Saxony-Anhalt as Hydrogen Valley? At least, that is the vision of politics and industry, because hydrogen is supposed to serve as a substitute for oil and gas in the economy at some point. The state of Saxony-Anhalt wants to play a pioneering role in this. So, for example, will our cars soon run on green hydrogen instead of gasoline or electric power? In the new episode of the podcast "Wissen, wann du willst", Lisa Baaske talks to Prof. Hermann Rottengruber from the Faculty of Mechanical Engineering about why hydrogen could be a real alternative, what the advantages are compared to electromobility and what is currently still causing problems with the hydrogen car.

Today’s Guest

Prof. Dr.-Ing. Hermann Rottengruber is head of the Department of Energy Conversion Systems for Mobile Applications at the Faculty of Mechanical Engineering. Among other things, the mechanical engineer conducts research on novel drive systems with a focus on alternative fuels, such as hydrogen. The technical focus at the department ranges from electromobility, thermal management; use of lost energies and exhaust gas heat to optimize vehicle efficiency, to the adaptation of conventional combustion processes to future traffic and environmental requirements.

*the audio file is only available in German

The Podcast to read

Intro-Voice: Know When you Want. The podcast about research at the University of Magdeburg

Lisa Baaske: Saxony-Anhalt as Hydrogen Valley. At least that is the vision of politics and industry. After all, hydrogen is supposed to serve as a substitute for oil and gas in the economy at some point. The state of Saxony-Anhalt wants to play a pioneering role in this. So, for example, will our cars soon be running on green hydrogen instead of gasoline or electric power?

My name is Lisa Baaske, I work at the university's press office and today's guest is Professor Hermann Rottengruber from the Faculty of Mechanical Engineering. Among other things, he is researching new types of drive systems with a focus on alternative fuels, such as hydrogen. We talk about why hydrogen could be a ossible alternative. What the advantages are compared to electromobility, and what is currently still causing problems with the hydrogen car. A warm welcome!

Prof. Hermann Rottengruber: Hello Ms Baaske.

Lisa Baaske: The essential question right at the onset- What would you choose at the moment? A car with an internal combustion engine, an electric car or a hydrogen car?

Prof. Hermann Rottengruber: The question is very individual, because it depends very much on the driving profile you have. And with my particular driving profile - a lot of long-distance driving - I would definitely opt for a vehicle with a diesel engine with an internal combustion engine. At the moment, this is still the most sustainable solution for me in terms of economy and also CO2 emissions. This is because the energy input is naturally very high for high mileage and the electricity does not yet come 100% from green sources. So the CO2 backpack is still there. And with this profile, the diesel engine is still the best solution.

Lisa Baaske: Yes, in fact, they just brought it up: CO2 emissions. In fact, when you talk about mobility, climate change always has to be taken into account. And combustion engines are somehow frowned upon as CO2 emitters. But how far have we come with electromobility? Is it realistic, for example, that trucks will soon be running on electric batteries?

Prof. Hermann Rottengruber: Here, too, we have to make a very clear distinction. In the passenger car sector, electromobility is currently experiencing a real boom, thanks in part to the strong political support. We are already very far along there. The product ranges are also very advanced. We definitely still have some catching up to do in the area of charging infrastructure, where things still look pretty bleak.

And in my opinion, the public perception of heavy-duty traffic - because it also produces really high CO2 emissions - is far too limited. The energy requirements there are so high that the strategies currently in place for battery-electric cars are not going to make any headway. So it will not be possible for battery-electric systems or battery-electric vehicles to provide logistics- services there in the foreseeable future.

Lisa Baaske: Okay, yes. You've actually already touched on it. The auto industry seems to see the future in electric mobility. Politicians, too, are backing electric cars and promoting them. Why is that, then?

Prof. Hermann Rottengruber: Yes, that is, one would say, a bit of a sleight of hand. Because in the case of passenger car mobility, the CO2 emissions during production, especially of the batteries and the provision of electrical energy, are completely ignored. They are CO2 free by law or by regulation, which is factually, technically not true and not comprehensible. And it seems that politicians are very interested at the moment in at least trying to implement this one path for the mobility of us citizens in Europe, with all the means at their disposal.

