When it comes to the energy transition, hydrogen is always mentioned. Why is that? What can it do?

Marco Zobel: The fundamental challenge in the future provision of energy is that we need an energy carrier that can do everything that the old fossil fuels can do. In other words, it is the answer to the questions of the future - how can energy be stored, how can it be produced and consumed?
 

So it's a little prodigy?

Zobel: Exactly. Hydrogen can be such a little wunderkind. It's basically a very volatile gas to begin with. That's why it very, very rarely occurs as a pure gas on Earth. Hydrogen is often bound, for example in the form of water. It is also found in natural gas, namely in methane. Conversely, this also means that these chemicals, which contain hydrogen, can also be produced from hydrogen and combined with each other. That's why hydrogen is a key element in the energy transition.
 

But what can hydrogen do?

Zobel: It has the charm that, technically speaking, it can be produced easily, namely from electricity and water. And then you can store it nicely.
 

So first of all, energy is consumed to produce hydrogen in the first place. So how can it be such an important energy carrier?

Zobel: I'll explain it like this: We've all gotten used to the fact that electricity and heat and all kinds of other energies are permanently available. That's because these fossil energy forms can be stored very well. Sure, nobody wants a pile of coal on their doorstep, but you can actually leave it there until you need it. The same applies to natural gas: If it's properly encapsulated, it lasts for centuries. And the same goes for crude oil. But it's more difficult with electricity. If we produce it, we have to use it directly. If you don't do that, the power grid will always have problems and become unstable. That means that either you only provide the electricity you need by means of power plants; or, in the case of renewable energies, they would have to be
be throttled if the electricity cannot be purchased. Or you need a buffer. So you take electricity from the grid and use it to produce hydrogen.
from it. And then you store it. 
 

So the electricity only lives in the hydrogen temporarily, a chemical energy store, so to speak.

Zobel: Exactly. And that's not all: Hydrogen is not only a buffer, but also a starting material for the chemical industry, for heat supply. It is a
very valuable basic chemical, a raw material that can be used in other processes. This is already being done, it's nothing new.
 

As I understand it, the surplus energy that is generated on windy and sunny days is used by producing something that we can use later, instead of just letting it go to waste. After all, we're always talking about green hydrogen, that is, hydrogen that is produced from renewable energies. And not from methane.

Zobel: That's right. Actually, one would always prefer to use the electricity directly. If you store something temporarily, energy is always lost in the process. But it can't be avoided. If you want to have something permanently - for industry, for cars - then you need buffer elements.
 

Let's take a look at the research project in Etzel. They are now investigating how hydrogen can be stored in the caverns. So far, only oil and gas have been stored there.

Zobel: The caverns are already suitable for hydrogen to a large extent in natural gas operation. But there are open questions about the technical requirements. For example, are the pipes and the measurement technology also suitable for hydrogen? But we also ask ourselves
But we also ask ourselves: How will such a hydrogen cavern be operated in the future? How often will hydrogen be stored and retrieved there? In what quantities? How quickly will it have to react?
 

That would be different from natural gas?

Zobel: Yes. Storing hydrogen would be a year-round endeavor. Unlike traditional gas storage, where gas is bought cheaply in the summer and stored to be used in the cold season. With wind power, other factors come into play: there are the fall and spring storms. There is also a lot of wind in the winter. That means the loading and unloading of a hydrogen cavern would look very different from a natural gas cavern. And then there is the aboveground technology, i.e. the compressors or the cleaning systems. If the storage facility is to be fast, the plant on top must also be fast.
 

But do we already know how much hydrogen has to be available and how quickly?

Zobel: That's where you run into the chicken-and-egg problem. You want to adapt the plants, but you don't yet know the future market. So we try to use simulation results, which we develop from our models, to give something like guidelines to be able to map the greatest possible dynamics. These are then quasi recommendations for action for the plant operators. 
 

What do you think will happen in the future with the use of stored hydrogen?

Zobel: The question is: Do you want a tractor that drives slowly but can pull a lot? Or do you want a racing car? Actually, it's not clear yet where the journey will take us. But it will probably be in the direction of a racing car.

IMAGES: OLTMANNS