Hydrogen storage

Research with synchrotron radiation for the storage of hydrogen

 © Andreas Stierle/DESY

Storing hydrogen

Hydrogen is attributed a central role as an energy carrier in the energy transition, because it is easy to produce, and storage and transport are also technically easily solvable. No exhaust gases are released when it is converted into electricity. Therefore, the task now is to find the most efficient and practical solutions for storing hydrogen. There are various possibilities for this: Storage under pressure, cooled (liquid) or both at the same time, in solids such as metal hydrides, adsorptively in porous materials or chemically bound in liquid organic hydrogen carriers (LOHC). Which technology makes sense depends on the application, for example whether a light and space-saving storage system is needed or whether weight is not a major factor.

Research goals

A hydrogen storage system should take in as much hydrogen as possible, keep it stable and release it easily when needed. To make these steps effective, they should require as little energy as possible. Each type of storage has its own advantages, but also limitations that should be overcome: The energy required for compression to 700 bar is about 12 % of the energy content of the hydrogen, and much higher still for liquid hydrogen storage, which requires strong cooling. Adsorptive storage by attachment to the surface of a highly porous material also requires cooling, and metal hydrides, which can absorb particularly large amounts of hydrogen, must be heated for its release. Research is therefore being conducted to find materials, structures and processes that require little cooling or heating. Using the reaction energy through an intelligent combination of processes can also help.

Researching hydrogen storage with synchrotron radiation

Synchrotron radiation allows the structural characterisation of materials at the atomic or molecular level. Therefore, it offers special opportunities in the study of materials that store hydrogen. In metal hydrides, for example, it is a matter of knowing precisely the heat transport, the movement of the gas through the hydride and the reaction rate with the hydride. Experiments with synchrotron radiation also made it clear why the combination of two different hydrides can lower the release temperature. Particularly high resolution is needed when investigating nanoparticles. The use of palladium, for example, is promising. At room temperature and atmospheric pressure, palladium can absorb about 900 times its own volume of hydrogen gas - but it is very difficult to release it again. But if it sticks to the surface of ultra-small palladium nanoparticles with an iridium core, it can be easily dissolved again at room temperature. The mode of action of catalysts, on the other hand, is the focus of the further development of LOHC technology, and here synchrotron radiation is used to investigate dehydrogenation and catalyst degradation processes at the atomic level.

Research landscape

The Helmholtz Association operates large-scale research facilities, including the synchrotron radiation sources in Germany. Research with synchrotron radiation on energy materials is therefore particularly concentrated there, but also takes place throughout Germany at universities, other research institutions and in companies. In the Helmholtz Association's Hydrogen Competence Atlas, the various research priorities of the Helmholtz Centres are clearly presented.

The Jülich Research Centre is a hydrogen research centre that focuses not only on the storage of hydrogen, but also on its distribution, production, use and system analysis. In the Living Lab Energy Campus of the Jülich Research Centre, hydrogen technology is part of an intelligent energy system that networks liquid and gaseous hydrogen technologies, lithium-ion batteries and photovoltaic systems in energy demonstrators via intelligent control programmes. In addition, LOHC technology in particular is being further developed in the new Institute for Sustainable Hydrogen Economy (INW). In September 2022, the Helmholtz Hydrogen Cluster HC-H2 in Brainergy Park Jülich was opened officially.

The foundations for this have been laid by researchers throughout Germany, especially at the Friedrich-Alexander University Erlangen-Nuremberg (FAU). The Helmholtz Institute Erlangen-Nuremberg for Renewable Energies (HI ERN) was founded in 2013 as a cooperation between the Forschungszentrum Jülich, the Helmholtz-Zentrum Berlin (HZB) and the Friedrich-Alexander-Universität Erlangen-Nürnberg. There, the existing activities in the field of material characterisation are to be further strengthened - using modern X-ray spectroscopy methods at the synchrotron.

Synchrotron radiation methods are also used at the Helmholtz Centre hereon to research energy materials. The "Material Design" department of the Institute for Hydrogen Technology, for example, is developing innovative functional materials based on metal hydrides and light metal hydride composites.

The mode of action of catalysts used in the storage of hydrogen is being researched at the Karlsruhe Institute of Technology (KIT) and the Helmholtz Centre Berlin (HZB) as well as in the newly founded CatLab, also using synchrotron radiation. In the Energy Lab 2.0, KIT scientists can research and directly test hydrogen and related processes.

Examples from research

To understand fundamental structures and processes, you have to look closely - and not just at one spot, but to understand a material as a whole. This is the strength of scattering methods like those used at the synchrotron. They elicit the deepest secrets of the storage materials and thus help to develop more effective processes. Some examples from research are listed below:

Green hydrogen from offshore wind power, Hereon, 26 August 2022

Federal government funds German-New Zealand hydrogen project, Hereon, University of Otago, 03 August 2022

Micrometer-sized particles encased in tailored polymer membranes. Hereon, 09 February 2022

Nano-chocolates that store hydrogen. DESY / Univ. Köln, 27 December 2021

Hydrogen Refuelling Now Five Times Faster. Hereon / IFW Dresden, DESY et al., 07.01.2020

Hydrogen on the march! New laboratories at the Institute for Materials Research. Hereon, Dez. 2017

Synchrotron radiation X-ray powder diffraction techniques applied in hydrogen storage materials - A review. Honghui Cheng et al., Progress in Natural Science: Materials International, Vol. 27/1, 2017