What are e-fuels?

E-fuels are synthetically produced fuels using energy from sustainable sources. Explained in simplified form: hydrogen produced by using renewable energy is put together with carbon dioxide captured from the air or from industrial complexes to gaseous or liquid hydrocarbon which is the basic element of fuel. These e-fuels can be considered carbon neutral because the combustion releases the same amount of CO2 that was captured from the air before.

Thus no additional carbon dioxide is released in the atmosphere while using an e-fuel. Regarding the production process of e-fuels three different methods are established by now: Power-to-X (PtX), Power-to-Liquid (PtL) and Biomass-to-Liquid (BtL). Considering these three different processes e-fuels can be divided into three main categories. Compared with conventional biofuels the production process of e-fuels doesn’t compete with the food production at all.

How are e-fuels produced?

The production process of e-fuels is quite simple. In general e-fuels are made out of water and carbon dioxide and no fossil oil is required. During the production process the chemical molecules of fossil crude oil are simply reproduced in the lab. The result is a synthetic crude oil substitute that can afterwards be processed to common diesel or petrol fuels.

There are several different procedures to make e-fuels. At first the production of e-fuels requires hydrogen which is gained through electrolysis from water. In order to produce green hydrogen only renewable sources of energy (such as wind or solar energy) are used in this process. A common method to produce e-fuels is called the Fischer-Tropsch-synthesis. In this process hydrogen is chemically connected to carbon (gained from carbon dioxide) and synthesized to a liquid fuel. Besides that there is another method called methanation. There are different ways to produce either synthetic diesel, jet fuel or petrol components. The illustration shows that in a schematic way:

Are e-fuels compatible with all cars or motorbikes with an internal combustion engine? 

E-fuels are produced synthetically and they are tailor-made to the specific area of application. Producers of e-fuel describe these new generation of fuels as a crude oil substitute which is processed as usual in the refinery process and blended with additives afterwards to be used in all diesel or petrol engines. Thus there is no limitation when it comes to the use in already existing vehicles.