In August, the UK government released its “UK hydrogen strategy” which outlines how the UK can become a world leader in the low carbon hydrogen economy. This new document sets out how the government seeks to achieve one of its ten goals for a green industrial revolution of building 5GW of low carbon hydrogen production capacity by 2030.
We recently reported on the challenges of, and the progress in, generating sufficient hydrogen to fuel a low carbon hydrogen economy. Research and commercial opportunity, and consequently patenting, in green hydrogen has significantly increased over the past decade. While producing more low carbon hydrogen is essential, this raises a further issue: how to distribute and store all this hydrogen?
It seems likely that hydrogen will not only have to be stored in stationary applications, but also in mobile applications for transport sectors such as heavy duty which are harder to electrify than, e.g., passenger vehicles.
Hydrogen storage methods
Hydrogen may generally be stored physically (i.e. as molecular hydrogen) or in another material.
Physical storage of hydrogen
Hydrogen may be stored in gaseous or liquid form. Storing hydrogen as a gas typically requires very high pressure tanks. Hydrogen can also be stored in liquid form in cryogenic tanks. When stored as a liquid, cryogenic tanks must be capable of maintaining the hydrogen at a temperature of -252.8°C (at a pressure of 1 atm).
On a larger scale, underground salt caverns and depleted undersea gas or oil fields have been considered for storing larger amounts of hydrogen, as they may be capable of storing TWh amounts worth of hydrogen.
Material-based storage of hydrogen
To increase the energy storage density of hydrogen, and reduce the energy required for high pressure or liquid hydrogen storage, hydrogen may be stored on the surfaces of hydrogen-adsorbing solids, or within hydrogen-absorbing solids.
Some proposed classes of materials for hydrogen-adsorption and -absorption include:
- Porous carbons for physisorption;
- Metal-organic frameworks (MOFs) for adsorption;
- Metal hydrides such as MgH2, NaAlH4, and LaNixHy
Yet higher energy storage densities for hydrogen may be achievable by using liquid organic hydrogen carriers (LOHCs). One interesting area of research and development are the catalysts required for hydrogenation and dehydrogenation of LOHCs such as cycloalkanes.
Many other materials have also been suggested as potential hydrogen storage hosts, and it will be interesting to see which storage method will ultimately become most commercially viable, and whether different solutions will become dominant for stationary and mobile applications.
Patent applications for hydrogen storage
Going by the numbers of patent application families published each year, research and development in hydrogen storage appears to have picked up recently. While from 2011 to 2015, the number of published patent application families related to hydrogen storage hovered just under 500 families per year, the number has increased significantly, especially in the last couple of years (see Figure 1).
The number of patent application families published in CPC class Y02E60/32, relating to hydrogen storage, has more than doubled since 2015, from 459 to 1235 in 2020, the last year for which full data is available. This increase in patent application families coincides with a renewed and improved push to mitigate the climate emergency, for which hydrogen production and storage is one of many possible strategies.
Looking at patent filings in “hydrogen storage” (CPC class Y02E 60/32) in more detail, many of the largest filers are automotive OEMs: Toyota, BMW, Honda, Daimler, Hyundai, GM, and Bosch are all among the 14 largest filers in this area (see Figure 2). Industrial gas and chemical companies such as Air Liquide and Linde are also large filers of hydrogen storage related patent applications.
Interestingly, while BMW has recently revealed a hydrogen-powered SUV and Toyota continues to release new hydrogen fuel-cell models, Daimler appears to instead be focussing their hydrogen research on heavy duty vehicles such as trucks. Looking at three IPC classification classes relevant to different methods of storing hydrogen, F17C 5/04 (Methods or apparatus for filling pressure vessels with liquefied, solidified, or compressed gases requiring the use of refrigeration, e.g. filling with helium or hydrogen); C01B 3/0015 (Reversible uptake of hydrogen by Organic compounds); and C01B 3/0031 (Reversible uptake of hydrogen by Intermetallic compounds; Metal alloys), shows a general trend across these IPC classification classes to increasing patent filings.
What does this tell us about the future of hydrogen storage?
With increased interest in climate-neutral technologies, it is clear that storage of hydrogen is an area of significant, and increasing, research and development activity. Although there is an 18-month delay between filing of a patent application and its publication, and as such patent filing numbers can never tell the whole story, it seems clear that European, US, and Asian automotive OEMs, and industrial chemical companies, are in a good position to take advantage of the continuing trend towards more sustainable energy generation, storage, and usage.
The hydrogen supply chain is complex, and will depend on hydrogen generation (as discussed here) as well as hydrogen storage and fuel cell development. As such, protecting your inventions at the various levels of this supply chain, be they related to the generation, storage, use, or transportation of hydrogen, may be essential. Judging by the patent data shown above, large European and Asian companies seem to be leading the way in developing hydrogen storage.
However, as also discussed above, many different materials and methods for storing hydrogen are being developed, and as such it is difficult to predict which material(s) or method(s) may end up on top.
At Reddie & Grose, our experts can advise you on the best ways to protect your intellectual property related to hydrogen, no matter which hydrogen storage technology your invention relates to.
This article is for general information only. Its content is not a statement of the law on any subject and does not constitute advice. Please contact Reddie & Grose LLP for advice before taking any action in reliance on it.