% discount rate applied afterthe end of the 30-year fleet service life. The integration was carried forward for 500 years for both discountrates, the long time being necessary in the r = 0 case in order to capture the full decay of the CO2.

The baseline aircraft, which cruises at Mach 0.84 at 39,000-40,000ft at the beginning and end of a 1,000nmcruise, has been optimised for minimum total operating cost and is similar in layout to the first aircraft inFig 11. Each successive point on the curves is at a reduced cruise Mach number and altitude, marked on thefigure. The reduction in flight speed, and the consequent increase in block time and reduced utilisation, is theprimary cause of the increase in total operating costs. Initially the optimiser reduces only cruise Mach numberbut keeps cruise altitude unchanged. After the kink in the curves both cruise Mach number and cruise altitudeare reduced, wing sweep is reduced, span increased, fuel burn reduced and the impact of NOX and contrailsand cirrus reduced. The curve with zero discounting shows primarily the impact of the changes on CO2 emissions,the 3% discounted curve reflects also the non-CO2 effects. Evidently, optimising the next generation of aircraftto fly lower and slower could substantially reduce climate impact at the cost of a relatively small increase intotal operating costs.

The authors investigated the effect of a range of technologies to reduce climate impact further: open rotorpropulsion; natural laminar flow control; low NOX combustors; reduction of contrail formation by tactical flightpath management and inclusion of some bio-kerosine in the fuel mix. The authors also investigated the effectsof uncertainty on their conclusions. There is too much detail in the paper to cover here but Fig 15 shows theeffect of combining these technologies in a new design. Relative to the baseline aircraft A1, cruising at Mach0.84 at 39,000 to 40,000ft, the baseline aircraft with all technologies except bio-kerosine, G1, cruises at Mach0.69 at an altitude of 33,000–35,000ft and, at a 3% discount rate, has an ATR of 0.555 times that of theoriginal baseline aircraft, G2 cruises at Mach 0.63 at an altitude of 21,000–29,000ft and an ATR of 0.524relative to the original baseline.

Given the uncertainties that still exist in the climate impacts of NOX, contrails and contrail-cirrus, these graphsare indications of what may be achievable, rather than definitive statements. Even so, they suggest stronglythat the aircraft to succeed the A320 and B737 has the potential to reduce the climate impact of aviationsubstantially. The combination of oil and carbon prices and the business model of the airlines using theseaircraft will determine the key design decisions. There is much work still to be done. Nevertheless, the recentwork on climate metrics and design options points to a future in which slower, lower flying aircraft could playa key part in reducing the climate impact of aviation.

IncentivesWe see from Fig 14 that the climate impact of the generation of aircraft that succeeds the A320 and B737could have substantially less impact on climate per passenger-km without any new technology, simply by beingoptimised for lower cruise Mach number and altitude. With the inclusion of the technologies being studiedwithin the Clean Sky JTI, and with tactical flight path management to reduce contrail formation, Fig 15 showsthat greater reductions appear possible, exceeding the ACARE targets, at relatively low cost to the operator.

The idea of flying lower and slower will not appeal to the travelling public. And, although the reduction in fuelburn will be a cost saving, and any further increases in fuel price will give that greater weight, the calculatedreduction in utilisation due to reduced flight speed may make the operators also unwilling to embrace theidea. Without interest from the operators, the manufacturers will not launch such an aircraft. The challenge toenvironmental policy makers and regulators is to devise incentives or constraints that will lead the operatorsand manufacturers to opt for a significantly slower, lower flying aircraft when the next generation is launched.

REFERENCES1. DALLARA, E.S., KROO, I.M. and WAITZ, I.A. Metric for comparing lifetime average climate impact of aircraft, AIAA

J. accepted for publication 2011.2. DALLARA, E.S. and KROO, I.M. Aircraft design for reduced climate impact, AIAA Paper 2011-265.

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Figure 14. Current technology designs optimised for minimum climate impact.

Figure 15. Designs incorporating advanced technologies optimised for minimumclimate impact.

3. KÄRCHER, B., BURKHARDT, U., PONATER, M. and FRÖMMING, C. Importance of representing optical depth variabilityfor estimates of global line-shaped contrail radiative forcing, PNAS, 9 November, 2010, 97, (963), pp 19181-19184.

4. SCHUMANN, U. Recent research results on the climate impact of contrail cirrus and mitigation options, 2010,ICAO Colloquium on Aviation and Climate Change, 12-14 May 2010, Montreal.

