Cordula Buse, Deputy Editor of ChemBioEng Reviews, talked with Karsten Müller, University of Erlangen-Nürnberg and Forschungszentrum Jülich GmbH, Germany, about his recent review article on the state of hydrogen storage technologies. Müller’s main research interest is the storage of energy, with a special focus on hydrogen.
What is the main challenge in hydrogen storage?
The main problem of hydrogen storage is low energy density. Classical approaches are based on elevated pressure or low temperatures. This requires special tanks and the final energy density is still insufficient. Furthermore, in the case of liquefied hydrogen, significant losses over time are unavoidable.
To overcome these issues, it is desirable to store hydrogen at ambient conditions. The chemical conversion of hydrogen, yielding covalently bonded hydrogen, is a possibility to achieve this task. One way to do this is the reversible hydrogenation of aromatic components, so-called Liquid Organic Hydrogen Carriers (LOHC).
How did you become interested in this topic?
Thermodynamics is my main scientific methodology. The LOHC technology is very promising thermodynamically, but there are also some thermodynamic issues related to it, which need to be addressed. The research on LOHC and other hydrogen storage technologies is particularly interesting because it connects several different fields of science like catalysis, thermodynamics, and process engineering.
How do we choose the best hydrogen storage technology?
Currently, there is a huge number of hydrogen technologies. Some are at an advanced stage of development and some are in earlier stages of lab research. If you look at the requirements of different applications and compare them to the strengths and weaknesses of the different approaches, you do not find a single, best solution for every scenario. However, future energy systems rely on sufficient storage capacities and hydrogen is most likely going to become an important element in this field.
A sound thermodynamic analysis is vital for an informed decision. Not only researchers with a focus on thermodynamics should be aware of this. Together with other aspects, such as the energy density and the dynamics of hydrogen release, it is important for understanding the pros and cons of the different technological options.
How far are the different storage technologies from commercial use?
Some of the more sophisticated hydrogen storage technologies have already reached early stages of commercialization. The operation of the LOHC technology, for example, has been demonstrated not only on a lab scale, but also on real technical systems. There are LOHC plants actually operated in different countries.
However, like all sophisticated hydrogen technologies, it is a new technology. It has reached an impressive level of market readiness, but there are still many opportunities for further improvement.
Which part of your work is the most challenging?
The work is highly interdisciplinary. Thermodynamics and catalysis meet fields like fluid dynamics, heat transfer, and separation science. Working on these different aspects at the same time is sometimes challenging, but it is also incredibly interesting.
What is the overall aim of your research?
Energy research is one of the hot topics today. It is crucial for our societies to find solutions for the challenges related to energy and the environment. However, advances in technology cannot solve all problems. Behavioral changes are unavoidable. Still, science and technology are vital for finding ways into a sustainable future. My aim is to contribute to this path—on the one hand, to strengthen our understanding of the field, on the other hand, to make technological progress and to push this development forward.
Are there any other topics your research group is investigating?
My work is not limited to hydrogen storage, but my group has a clear focus on energy storage. Thermal energy storage, in particular, offers many fascinating research questions. We are studying, for example, the effects inside latent heat storage systems with computed tomography.
X-ray images enable a view into otherwise inaccessible apparatuses. The specific features of X-ray computed tomography finally give the three dimensional information about the effects inside. This technic allows to see how melting or crystallization fronts move through the storage. Getting this kind of insight into the effects is particularly important for improving heat transfer
Investigating the different types of energy storage—isolated, but also in their interplay—is bringing up new research topics again and again.
So how important is interdisciplinarity?
The tendency towards more interdisciplinary scientific work we have seen in recent years is great. We should proceed on this path. The complexity of scientific questions is often overlooked if all scientists only focus on their specific field. We need collaboration across the borders of scientific fields and with fields outside of science. Energy and environment are topics that must be addressed by scientists and engineers, but that does not cover the whole picture. We should strengthen our connections to different fields of academia, like social sciences and ethics. And of course, we should reach out to the general public, because only solid scientific information enables reasonable decisions.
Thank you very much for the interview!
The articles they talked about
- Technologies for the Storage of Hydrogen Part 1: Hydrogen Storage in the Narrower Sense,
ChemBioEng Rev. 2019.
- Technologies for the Storage of Hydrogen. Part 2: Irreversible Conversion and Comparison,
ChemBioEng Rev. 2019.
Also of Interest
- Hydrogen Storage under Ambient Conditions,
Catharina Goedecke, Daniel Teichmann,
ChemViews Mag. 2015.
Dr. Daniel Teichmann, Hydrogenious Technologies, talks about hydrogen storage and the challenges of founding a company