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Safran on the biofuel trail


To address the issues of climate change, Safran is committed to developing sustainable alternative fuels. Nicolas Jeuland, Safran's fuels of the future expert, explains the challenges surrounding the research being conducted in the field of alternative fuels for the aviation sector.

Biofuels take off
Produced using non-food crops, biofuels improve aviation's carbon footprint. Safran Aircraft Engines is participating in their certification by testing them on its engines. In 2013, an Airbus A321 flying from Toulouse performed a routine landing at the Paris Air Show (see box). The novelty was that one of its CFM561 engines was powered by kerosene containing 10% farnesane. This substance is derived from the transformation of sugar cane into basic molecules (farnesene) thanks to microorganisms acting during fermentation. Once hydrogenated, the farnesene molecule becomes farnesane and may then be directly incorporated into an aviation fuel such as kerosene.

Aviation is responsible for around 2% of global CO2 emissions associated with human activities, and this figure is rising as traffic increases. It is for this reason that numerous aviation industry players are seeking to reduce the sector's environmental impact.. The primary objective is to halt the rise in CO2 emissions by 2020 and then to reduce them by 50% by 2050. "It is clear that these objectives can only be met via a package of technological solutions relating to engines and aircraft, as well as the optimization of air traffic", explains Nicolas Jeuland, Safran's fuels of the future expert. "Sustainable alternative fuels are considered to represent one of the key factors in meeting this goal." The Group is thus working actively with its partners on the development of less polluting alternative fuels, within the context of the Air Transport Action Group and the Committee on aviation environmental protection.


A biofuel / kerosene mix

Four types of biofuel (see box) are certified for blending with kerosene. The biofuels in question require no adaption to engines and each of them has demonstrated perfect compatibility with all materials and equipment via the certification process. The blend proportions differ depending on the processes used: 10% farnesane (see box) for 90% kerosene, for example, or up to 50% biofuel with the HEFA technique. "It isn't feasible today to develop engines dedicated to a single type of alternative fuel because it has to be possible to refuel aircraft all over the world", specifies Nicolas Jeuland, Safran's fuels of the future expert. The so-called "drop-in1" fuel blend thus has a major role to play today in reducing CO2 emissions in the aviation sector."

Safran has been testing alternative fuels in its engines since 2007. Dozens of in-flight tests have been conducted on the Toulouse ? Paris route using a farnesane and kerosene mixture on Airbus A321 aircraft fitted withCFM56 engines operated by Air France-KLM, within the context of the Lab? Line for the Future project supported by the DGAC (French Department for Civil Aviation). "Globally, it is estimated that some 2,500 commercial flights have taken place over the past five years using alternative fuels of various types", continues Nicolas Jeuland.

Economic and ecological stakes

Large-scale recourse to these alternative fuels is nevertheless governed by the principle of economic sense as well as genuine ecological benefits. Thus, a high-output production process may raise environmental issues if it involves using coal or non-sustainable crops (this is mostly the case for palm oil, for example). "A number of other factors also come into play, such as the fact that, due to their chemical composition, some alternative fuels deliver an additional environmental benefit by reducing turbine output particle emissions", adds Nicolas Jeuland.

Safran is thus seeking to evaluate the strengths and weaknesses of each of these biofuel processes and validate their compatibility with the technologies in question: "The challenge is to identify which one of the existing solutions will be economically viable and the most environmentally friendly, be it in terms of the raw materials required, the production methods employed or their use", concludes the expert.


1 A "drop-in" fuel is one that can be used as a partial or complete substitute for conventional kerosene with no operational impact (no changes required to infrastructures, particularly airports) or changes required to aircraft or engines, either existing or under development.