5. FORSTER, P., RAMASWAMY, V., ARTAXO, P., BERNTSEN, T., BETTS, R., FAHEY, D.W., HAYWOOD, J., LEAN, J., LOWE, D.C., MYHRE,G., NGANGA, J., PRINN, R., RAGA, G., SCHULZ, M. and VAN DORLAND. Changes in atmospheric constituents and inradiative forcing, Climate Change 2007: The Physical Science Basis. Contribution of Working Group I tothe Fourth Assessment Report of the Intergovernmental Panel on Climate Change, 2007 CambridgeUniversity Press, Cambridge, United Kingdom and New York, NY, USA.

6. SCHUMANN, R.U. and SAUSEN, R. Climate optimized routing of flights, 2010, ICAO Colloquium on Aviation andClimate Change, 12-14 May 2010, Montreal.

7. COLLIER, F. Integrated System Research Program, Environmentally Responsible Aviation (ERA) Project, A NASAaeronautics project focussed on midterm environmental goals, 2010, Second UTIAS-MITACS InternationalWorkshop on Aviation and Climate Change, Toronto, 27-28 May 2010, http://goldfinger.utias.utoronto.ca/IWACC2/IWACC2/About.html

8. WAHLS, R., DEL ROSARIO, R and FOLLEN, G. Overview of the NASA N+3 Advanced Transport Aircraft ConceptStudies, 2010, Second UTIAS-MITACS International Workshop on Aviation and Climate Change, 27-28 May2010, Toronto, http://goldfinger.utias.utoronto.ca/IWACC2/IWACC2/About.html

9. ZINGG, D and MARTINS, J. High-fidelity multi-disciplinary optimization for future aircraft design, 2010, SecondUTIAS-MITACS International Workshop on Aviation and Climate Change, Toronto, 27-28 May 2010,http://goldfinger.utias.utoronto.ca/IWACC2/IWACC2/About.html

10. LANGHANS, S., LINKE, F., NOLTE, P. and SCHNEIDER, H. System analysis for future long-range operation concepts,2010, Paper 11.3.4, Second International Congress of the Aeronautical Sciences, Nice, September 2010.

11. HENDERSON, R.P., MARTINS, J.R.R.A. and PEREZ, R.E. Aircraft conceptual design for optimal environmentalperformance, submitted to Aeronaut J 2011.

12. POLL, D.I.A. On the effect of stage length on the efficiency of air transport, Aeronaut J, May 2011, 115,(1167), pp 273-282.

OPERATIONS

2010/11 has proved to be another difficult year for airlines. The pressure on airlines to cut fuel burn hasagain intensified during 2010, on account of the high oil price. The price of fuel has continued to rise duringthe first part of 2011, accentuated by domestic unrest in some key oil producing areas. The environmentalpressure on airlines to cut CO2 emissions has also intensified and 2011 will be the last year that airlines cansimply go out and buy more fuel. From 1/1/2012 aviation fuel in Europe will be included in the EuropeanETS system. While longer-term measures to cut fuel burn still remain an important part of the plan to curbaviation emissions, and remain the only realistic way to cut emissions substantially, the airlines are applyingconsiderable pressure to the aircraft manufacturers to come up with quick solutions. 2010 saw two significantdevelopments in this area. Airbus have devised a revised winglet (called a sharklet), which is now available onsome current Airbus models. It is claimed to cut fuel consumption by 3.5%. Some airlines have already orderedsharklet-fitted aircraft.

The second development, currently at an earlier stage of development, is the production of an electric motoron the undercarriage wheels. This would enable an aircraft that has landed to shut down its engines and taxiusing the electric motor powered by its APU. Given the taxi times and distances to stands at many Europeanairports, a significant fuel saving can be expected. It would also avoid the need for pushback tugs to enableaircraft to leave the stands, saving further fuel and a potential operational delay. It also provides an easy wayof taxi-ing out, provided the issues surrounding the later start-up of the engines can be overcome. The fuelsavings would be offset by the extra weight of the motor but initial results look promising. There will also bereduced CO2 emissions from the tow trucks, as they will be used significantly less.

Besides the fuel saving on landing, there are two other significant savings. First there will be a significantreduction in noise near taxiways and stands, helping to improve the airport noise footprint and, second, reducedfuel use on the ground will cut both the emissions of CO2 and NOX. This is especially important at majorairports, as the air quality, and NOX concentrations in particular, are close to (and in some cases, beyond)European limits. This development offers a realistic and practical way of bringing concentrations down (althoughthe problems associated with high levels of road traffic on the M4 and M25 at Heathrow will remain).

