Wiki - All about hydrogen

Updated on 19 May 2024

Solid-state hydrogen storage

Hydrogen is an energy carrier with a high energy density per weight, but it is also a light gas. Our article hydrogen describes this in more detail. For this reason, the DASH solid-state hydrogen storage systems are a interesting option for the hydrogen infrastructure. In these storages, hydrogen is stored neither in the liquid nor in the gaseous form, but as a solid in an inorganic carrier material, the metal hydride.

Basics of the technology #

The basis of this form of hydrogen storage is that the metallic compounds used by GRZ Technologies absorb the hydrogen under the right conditions. This process is shown below.

Hydrogen is stored in a solid carrier material.

During absorption, the hydrogen molecules (H2) split into individual hydrogen atoms (H). The individual hydrogen atoms then move into the interstitial sites of the metal alloy. The distances between the individual atomic nuclei become significantly smaller than they would be the in the gas phase. As a result, the volumetric density of the hydrogen storage is very high, and so is the energy density of the system. Different alloys can be used for this process. An example of an alloy is LaNi5. The following chemical reaction takes place, when hydrogen is absorbed by such an alloy:

LaNi5 + 3H2 ⟶ LaNi5H6

It is important to state that this alloy is a single example from a whole class of materials. GRZ Technologies engineers develop the best material for each product and thereby optimize the properties of the overall system.

Comparison to other storage methods and technical advantages #

However, to use metal hydrides as a solid-state hydrogen storage, not only the selection of the material is decisive. The properties of the overall storage system must be optimized too, as described in the section “System Design and Manufacturing”. A key aspect of DASH storage technology is the high volumetric storage density. It depends on the storage material and is limited both by the size of the gaps between the atoms in the carrier material and the distance between the individual H atoms. According to the Westlake criterion (see, e.g., D.G. Westlake, J. Less-Common Metals 91 (1983), pp. 275-292), volumetric storage densities of up to 245 kgH2/m3 are theoretically possible with this technology. For comparison: liquid hydrogen has a density of 71 kgH2/m3 and gaseous hydrogen at 900 bar approx. 40 kgH2/m3. GRZ’s metal hydride-based technology is extremely cycle-proof and allows for lifetimes of 25 years or more. We can use the entire available capacity without restrictions. Finally, an important feature of the technology is its environmental friendliness. The metal hydride hydrogen storage device DASH impresses with a significantly reduced ecological footprint compared to existing competing energy storage solutions such as lithium batteries. The storages are fully recyclable, and the energy used for the production of the storages is much lower.

The properties of this form of hydrogen storage are summarized and compared to other forms of hydrogen storage in the table below:

Pressurized gas (low pressure)Pressurized gas (high pressure)LiquidSolid state
Advantages• No compressor required
• Widely available
• Moderate pressures
• High volumetric density (in particular at 700 bar(g))• High volumetric density
• Scalable
• Low levelized cost of storage
• Very high volumetric density
• Excellent safety
• Low pressure
• Maintenance free
• No compressor or liquefier required
• No losses during charging and discharging
Disadvantages• Large volume
• Not the entire storage capacity can be used
• Safety-related restrictions and cost
• Significant energy losses during compression
• Not the entire capacity can be used
• Safety-related restrictions
• Compressor is required
• Significant energy losses during liquefaction
• Safety-related restrictions
• Technical complexity: Boil-off, continuous cooling required, etc.
• Lower gravimetric density
Did this article help you?