Learn all about synfuels (e-fuels)

What are e-fuels, what substances does the term cover, how are they synthesized, for what usages and with what advantages and limitations? A summary note* and an online report address the questions associated with the properties and usages of e-fuels.

Video: the future of synfuels (in French)

E-fuels: summary note*

**he summary note is the fruit of the work of the EVOLEN Hydrogen and Industry committee, particularly the members of its working group dedicated to "e-fuels and synthetic substances".

See the full summary note

Synfuels, or e-fuels, are produced from renewable or low-carbon electricity, carbon dioxide or nitrogen in the case of e-ammonia, and hydrogen derived from electrolysis. In liquid or gas form, their emergence alongside biomass-derived biofuels, offers a relevant alternative solution to defossilize transport and industry, without creating conflicts of use with agricultural products, thereby enabling a reduction in the climate impact of these activities.

What are these substances? How are these substances produced and for what usages? What are the advantages and limitations associated with these substances? What potential production volumes can we expect and what are the barriers to their development? The summary note attempts to answer all these questions, with the aim of providing a comprehensive set of definitions and an insight into e-fuels and their future development.

The document focuses on the uses of e-fuels as synfuels for mobility, concentrating on four e-fuels in particular: e-methane, e-methanol, the family of paraffin-based e-fuels including e-gasoline, e-diesel and e-kerosene, and e-ammonia.

E-fuels as alternative fuels

Water electrolysis makes it possible to convert renewable or low-carbon electricity into hydrogen, which is easier to transport, stock and distribute than electricity. Other than traditional usages reserved for industry and fertilizer chemistry, hydrogen can be used in mobility to power an electric motor via a fuel cell, or directly as a fuel in an IC engine.

Hydrogen, a gas at atmospheric pressure, has a high energy density by mass, but a very low energy density per unit volume. As a result, to be stored in reasonable-sized tanks, it has to be compressed at very high pressure, between 300 and 700 bar, or liquefied at -252°C. Both these options require high energy consumption and there are major technical and technological challenges associated with onboard equipment.

Another option for using renewable or low-carbon hydrogen is to convert it into synfuels, or e-fuels, by reacting it with CO₂ or nitrogen. These fuels, which, like e-methane, can be in gas form in ambient conditions, but are generally liquids, are easier to transport, store and use than hydrogen; they represent a promising future option for air and sea transport - where pure hydrogen appears difficult to use over long distances for the reasons outlined above - as well as for some river and road transport.

Principal e-fuel synthesis methods (in French)

Which e-fuels for which uses?

E-methane

In liquid form, one of the major advantages of e-methane is that it can be incorporated in LNG (liquefied natural gas) and thus benefit from existing infrastructures and regulations. In gas form, it can cover traditional natural gas usages (heating, electricity) and also be used in road (LNG) and sea transport.

E-methanol

E-methanol, which is already produced in small proportions on an industrial scale, particularly for the chemicals industry, is a promising fuel for the shipping sector. It is known to industry, energy-dense and liquid at ambient temperature. Easy to incorporate in gasoline for existing vehicle powertrains, and used in dual-fuel engines in the maritime sector, e-methanol can also be deployed rapidly. It is also an option for decarbonizing the production of chemicals (formaldehyde, acetic acid, etc.) and olefins (ethylene, propylene). However, methanol is associated with a degree of toxicity that requires specific precautions when used as a fuel.

Paraffin-based e-fuels

With properties similar to those of their fossil equivalents, the use of paraffin-based e-fuels in the road, maritime and aviation sectors is therefore a potential option.
- E-diesel is particularly aimed at road transport. With properties that are comparable with or even superior to those of conventional diesel, it can be used in its pure form or as a blend in commercial diesel.
- E-kerosene is aimed at the aviation sector. It is an example of a Sustainable Aviation Fuel (SAF).

E-ammonia

E-ammonia is a fuel under close scrutiny by the shipping industry, since it is an economical synfuel that is easy to produce; it is also the only one not to contain carbon. However its high toxicity and the dangers it represents for the environment remain an obstacle to its large-scale development as a fuel, particularly in confined spaces like ships. Further R&D efforts are required for safe use in these types of environments. E-ammonia is also an option for decarbonizing the production of chemicals (fertilizer, explosives).

To find out more, consult the summary note:

[Link]

La décarbonation des procédés et la production de carburants de synthèse au cœur des travaux d'IFPEN

Pilote Fischer-Tropsch sur la raffinerie ENI de Sannazzaro

Les équipes d'IFPEN participent au déploiement de procédés décarbonés par le biais de l'utilisation d'hydrogène décarboné, d'électricité et de biomasse, et par la valorisation du CO2. La conversion de la biomasse ou du gaz naturel en carburants liquides de synthèse s'effectue notamment par le biais du procédé Fischer-Tropsch. Si cette technologie remonte au milieu du siècle dernier, tout l'enjeu des travaux menés par IFPEN consiste à améliorer son rendement, ses coûts de production et son empreinte environnementale. Après plus de 15 ans de recherches en partenariat avec ENI, IFPEN a mis au point un nouveau procédé Fischer-Tropsch commercialisé par Axens sous le nom de Gasel®. Reposant sur une synthèse Fischer-Tropsch et un upgrading, il se caractérise par un haut niveau de productivité et par l'absence de soufre, d'azote et de composés aromatiques dans le carburant de synthèse obtenu, ce qui améliore les performances environnementales des véhicules, notamment sur les particules de tailles inférieures à 23 nm.

Depuis juillet 2021, la proposition de réglementation de la Commission Européenne du package Fit for 55 dite « ReFuelEU Aviation » propose une incorporation minimum de 5 % d'e-fuel dans les carburants d'aviation en 2035 et de 28 % en 2050. Pour respecter ces ambitions, il est nécessaire de disposer de procédés fiables et capables de fortes capacités. Aussi, afin d'accompagner l'émergence du marché des e-fuels, IFPEN a lancé avec Axens le développement d'une technologie permettant la production de CO à partir de CO₂ et d'H₂ (réaction dite de Reverse Water Gas Shift).

Le développement de la brique amont Reverse Water Gas Shift et du captage de CO₂, par exemple sur émetteurs industriels via le procédé DMX™, permettra de compléter cette technologie pour disposer d'une chaîne complète depuis le captage du CO₂ jusqu'à la production de carburants de synthèse.