The big change next year for aviation is the extension of the existing European ETS system to include aviation.Although it has not yet cleared all the legal hurdles, the scheme in essence provides for existing aircraft


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Good

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operators to receive allowances equal to 97% of their emissions produced in 2004-6. The number of allowanceswill reduce to 95% the following year, necessitating airlines to buy more allowances (through the carbon tradingsystem) each year or reduce their emissions. Costs to the industry will rise, as at least 15% of the allowancesto be allocated will be auctioned. However this proposal has been criticised by some environmentalists, and theEU commission are currently reconsidering their position, and a final decision will not be announced until laterin the year. In addition, airlines may buy allowances from other (industrial) users, and they will need to do soif airlines are to continue to expand at historic rates. This could be expected to force up the price of theallowances significantly. Coupled with the increase in the costs of the Airport Passenger Duty last year (whichthe Government is not planning to reduce, despite aviation joining the ETS), the era of the cheap flight iscoming to an end.

This scheme has already had an impact. First, because some airlines, including British Airways, have startedbuying allowances (they do not have to be used in the year of purchase). Second, this is the last year thatnew routes can be launched without the additional expense of buying allowances to cover the resulting increasein CO2 emissions. So it will be more expensive to start a route in subsequent years. Third, it will put increasingpressure on airlines to eliminate underperforming routes, as if they are dropped, the need to buy so manyallowances will be reduced, so saving cost. Fuel burn on very short (regional) routes is the highest per km, onaccount of the high fuel required to take off, so the economics of these routes will be disproportionally affected.

The other significant development during 2010 was that several airlines undertook trials with Biofuels. The focushas been on the so called ‘drop in’ fuels, where no modification is needed to the engine, thus permitting aircraftto fill up on biofuels where these are available, and to use conventional fossil sourced fuels where they arenot. This flexibility is seen as key by the airlines, as otherwise the flexibility of their fleet would be reducedif only some aircraft could fly to certain destinations. It also enables biofuels to be produced from differentsources, depending on what is available and practical to produce locally.

Although the trials were judged to be a technical success, two problems remain: those of cost and availability.Cost of biofuels remains stubbornly high and well above conventional fossil fuels. The recent increases in fuelprice will serve to narrow the gap but even if fossil fuels increase to $150 a barrel, biofuels will still be moreexpensive. The introduction of the EU ETS scheme, referred to above, ought also to make biofuels more financiallyattractive but, unless the carbon price rises significantly above the current €12-14 a tonne of carbon emitted,then the effect will not be significant.

The availability of biofuels has also been a concern. Partly because the EU has stipulated that all fuel sold forcars should have a legally binding % of biofuel in it, the demand for and price of Biofuels has risen. It istherefore currently both difficult to obtain biofuels in the required quantities and at a reasonable price foraviation use. It should be noted that the stringent quality controls required for aviation fuel use is one of thereasons cited by fuel companies for their high prices.

The green credentials of aviation have been under attack for several years. This allowed the previous Governmentto introduce the APD, this Government to raise it, and next year ETS will have to be reflected in the economicsof aviation as well. There is an even greater need today for further research and development into how aviation,an essential component of 21st century business, can continue to expand while reducing its environmentalfootprint — Greener by Design.

ROUND TABLE ON ECONOMIC INSTRUMENTS

The Round Table was convened in September 2010 as part of the Market-Based Options Group’s long-termproject to establish the effectiveness of economic stimuli in influencing aviation’s environmental performance. 27organisations, covering Government, regulators, advisory bodies, carriers, manufacturers, and environmental NGOs,and consultants were invited and 13 accepted.

GBD has for four years been testing the conventional nostrum than cost increases would reduce demand, leadingto a reduction in capacity/frequency and a stimulus to renew fleet and develop more efficient aircraft. We tookas a starting premise the assumption that for taxes or charges to be considered effective they must

■ Stimulate a reduction in capacity/ATMs

■ Encourage an overall reduction in fuel burn

■ Stimulate fleet replacement with more efficient models (if available)

■ Stimulate accelerated commercialisation by airframe and engine manufacturers of more efficient technologies Rolls-

Royce.


Those tests have gone through three stages:

■ Desk research on elasticities, which following an examination of 128 studies, some frequently relied uponas the basis for subsequent elasticity calculations, found significant methodological flaws in most of them,with material omissions in others.

