The “easyJet ecoJet”: to cut CO2 emissions by 50% by 2015


EasyJet: The Story of England's Biggest Low-Cost Airline
EasyJet has today become the first airline to outline the environmental requirements that must be met by the next generation of short-haul super-clean aircraft; and unveiled its design of what such an aircraft could look like for operation by 2015.



Dubbed the “easyJet ecoJet”, the aircraft would need to be 25% quieter and would emit 50% less CO2 and 75% less NOx than today’s newest aircraft (the 737 and A320 families of aircraft).



The aircraft will incorporate the latest research by airframe and engine manufacturers around the world – all of which can be incorporated into an aircraft that should be in operation by 2015. The projection for the 50% CO2 reduction is based on the findings from the latest research by the industry leaders and will come from the engines (25%), the lightweight airframe (15%) and from improvements to air traffic control technology and design (10%).



In easyJet’s current configuration and operation, the projection for the eco-liner would generate less than 47g of CO2 per passenger km. For comparison, easyJet’s current operations generate 97.5g of CO2 per passenger km, the Toyota Prius emits 104g of CO2 per kilometre; and the European car industry has recently been given a target to achieve 130g of CO2 per kilometre.



The design will contain a number of key features to make it radically more environmentally efficient:



Rear-mounted “open-rotor” engines offer unrivalled environmental performance for short-haul flying due to their higher propulsive efficiency. However, there are significant difficulties in fixing such a large engine under a wing of a narrow-body aircraft, making rear-mounting of the engines the optimum solution. A lower design cruise speed to reduce drag and a shorter design range to reduce weight. Noise reductions are expected to come from a gear box between the engine and the open-rotor blades keeping them subsonic during take-off and landing, the use of the rear empennage to shield the ground from engine noise, and airframe improvements (such as no slats on the front of the wing). The airframe will be made of advanced weight-reducing materials similar to those used in current projects like the Boeing 787, which itself is estimated to be 27% more fuel efficient than the aircraft it will replace in many fleets



Even as global demand for air travel matures over time, several step-changes in technology will be needed to reduce the emissions from aviation in 2050 to below 2005 levels. The “easyJet ecoJet” will be the first of these step changes and alone could lead to a stabilisation of emissions from short-haul aviation at 2005 levels until 2035 providing massive environmental benefits.



Speaking at a press conference to unveil the “easyJet ecoJet”, Andy Harrison, easyJet Chief Executive, said:



“The aviation industry has an excellent record in reducing the environmental footprint of aircraft. Today’s aircraft are typically 70% cleaner and 75% quieter than their 1960s counterparts. Now we are planning the next generation that will help towards taking the plane out of the emissions equation”.



“EasyJet is already setting the environmental standard in the airline industry. Our fleet of 131 aircraft has an average age of only 2.3 years – the youngest of any major airline in Europe. We have recently called for over 700 of the dirtiest aircraft to be banned from Europe’s skies and are active supporters of the EU’s Emissions Trading Scheme and Single European Skies programme”.



“The aircraft example we have unveiled today represents the next major step forward in airframe and engine technology. The lightweight structure and open-rotor engines are based on technologies that are being developed right now by the major manufacturers. The “easyJet ecoJet” is realistic and it is achievable. If the “easyJet ecoJet” were to be made available today we would order hundreds them for fleet replacement and to achieve the ‘green growth’ that our industry has committed to”.



The easyJet ecoJet - Question and Answer



Q: What is the environmental performance that easyJet is calling for and how will this be delivered?

A: Modern aircraft cost tens of millions of dollars and have economic lives measured in decades. Developing the next generation of short-haul jet aircraft will require billions of dollars of investment – something that will not be repeated for another generation. It is not worth electing to make this considerable investment unless the environmental benefits (which equate to economic benefits for the airlines) are significant.



The easyJet ecoJet should deliver 25% less perceived external noise, 50% less CO2 and 75% less NOx per passenger km compared to a new aircraft built in 2000 (the ACARE reference year). There is a fundamental tension between the individual ACARE environmental targets (for example, the CO2 performance can be improved by increasing the engine combustor temperature, but this generates more NOx) and easyJet believes that the focus should be on solving the CO2 target (as the global warming impact of CO2 is measured in decades whereas some of the non-CO2 effects of aviation have impacts measured in days) while achieving the best possible outcome for the other two targets.



The CO2 reductions are expected to come 25% from the unducted fan engine, 15% from the airframe and 10% from air traffic control improvements. The European Council recently confirmed that the implementation of the Single European Sky and SESAR projects for the optimization of air routes and air traffic management to be a further key element of a comprehensive approach to reducing aviation greenhouse gases and easyJet is an active supporter of these projects.



The noise reductions are expected to come from a gear box between the engine and the open rotor blades to keep the tip speeds subsonic during take-off and landing, the use of the rear empennage to shield the ground from engine noise, airframe improvements (such as no slats on the front of the wing) and ATC improvements (e.g. steeper continuous descents).



