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Air Liquide makes equity investment in solid state hydrogen storage start-up Hydrexia

Air Liquide, through its subsidiary ALIAD, which is dedicated to investments in technology start-ups, has made an equity investment in solid-state hydrogen storage company Hydrexia. Founded in 2006, Australia-based Hydrexia is a spin-off of the University of Queensland and is seeking to commercialize a magnesium hydride hydrogen storage technology.

Hydrogen storage in the form of magnesium hydrides is a technology that has been known since 1975, with its industrialization and commercialization being slowed down until now because of the high production cost. Hydrexia’s new alloy should make it possible for the production of fixed or mobile stocks at a competitive price compared to existing technologies, combined with a higher storage density, Air Liquide says.

Hydrexia’s magnesium hydride technology is based on an alloy which negates the need for expensive, energy intensive and difficult-to-scale, traditional ball milling. The alloys are produced using conventional casting equipment, and are therefore expected to have significant economic benefits over hydrogen storage materials produced by high energy processes.

Hydrexia’s technology is produced by conventional casting processes and milled into flakes that are tens of microns thick, orders of magnitude larger than ball milled nanoparticles. These flakes are stable in air, removing the risks associated with handling pyrophoric nanomaterials.

Hydrexia says that its material has fast and controllable kinetics and reduced activation time for the first hydriding reaction. The short activation time provides an additional reduction in production time and cost. During the activation process, the flakes break down into smaller particles.

Air Liquide intends to use the technology for industrial hydrogen markets such as glass, steel and chemicals. In concrete terms, Air Liquide could deliver hydrogen stored in the form of hydride to its customers rather than in cylinder or bulk.



Magnesium hydride is 7.66% hydrogen by weight:

That works out to around 2.5kwh/kg, way in excess of anything we can do with batteries, and around 10 times the specific energy of those in the Tesla.

Of course, in practise we would not do nearly as well, with packaging weight and other losses, but still it is a lot better than we can do in reality with batteries short of lithium air or some such.


On the other side, this stuff requires special processing in a plant.  It puts the FC advocates farther and farther away from the "make your own fuel" argument.

What's the energy overhead of making the magnesium?


Hi EP, there is a discussion of this topic here:

Most of this is way above my head, but you might find it of interest, although this study concentrates on nanoscale materials, seemingly a different technology than that Hydrexia is using:

'The major impediment for a practical application of bulk-MgH2 is said to be its high desorption energy at 75 kJ/mol [H2] which is also found experimentally [4].
High desorption energies yield high desorption temperatures as shown in subsection 2.3. Hence bulk-MgH2 appeared to be a bad option, even though it seemed to
be an attractive storage material as 7.7 percent of its weight contains hydrogen.
Nevertheless, one would not give up on magnesium hydride as storage material. That is why one concentrated on magnesium hydride on nanoscale and found that
the desorption energy decreases for clusters containing less than 20 magnesium atoms [5].'


Low desorption energy suggests that it would become pyrophoric.


Apparently some are doing a second pass after the hydrogen is released from the hydride, and adding water so that additional hydrogen is released and magnesium oxide formed.
That would put the energy by weight up to something like 15%, and leave non-combustible oxide.


And one heck of a lot of heat energy released in the reaction, representing energy lost.  I ran those numbers a good many years ago; if you need efficiency, that is the wrong place to look.

I suppose one virtue is that water from a PEM FC could be recycled to the hydrogen system, avoiding the need to carry it.  But why not just a magnesium-air battery and avoid the middleman?


This is just a niche product for industrial users of h2 that arnt already near an h2 producer and or a h2 pipeline.

Its primary benfit is its cheaper to produce and transport then it is to truck h2 in liquid or gas state with current medium pressure h2 tankers.

It likely will prove to be a waste of time the instant the newer tech h2 tube trucks get produced in number. After all even 30 metric tons of the stuff would only result in moving about 2 or less metric tons of h2 they could use. Yes current gaseous h2 tube trucks only carry .35 metric tons each but supposedly newer truck designs can carry far far more.


Magnesium air batteries would be lovely, but we are no where near building reversible batteries.
Hydrogen storage, OTOH, we can do, and the only question is if using a hydride can beat the performance of a CF tank.


".. but we are no where near building reversible batteries."?

15 years and over 5 million Prii alone have reversed battery charge flow.


Clearly I was talking about reversible magnesium batteries.

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