Study: E-fuels too important for the energy transition to burn them in cars

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A new study addresses a phenomenon that has once again become topical: because there is once again increased discussion about only allowing new cars with combustion engines until the end of 2034, as decided by the EU in 2023, "e-fuels" are often mentioned as an alternative. If combustion engines were to run on synthetic, electrically generated fuel, no climate-damaging carbon dioxide would be produced and combustion engines would no longer be a contributor to the greenhouse effect. This means that vehicles with thermodynamic drive systems could continue to be produced in line with the so-called "technological openness" and, thanks to e-fuels, no phase-out date would have to be observed. In this view, e-fuels are seen as a way of avoiding the switch to e-cars and are also advertised as such by political players.

However, e-fuels were never primarily intended to power motor vehicles, but are intended to play a key role in decarbonization where electric power storage cannot be used: for example, in air traffic and the transport of goods by ship. In these areas, these fuels are accepted as a compromise that has to be made because their production is comparatively wasteful of energy. In addition, there is not (yet) enough surplus electrical energy available to produce large quantities of these fuels. After all, production requires significantly more energy than the fuel can supply.

Simple correlations

A study commissioned by Klima-Allianz Deutschland from the Forum Ökologisch-Soziale Marktwirtschaft (FÖS) has once again confirmed the simple correlations involved in replacing fossil fuels with e-fuels and the clear conclusions that can be drawn from them. The think tank concludes that the electrification of cars and the modal shift must be accelerated if e-fuels are to play their intended role in climate protection.

In the study, the FÖS evaluated the relevant available findings on this topic. For this so-called meta-study, work by ADAC, the International Council on Clean Transportation (ICCT), the German Federal Ministry for the Environment (BMUV), the Fraunhofer Institute for Systems and Innovation Research (Fraunhofer ISI), the International Energy Agency (IEA), Transport & Environment (T&E) and the Association for Electrical, Electronic & Information Technologies (VDE) was systematically compiled in order to draw scientifically sound conclusions from the material.

Global production does not cover German demand

No relevant quantities are available in the short term; larger quantities are on the horizon, but would come too late. The study calculates that with around 50 pilot projects for e-fuel production currently being planned worldwide and a further 20 with a chance of being realized in the foreseeable future, around 5.9  million tonnes, corresponding to 70 TWh/year of e-fuels, can be expected in 2030. This means that the planned global production of e-fuels would not be enough to cover the current demand for air and sea transport, even in Germany.

By 2050, much more could be produced, namely around 75,600 TWh/year of hydrogen or 54,800 TWh/year for e-fuels. For 54,800 TWh/year, however, all available hydrogen would have to be used for e-fuels. However, since hydrogen is needed in particular for the decarbonization of the chemical industry or steel production, only a portion remains for the production of e-fuels; the study estimates 20,000 to 25,000 TWh of e-fuels in 2050. Germany could thus achieve the decarbonization required for the climate targets – if the passenger car fleet is already largely electrified by 2045. Even in this optimistic, extended scenario, there would be no leftover fuel that could be burned in cars.

Ramp-up "clearly too slow"

However, the production of e-fuels on an industrial scale would have to be able to keep pace with the expansion of renewable energies, in addition to a much faster ramp-up of hydrogen production capacities than before: for example, only two percent of the green hydrogen capacities announced for 2022 were actually produced. The study considers growth similar to that of wind power to be "ambitious, but clearly too slow to meet future demand".

According to the scientists' findings, e-fuels could supply a small residual stock of combustion engines in global passenger car traffic, but only if the energy requirements of road traffic are significantly reduced through the electrification of vehicles. The study estimates 190  million vehicles, corresponding to around ten to 15  percent of today's car population. By 2050, production costs could fall to 1 to 2 euros in today's purchasing power, corresponding to a consumer price including taxes and levies of around 2.50 euros/liter "if the supply of e-fuels keeps pace with demand and there are no shortage prices", as the FÖS summarizes.

This far exceeds the operating costs for an electric car. The study notes that an electric car in the compact class is already more than 5000 euros cheaper than a comparable conventional car over a holding period of four years. According to the study, the cost advantage could even rise to 10,000 euros by 2030. The demand for e-fuels for cars is therefore likely to fall.

Energy for six times as many e-cars

The efficiency of e-cars is already 70 to 75 percent today, as electrical energy is stored and used without conversion. E-fuels, on the other hand, require energy-intensive production and conversion processes with an efficiency of just 13 to 16 percent. In other words: "The same amount of electricity can be used to power around six times as many e-cars as e-fuel burners", as the study states. For example, 150 wind turbines could supply 240,000 e-cars with electricity, but only 37,500 combustion engines with e-fuels.

The overall balance over the entire life cycle, from production to operation to disposal, is already 40 to 50  percent better than that of a conventional car. Of course, carbon dioxide is still emitted today to generate the electricity used to power electric cars, but this proportion decreases the more electricity can be generated from renewable energies – and equally for every electric car already on the road.

However, another effect also mentioned in the study is difficult to quantify: the harmfulness to health caused by exhaust fumes. Although combustion engines that run on e-fuels do not emit any climate-damaging carbon dioxide on balance, the type of combustion produces by-products that are largely rendered harmless in modern engines by catalytic processes and particulate filters. Nevertheless, a small amount will unnecessarily and potentially affect the health of residents and vehicle users if combustion engines can continue to be used.

Wanting to reverse the so-called end of the combustion engine is currently back in vogue among right-wing parties. Most recently, the center-right EPP alliance advocated this at EU level. Under pressure from the FDP, the German government had already demanded exemptions for so-called e-fuels from the EU much earlier.

(fpi)