On 9 October, the Council of the European Union adopted the Refuel EU Aviation Regulation, while a few months earlier, in July, it adopted the Fuel EU Maritime Regulation. Both set targets for developing sustainable fuels in the aeronautics and maritime sectors for 2025 and 2050: by sustainable fuels, we mean biofuels – derived from biomass – and electrofuels, which refer to liquid or gaseous fuels, synthesised from hydrogen: e-kerosene, e-methanol, e-ammonia, e-methane.
LThe share of these sustainable fuels in aviation should thus reach at least 70% by 2050, while the greenhouse gas intensity of fuels used in ships – that is to say the quantity of greenhouse gases emitted during the production and combustion of these fuels, relative to the useful energy they contain – is supposed to fall by 80%.
In a recently published opinion, Ademe focuses on the role of electro-fuels in this transition. The figures are clear: both sectors will also have to adopt a moderation approach, unless they want to dedicate a more than substantial share of the country’s energy production to these transports, to the detriment of other sectors.
Sectors that are difficult to decarbonize
PrLet us state that few technological options exist to decarbonize these high-emitting sectors, while there is urgency: in 2019, these two sectors represented 19.6% of GHG emissions from transport in France. And manufacturers do not seem to be considering a slowdown in traffic.
Furthermore, it is impossible to electrify these modes of transport – except for short-haul and business aviation, which could switch to batteries, but these only concern a small proportion. For the majority of planes and boats, it is neither realistic nor feasible to equip them with batteries, for reasons of mass and distances to be covered. In some cases, however, hybridisation may be possible, as well as additional sailing aids, by taking advantage of the wind.
Hence the focus of the new European regulations on biofuels and electrofuels (or e-fuels). The latter, which we are interested in here, require hydrogen (produced by water electrolysis) and CO for their production.2 (capture, transport and use), which must be non-fossil after 2040.
AndIn its opinion, Ademe quantified the volumes of electricity and CO2 necessary for the production of the quantities of hydrogen and its derived electro-fuels that would allow the decarbonization of these sectors. In the case of maritime transport, it is based on the hypothesis of a 22% contribution of biofuels as reinforcement. It also assumes that CO2 used is of biogenic origin – CO2 from the plant cycle, which could for example be a co-product of methanization or the paper/cardboard industry.
She concludes that these fuels will not be enough and that a sober approach in the air and maritime sectors is essential.
To obtain these figures, Ademe considered two scenarios:
– one where energy demand would be low – as modelled by Ademe in 2021 in the Transition(s) 2050 scenarios, i.e. 35% less than today.
– and the other where it would jump by 70%, as anticipated by the professional sectors of the two sectors which are banking on an increase in traffic.
These estimates also vary according to the expected performance of these fuels, with more or less optimistic options. The best prospects, on which manufacturers are banking, as well as the most pessimistic ones have thus been considered. Because major uncertainties remain, particularly on the manufacture of kerosene for which the Fischer-Tropsch process, which must operate the combination of carbon dioxide with hydrogen to synthesize hydrocarbons, remains to be validated.
Finally, the study assumes that these e-fuels would be produced in France 100% for domestic flights and national navigation, and 50% for international navigation and flights. An ambitious hypothesis since today, for example, 20% of international ships serving France refuel in France. However, it is in line with the desire of French ports to position themselves on new fuels.
Increased energy needs
The results show that decarbonizing both sectors will, no matter what, require colossal amounts of electricity and CO.2 in view of our capacity to produce them by 2050. In the most energy-intensive scenario, which assumes a high demand for e-fuels, this would require 175 TWh of electricity – or around 13 EPR nuclear reactors – and 18.6 Mt of CO2 biogenic.
To understand the problem, these figures should be put into perspective with the total renewable or low-carbon electricity production envisaged by 2050 in France, which could be between 525 TWh and around 700 TWh, without taking these new needs into account: the RTE Sobriety scenario (estimated at 555 TWh in 2050) or the Ademe S2 scenario – rather sober – estimates it at 525 TWh of electricity per year. The N2 Energy Futures scenario developed by RTE estimates it at 688 TWh.
The other element concerns CO deposits.2 biogenics available: they are estimated at 16 Mt of CO2 in the Ademe S3 scenario, which uses the most biomass as an energy source. This is less than the need for these sectors alone. Not to mention that this use of CO2 competes with the one to be stored to achieve carbon neutrality.
In other words: in the event of a strong increase in air and maritime traffic between now and 2050, the resources dedicated to their decarbonization would represent ¼ of the country’s renewable or low-carbon electricity and much more than CO2 biogenic available.
The need to contain demand
These figures show that such a trajectory is likely unsustainable. The other path, which relies on contained demand for fuel, already appears more realistic. Banking on a moderate increase in traffic, Ademe estimates the resource requirements at 44 to 68 TWh per year, and between 5.8 and 7.3 Mt CO2 per year for CO requirements2 biogenic.
In the case of a “reasoned” deployment of e-fuels, desirable so as not to penalize other sectors which will need electricity and CO2 to decarbonize (industry and transport in particular), the European decarbonization objectives for air and maritime transport seem achievable, with production in France.
This would, however, require prioritization of electrical and CO resources.2 at the national level, for example within the future French Energy Climate Strategy, currently in preparation. But it appears essential, in parallel, to develop short-term policies to moderate the growth of international traffic, and to shift to other modes of travel for short haul flights.
Still a lot of uncertainty
It should also be noted that the opinion has limitations and that certain aspects will need to be examined in more depth. It assumes that all e-fuels will be produced in France. However, the location of production sites will depend on several factors, including the presence of a source of CO2 biogenic nearby and its cost, as well as the availability of the electrical network for connecting the electrolyser.
The complete environmental assessment of e-fuels for the entire chain will also need to be further explored. E-fuels have a non-zero carbon footprint that will need to be specified, depending on the production method and the resources used. There is some doubt, in particular, about CO2 : will it really be biogenic, thus not contributing to the greenhouse effect? The European regulation leaves the possibility, until 2040, of using CO2 fossil… we will have to ensure that in the long term, this possibility is not maintained.
Otherwise, the carbon impact would be much greater and the benefit of using them reduced. Furthermore, if CO resources2 biogenic were not sufficient, some suggest capturing this CO2 in the air, by using DAC technology (Direct Air Capture): certainly, but this technology, not yet mature, would generate additional energy consumption (electricity, heat) which would then have to be considered.
Other aspects to consider include water vapor trails (contrails), whose weight in the GHG emissions induced by an airplane flight is gradually being discovered – e-fuels will not have a positive effect in this area.
While e-fuels could have promising applications for both aviation and maritime, they will not replace a change in usage. Being aware that the equation still has many unknowns is also essential.