■ Interviews with a range of full service, LCC and charter carriers.

■ Observation of UK, European and US responses to a full economic cycle.

Which took us to provisional conclusions that

■ Only CAA (2005), DfT (2007) and possibly the MARKAL-ED and Dutch Aero models came close to producingelasticities based on reliable assumptions, but that even these may have overlooked important factors (forexample, the difficulty of measuring price sensitivity independent of all the other variables in the demandfunction; and the propensity/ability to adjust travel/holiday expenditure without affecting the air travelcomponent);

■ On the basis of observed responses to significantly increased fuel costs and then high fuel prices combinedwith an economic downturn, it would seem that for aviation-related instruments to make a significantdifference, they would need to induce the equivalent of replicating, on at least a medium-term basis, therecession of the past two years.

The Round Table participants were asked six questions: — how reliable are elasticity assumptions; how areprice and income elasticities expected to evolve; how have forecasts of environmental responses to stimuli (e.g.APD) compared with actual responses; can the response to fuel price spikes be regarded as an analogue for afuel tax (or any other tax/charge such as ETS, CO2 charge, etc.); if we had only experienced one of the doubleshocks of fuel price spikes + recession, what impact would that have had on ATMs/RPKs? What lessons can bedrawn from the economic cycle on the resilience of carriers/pax to cost/price increases; and what level ofnegative economic stimulus would be required to accelerate commercialisation of nextgen technologies/fleetreplacement?

A full note of the contributions is available at http://www.greenerbydesign.org.uk. The group confirmed GBD’sprovisional findings and concluded that:

■ Because a number of material factors (in particular countervailing issues and opportunity costs) are notadequately reflected in current models, assessment of the environmental impact of APD and the EU ETSmay be subject to a wide margin of error but such evidence as is available indicates that it is unlikelyto be significant at current tax and permit cost rates.

■ The models do not currently allow for the impact of migration where measures are imposed at a nationalor sub-regional level (or even where they are not global).

■ While the industry’s resilience to the intended stimulus of economic instruments may, at least in the shortto medium term, have been eroded by cost and capacity-trimming induced by a combination of a rise infuel price and recession, it is still likely to be the case that economic instruments (compared with, say,regulatory signals) are only likely to achieve material improvements in its environmental performance (see5. above) if they exert pressure close to that experienced between 2008-10. Further work is needed toestablish whether a focus on carbon pricing would achieve the best tradeoff between environmental benefitand economic detriment.

■ An element that was not considered when the GBD project was initiated was cross-elasticity between avgasand biofuels — i.e. whether it would be possible for instruments to be used to stimulate biofuelcommercialisation by increasing the price of kerosene (and possibly hypothecating revenues to subsidiseearly adoption of biofuels).

■ Economic instruments are unlikely to stimulate either fleet replacement or acceleration of nextgentechnology commercialisation. Regulatory standards are likely to be a more effective driver.

■ Although models take a long-term view, from the point of view of effectiveness within typical politicalhorizons, when economic stimuli are introduced is at least as important as their level. At times of economicoptimism, carriers and passengers are less sensitive to such stimuli.

The final stage of the GBD project will need to assess:

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NASA.


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■ how the industry absorbed/adapted to cost increases and demand reductions;

■ the extent to which it did so rather than react directly to APD/fuel price/economicdownturn;

■ the ‘new’ industry/market model and its sensitivity;

■ differences in likely airline/passenger responses to passenger taxes, ETS, carbon pricingand fuel taxation;.

■ the market conditions/signals that economic instruments must seek to replicate.

Boein

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Air Travel – Greener by Design draws on the expertise of industry and academia.Any views expressed in this report are those of Greener by Design and do notnecessarily represent the view of the Royal Aeronautical Society as a whole.

For further information contact:Air Travel – Greener by DesignRoyal Aeronautical SocietyNo.4 Hamilton PlaceLondon W1J 7BQ, UKTel: +44 (0)20 7670 4300Fax: +44 (0)20 7670 4309www.greenerbydesign.co.uk

We are grateful for the support the Department for

Business Innovation and Skills gives the Greener by

Design initiative.

Annual Report 2010-2011 Q6:Annual Report 2005-2006.qxd...Annual Report 2010-2011 3 Jonathon Counsell of BA called for UNFCCC regulation to enforce the goal of a 50% cut in net emissions

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