He is Empa's expert on vehicle drive systems: as head of the Automotive Powertrain Technologies laboratory, Christian Bach and his team are looking for ways to convert road traffic from currently being based almost entirely on fossil fuels over to renewable energy in the future.

Empa's expert on vehicle drive systems: Christain Bach. Photo: Basil Stücheli

Mr Bach, mobility is crucial in tackling the climate crisis. Why?
If we are seeking to have a CO2-neutral economy by 2050, this primarily means that we have to stop using fossil fuels from that date onwards. Mobility accounts for the highest proportion of fossil fuels in Switzerland. However, mobility will only become more climate-friendly with the additional production of renewable energy. Otherwise, we run the risk of other sectors “stealing” clean energy.

Can this be achieved with current climate-friendly technologies?
We can get most of the way there by switching to renewable energy. However, the net zero target is very ambitious. We will not be able to avoid extracting additional CO2 from the atmosphere. In nature, there is a permanent balance between CO2 sources and sinks. The original sin of climate change is that we have tapped fossil sources on a large scale without creating corresponding sinks.

Sinks? Mobility as an “energy consumer” has a role to play here?
It is not only possible – it has to be done. For example, there is intensive discussion about the recovery of CO2 from the atmosphere in Power-to-X concepts. We are currently planning to construct a system of this kind. Hydrogen, which is produced from excess electricity temporarily or locally, can be converted into energy carriers such as methane or liquid hydrocarbons, which can then be used to replace natural gas, diesel or kerosene. The great model for this process is photosynthesis.

Aren't synthetic fuels inefficient? Why not run electric cars directly on renewable energy?
In the future, electric mobility will cover a large part of road mobility, but not long-distance and heavy goods travel. In addition, electric and hydrogen mobility in winter will also depend on the supply of imported, renewable energy, and we believe that this is only possible with synthetic energy sources. To cut a long story short, it takes both!

Why can't surplus electricity be stored in the power system?
Surpluses can be stored briefly using pumped storage power plants and batteries. The additional storage capacities required for day/night balance is already enormous. In this area, electric vehicles could bring system benefits by using their batteries.

And do we put the rest into synthetic energy sources?
Precisely! Although this has a poor degree of efficiency, it offers the impressive advantage that the surplus electricity can be shifted to other energy sectors where it can replace fossil fuels. More CO2 could be extracted from the atmosphere and converted into storable limestone, which is why even energy sources with negative CO2 emissions could be achieved.

Christian Bach

"There is no getting around theneed to fundamentally rethink mobility." Photo: Basil Stücheli

So, will we be producing these fuels locally? Not only locally.
However, we are also looking at the possibility of large-scale plants in desert regions. If 50% of the miles driven on the roads of the world were powered by electricity and 50% by synthetic fuels, significantly less than one percent of the world's desert area would have to be equipped with solar systems to produce these synthetic fuels. And we would be rid of the CO2 problem in road transport! It's important to keep saying that we don't have an energy problem on Earth, we have a CO2 problem.

Isn't it too expensive to extract CO2 from the atmosphere?
The economic feasibility of synthetic fuels is a major challenge indeed. But the most significant cost block is electricity, not CO2 costs. The overall costs are manageable, especially in the area of road transport, where energy costs are very low.

That sounds technically convincing. What are the chances of the proposal in the political and economic reality?
As soon as economic concepts are enshrined in law, implementation can begin. The draft CO2 law in Switzerland is a first piece of the puzzle. There will certainly be a need for more of this, especially in large countries. Which makes me feel confident that we will see a positive attitude in environmental circles and in the car industry.

Will we be able to keep driving powerful engines with a clear conscience?
It is evident that synthetic fuels are more expensive than fossil fuels. That's why synthetic fuels will increase the push towards more fuel-efficient vehicles. However, there are other aspects, such as traffic at a gridlock. There is no getting around the need to fundamentally rethink mobility. We assume that the technical measures mentioned will be complemented by nontechnical initiatives such as car sharing, mobility pricing and automated vehicles, especially in cities.

How do you think your efforts to convince people are going to work in the political arena?
I think that the discussion is too focused on the advantages and disadvantages of individual technologies. However, if we wish to lower CO2 emissions to zero, the drive technology is of secondary importance. First and foremost, we need to switch from fossil fuels to renewable energy. This is as simple as it is crucial. This requires a political consensus that is still lacking today. The market itself can decide which technology is to be used where.

A conversation with Roland Fischer.