ADEME outlines its approach to decarbonising air transport

To hear the CEO of Aéroports de Paris, Augustin de Romanet, recently invite travellers to the microphone of BFM " to be more reasonable air travel "This may seem paradoxical. And yet, this position illustrates the climate challenges facing an entire sector which, without action on the part of its players, but also passengers, would see its CO₂ grow by 50 % by 2050. This is a far cry from the targets set by the Paris Agreements or the commitments made by IATA and ATAG, which are aiming for Zero Net Emissions by 2050.

But with air transport accounting for 5.3 % of France's carbon emissions in 2019, more than twice as much as thirty years ago, how can we tackle the crucial issue of decarbonising the sector? ADEME conducted a 21-month study in conjunction with the Civil Aviation and Energy and Climate Directorates and industry players such as Airbus, Air France, ADP, easyJet and Safran. The study will feed into the debates surrounding the new national low-carbon strategy, and will be presented to the European Parliament and the Council. the results robust"  intend to bring " rationality in orders of magnitude and passionate debates" said Baptiste Fabert Perrisin, interim director of the government agency focusing on ecological transition.

In addition to minor levers such as modal shift to other modes of transport and increasing aircraft load factors, the three main levers The levers for the sector's transition are well known: the energy efficiency of equipment, a reduction in the carbon intensity of the energy used and traffic calming. Based on these three levers, ADEME has envisaged three scenarios showing the expected effects depending on the direction taken: all-technology, traffic calming or a scenario combining the two approaches with greater moderation. In the end, the message is relatively encouraging, provided that efforts are maintained: " It is possible to reduce CO emissions by 75%.₂ flights departing from France if we activate all these decarbonisation levers" says Baptiste Fabert Perrisin.

Technological breakthrough or traffic reduction, ADEME's two approaches

The first scenario, that of a technological breakthrough, is based on renewing fleets as quickly as possible, improving flight and ground operations, the expected arrival of hydrogen-powered aircraft and the development of new technologies. the increasing use of sustainable fuel. Better known by the acronym SAF (for "sustainable air fuel"), fuels made from waste oils or animal fat residues emit 65 % of CO₂ less than paraffin and -88% for synthetic fuels made from decarbonised electricity.

According to this scenario, the sector's annual emissions would rise from 25 million tonnes of C0₂ in 2025 to 15 million in 2040, ending at 9 million tonnes by 2050. This compares with 35 million tonnes if the sector remained inactive. However, there are several limitations to this scenario, firstly because hydrogen-powered aircraft are not expected before 2035, and their use is likely to be limited to short- and medium-haul flights, accounting for only 7% of flights in 2050. On the other hand, 17% of French electricity production in 2050 should be used to produce low-carbon electrofuels and hydrogen.

Whatever the scenario - all-technology, traffic calming or blending - the production of biofuels would use a third of the available residues. " Choosing to supply the aviation sector on a massive scale with biofuels, electrofuels and hydrogen is the right choice. the result of a public policy choiceThis involves prioritising the various sectors (transport and roads, construction, industry, bioeconomy, etc.).emphasises ADEME.

Obviously, the introduction of sustainable fuel, which is more expensive to produce, will have a cost for airlines, which will be reflected in ticket prices. All this will have an effect on demand and contribute to a more limited increase in traffic, with ADEME forecasting a reduction of 15 to 19% compared with 2019. But what effect could a real moderation in air travel have?As even those involved in the smooth running of the business, such as the CEO of ADP, are now urging?

This is what ADEME has sought to estimate through a scenario in which the development of SAF use is combined with sobriety measures to stabilise the level of air traffic. These measures could take many forms, such as capping the number of flights, taking action on advertising or raising passenger awareness. " Frequent travellers don't know their cumulative emissionsThis is due to a lack of tools and communication between stakeholders, despite a regulatory obligation dating back to 2013." says Marc Cottignies, technical coordinator of the study at ADEME. For his part, Baptiste Fabert Perrisin also mentions work to be done within companies on incentives to take less air travel, even when a train alternative exists for journeys of more than 4 hours: "We have a branch in Sophia Antipolis and a bonus is paid to teams whose agents take the train to get there, which has led to a drastic reduction in air travel." 

Encouraging moderation

In the end, this scenario, which is based on an overall drop in traffic of -15% compared with 2019, is the one that has the most logical impact, the fastest impact on CO₂. Thus, by limiting air travel, emissions from the sector would fall from 24 million tonnes today to 22 million in 2025 and 15 million in 2035. At that point, the other scenarios would still be at over 20 million tonnes, before beginning an accelerated descent to 9-10 million tonnes of CO₂ emissions in 2050. According to ADEME, this traffic calming strategy would lead to the emission of 5 million tonnes of CO2 per year in 2050.

However, the truth often lies somewhere in between: neither all technological nor all restrictive, the median scenario, presented by ADEME as " less risky in terms of technology and social acceptability" implies more moderate application of all decarbonisation leversWhile it will not bring about a significant reduction in CO₂At just -20 % between 2019 and 2030, this scenario concludes by 2050 with results fairly close to those of the scenario based exclusively on the technological breakthrough. Results which, if we read this study between the lines, could be further improved by a decade of travelling less.