As the world transitions towards a more sustainable future and low-carbon economy, interest and investment in green energy continues to grow year-on-year. Many nations have set goals for net zero by 2050 and to achieve this, all kinds of energy usages must be considered.
Although currently a modest player, hydrogen is enjoying a renewed and rapidly growing attention globally, particularly as its combustion produces no carbon dioxide and very little air pollution.
Hydrogen has realistic potential to help decarbonise even the heaviest of industrial processes and economic sectors, where reducing carbon emissions is both urgent and difficult. In the European Union’s 2018 publication A Clean Planet for all: A European Long-term Strategic Vision for a Prosperous, Modern, Competitive and Climate Neutral Economy, hydrogen features in all eight scenarios proposed to reach net zero by 2050. The EU published a unique hydrogen policy in 2020 designed to support the rapid growth in the sector.
Although hydrogen is the simplest of all the atoms, there are challenges in turning it into a powerhouse of the economy, and significant innovation is required in the coming decades to meet these global goals. This innovation must cover the whole lifecycle of hydrogen, including production, storage and use.
This report covers each related technology, using the most recent patent data and filing trends.
Production – the spectrum of hydrogen
Depending on how hydrogen is produced, it is assigned a colour, and there are three main varieties.
“Grey” hydrogen is currently the most used type of hydrogen, made through steam reforming of natural gas. This process has the downside of producing (amongst other pollutants) carbon dioxide and “grey” denotes its release into the environment.
However, if the carbon dioxide is captured, it is termed “blue” hydrogen. Several carbon capture technologies exist and continue to develop, but the most widely used is by simply trapping the carbon dioxide underground. Carbon capture is covered here in this report.
The ultimate goal is “green” hydrogen made from the electrolysis of water, powered by renewable energy. This process – that splits water into hydrogen and oxygen – allows capture of hydrogen as a commodity, while releasing oxygen into the environment with minimal pollution.
Therefore, hydrogen is seen as a ‘clean’ energy storage mechanism. Excess energy produced from renewables, such as solar, can be used to generate green hydrogen. The energy that is stored in the hydrogen can then be released to power a national grid, heavy industry plant or an ordinary car on demand.
Green hydrogen from electrolysis
Grey hydrogen continues to dominate hydrogen production via steam-methane reforming to produce hydrogen (H₂), carbon monoxide (CO) and carbon dioxide (CO₂). The cost to produce it remains significantly lower than both blue hydrogen and green hydrogen. Consequently, grey hydrogen covers most of the market, with the associated environmental impact.
However, there is significant growth potential for both blue and green hydrogen technologies, with the latter being the global priority. The International Energy Agency’s scenarios predict that by 2030, when total production exceeds 200 Mt H₂, 70% will be produced using green and blue methods. By 2050, when production should exceed 500 Mt H2, almost all will be green hydrogen.
Electrolysis production of green hydrogen has grown from the mid-1990s, steadily rising year on year. Indeed, there has been a similar significant increase in the patent filing rate, reaching record highs in recent years. A continuing upward trend over the next decade seems likely.
Figure 1: Thirty-year trend: priority filings - electrolysis production of green hydrogen
Global patent activity
The highest number of new patent filings for green hydrogen are coming from Europe, followed closely by South Korea, Japan and the U.S.
Figure 2: Fifteen-year trend: priority filings, by jurisdiction – green hydrogen
Looking at broader innovation in green hydrogen, it is clear that innovation in producing hydrogen by electrolysis is predominantly coming from the chemical aspects of the technology, while innovation in electrical and mechanical engineering aspects is increasing more slowly. Specifically, surface technologies and coatings are driving growth, followed by materials/metallurgy and machinery/apparatus at similarly lower rates.
Figure 3: Fifteen-year trend: priority filings, by technology classification - electrolysis production of green hydrogen
Green hydrogen is produced through the electrolysis of water in an electrolyser. The key components of an electrolyser are an anode and a cathode separated by an electrolyte. Depending on the electrolyte, the electrolysis functions in different ways.
Currently, there are three dominant electrolysis methods used in green hydrogen production:
1. Alkaline – hydroxide ions are transported between electrodes through an alkaline medium. Liquid mediums (e.g., sodium or potassium hydroxide) are most common mediums, but newer solid alkaline exchange membranes are in development.
2. Polymer electrolyte membrane (PEM) – the electrolyte is a solid speciality plastic material which transports protons generated at the anode from the reduction of water, which migrate to the cathode and combine with the electrons in the circuit to produce hydrogen.
3. Solid oxide electrolysis – the electrolyte is a solid oxide ceramic that selectively conducts negatively charged oxygen ions (O2-) at elevated temperature.
Each method has its advantages and disadvantages, for example, solid oxide systems require temperatures more than 500°C whilst PEMs operate below 100°C. Patent filing trends suggest all three methods seem to be developing at even rates with highest growth in alkaline electrolysis, but there has been a significant uplift in filing in all three over the last five years.
Figure 4: Filing activity 1997-2020: electrolysis methods
The high-filing patent applicants in green hydrogen production are led by large multinational companies including Honda, Toshiba, Siemens and Linde. Each has been consistently filing patent filings over the last decade, but with a significant upsurge in filings across the group in the last few years. Other high filers include specialist hydrogen production start-up companies, such as South Korean firm Kwatercraft, as well as more established, smaller firms moving into the hydrogen product field, such as Japanese company Kobeico ECO solutions.
