The liquid carrier used for hydrogen storage is known in the trade as LOHC (Liquid Organic Hydrogen Carrier) .The Erlangen researchers see great potential in the LOHC technology used, a specialty of the Chair of Chemical Reaction Technology (CRT) at the FAU. 

 

The liquid carrier absorbs large amounts of electrolytically generated hydrogen via a chemical reaction and can then be safely stored under normal ambient conditions for pressure and temperature. Only under very specific conditions within a chemical reactor, the hydrogen can be released again from the carrier. 

 

As far as storage and transportation requirements are concerned, the carrier can be compared with conventional diesel - a major advantage over other hydrogen storage technologies, which usually require high pressures or very low temperatures. Incidentally, the carrier is already widely used in industry - there, however, as thermal oil for heating and cooling processes. 

 

When used as LOHC, however, it allows the repeated storage and release of energy in a closed cycle process. In contrast to fossil fuels, the LOHC is not consumed in the process, but can be repeatedly loaded and unloaded with hydrogen. The container in Erlangen can currently store about 300 liters of LOHC, which corresponds to an energy stored in hydrogen of almost 600 kilowatt hours. 

 

That's enough to cover the electricity needs of a smaller industrial operation over several hours. However, additional storage tanks can easily increase the stored amount of energy many times over.  

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© Kurt Fuchs / Fraunhofer IISB

The interior of the new container enables efficient generation and production of hydrogen.

© Kurt Fuchs / Fraunhofer IISB

The container's electrical compartment houses highly efficient power electronics for connection to the institute's DC network.

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With the new research facility, the scientists in Erlangen want to get to the bottom of various questions: How can an LOHC-based energy storage system be used to record fluctuating energy production processes, such as those that occur? B. occur in the locally installed photovoltaic systems?

 

 How can such systems be compactly integrated into a single container? And how can such a system be efficiently integrated into industrial energy networks? At Fraunhofer IISB, the system is connected to the local DC grid. The institute has many years of expertise in the field of DC technology. 

 

Local DC grids make it possible to avoid unnecessary conversion losses from direct current to alternating current in interaction with local producers.Due to the extreme compactness of the container system, a large number of tailor-made solutions was necessary, which the involved employees - engineers and technicians - occasionally pondered. 

 

"But so far we have accommodated everything", says the deputy project leader in the LZE pilot project "DC Backbone with Electricity-Gas Coupling", Michael Steinberger, with a grin. "And only through interdisciplinary cooperation can our research project be successful," continues Steinberger. The qualified electrical engineer has developed into a fuel cell specialist in recent years and is also responsible for control technology in the container. 

 

Steinberger was able to draw on the valuable support of communications experts at the Fraunhofer Institute for Integrated Circuits IIS to design the control technology. However, in-depth knowledge of chemical processes is also necessary: ​​for example, the LOHC reactor is a development of the CRT, with which there is close cooperation in the framework of the Leistungszentren Elektroniksysteme.

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