Aviation has been one of the more difficult areas for emissions-reduction technology. After a period of rapid advance, the basics of aircraft design have changed very little in recent years. Evolution has focused on passenger experience and on radar, with little attention to emissions reduction. As a result, aviation causes great concern for those who want to tackle climate change.

Although aviation’s contribution to global emissions is small, at 2%, it is on the up and is projected to rise by 3% by 2050. While technological advances could reduce emissions without dramatic changes in consumer behaviour in many sectors, campaigners argue that the only way to reduce aviation emissions is for people to take fewer flights.

There have been some small triumphs. The annual GreenTec awards now has an aviation category, and this year’s winner was European plane manufacturer Airbus. It won the award for a project to develop a fuel-cell battery that would allow planes to be powered by electricity while they are on the ground, avoiding the need to use their engines. The Airbus battery uses hydrogen fuel cells to create electricity, which does not produce carbon dioxide emissions (see pages 18-19).

This technology has a great deal of promise, but it faces a familiar hurdle when it comes to aviation: old aircraft. Planes are in use for many years and the potential to retro-fit existing planes with this technology is limited.

“It requires significant changes to the current system architecture,” says Axel Krein, senior vice-president for research and technology at Airbus. “It is possible on all new aircraft, but on existing aircraft only part of the benefit can be felt.”

Significant emissions-reduction technology could be decades away. The CleanEra research scheme, run by Delft University of Technology in the Netherlands, is developing an “ultra eco- friendly plane” that would have no emissions footprint, but the feasibility has yet to be established.

Krein says that technological advances are a feature of Airbus’s existing aircraft. For instance, the A320, now in commercial operation, has improved aerodynamics, and a new engine design that reduces fuel consumption by 15%. The A350, which is currently being tested, could achieve a 25% reduction in fuel use and is expected to be ready for commercial use by the end of 2014.

Cleaner skies

The European Commission is funding this type of research through its Clean Sky initiative. For Clean Sky II, part of the Horizon 2020 programme for research funding from 2014-20, it wants €3.6 billion to be spent on public-private partnerships in this area, with €1.8bn coming from the EU. “Normally these programmes have a three-year time horizon, and it is sometimes difficult for companies to commit to just three years,” says Krein. “The Commission has committed itself to seven years, so this gives us quite some time to pursue these technology developments up to demonstration level.”

However, many environmental campaigners are sceptical about the potential of emissions-reduction technology in aviation. Efforts in international forums such as the International Civil Aviation Organization that concentrate on technology are dismissed as merely a bid to delay the action that really needs to be taken – getting people to fly less often.

The activist group Plane Stupid has staged demonstrations across Europe, often by trying to halt flights. Tests on the use of biofuel in planes have really irked the green campaigners. Friends of the Earth Europe has called them a “convenient blind alley” for the aviation industry, “facilitating the industry’s expansion plans, avoiding pressure to reduce fuel use and diverting political attention from the real need to cut air travel in order to reduce climate change”.

In 2011, a group of airlines and biofuel producers released a ‘flightpath’ to increased use of biofuel. The group said 3.7% of aviation fuel consumption in Europe could come from biofuel by 2020. The plan calls for the production of 1.2 million tonnes every year until then.

Airbus was one of those that took part and Krein says: “We have worked with sustainable drop-in fuels on many different aircraft, in different configurations, and we are now comfortable that the fuels which we have flown will be able to be injected into the fuel system of an aircraft in the future. The issue now is the scale and the cost. That is where the focus should be at the moment, to see where the quantity can be available. That next step needs to come from the producers.”

But, he says: “In the end, none of the efforts alone can deliver enough to achieve the target. It has to be a combination of the technology, better air traffic management and sustainable fuels.”