This article is part of our special report Greening aviation.
SPECIAL REPORT / Revolutionary changes in aircraft engines, coupled with more streamlined aircraft designs, are making flying cleaner as the industry aims to slash carbon emissions by half in the decades ahead. EurActiv reports from the Farnborough International Airshow.
One promising development that is supported by a European Union research programme is the open rotor engine that can propel an aircraft with up to 35% more efficiency than the conventional jets used today.
But there’s a huge drawback: the counter-rotating propellors, which look like a twin set of twisted fan blades, are noisy. Researchers who tested similar engines more than 30 years ago had to shelve plans for commercial development in part because of their ear-piercing sound.
The open rotor technology is symbolic of the challenges faced by both policymakers and the airlines in trying to solve one environmental problem without creating another. The drive for the use of biofuels in aviation has, for instance, spurred concerns amongst environmentalists that when the impact of production is included, plant fuels do little to reduce greenhouse gas emissions.
What is clear is the need to improve efficiency to reduce the costs of complying with EU emissions rules and to meet aviation industry commitments to cut carbon emissions to 50% of 2005 levels by mid-century.
“Operational efficiency is the Number One thing to improve profitability and competitiveness,” Ray Conner, the new president of Boeing’s commercial airplanes division, told journalists at the Farnborough International Airshow in Britain on Monday.
Lighter and more streamlined
In trying to meet those goals, aircraft manufactures have turned to lighter and more durable metals like titanium, sleeker aircraft designs, slimmer seats and even low-energy lightbulbs to save fuel. But above all, engines have to do more with less.
Backed by the EU-aviation industry Clean Sky partnership to promote greener flying, companies like Snecma, a division of France’s Safran Group, and Britain’s Rolls-Royce are testing open rotor engines to ensure that they are safe – and quiet.
They are part of the growing technology field aimed at improving efficiency and lowering aviation emissions as the industry grows in the decades ahead. Already, revolutions in engine technology, streamlined wing and fuselage design and lighter component parts have helped reduce fuel use by 30% since 1990, according to Sustainable Aviation, an industry organisation in Britain.
Environmental concerns alone are not driving changes – many European and American airlines are struggling to squeeze out profits as passenger numbers level off in turbulent economic times, and cutting fuel cost is a quick way to bring down expenses. They are also concerned about long-term stability of fossil fuel supplies as global demand for passenger travel grows.
A boom market
Both Europe’s Airbus and Boeing, the leading American aircraft maker, project a surge in production in the next 40 years, driven by growing passenger numbers in emerging countries and the need for airlines in the traditionally dominant markets of Europe and the United States to replace older, less efficient airplanes.
Boeing’s newly published Current Market Outlook projects that world airlines will need 34,000 new aircraft by 2031, up from 19,890 in service today and more than five times the number of passenger aircraft in service in 1977.
The US market research firm Forecast International, in a reported released at the Farnborough air show, estimates that 14,655 new large airliners will be needed over the next decade, with Airbus and Boeing battling for much of that market.
More economical aircraft are not the only way to lift profits while lower pollution. Europe’s plans to consolidate national air traffic control systems would reduce flight delays and improve environmental performance – although the EU’s signature programme to improve traffic management, the Single European Sky, appears to be well off target.
Aviation industry officials have told EurActiv that the European Commission is likely to propose a revamp of the Single European Sky as early as next year, in effect conceding that the earlier plans were too ambitious.
Meanwhile, passenger airlines continue to look to their suppliers for innovations to boost efficiency. Lighter but more durable metals like titanium used in engines, landing gear and fittings have helped reduce aircraft weight. Arch-rivals Airbus and Boeing say the newest versions of their traditional workhorse aircraft – the A320neo and Boeing 737 Max – will deliver double-digit improvements in efficiency.
Engine for the future
But technologies like the open rotor are not likely to show up on aircraft anytime soon. Aircraft would have to be re-engineered and designed to accommodate their rear-mounted propellers. Their use would also be limited to single-aisle aircraft rather than the larger, continent-hopping jets that emit more carbon gases.
And solving the noise problem could take time. Aside from the research taking place in Europe, the US space agency NASA, in a report released last year, concluded that despite efficiency advantages of open-rotor technology, noise presented a significant setback with current technology.
Safety issues also remain a concern. Ian Lane, who heads the stress methods and expertise for Airbus in Britain, says aircraft would have to be redesigned to handle the impact of flying fragments should an engine break apart in flight – a rare but not unprecedented occurrence.
Still, he says design changes in future models can be made to ensure safety and the efficiency of open rotors.
“Our customers need reliable aircraft that work today. We don’t force technology on a customer. But, he said at an innovation exhibition at Farnborough, “every new airframe is an opportunity to incorporate new technologies.”
“Efficiency is … economic return to the airline, so they have every incentive to absolutely minimise the amount of fuel burn and CO2 produced,” Alan H. Epstein, vice president of technology and environment for Pratt & Whitney, told EurActiv in an interview.
Boeing has completed assembly of an American Airlines, Next-Generation 737-800 - known as the ecoDemonstator - to be used as a flying test bed for validating environmentally progressive technologies, the company said in a statement from the Farnborough International Airshow in England.
"The goal of the ecoDemonstrator programme is to accelerate integration of these technologies for more fuel efficient, quieter, cleaner, more advanced sustainable material solutions for the future," said Jeanne Yu, Boeing Commercial Airplanes director of Environmental Performance. "Demonstration programmes give us a platform for better learning about new technologies in application. This helps us incorporate these technologies more rapidly."
Airbus officials welcomed the announcement of an 8.1 billion budget for the EU’s seventh framework programme announced by EU Commissioner for Research, Innovation and Science, Máire Geoghegan-Quinn. The budget includes more than 400 million for aviaiton projects including the Clean Sky programme.
Axel Krein, head of research and technology at Airbus, said in a statement: “We believe that the leveraging approach of FP7, which matches public and private resources, is an essential tool in stimulating European competitiveness and ensuring the region’s technological leadership for years to come. A €100-million investment in R&T in the aeronautics sector is estimated by governments and institutions alike to raise GDP by €700 million over 10 years, driving as it does real innovation. Aeronautic R&T also has significant positive spin-offs that spur technological breakthroughs in many other industrial sectors."
The aviation industry wants to save costs and cut their carbon emissions to comply with polices like the EU’s Emissions Trading System. The industry aims to improve fuel efficiency by an average of 1.5% per year in order to halve emissions by 2050 from 2005 levels.
Doing so won’t be easy with passenger traffic forecast to double in two decades. The Air Transport Action Group, a Geneva-based industry group, estimates that the number of people flying will rise from 2.7 billion today to 5.9 billion in 2030. That will require more than 45,000 aircraft, more than twice the number in service today.
While carbon dioxide emissions from passenger airlines account for some 2% of the total, aviation emissions are growing at 6% to 7% per year in the EU, according to Friends of the Earth Europe, an environmental group. An Organisation for Economic Cooperation and Development transportation report shows that aviation carbon emissions in the EU-15 rose 85% from 1990-2007, a time of liberalisation and surging passenger traffic.
- European Commission: Clean Sky
- Industry and trade associations
- International Air Transport Association: Environment
- International Air Transport Association: State of the industry speech
- Air Transport Action Group: Powering the future of flight European Petroleum Industry Association: White Paper on Fuelling EU Transport
- NASA: Initial Assessment of Open Rotor Propulsion Applied to an Advanced Single-Aisle Aircraft
Business and industry
- Transport and Environment: Aviation