Annual Report 2020

In a world of battery-powered e-mobility, conventional fuels would be rendered obsolete. But can the energy requirements of the entire transport sector really be met by the electricity grid alone? Professor Dr. Michael Bargende from the University of Stuttgart and Dr. Martin Berger, Vice President Corporate Research and Advanced Engineering at MAHLE, see other technology pathways as an opportunity to achieve the climate targets.

There is a lot of talk about battery electric vehicles at the moment. But market research suggests that many newly registered vehicles will still have a combustion engine even several decades into the future. What’s going on?

A case in point of this misunderstanding is the announcement that, by 2035, General Motors intends to sell only vehicles with powertrains that do not produce direct emissions.* Many people have equated this with a complete switch to electric vehicles, but, for one thing, “aspiration” means a “hope or endeavor” rather than a “resolution.” Moreover, General Motors has by no means said that it no longer intends to sell combustion engines. After all, it is perfectly conceivable that, in the future, cars with internal combustion engines will minimize their local pollutant emissions to such an extent that they will no longer have any environmental relevance (so called “zero-impact” emissions). And as far as CO2 emissions are concerned, combustion engines aren’t inextricably linked to fossil fuels.

*Source:, „An aspiration to eliminate tailpipe emissions from new light-duty vehicles by 2035.“

I agree completely. The challenges posed by local pollutant emissions will be resolved under all conceivable boundary conditions with exhaust emission standard Euro 7, if they haven’t already been by Euro 6. But when it comes to the reduction targets for CO2 emissions, electric vehicles are currently the be-all and end-all—especially for legislators. However, this way of thinking merely shifts the responsibility for reducing CO2 to another sector, which doesn’t solve the problem. On the contrary, the energy still has to be converted somewhere and then distributed. And before we ban the combustion engine entirely, we should first ask ourselves whether it wouldn’t be more advisable to stop using fossil fuels instead. At the very least, we should remain open to different technologies.
Professor Dr. Michael Bargende works at the University of Stuttgart, where he is the Chair of Vehicle Drives in the Institute of Automotive Engineering (IFS). He is also a member of the Board of Management of the Research Institute of Automotive Engineering and Vehicle Engines Stuttgart (FKFS). Before joining the university, he worked in research and development at the Daimler Group for around 17 years.
The production capacity would have been in place long ago, had policymakers and legislators recognized synthetic fuels as a means of reducing CO2.
What might a climate-friendly drive concept incorporating a combustion engine look like?

We’re already seeing the beginnings of that concept here and now. It’s a matter of using existing plug-in hybrid vehicles the right way, for example. To this end, drivers need to have sufficient everyday options for recharging their batteries—designed with a relatively compact form factor—over and over again. On the other hand, renewable electricity must always be available for electric vehicles, otherwise the whole concept makes no sense from an environmental perspective ...
I’m convinced that the future of private transport will be electric in the first instance. But what does that mean exactly? In urban settings, it’s highly probable that we’ll drive battery electric vehicles. That’s because people in these areas aren’t necessarily reliant on public charging stations. Many motorists can simply charge their car at home via a wallbox or in their building’s underground garage, for example. Outside metropoli tan areas, however, the logistical effort associated with purely battery-powered electric vehicles is too great. In my view, a hybrid drive with an electric motor and a combustion engine is the better solution here if that combustion engine is run on renewable fuels. And if we look at the commercial vehicle sector, it’s difficult to imagine how driving a battery-powered 40-ton electric truck from Munich to Hamburg can be economical and environmentally friendly, even under the most favorable conditions. In this context, we’ll still be dependent on chemical energy carriers in the future.
If we’re serious about meeting the climate targets in the transport sector, there’s no way around using synthetic fuels as a complement to e-mobility.
Dr. Martin Berger has been in charge of Corporate Research and Advanced Engineering at the MAHLE Group since January 2020. Before that, he spent five years as Director of Engineering Services at MAHLE Powertrain.
Which climate-friendly fuels do you see as having the advantage?

The most important thing is to use nonfossil fuels. On the one hand, these include hydrogen and ammonia, both of which are carbonfree. That’s good to begin with, in terms of avoiding CO2. However, these are gaseous fuels whose energy density is rather low in relation to volume. In the case of hydrogen, they need to be compressed at high pressure or liquified at very low temperatures to prepare them for use, which, incidentally, also makes them really difficult to store.
So, is it better to convert the hydrogen into e-fuels in a second step?

That is the case for some applications at least. In my view, the best energy carriers are carbon-based fuels obtained using renewable electricity—synthetic gasoline or diesel, or even methanol, for example. These fuels are liquid at normal temperatures, and they don’t need to be supplied under pressure just as we’re used to with fossil fuels. They have a high energy density and are easily stored in tanks. If the carbon were to be captured from the environment beforehand in order to produce these fuels, we’ll also have created a circular economy for CO2 thus generating hardly any additional CO2 emissions.
How do you respond to skeptics who argue that the efficiency of e-fuels is substantially lower compared with using electricity directly in battery electric drives?

