Viewpoint

Are e-fuels a viable alternative?

The container plant at Energy Lab 2.0 produces up to 200 l synthetic fuel mix per day. (Photo: Amadeus Bramsiepe, KIT)

For months, there has been discussion in Germany and Europe about whether and how synthetic fuels such as e-fuels could be a climate-neutral alternative to gasoline and diesel. We asked our experts Maximilian Fichtner and Olaf Toedter for their perspectives.

Maximilian Fichtner is a chemist and Managing Director of the Helmholtz Institute Ulm. Copyright: KIT

"For me, e-fuels are indispensable for certain applications, but unfortunately also a very costly solution."

In times of scarce energy from renewables, we should ask ourselves in principle whether it doesn't make sense to produce e-fuels in climatically favorable areas such as South America and then bring them to Europe. Porsche is planning such a plant in Chile, the world's largest to date. When the plant is eventually completed it will produce 550 million liters of e-fuels per year. That sounds a lot, but it's only a little more than 1 percent of the annual fuel demand for passenger cars in Germany. So we would need – for Germany alone – much more than the 60 e-fuels projects currently planned worldwide, which are to be completed by 2035 and of which only a small fraction have been financed.

Specifically, I see two challenges: One is the question of where the electricity will come from. Large amounts of electricity are needed to split water molecules via electrolysers to produce hydrogen. However, the Chilean regional government has stopped the expansion of wind power plants on site for the time being. This could also happen to other similar projects that aim to generate electricity in other regions around the world where the local benefits are questioned. If one wanted to generate a sufficient amount of electricity from renewable energies in Germany, one would need several hundred such wind farms, but where should they be located and who should operate them? Quick solutions and the approval of such plants are not to be expected in Germany. However, quick decisions are needed if positive climate effects are to be achieved soon.

Secondly, it is not clear to me where the CO2 needed for the e-fuels is to come from: Porsche wants to rely on direct air capture for this, a process in which CO2 is extracted directly from the ambient air, but this is very energy-intensive. At the world's largest CO2 filter plant in Iceland, 4,000 tons of CO2 are currently extracted annually, whereas the plant in Patagonia would need 600,000 tons of CO2 per year. This means that 150 such plants would be needed. An alternative currently under discussion, such as transporting liquid CO2 from industrial processes in the north to Patagonia by tanker, would not be climate efficient in any way. The CO2 would merely be diverted from a large chimney stack into many exhaust pipes.

Nevertheless, I think research and development on e-fuels makes sense, because e-fuels will be needed. With the plant in Patagonia, a laboratory plant is put on an industrial scale, which is already the beginning of a learning curve. E-fuels are needed primarily for shipping and air travel. Major shipping companies such as Maersk have already announced their intention to use more environmentally friendly e-methanol in new ships. In contrast, I do not consider the use of e-fuels in the combustion engines of passenger cars to be very effective. Since they are not widely available, they could be mixed with conventional fuel in a similar way to biofuels. But other problems remain, such as the one-third higher CO2 emissions compared to a battery-powered vehicle. Further, this delays the phase-out of fossil fuels, and cities continue to suffer, because we would still have emissions of soot, NOx, the noise and the vibrations even with e-fuels. For me, e-fuels are indispensable for certain applications, but unfortunately also a very costly solution.

Olaf Toedter coordinates the reFuels project and conducts research at KIT's Institute for Piston Engines. (Copyright: KIT)

"Overall, I am optimistic about the development of e-fuels, because there are a large number of international projects in which demonstration plants are being built."

E-fuels can definitely be a climate-friendly alternative to gasoline and diesel in passenger cars with combustion engines. At KIT, we are doing research on reFuels, which is a made-up word we deliberately chose, where "re" stands for regenerative. We want to show that regeneratively produced fuels such as e-fuels can be used in airplanes, ships, trains, and even in passenger cars, and that existing fuel standards can be complied with. In our Energy Lab 2.0 and bioliq® research laboratories, for example, we produce e-fuels from the electrolysis of water using renewably generated electricity and CO2. Our aim is to use CO2 taken directly or indirectly from the atmosphere as a building block for the carbon for the regenerative fuels, i.e., either indirectly via plants, via residual and waste materials, from industrial waste gases, or via the direct air capture process.

In our pilot plant, we succeeded in synthesizing several thousand liters of these fuels. To do this, we looked at various synthesis paths, optimized them in terms of efficiency and tested the fuels produced using them as standard fuels. All the tests were positive, and the processes work so well that they could be scaled up to industrial scale. For this large-scale industrial implementation, we need a demonstration plant in the order of several 10,000 tons/year as an intermediate step. Planning and implementation would take three to four years, which would be the next step in industrialization. Based on this, a large-scale plant larger than 500,000 tons of synthetic fuels per year could be implemented in the subsequent step.

However, because of the high electricity requirements, Germany would not be a suitable production location for fuels with electrolysis hydrogen. Instead, it would have to be regions with a lot of wind and solar energy, such as Spain, Greece or Portugal. It would make sense to run the e-fuels process in these favorable regions until an intermediate product is produced, for example, methanol. This would be the part of the process that requires a lot of energy. However, the processing into the target product, i.e., up-grading to fuel, could take place in Germany, for example, in converted refineries. That would be a sustainable use of the existing refinery infrastructure.

Overall, I am optimistic about the development of e-fuels, because there are a large number of international projects in which demonstration plants are being built. If this trend continues, the question for me is not whether renewable fuels have a future, but rather whether we will get any at all in Europe. This is because the demand for them will be very high worldwide and the countries that have access to such favorable locations will use this to their economic advantage. In our project, we also examined the cost effect: Overall, the synthesis costs for these fuels at suitable locations are of a similar order of magnitude to the production costs of conventional fuels today. Nor do we see any significant difference in system efficiencies compared with a battery-powered vehicle, if we include all processes, such as energy transport, energy storage and climate effects. If we take into account that we already import more than 70 percent of our energy sources, the approach is to replace fossil fuels with renewably produced ones such as e-fuels. This is another step toward CO2-neutral mobility.

23.05.2023 Maximilian Fichtner and Olaf Toedter

Are e-fuels a viable alternative?

Readers comments

As curious as we are? Discover more.