E-fuels thus represent all liquid or gaseous fuels from decarbonated sources such as water electrolysis. This category includes potential fuels as distinct as ammonia, methanol or butanol. A look at the potential advantages of these fuels to ensure the energy transition to a low-carbon economy. This, before addressing the limits to their development.
What are E-fuels?
Non-carbon fuels from water electrolysis
E-fuels are characterized by their non-carbon origin, generally from the electrolysis of water. As such, they are fundamentally defined by their production method and their positive effect on the environment. These fuels are called synthetic fuels because they are created directly by electrochemical operations.
In fact, there are a large number of this type of fuel in use today or still under study. The German company Audi, for example, has developed an E-diesel and an E-gasoline of a quality equivalent to conventional fuels. His Audi G-Tron is equipped with an engine that runs on synthetic fuel from compressed natural gas (CNG). This shows the diversity of these fuels, which can take a liquid or gaseous form.
Ammonia and methanol as the preferred solution
Currently, ammonia and methanol are the two main chemical compounds used to produce these synthetic fuels. Ammonia has the advantage of already being used massively in the manufacture of fertilizers. Consequently, the storage and transport of this liquid are subject to a certain control of the industrialists reducing the costs. In addition, the storage of ammonia does not require the creation of high-pressure storage tanks.
This ease of storage and transport is also true for methanol, which appears in liquid form at normal temperature. Iceland has relied in particular on this compound by using renewable energies as sources of electrolysis. Finally, it should be noted that methanol and ammonia can be mixed together to improve the quality of synthetic fuel.
E-fuels: considerable advantages in the energy transition
Potential substitutes for hydrocarbons
When we talk about E-fuels, we are referring to a number of decarbonated liquids or gases. Also known as electrofuels, these liquids or gases can replace hydrocarbons in the transportation sector. They are characterized by their high energy density, which allows them to supply vehicles with energy over long distances.
Also, being mainly liquid, these fuels have the advantage of not requiring the development of new refill stations. Indeed, electrofuels, unlike batteries, can be easily transported and installed directly at service stations. Today, there are already a large number of stations where this type of fuel can be used.
However, these fuels must be derived from decarbonized sources to be truly qualified as electrofuels. The first method is to combine conventional fuels with CO2 capture technologies (CCS). The objective here is to create a carbon-neutral fuel directly from fossil fuels. Nevertheless, the low technological maturity of CCS is still a major obstacle to the development of this type of fuel.
At present, water electrolysis seems to be the most promising technique for decarbonizing fuels. This technique is based on the use of low-carbon electricity to create a chemical reaction following the decomposition of water. The advantage is to use decarbonized sources to enable the advent of a totally carbon neutral liquid or gaseous fuel. In the context of theParis Agreement, this dual characteristic of being liquid and carbon neutral could prove decisive.
E-fuels: a necessity to decarbonize air and sea transport
The difficult decarbonization of air and sea transport
Air and maritime transport are currently two of the most difficult sectors to decarbonize. However, the objectives of theParis Agreement cannot be achieved without a deep reduction of their CO2 emissions. The challenge is to find a suitable substitute for the jet fuel and heavy fuel oil used so far.
Electric batteries, in particular, seem unsuitable for air transport because of their weight. Similarly, the difficulty of installing charging stations in the open sea hinders the electrification of maritime transport. Only biofuels currently represent a credible alternative to conventional fuels. Nevertheless, their growth will remain limited due to competition with food production.
The electrofuel solution
Unlike biofuels, E-fuels do not suffer from competition with agriculture. According to a study by Cerulogy, electrofuels would require four times less land than their rivals. In other words, the growth potential of these synthetic fuels far exceeds that of biofuels.
In addition, second-generation agrofuels from plant waste will not be able to produce enough to meet demand. In fact, electrofuels are a much more effective solution for decarbonizing air and sea transport. In addition, their energy density makes them much more attractive than batteries in these sectors.
Therefore, E-fuels have clear advantages in decarbonizing sectors with high abatement costs. Easy to store and transport, these low-carbon liquid synthetic fuels have similar characteristics to conventional hydrocarbons. Above all, their main advantage consists in their compatibility with existing infrastructures, thus reducing the cost of the energy transition.
However, the development of electrofuels will depend on the ability of manufacturers to reduce the price of these fuels , particularly in view of the energy requirements for their production.