Lisa Baaske: Yes, in Europe, electromobility is definitely very high on the agenda here. But how does it actually look globally? Are all countries focusing on electromobility?

Prof. Hermann Rottengruber: No, not at all. Here in Europe, we are fortunate in that we have a very well-developed infrastructure and live in a very well-developed world. In our country, the switch to electromobility is also conceivable, and driving distances are relatively short. However, in many parts of the world - let's take a look at the USA - the breakthrough of electromobility is by no means as clear-cut as we see it here, especially in the large-scale areas.

Politicians are also not as clearly committed to electric vehicles as they are in Europe. And China, the big market - 40% of the vehicles produced in Germany are now sold in China, or even more in some cases. And they promoted the electric vehicle very strongly a few years ago, but have now clearly rowed back in the last two years and have explicitly taken up their national research agenda, the further development of combustion engines. And even if you look at it from the industrial side, there are more and more Chinese manufacturers who are bringing really competitive combustion engines to the market. And in the next few years, we will certainly see some products in Europe as well, with production declining. So it's not like this is a global trend. If you take emerging markets and developing countries, there is no chance of bringing battery electric vehicles to market in the foreseeable future. It's a very Eurocentric world that we have here, with a strong focus on electric vehicles.

Lisa Baaske: And what is your assessment? Is the future more likely to be the electric car or the hydrogen car?

Prof. Hermann Rottengruber: So in the long term or medium term, we will definitely have a mix. In small-scale mobility, i.e. passenger cars with relatively short daily journeys and a very short route profile - at least as we find it in Central Europe - we will see a very strong shift toward battery and electric mobility. Quite simply because it is the optimal solution in this application. For vehicles that have to overcome greater transport performance, i.e., long-distance profiles and, above all, also transport loads. In other words, all truck traffic that goes beyond urban delivery traffic, in my opinion the battery-electric system will only become established in part or to a very small extent. Alternative fuels and combustion engines may be needed there, or the hydrogen vehicle will become established. But even there, the situation in the world is not yet clear, because both one solution and the other solution naturally have their advantages.

Lisa Baaske: Yes, as always, everything has its pros and cons. But how exactly does a car powered by hydrogen work?

Prof. Hermann Rottengruber: Yes, there are basically two ways to power a vehicle with hydrogen. The simplest, of course, is to use hydrogen as a highly combustible gas and to use the hydrogen as a fuel, as in the case of an internal combustion engine - specifically, a gasoline engine, i.e., today's gasoline engine - to substitute gasoline with hydrogen. The technology is roughly comparable to what is used today with LPG or natural gas vehicles.

The challenge here is to store the hydrogen and carry it around in the vehicle. And the other technology that also has the problem of transport and storage is the fuel cell system. It does not use hot combustion, as in the classic internal combustion engine, but cold combustion, which splits the hydrogen via a catalyst - usually the precious metal platinum is used - and then generates electricity. So the hydrogen fuel cell, in combination with the hydrogen storage system, is now practically the battery in the battery-electric vehicle, and the powertrain is still an electric powertrain via the electric vehicles.

Lisa Baaske: Is it essentially with the second variant still in the broadest sense an electric car then?

Prof. Hermann Rottengruber: That is correct. This is not an internal combustion engine vehicle, but an electric vehicle in which the hydrogen and the hydrogen tank naturally take over the function of the battery.

Lisa Baaske: And which of the two variants is likely to prevail? Or can it prevail? Or is there no decision, but both variants are possible?

Prof. Hermann Rottengruber: At the moment, we are in a transition phase to change our mobility, and for passenger cars - for vehicles in the passenger car class, heavy passenger cars and smaller trucks - let's just assume that it will come down to the fuel cell. There are several reasons for this, but in the case of commercial vehicles, especially heavy commercial vehicles, the hydrogen combustion engine currently still offers enormous cost advantages combined with very good efficiencies. And if you want to think about a conversion in the short or medium term, in terms of CO2-free heavy-duty transport, the hydrogen combustion engine has very good chance at the moment, and many commercial vehicles in Europe and worldwide are on the verge of entering this market.

Lisa Baaske: You had actually already hinted at it a bit, but what is the difficulty with hydrogen propulsion?

