Interview with Prof Dr Matthias Bauer
The transition away from fossil fuels and towards renewable energies is essential for successful climate protection. Prof Dr Matthias Bauer, Professor of Inorganic Chemistry of Sustainable Processes at Paderborn University, is certain that there is no alternative to the sensible use of hydrogen. He is researching the production and storage of green hydrogen in various projects. In the interview, the Paderborn scientist also explains that there are still a few hurdles to overcome, especially when it comes to storing and transporting hydrogen, before the smallest molecule can make its triumphal march in transport, industry and as an energy source.
Prof. Dr Bauer, together with the French partner organisation "Agence nationale de la recherche" (ANR), you are researching the production of green hydrogen in a DFG-funded project. When is hydrogen "green"?
Green hydrogen is the type of hydrogen that is produced without the use of fossil fuels. Currently, hydrogen is still very often obtained from steam reforming or coal gasification, for which methane and coal are required. Traditionally, we talk about green hydrogen when the electrolysis of water into hydrogen and oxygen uses green electricity from renewable energies that does not produce CO2. As I understand it, both the raw materials and the energy sources should be renewable.
You rely on sunlight and available raw materials such as iron to produce hydrogen. What characterises your research?
We are conducting basic research to investigate the fundamental processes of photocatalytic hydrogen production. Normally, hydrogen is mainly produced by electrolysis, i.e. purely electrochemically using electricity. In contrast, we work photochemically by splitting water and utilising sunlight as a truly inexhaustible source. If you want to break water down into its components in this form, you always need a catalyser. And for this we use metals that are available. As the fourth most common element on earth, iron naturally plays a major role.
The project will run until the end of 2024. What findings have you made so far?
We are combining a photocatalyst that collects sunlight with a catalyst that breaks down water into hydrogen. This means that we transfer the sunlight collected by the iron to the energy from the cobalt in order to convert the substances. Chemically, of course, there are many, many fundamental processes involved that take place in a billionth of a millionth of a second. We are trying to visualise these with ultra-short flashes of light, known as femtosecond spectroscopy. This allows us to visualise the individual processes. This is how we first understand how the transfer of solar energy from one centre to another works.
The production of green hydrogen alone is not enough, it also needs to be stored appropriately. Is the infrastructure for this already in place?
It is often claimed that the gas network can be used to transport hydrogen. And that is basically correct. Any gas can be transported. Unfortunately, hydrogen has an unpleasant property. It is the smallest molecule we know of. As a result, the hydrogen molecule also moves the fastest and every time you want to connect a pipe, the hydrogen simply diffuses out. In other words, you can have a tight connection by technical standards and the hydrogen can still escape from this screw connection. And that makes it problematic, of course. If you want to transport hydrogen in this way, you currently have to accept large losses or think about other methods of transport.
Are there already solutions in this area?
There are solid hydrogen storage systems such as hydrides, in which hydrogen is stored and extracted under pressure, and liquid organic hydrogen carriers (LOHCs), in which hydrogen is chemically bound in a liquid. Both processes are already mature. We also want to develop solid, iron-based hydrogen storage systems that can store almost as much hydrogen as LOHCs. In this case, the hydrogen is stored in a reactive state. At higher temperatures, water can then be passed over the iron, which in turn produces iron oxide and hydrogen. You therefore have a system in which you can switch back and forth between hydrogen storage and hydrogen source. These storage systems can be used very well for decentralised applications, for example in a heating system that is operated with a fuel cell.
Keyword energy transition: What role does energy research at universities play in the development of the hydrogen economy?
A university as a whole can achieve a great deal and Paderborn University is also broadly positioned in this area. As chemists, we conduct basic research. We want to understand and develop the molecular processes that will later be used and use this understanding to improve them. Then, of course, the engineers also come into play, looking at which energy sectors can be supplied with hydrogen without causing problems. In mechanical engineering, hydrogen - to whatever extent and in whatever area it can be used sensibly in the future - plays an important role with regard to new mobility. For example, would it be possible for a farmer to generate electricity and then hydrogen with the wind turbine in his field, store it and then use it to refuel his tractor? And finally, you can also look at the whole thing sociologically. How does a change in mobility behaviour affect the prosperity of society? I therefore believe that we at the University of Paderborn can look at hydrogen from a wide variety of perspectives and that is precisely what is so exciting.
The production of green hydrogen is still expensive. How optimistic are you that green hydrogen will be affordable in the future?
Of course, a lot depends on how research is promoted. It's a long way from realisation to technology. However, if we want to achieve the CO2 targets, there will be no getting round hydrogen sooner or later. We will always have to import hydrogen, but the moment its technological use becomes economically viable, hydrogen will go its way.
This text has been translated automatically.