The NOx reduction is expected to come from improved combustor technology within the engine, combined with a lower requirement for installed thrust.



Q: What is the ACARE program and what are its environmental goals?

A: Launched at the Paris Air Show in June 2001, the main focus of the Advisory Council for Aeronautics Research in Europe (ACARE) is to establish and carry forward a Strategic Research Agenda (SRA) for aeronautics research that will influence all European stakeholders in the planning of research programmes, including national and EU programmes, in line with the associated Vision 2020 and the targets it identifies.



With a budget of €1.075 billion allocated to the ‘Aeronautics and Space’ thematic priority, out of a total €13.345 billion for ‘Focusing and Integrating Community Research’ in Framework Program 6 (FP6), ACARE is now regarded as the most advanced of the “Technology Platforms”, which are organizations aimed at providing a framework for the definition of research and development priorities, timeframes and action plans in key industrial sectors.



The headline objectives to be achieved through the implementation of ACARE’s SRA include the challenge of meeting continually rising demand or air travel whilst demonstrating sensitivity to society's needs by reducing the environmental impact of the manufacture, operation and maintenance of aircraft. The specific environmental targets are for an aircraft manufactured in 2020 to achieve 50% and 80% cuts in CO2 and NOx emissions per passenger km respectively, and a reduction of perceived external noise by 50%, all relative to a baseline of the best technology aircraft available in 2000. As the ACARE targets are so well established and accepted in the industry, easyJet has elected to define its environmental requirements in the same format



Q: What impact will the easyJet ecoJet have on emissions from aviation?

A: Considering fuel is such a considerable proportion of operating cost, airlines already have a strong incentive to be as environmentally efficient as possible – assuming they are profitable enough to invest in the acquisition of new aircraft.



With a 50% reduction in CO2 and a 75% reduction in NOx emissions per passenger km, the easyJet ecoJet delivers a step change in environmental performance. The current scientific understanding of the non-CO2 effects of aviation is rated as being ‘poor’ or ‘fair’ but, using the latest scientific knowledge, the easyJet ecoJet should deliver a 60% reduction per passenger km in the total (CO2 plus non-CO2) atmospheric environmental effects of each flight.



Even as global demand for air travel matures over time, several step-changes in technology will be needed to reduce the emissions from aviation in 2050 to below 2005 levels. The “easyJet ecoJet” will be the first of these step changes and alone could lead to a stabilisation of emissions from short-haul aviation at 2005 levels until 2035 providing massive environmental benefits.



Q: How realistic is this?

A: This is realistic and it is achievable. The aircraft will incorporate the latest research by airframe and engine manufacturers around the world – all of which can be incorporated into an aircraft that should be in operation by 2015. The projection for the 50% CO2 reduction is based on the findings from the latest research by the industry leaders and will come from the engines (25%), the lightweight airframe (15%) and from improvements to air traffic control technology and design (10%).



We also need the appropriate policy frameworks that will provide the right incentive structure (the European Union’s Emissions Trading Scheme); an efficient operating environment (the Single European Skies programme) and avoids local taxes that hinder the airline industry from investing in research and technology.



Q: How will the environmental performance of the easyJet ecoJet compare with other forms of transport?

A: in easyJet’s current configuration and operation the easyJet ecoJet would generate less than 47 g CO2 per passenger km. For reference, this is 23% less than current average CO2 emissions per passenger km from rail journeys in the UK and the average CO2 emissions per passenger km from car journeys in the EU are more than double this .



Q: Why does the aircraft have unducted fan (open rotor) jet engines and why are they at the back of the aircraft?

A: The environmental performance (fuel efficiency) of a modern jet engine is related to the mass of air that the fan can move, which is driven by the rotor diameter of the fan blades - the larger the fan, the greater the propulsive efficiency. Conversely, containing such a large diameter fan in a casing would have significant weight and drag penalties. Current research indicates that, in the short-haul sector of the market, unducted fan (open rotor) engines offer unrivalled environmental performance due to their higher propulsive efficiency. However, there are significant design penalties in fixing such a large engine under a wing of such a small aircraft, making rear mounting of the engines the optimum solution.



Q: What should the range of the easyJet ecoJet be?

A: At present the median sector length in the short-haul market is around 500 nautical miles (~900 km) and 98% of all commercial flights in the 120-240 seat segment are below 2,000 nautical miles. Therefore the design range of the easyJet ecoJet should be 2,000 nm or less – reducing the design range reduces the weight and size of the aircraft. For the minority of customers who fly routes beyond 2,000 nm an ‘ER’ version can be developed (with additional fuel tanks and a lower seating density or payload capability).



Q: When should it be built?

A: developing and validating new technology takes time, so an entry into service of 2015 is practical if the industry starts research and technology programs now (including using structures such as the European Union’s Seventh Framework Programme for research and technological development - FP7). This should allow a full development program launch in 2010, followed by a 5 year development and flight testing program and an entry into service in 2015



Q: How many seats will the easyJet ecoJet have?