Prof. Hermann Rottengruber: The hydrogen vehicle essentially faces the major challenge of energy storage - as do all vehicles, by the way. The battery electric vehicle is also struggling with range problems and energy availability problems. But storing hydrogen in a mobile system in a vehicle is of course much more complex and much more difficult, as we know it from gasoline or diesel, i.e. from conventional fuels.

Incidentally, this is also the reason why these fuels and these types of engines have become so widespread over the last 100 years, because it was so easy to carry them in the vehicle. In order to be able to transport hydrogen in a vehicle - given today's technology, i.e. technology that is available in series production today - you either have to compress it very rapidly to 300 to 700 bar. These are the two industry standard pressures used today. Or you can make it cool down very strongly. Very strongly means 20 Kelvin, i.e. 20 degrees Celsius above absolute zero. So -253 degrees - that's already quite a plank, which then doesn't necessarily make storage any easier. Because then you either need a vehicle tank that can withstand the high pressures or you need a tank that can maintain such low temperatures, because the hydrogen naturally warms up while it's in your tank.

So those are the two big challenges, and they've all been solved in series applications. It's not that it's still on a laboratory scale, but the step into large-scale production still has to be taken, of course, but the technology is available.

Lisa Baaske:Which of the two drive systems, electric or hydrogen, is better for the environment in the long term?

Prof. Hermann Rottengruber: That's a very good question, because it essentially always depends on which primary energy source you tap. And in a world in which hydrogen can be produced regeneratively from sustainably generated electricity - which is then also the so-called green hydrogen - it essentially no longer matters much which path I take. The condition is that I have enough primary energy available and can use it economically to generate hydrogen or electricity, i.e. green electricity.

Then the calculation is the same, then both are more or less equally CO2-friendly, equally climate-friendly. The argument that often comes up in the discussion today and is also superficially correct: with today's shortage of green electricity, which we are especially here in Germany, a country that has very little sunshine most of the year and also does not have the same amount of vegetation in all regions, that we simply have too little renewable energy.

In this situation, it is understandable and also correct to say that the little electricity we have should be put straight into the battery-electric vehicle and used there, and not simply converted into hydrogen via a process chain that is fraught with losses. If, however, and this is also where the plans are going worldwide, in regions where these renewable energy sources, i.e. sun, wind, are available in abundance and where no people live.

There are such regions in the world. There, the green electricity can be produced, it is ecologically almost the same away or identical. Which energy source or which energy carrier I choose, be it electricity, be it hydrogen or intermediate products, because the whole thing has to be transported. This is where hydrogen offers its great advantage. You don't need battery storage to store green electricity generated invariantly, i.e. at a time when the sun is shining or the wind is blowing.

When it is converted into hydrogen, this is more or less a free gift. That's the big advantage, and of course it's also a big bonus in terms of ecology or environmental compatibility.

Lisa Baaske: When you also talk about hydrogen cars, it is also important that it is green hydrogen and therefore equally good for the environment?

Prof. Hermann Rottengruber: Essentially yes, it's the same as battery electric cars. If it comes from the electricity mix as we have it in Germany today, nothing is gained. That's why my statement about the car earlier, also technically correct. (laughs)

Lisa Baaske: Understand. (laughs) What are the main differences in the carbon footprint of an electric or hydrogen car, i.e. in the areas of use, production and perhaps also disposal?

Prof. Hermann Rottengruber: So the subject is still being researched intensively at the moment, because the technologies with which, for example, batteries are manufactured and with which hydrogen fuel cell systems are also manufactured are, of course, still developing further. The disadvantage of batteries at the moment, and there is still no real solution in sight, is the climate or environmental balance, which is very, very poor in the production of batteries. The drying effects, the extraction of lithium is not solved in an environmentally friendly way in all parts of the world, just like the provision of raw materials for batteries.

I'll just mention the keyword cobalt, which is mined in Africa under very questionable circumstances. That is, of course, a point. This is somewhat less dramatic in the case of fuel cells. You do need platinum, but the mining is already known to a certain extent and is also presented in a reasonably sensible way. So in terms of raw materials, it's a question of whether the trend is more toward hydrogen vehicles. With the direct use of the generated energy - that is, if I generate green electricity, I can of course fill it directly into my electric vehicle via a line and distribution. With hydrogen, I still have the problem that I first have to convert the electricity into hydrogen and then possibly also convert hydrogen for transport into another carrier substance - ammonia or methanol, for example, are being discussed - which naturally extends the efficiency chain somewhat, i.e. the efficiency goes down.

