Electricity-based fuels, or E-Fuels, are Renewable fuels whose energy originates from electricity. The term refers more to their production process rather than the fuel itself. The processing is always based on hydrogen, which is produced through the electrolysis of water. The hydrogen can then be converted into gaseous or liquid fuels through various methods (see the following figure).

E-Fuels enable the chemical storage of electricity generated from renewable energy sources (such as photovoltaic, wind power, etc.), making it usable independently of time. Additionally, they can be produced alongside biofuels, significantly increasing the potential of renewable fuels. The use of E-Fuels, for instance, allows vehicles to be powered not directly by electricity but by storing the electrically generated energy chemically in synthetic fuels.

By using these alternative E-Fuels instead of directly powering vehicles with electricity, issues related to entirely new infrastructure and the limited charging capacity of batteries can be avoided. Compared to electric cars, which directly use generated electricity, E-Fuels can help bypass long charging times and potentially offer higher energy storage capacities. If only renewable energies and non-fossil CO₂ are used in their production, E-Fuels can offer a CO₂-neutral alternative to traditional fossil fuels, contributing to the defossilization of the transportation sector. However, compared to the direct use of electricity in battery-electric vehicles (BEVs), the production and use of E-Fuels involve numerous conversion steps and are, therefore, significantly more energy-intensive.

Unlike all previously introduced fuel types and production methods, E-Fuels are entirely synthetically produced, and the energy stored in them does not come from organic growth but is converted into chemical energy using electricity. This typically happens through the conversion of water into hydrogen, which occurs via electrolysis powered by electrical energy. The hydrogen can then be combined with other molecules, usually carbon dioxide (CO₂), through synthesis processes to create either liquid (Power-to-Liquid: PtL) or gaseous (Power-to-Gas: PtG) fuels. This process is referred to as electrochemical or Power-to-Fuel conversion. In the following lesson, you will learn more about the various types of E-Fuels.

Technologies for producing electricity-based fuels are available but are mostly still in the demonstration phase. Due to the high energy requirements, the production costs of E-Fuels are currently very high, but it is expected that they will decrease as the technology scales up, electricity costs drop, and conversion efficiency improves. However, some losses are thermodynamically inevitable, meaning they cannot be entirely avoided. Therefore, it is expected that E-Fuels will remain more expensive than, for example, biofuels or the direct use of electricity in the medium to long term.

You can work through the following chapter in full, or jump to individual lessons that are of particular interest to you:

Hydrogen

CO₂ Supply

Methane Synthesis

Methanol Synthesis

Fischer-Tropsch Synthesis and Conditioning

Quiz on "Electrofuels"

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