Process and Plant Engineering for Chemical Hydrogen Storage (INW-4)

Scientific work at the Process and Plant Engineering for Chemical Hydrogen Storage subinstitute (INW-4) focuses on connecting the hydrogen conversion units with the surrounding application-specific aggregates to form an optimized system. Depending on the application, the system under consideration may be, for example, a storage system (combination of electrolysis, hydrogen/storage material conditioning, hydrogenation reaction) or a hydrogen supply system (combination of dehydrogenation reaction, hydrogen purification, and hydrogen compression). In both cases, the full system must be optimized, which is something that does not automatically result from the optimization of the individual components. In this context, a particularly promising area for future development work, which has hardly been considered so far but is critical for the economic success of all hydrogen storage technologies, is control and regulation technology as well as automation technology for the full systems under consideration. This can be easily illustrated using the example of heat utilization and heat integration. While some steps generate heat in the system (hydrogenation, compression, conversion into electricity), others consume heat in the system (dehydrogenation, purification, conditioning). However, optimal heat integration requires not only apparatus for efficient heat transfer but also full system optimization. This is the only way to achieve the best possible balance between heat generation and heat consumption and to maximize system efficiency.

Many of the systems developed are operated in a decentralized manner and without operating teams. This gives rise to important safety issues that must be managed through an intrinsically safe system design as well as through appropriate safety mechanisms and routines. Although by chemically binding hydrogen to carrier molecules, the core technologies of HC-H2 have clear advantages over hydrogen storage in elementary form (compressed hydrogen, cryogenic hydrogen), these safety aspects are extremely important for the construction and operation of conversion apparatus. Additional safety aspects are related to the acute toxicity (methanol, ammonia) and/or flammability (alcohols, organic vapours) of individual components.

During operation, the storage and release facilities are usually subject to dynamic performance requirements resulting from external factors (e.g. availability of wind and solar radiation as variable input parameter of renewable hydrogen production) and the operator’s performance requirements. For each performance requirement, the optimal operation of all system components must be determined using a model and the system must be controlled and regulated accordingly. Appropriate system models as well as hardware and software solutions exploit the potential of effective, model-based system control and thus enable optimal operation of the developed systems at every operating point. It is therefore expected that work at INW-4 will become closely intertwined with demonstration projects and thus directly influence their design.