A: The easyJet ecoJet will form a family of aircraft from 150-250 seats in single class configuration (130-220 seats in 2-class).



Q: What will the easyJet ecoJet be made of?

A: The easyJet ecoJet will be manufactured from advanced weight reducing materials. As a short-haul aircraft, the exact composition of the easyJet ecoJet will largely be driven by issues of industrialisation: as some version of the easyJet ecoJet will remain in production beyond 2040 the industrial requirement will be to produce more than 60 aircraft a month. One would expect the wing to be manufactured out of carbon fibre.



Q: Why is the wing swept forward?

A: In addition to engine efficiency and weight reduction, one of the primary methods of reducing fuel burn is by reducing drag. Conventional jet aircraft currently suffer increased drag from turbulent airflow over their wings. A wing profile that allows the easyJet ecoJet to maintain laminar flow over a significant proportion of the wing will greatly reduce cruise drag.



Giving the wing a slight forward sweep increases the proportion of laminar flow over the wing (as the clean airflow from the wingtip tends to flow to the wing root in contrast to the turbulent air from the fuselage being dragged across the wing with conventional reverse sweep). In addition, it improves the stall performance of a laminar flow wing. Minimising drag is imperative in the design of glides and most gliders with laminar flow wings also have a slight forward sweep to the wing.



Q: How much will the easyJet ecoJet cost?

A: new production techniques and the volume of production should allow the easyJet ecoJet to be produced for less than the current generation of short-haul aircraft.



Q: When someone manufacturers the easyJet ecoJet (or an aircraft that can match or exceed its environmental performance), how many will easyJet buy?

A: easyJet currently has 131 aircraft in service and continues to grow at 15% per year. As a consequence, easyJet potentially will have a fleet requirement for both replacement and growth of 500 aircraft by 2015.



Q: How fast will it fly?

A: The requirements of a laminar flow wing will dictate a slightly slower design cruise speed – Mach 0.75 compared to Mach 0.78/0.79 for today’s conventional designs. On the average short haul sector this would add 3-10 minutes to the flight (imposing a financial cost on the airline), but it is anticipated that air traffic control improvements and faster turn around times on the ground will compensate for this increase in flight time



Q: How efficient will the easyJet ecoJet be on the ground?

A: The easyJet ecoJet will have at least 3 full size doors, allowing airlines such as easyJet to board passengers through all three doors, speeding up turn around times. Even boarding from a single jetbridge connected to door 2 (the central pair of doors) will speed up boarding times, as passengers would be able to head either up of down the aircraft upon entrance (instead of forming a single queue once inside the aircraft). The easyJet ecoJet will also be a more autonomous aircraft, requiring less ground equipment (e.g. as the fuselage is closer to the ground, a belt loader will not needed for the bulk loading and unloading of baggage).



Q: Will the cabin of the easyJet ecoJet have one aisle or two?

A: In the short haul sector a single aisle is more environmentally efficient (less drag). One wide aisle (wide enough for two passengers with hand luggage or two catering trolleys to pass each other) will probably achieve shorter turn around times on the ground, as well as better in-flight service in the air, compared to two narrower aisles.



Q: Who will build the easyJet ecoJet?

A: easyJet is working closely with all the relevant airframe and engine manufacturers on the next generation of short-haul aircraft. easyJet’s suppliers have become used to the challenging demands an innovative company such as easyJet places on them and easyJet is confident that the future supply of aircraft and engines in the short-haul sector will remain competitive.



Q: How high will the easyJet ecoJet fly?

A: The easyJet ecoJet will fly at the same altitude as current short-haul aircraft. However, the most fuel efficient climb profile to cruise altitude may be different.



Q: The current generation of aircraft are sold out for years to come. Why should the manufacturers invest in new technology now?

A: Manufacturers normally replace product lines when the market place indicates to them (via declining sales) that the product is no longer competitive. easyJet operates the latest versions of both the Boeing B737 and Airbus A320 family aircraft and their environmental and operational performance are similar. As such, neither product line can create a compelling enough argument to airlines at the exclusion of the other. In addition, global manufacturing capacity has not kept up with the growth of the sector as new markets in the developing world have opened up.



‘The market’ will therefore not give the manufacturers the usual signals that airlines need a new product. This is why customers such as easyJet must inspire the manufacturing sector to develop new offerings.



Q: Should research and technology focusing on conventional engine architectures continue?

A: Much of the research will be common (e.g. core and combustor). Concerning fan and gearbox technology, easyJet believes the immediate focus in the next 2-3 years should concentrate on unducted fan technology, with research into improving conventional jet engine architectures being retained as a ‘plan B’ option.

Source: Easyjet

PT Comment:  
Great to see that easyJet is making an investment and commitment to the environment. No doubt it will pay dividends in the future.

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