German researchers make hydrogen storage tanks from industrial waste

Large container ships sometimes sail the oceans for weeks. Unlike a car, you can’t just equip them with a battery and an electric drive. Because there are not enough charging stations at sea. Experts therefore see a possible application for the fuel cell here. It converts hydrogen into electricity and uses it to power an electric motor. In this way considerably higher ranges can be achieved than with a battery. Until now, however, the storage of hydrogen is still a problem. In order to work as space-saving as possible and at moderate temperatures, so-called metal hydride storage systems are used. Certain metal compounds are first ground into a powder and then brought into contact with the gaseous hydrogen. The result: The two hydrogen atoms of the molecule separate from each other and bond to the metal atoms. The so-called metal hydrides are formed.

 

The extraction of the very pure metals causes environmental damage

The connection of the atoms reduces the volume required for storage. This is critical for use on container ships, where space is naturally limited. The second major advantage is that the reaction can also be reversed quickly and easily to release the hydrogen again. But there is still a problem with the metal hydrides. Until now, these have been obtained from very pure metals and processed in a complex manner. However, the extraction of the metals not only poses problems for the environment, but also causes additional CO2 emissions. The same applies to further processing. Researchers from the Institute for Hydrogen Technology at the Helmholtz Center Hereon have now made an important discovery in this regard: They used metal waste from industry to obtain the coveted metal compounds. Ideally, the hydrogen storage could be obtained in the future within the framework of the established circular economy.

For example, metal waste can be recycled sensibly

This approach has two major advantages. On the one hand, millions of tons of industrial metal waste are generated every year in Germany alone. There is therefore sufficient material available for further processing. In addition, the exact composition of the alloy in question does not play a major role in this form of further processing. This means: In theory, even metal waste that was previously considered not meaningfully recyclable can be used. The researchers are therefore confident that their research project will ultimately result in products that can be used industrially. In order for ships to actually sail the world’s seas purely on hydrogen, a second point must be met: sufficient green hydrogen must be available. This in turn requires large amounts of green energy. Because only if the energy-intensive production is covered by sustainable energy sources, the use of hydrogen is truly climate neutral.

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