As already discussed in the last question, however, it is a question of the availability of green electricity. If it really is available in abundance, this further processing is no longer a big problem. And then you have the big advantage that I can use the stuff for a very long time, practically indefinitely - which is a very long term - but let's say for a very long time for technical applications.

Lisa Baaske: In fact, I don't have an overview at all. I have the feeling that electric cars are now a dime a dozen. But what about hydrogen cars?

Prof. Hermann Rottengruber: The hydrogen car portfolio in Germany is indeed very clear. In my opinion, there are currently two models from-a Korean, a Japanese manufacturers-that are actually available on the market as vehicles for purchase. Various other manufacturers - Daimler, Benz and also BMW - offer vehicles in the form of leasing, but they still have very low numbers. Essentially, there are two cars compared to the electric vehicle fleet, of course, very few at the moment. The reason for this is that the fuel cell or hydrogen vehicle has been treated a bit stepmotherly in Europe in recent times, but in markets such as California or Japan, for example, they have been deliberately focusing on hydrogen mobility for a very long time, and of course more models are on the way there and some are already available. In Germany, there are just these two from Hyundai and Toyota.

Lisa Baaske: If I were to buy one of these two models, how much would a hydrogen car cost? Or will it perhaps cost more later, when it is more established on the market?

Prof. Hermann Rottengruber: In my opinion, hydrogen vehicles will not penetrate the small car segment. I don't have the prices for the vehicles in my head. I think the Toyota is around 80,000 €, so it's definitely a more expensive vehicle. But that essentially has to do with the fact that the technology that's in there is also very complex. And that's why the statement I made earlier - in heavy-duty traffic and in the commercial vehicle sector or in vehicles that also have a high transport capacity, that have a high power density - the hydrogen vehicle is definitely competitive there and it has another advantage: it has permanent availability. It is also not so unimportant for many applications. If you take, for example, emergency vehicles of the fire department, the police, the rescue service - to give an example, obvious examples - there you can't afford to be hooked up to the charging station for a few hours, they must always be available. That's a big advantage of the hydrogen vehicle, because you can also refuel it very quickly. And of course, commercial vehicles, there the portfolio is much larger. In my opinion, there are already seven or eight vehicles available in Europe from well-known manufacturers - Hyundai also produces commercial vehicles - and the portfolio is growing much faster than it is for passenger cars at the moment.

Lisa Baaske: Yes, with rising gasoline prices, a central question is of course: What does hydrogen cost? And if we fill up with hydrogen instead of gasoline in the future, would it be cheaper for drivers?

Prof. Hermann Rottengruber: At the moment, hydrogen is significantly more expensive than gasoline and diesel. This also has to do with the fact that, just as with green electricity, green hydrogen is not available in abundance in Germany. We are currently using so-called "gray hydrogen", which is produced from natural gas. A, not very ecological - B, because of the gas prices we saw last year, of course not very economical either. At a hydrogen price per kilo of €5 - that's the rule of thumb - we are roughly compatible or roughly the same as the price of gasoline and diesel that we had six months ago, about €1.50, €1.60. In the first instance, hydrogen is then also economically within the range of the fuels that we have today.

Lisa Baaske: In the long term, will a third infrastructure be needed for hydrogen cars? That is, in addition to normal gas stations and electric pumps?

Prof. Hermann Rottengruber: Yes, it is absolutely necessary to build up an infrastructure there, but it is already in the process of being built. In Germany, we are now aiming for a number of 400 to 500 service stations at the moment. At first glance, that sounds a little low, because as always, if you look for one, you won't find one. But if you look at how many gasoline and diesel stations we have, it is definitely going in the right direction. If you then increase this by a factor of three or four, then it would certainly be possible to use hydrogen as fuel in Germany across the board and to the benefit of customers.

