E-fuel and battery drive compared
Federal Transport Minister Volker Wissing had announced his abstention for the vote in the EU Council of Ministers on the ban of all combustion engines from 2035 onwards, unless an exception was made for climate-neutral e-fuels. Because without the German “yes” the “no” of Italy and some Eastern European states cannot be outvoted, the vote was postponed. Criticism is now pelting Wissing from the Greens and environmental associations. We don’t quite understand why.
E-fuels must not be confused with biodiesel or fuels with the ethanol admixture that is common today, such as in E-10. E-fuels are produced fully synthetically in a process known as power-to-X. The basis is an electrolysis process in which water is split into hydrogen and oxygen. The hydrogen is then combined with carbon dioxide, usually captured from the air, and aggregated into longer hydrocarbons via several processes. The resulting “drop-in fuels” resemble the chemical composition of conventional fuels. They can be transported in simple tankers and dispensed completely unproblematically via the existing filling station network, replacing diesel, petrol or paraffin in a climate-neutral way, provided that their production was carried out with green electricity.
Another advantage: unlike lithium-ion batteries, they also have the same energy density as the fuels they replace: While diesel can produce around 12,000 watt-hours of energy from one kilogram of fuel, the battery currently only manages around 150 to 250 watt-hours per kilogram of battery weight. Mainly because of this weight advantage, the technology is likely to be used in trucks and on ships in the future.
But as always, the same applies here: Where there is light, there is shadow. For one thing, the combustion of e-fuels produces almost as much nitrogen oxide and carbon monoxide as conventional fuels. So we won’t be able to do without exhaust gas aftertreatment with urea any time soon. Secondly, the entire process is currently still very energy-intensive. If the electricity for electrolysis and CO2 capture were instead fed into the battery of an electric vehicle, the electric car could drive much further with the energy. However, a general judgement on the inefficiency of the use of e-fuels in passenger cars cannot be made on this basis anyway. For some means of transport, the battery is simply not an alternative: an aeroplane would probably have to charge so many batteries for the long haul that there would be no more room for passengers. Anyone who has ever tried to pull their caravan to Italy on holiday with an electric car knows what I’m talking about.
So what is the argument for banning by law the use of a technology that will be urgently needed in cars in the future? Perhaps some of the critics should take another look at how high the CO2 backpack of electric vehicles is due to the emissions from battery production. Jonaneum Research assumes for a car of the Golf class at the German electricity mix more than 200,000 kilometres at which an electric Golf would start to reduce emissions compared to a diesel Golf. Even if one prefers to follow other studies that determine a lower rucksack, the fact remains that an internal combustion car powered by e-fuels would be significantly lower in emissions and more climate-friendly than an electric car, if only because of the non-existent rucksack. And even the lower energy efficiency may not be a problem in the future. If as few fossil fuels as possible are to be used even during a cold dark period, capacities will have to be built up that will lead to an oversupply of electricity when the sun and wind are blowing. However, there is still no satisfactory storage solution for this oversupply. In any case, the capacity of the batteries installed in electric cars that happen to be hanging at the charging station at the time will not be sufficient to absorb the surpluses.
Away from party politics, the question arises as to what reasons could ever speak in favour of banning the use of e-fuels in passenger cars. If e-fuel cars turn out to be uneconomical, the market will make them disappear on its own.
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