Our planet potentially has many more times the solar or wind energy available than we will ever need. So, the question of efficiency is secondary for now. Instead, we should be asking how we can get renewable energy to consumers on a large scale. Just as reserves of fossil fuels lie far away from most advanced economies, the same applies to renewable energy potential. For example, it makes much more sense to locate large solar power plants in North Africa or on the Arabian Peninsula than in Europe.

The customer paradox

Ultimately, it is the user who decides. But at the moment, expectations and needs in private transport are still strongly influenced by the possibilities of combustion engines.

40 km

100 % of those surveyed drive an average of 40 km per day.

500 km

68 % of those surveyed expect their vehicles to have a cruising range of around 500 km.

max EUR 800

67 % of those surveyed would only be willing to pay up to EUR 800 more for an electric vehicle (compared with a comparable vehicle with a combustion engine).

Cruising ranges

The distances that passenger cars can travel today after five minutes at the pump or charging post.

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So, the energy transition in no way involves the advanced economies becoming more self-sufficient ...

The opposite is the case. But how will we transport the electricity produced, for example, in North Africa to Europe? An electricity cable under the Mediterranean, for instance wouldn’t work, because we’re talking about gigawatts of power. That means we need to produce a chemical energy carrier on site, be it hydrogen, ammonia, or synthetic gasoline or diesel. Once it has been transported to the consumer, it no longer makes sense to convert the fuel back into electricity. So, in a world based entirely on energy from renewable sources, we’ll still have chemical energy carriers too.
Let’s take the example of the European Union. Although it’s one of the world’s largest economic areas, it imports around two-thirds of its energy requirements mostly in the form of oil and gas. If EU countries want to avoid the CO2 emitted as a result, they need to import other forms of energy, because it’s patently clear that they cannot cover their requirements themselves. But, for the reasons Professor Bargende has just given, the imported energy cannot be purely electrical. One option would be to store the energy as a gas in the form of hydrogen or a synthetic natural gas and transport it via pipelines. Incidentally, this would allow us to use pre-existing infrastructure as storage. In Germany, for example, the largest available energy storage system is currently the gas network. Another option is to liquify the electricity and transport it as an e-fuel in tankers. But if the renewably generated energy is already stored in the form of a chemical, it can then also be used directly in combustion engines.
We touched on efficiency already. Is it even possible to do a scientific well-to-wheel comparison between a vehicle with a combustion engine and a battery electric vehicle?

No. The data for this is insufficient and doesn’t take full account of the underlying complexity. Certainly, many well-to-wheel efficiency studies have been carried out. Yet they all come to different conclusions because they have all applied different boundary conditions. From my point of view, there are much more important factors when it comes to evaluating technologies.
Such as?

The benefit to the customer, for example. So, the question would be: What is the cost-benefit for customers? In urban areas, I would expect electric vehicles to offer the greatest benefit from this perspective. On longer journeys and in the heavy-duty commercial vehicle sector, on the other hand, combustion engines using chemical energy carriers provide the greatest benefit. On that basis, developing the right vehicle and fuel concepts is vital.
We’ve talked a lot about the future. But what advantages can e-fuels already offer today?

The biggest advantage of synthetically produced gasoline or diesel fuels is that they can be blended directly with fossil fuels. By using admixtures, we can start using climate-friendly fuels in the existing fleet right now. This way, we can reach almost all of the global vehicle population directly with a corresponding strong leverage effect in terms of carbon footprint.
There are around one billion motor vehicles on the world’s roads, most of which have combustion engines.

There are technology path ways that help the climate both economically and environmentally. That’s why we believe that all options should be pursued. We don’t have the time to wait until there are only fully electric vehicles on our roads, powered entirely by green electricity. For the reasons we’ve just discussed, this won’t happen in the medium term anyway. If we’re serious about meeting the climate targets in the transport sector, there’s no way around using synthetic fuels as a complement to e-mobility.
How can we create the necessary production capacity for these fuels?

That’s a political and economic question rather than a technical one. The production capacity would have been in place long ago, had policymakers and legislators recognized synthetic fuels as a means of reducing CO2. So far, they have not done so. As long as CO2 is emitted from vehicle tailpipes, it will be taken into account—even if great effort has been made to capture it from the atmosphere in the first place. The CO2 emissions from the chimney of a power plant using fossil fuels to generate electricity for electric vehicles are, by contrast, overlooked by exhaust gas legislation. It doesn’t make sense.
According to our calculations, e-fuels would be around one euro per liter more expensive to produce than fossil-based gasoline or diesel. If there is the political will, this difference can be covered or at least reduced by adjusting taxes or offsetting it against fleet emission targets. One thing must be very clear here: this is not about demonizing the electric vehicle. Rather, it’s a matter of fair competition between technologies.

The mix of the future

A discussion about clean fuels that considers all technologies is still important when it comes to climate protection. This is evidenced by the forecasted distribution of powertrain technologies in new vehicles in the three major markets USA, China, and the European Union in 2035.

Source: PwC, Digital Auto Report 2020
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