It seemed as if experts and the automotive industry were in agreement: the future belongs to the electric car. But in the weeks leading up to the general election, that sounded less clear. In the fight against climate change and to meet CO₂ requirements, there was suddenly talk of alternatives that are just as clean without having to completely convert our vehicles. The key to this: synthetic fuels or e-fuels. They make the current cars cleaner, which in turn can continue to use the existing petrol station network. But is it really that simple? The most important questions and answers.
What actually is a synthetic fuel?
The drive to replace gasoline and diesel has been around for decades. At first, researchers tried to make fuel from corn or rapeseed, and later from waste, manure and other residues. These procedures have not caught on. The so-called e-fuels now use an element that seems to be infinitely available: water. The model is photosynthesis in nature. With electricity obtained from wind power or solar energy, a so-called electrolyser splits the water into its components oxygen and hydrogen. The latter is enriched with CO₂. The result is e-fuels – synthetic gas or liquid gasoline, diesel or kerosene.
Are e-fuels climate neutral?
Theoretically yes. The CO₂ for the production of synthetic fuels ideally comes from the air or from biomass power plants. It burns in the car or truck and thus gets back into the air – a closed cycle. But that only applies if the electricity used for production is green. A problem that e-fuels share with electric cars. If you drive with electricity from coal-fired power plants, your climate advantage over vehicles with combustion engines will also decrease.
How much does the exhaust gas pollution decrease?
E-fuels have the advantage over conventional fuels such as gasoline, diesel and kerosene that they do not contain any sulfur or aromatics such as benzene. There is also less soot pollution, which would lead to fewer contrails in the sky for aircraft. The better emission values would also help cars to meet the new Euro 7 emission standard, which is to apply from 2025. Since the innovative fuel is not prescribed as an admixture, there is no environmental bonus for motorists.
Where can synthetic fuels be used?
In principle everywhere: in cars, trucks, airplanes and ships. The existing network of filling stations can be used to refuel – at least in theory. This is why e-fuels are so popular in the arguments of politicians. The image that is conveyed is that everyone can continue to drive their previous cars without having to switch.
If the benefits of synthetic fuels are so great, why aren’t they being used widely?
Anyone who listened very carefully to the Bundestag election campaign would have noticed that whenever it came to climate change and e-fuels in particular, it was quickly added that German scientists and researchers play a decisive role in this question. An elegant paraphrase for the fact that synthetic fuels are not yet ready for use across the board in traffic. Current cars could theoretically fill up with e-fuels, but only to a certain percentage, comparable to the bio-gasoline E10. They have a lower density than fuel from fossil fuels; too high a proportion would cause the fuel to fall outside the relevant standard and damage the engines. The Institute for Technology in Karlsruhe is currently researching this in a pilot project, your synthetic diesel can be mixed with conventional fuel up to 26 percent. If this proportion is to be higher for new vehicles, these would have to be specially designed for e-fuels.
Are e-fuels already being produced in sufficient quantities?
There is currently no synthetic fuel to fill up with. It is mainly produced in pilot and research projects. The quantities are small. Audi and its industrial partners operate a plant in Werlte near Oldenburg, while Porsche is building a plant in Chile in 2022 that will initially produce 122,000 liters of e-fuels. The area near Punta Arenas in Patagonia is surrounded by a strong band of wind, and the power supply is to be ensured with the help of wind turbines. In the next two years, the German manufacturer and its partners are planning a production volume of 55 million liters.
How is the energy efficiency?
A fundamental weakness of the fuel alternative is that burners are poor consumers of food. The overall efficiency of a car that runs on e-fuels is between 20 and 30 percent, the ADAC only speaks of ten to 15 percent – The rest of the energy is released into the environment as waste heat. The energy efficiency of an electric car, on the other hand, is 70 to 80 percent. In addition, the production of e-fuels is very complex. To produce fuel for 100 kilometers, the same amount of electricity is required which is enough for an electric car for 700 kilometers. In order to produce this huge amount of energy, green electricity generation would have to be massively expanded.
How expensive is a liter of synthetic gasoline or diesel?
E-fuels are not yet ready for the market. That makes them expensive. The ADAC estimates that they currently cost 4.50 euros per liter to manufacture. If synthetic fuels were produced in larger industrial plants, the price could fall to 1.10 euros. That is the estimate of the Chemieanlagenbau Chemnitz company, which operates a pilot plant in Freiberg in Saxony. The current high electricity price speaks against this. The Wuppertal Institute forecasts a price of 2.29 euros by 2030. In comparison: a liter of gasoline costs 40 cents to produce.
Can e-fuels be an alternative to electric motors?
There are a number of reasons against the use of synthetic fuels: There are hardly any production facilities, they are too expensive, energy efficiency is comparatively poor, and electricity consumption is high. That is why many experts do not assume that they will prevail over electric cars in the private sector. On shorter journeys, the electric vehicles are clearly superior to the cars that fill up with e-fuels in terms of energy efficiency. There is potential where electromobility reaches its limits: in long-distance transport. In order to achieve the climate targets, planes, ships and trucks also have to massively reduce their CO₂ emissions. Synthetic fuels could offer a way out here.