25 April 2017
A Clean Sky for Europe - Technology for aviation in the 21st century


By Siim Kallas, Vice President in charge of Transport, European Commission
Autumn 2012


In recent years, air transport has grown faster than any other transport mode. This annual growth is expected to continue and rise even further in the years to come, representing a good economic opportunity for European industry.

However, while maintaining today's current high safety levels, this growth will be accompanied by more challenges that affect the competitiveness and sustainability of air transport. Reducing the impact of air transport on our environment, improving its efficiency and affordability, and reducing its dependence on fossil fuels are crucial to ensure its viability.

Despite the many industry improvements made in aircraft energy efficiency over decades - new aircraft are quieter than before and burn much less fuel – the effect of such intense demand for air travel will still outstrip these environmental gains.

So clearly, there is still a long way to go. Europe is determined to make substantial and sustained investment in research to develop more technologies for today, and the innovation that we will need for tomorrow.

Meeting the EU's wider climate change targets will require deep cuts in emissions from transport over the medium term. Transport, as a major polluter responsible for about a quarter of the EU’s greenhouse gas emissions, will have to cut by at least 60% by 2050 compared with 1990 levels.

ACARE, the Advisory Council for Aviation Research and Innovation in Europe, has set a goal of reducing fuel consumption and carbon dioxide emissions by 50% per passenger kilometre by 2020, and emissions of nitrous oxides by 80% in landing and take-off.

And by 2050, the European Commission would like to see 40% of aviation fuel as low-carbon and sustainable, since the ultimate solution to decarbonising transport is to replace finite fossil resources with CO2-neutral alternative fuels.

So how can we make Europe's skies cleaner?

There are three technological ways forward which should be combined:

  • promoting alternatives to replace conventional fossil fuels as aviation fuel;
  • designing more energyefficient and eco-friendly aircraft and engines;
  • modernising air traffic management to cut congestion by optimising airspace capacity, aircraft routes and airport operations, to gain fuel and time efficiency.

Studies have shown that CO2 reductions of up to 80% can be achieved by using biofuels and optimally innovative technology, which is why a top priority in European aviation research today is to develop greener engine technologies which are compatible with biofuels.

This should lead to a new generation of aircraft and equipment that will consume less fuel, generate lower emissions and make less noise.

Firstly, with fuel, the challenge is to find a substitute for liquid kerosene as the power for gas-fired aircraft turbines. A logical first step to be taken now would be to develop synthetic alternatives as a 'technology bridge' before progressing to the ideal solution: biomass-derived kerosene produced through 2nd and 3rd generation processes, unlikely to be available in large quantities before 2030.

Synthetic fuels are currently not cost-competitive, but a nondisruptive option to replace oilbased fuels; they also allow for a wide range in the blending ratio with mineral oil fuels to provide a smooth transition from fossil to renewable and sustainable fuels.

Moving further into the future, the ultimate goal would be to develop advanced liquid biofuels based on renewable material such as ligno-cellulosic feedstock and wastes, to be available as a high-energy density substitute for kerosene. However, sustainability criteria, supply of raw materials and final price will be major considerations.

A number of airlines in Europe have started to test using biofuels to investigate supply and operations, as well as to measure performance.

In research and development, the European Union already has several highly valuable cooperation programmes in place, some national and some EU-funded. Given that aviation has a very lengthy R&D cycle, the EU has a long-term commitment to invest heavily in this area.

While all the different programmes move in the same general research direction, none is as important or wideranging as the Clean Sky Joint Technology Initiative: the EU's largest ever aeronautics research programme, which covers operations from research and first testing to in-flight demonstrations eventually leading to commercialised deployment.

It is geared to developing technologies to reduce emissions of carbon dioxide, nitrous oxides and noise, while searching for innovation breakthroughs in more efficient propulsion systems, on-board flight management systems and in aircraft design for all main commercially used air vehicles.

This flagship public-private programme is looking at all possible and potential improvements - anything from new designs of wings and blades to reduce drag, to low-weight aircraft using smart structures, or advanced electrical systems to eliminate noxious hydraulic fluids and reduce fuel consumption.

Technology innovation must also go hand-in-hand with improvements to air traffic management, the third essential element in our strategy for improving performance in Europe's crowded skies.

This is where the Single European Sky initiative and its technological pillar SESAR come into play. They are designed to combine efficient fuel consumption with optimised aircraft access to airports and flight trajectory management, with the objective of making aviation more sustainable and better performing, and aiming to further reduce emissions by 10% per flight through ATM improvements. Developing and deploying a new air traffic management generation, with continued longer-term upgrading and improvement, are SESAR's core objectives.

When fully implemented and deployed, these ambitious programmes will address the current airspace capacity limitations, reduce fuel-wasting aircraft congestion and delays by aligning flight planning in the best way possible so as to meet expanding demand.

It is only by combining all three of these ways forward that we will be able to achieve a significant 'greening' of aviation and for this, it is essential for Europe's private and public sectors to work closely together. This is how we can move towards a cleaner European sky and allow aviation to play its full part in helping transport reduce its overall carbon footprint.