Lisa Baaske: So let's assume that we will all be driving hydrogen cars in the future. Unlike oil, hydrogen does not exist in pure form on earth. It has to be produced first. Would it just be possible to produce enough hydrogen and, above all, in a climate-friendly way?

Prof. Hermann Rottengruber: As I said before, we will certainly not all be driving around in hydrogen cars. For some applications, the battery electric vehicle is simply well suited and good in terms of efficiency and usage characteristics. Today, it is no longer possible to produce hydrogen in the quantities needed in a climate-friendly way. Of course, there is still a lot of groundwork to be done. But from what we hear on the scene, people who are working on this and the programs of the German government that we are now seeing are clearly aimed at developing sources to produce hydrogen in a climate-friendly way. The primary aim is to develop regenerative sources in regions outside of Central Europe. The regions in North Africa, on the Arabian Peninsula - there the sheikhs are investing in regenerative power plants, solar power plants and wind power plants. In South America - in the Roaring Forties, where there is a lot of wind around Cape Horn - Chile is working on generating renewable electricity and then exporting it. So there's something going on, and if we're serious about the energy transition, it certainly won't happen here in Germany, but globally. Climate change is also a global problem and I am confident that in a few years, we will have so much renewable electricity that we will also have to produce hydrogen, quite simply in order to be able to store and transport the energy.

Lisa Baaske: In fact, I personally only know hydrogen from chemistry lessons, and when you think of chemistry and laboratories, you somehow always think of explosive mixtures. Is such a hydrogen car actually dangerous?

Prof. Hermann Rottengruber: Yes, that is a very important point. I was also involved with the subject of hydrogen ever since I got my engineering degree - and that's been 25 years or more now. In any case, the first thing that comes up when you say you're doing something with hydrogen is the airship disaster at Leikhurst - the Hindenburg blew up. Yes, hydrogen is indeed a very combustible, a very active gas --- but it also has some advantages: It is very light and has high diffusion coefficient properties. So the oxyhydrogen reaction that everyone knows from chemistry classes can be produced, but you have to work a bit hard to really create this highly explosive mixture. Hydrogen as a vehicle fuel has its safety challenges, of course: It's stored under pressure, it's stored cryogenically, it's not all that safe, and if you have a leak, a leakage of hydrogen, you have to respond to that in terms of safety, of course. But that can be done very well. So I was once part of a series vehicle project at BMW and we made a very good and sophisticated safety concept and our safety analyses showed that it was basically no more dangerous than gasoline and diesel. A colleague of mine, who was responsible for the approval of the vehicles, said at the time: "Well, if you wanted to approve gasoline and diesel today, you would never get approval. Because they also have their safety-related problems, they are heavy, flow down and burn the floor-and is harmful to health, toxic - hydrogen is not all that, it escapes upwards. It is a different safety challenge, but if that can be handled and cleverly managed with simple measures that can also be solved technically. We don't need a new invention to make hydrogen safe.

Lisa Baaske: Okay, then I'm reassured and now I know a lot more about hydrogen than just from chemistry lessons. (laughs) But that actually brings us to the final question. In principle, we've come full circle, because we're going back to the first question. You said you would now choose an internal combustion engine, a diesel. What kind of car would you choose in the future?

Prof. Hermann Rottengruber: Yes, in the future, if you ask me in the next 3 to 4 years, I will probably stick with a diesel vehicle, possibly with a hybrid. If my driving profile doesn't change, then I will probably be a customer for a hydrogen vehicle because I am a long distance driver. However, if I only drive a long haul once in a while, then an electric vehicle would be interesting to me. But for mileage that goes beyond 50 kilometers a day, 60 kilometers a day, and that's on a regular basis, you get into the range where you can also think about buying a hydrogen vehicle. So if I need a city vehicle, definitely a battery electric vehicle in the future. But if I have a long distance ahead of me or am a long-distance driver, then the hydrogen vehicle is definitely a sensible solution.

Lisa Baaske: Maybe we should make an appointment now for the future so that we can repeat this podcast again to find out exactly what kind of car you' re driving. In any case, many, many thanks, that's it for today's episode. I definitely learned a lot. I hope the listeners did too. Thank you very much for being here. Thank you for listening. Stay healthy and tune in next time.

Outro-Voice: Know When you Want. The podcast about research at the University of Magdeburg.