Figure 5: Filing activity 2015-2020: high filers - green hydrogen production
Future advances in industrialisation of green hydrogen production are likely to arise from developments in materials, surfaces, and coating technologies. However, emerging disruptive technologies will also continue to develop, such as photo-electrochemical catalysts and biological methods.
The applications of green and blue hydrogen
Current global demand for hydrogen is dominated by its use as a raw material in industrial manufacturing processes. The Asia-Pacific region currently accounts for half of global industrial hydrogen demand, with China alone accounting for a significant portion for ammonia and methanol production, whilst India has strong demand for iron and steel production. The use of green hydrogen presents an opportunity to help decarbonise industry feedstock relying on crude oil.
However, there is also currently growth in the use of blue or green hydrogen as a fuel source to generate electricity, especially in the transport sector.
Fuel cells and the transport sector
Whilst an electrolysis cell can produce hydrogen (as discussed above), the cell can be driven in reverse to operate as a fuel cell: inserting hydrogen and air as fuels to produce power, with the by-products merely water and heat.
Fuel cells for vehicle applications commonly employ polymer electrolyte membrane (PEM) technology combined with on-board hydrogen storage.
Use of hydrogen to generate electricity in vehicles through fuel cells is already a commercial reality, even for the family car. However, for the foreseeable future it appears that the benefits of hydrogen fuel cells may mostly be found in the heavier-duty transport sector, such as marine, trains, buses and trucking.
Without the significant investment in the underlying distribution, storage and refuelling infrastructure that is required for wider population use, the mainstream application of hydrogen fuel cells in the family car is unlikely to emerge.
Nevertheless, the competitiveness of hydrogen fuel cell electric vehicles (FCEVs) is growing, with more than 40,000 FCEVs on the road in 2021. Associated costs of hydrogen fuel cells continue to drop, falling 70% between 2008 and 2020.
There was a sharp increase in patent applications for hydrogen fuel cells generally at the turn of the millennium, peaking in 2004 and receding to a constant level by the end of the 2000s. This surge in innovation between 1998-2008, and the subsequent drop-off, is likely reflected in the falling cost once the technology reached a viable level of development post-2008.
The small, recent upsurge in patent filing activity is being driven by fuel cell use in transport. Record-high patent filing activity for this sector in 2020 reveals applications relating to all types of transport including trains, lightweight aircraft, autonomous underwater vehicles, and even the family car. There is also an increase in hybrid battery systems that include hydrogen management, which may be a new area of growth in coming years.
Figure 6: Fifty-year trend: global priority filings - hydrogen fuel cells
In contrast to electrolysis, innovation in the fuel cell sector comes from improvements in both electrical and mechanical engineering. Such patent filings have risen sharply and steadily since the mid-2010s, whilst filings relating to chemical inventions have stayed constant over the last decade.
This increase in engineering innovation appears connected to technologies improving safety and function, such as gas detection, monitoring, and diagnosis of faults in pressure and precise control of valves and machinery. The rapid development of such technologies may be helping to progress the application of these cells in the large-scale transport sector.
Figure 7: Forty-year trend: priority filings, by technology classification - hydrogen fuel cells
Most top patent filers over the last decade in hydrogen fuel cells adapted for transport are large, automotive multinationals; Asia-pacific companies and German companies including Bosch, Audi, and Daimler (now Mercedes-Benz Group)
Figure 8: Filing activity 2012-2020: high filers - hydrogen fuel cells
If fuel cell technology is well established, and current innovation is focused on incorporating and managing the fuel cell use in transport, can we expect a surge in FCEVs on our roads in the near future? Perhaps, but there remain significant pieces of the puzzle to put in place first.
Storage
There is still a significant gap to fill between producing the hydrogen in an environmentally friendly manner and using it as a fuel – how to store the hydrogen?
The storage of hydrogen presents significant challenges to overcome for hydrogen to become a viable mainstream fuel, especially in the transport sector.
Hydrogen has an advantageous, high-energy density on a mass basis compared to other transport fuels. However, its Achilles heel is its lower volumetric energy density (it takes up more space in an ambient environment).
A big problem to address for application in transport sectors is how to store enough hydrogen in a vehicle for a driving range of 300 miles on a single fill, whilst also meeting criteria relating to weight, volume, efficiency, durability, refuelling time and cost.
There are several technologies being explored, split between ‘on-board’ vehicle refuelling (such as compressed tanks, sorbents and metal hydrides) and regeneration off-board the vehicle (for example, chemical hydrides such as borohydride or ammonia borane).
On-board refuelling is currently favoured, and the most common, currently used storage systems involve high-pressure compression tanks, as shown by the current upsurge in patent filings for this technology:
Figure 9: Forty-year trend: global priority filings - hydrogen storage
Once more, and unsurprisingly for a field with high capital investment costs, many of the same multi-national companies as discussed above appear again in the list of recent high filers for compression tanks in the transport sector. Of the top filers, it is notable that AIR Liquide, a French multinational industrial gas supplier, is directing its filings toward the refuelling stations and technology for refuelling the on-board tanks, rather than the tanks alone.
Figure 10: Filing activity 2017-2020: high filers - hydrogen storage
Summary
Some aspects of the technology along the hydrogen lifecycle may still need to advance significantly before a truly viable mainstream hydrogen economy can be established, particularly in terms of generating green hydrogen and storage.
However, it may be that in some areas the technology is not too far away, for example, hydrogen fuel cells. In such areas, it may be that high levels of capital investment in infrastructure, favourable regulations, and/or government support, will be required to progress the technology further, to bring it into the mainstream economy.
Technological development, investment and regulations are not the only hurdles. The prospect of driving a car that extracts energy from hydrogen may also cause many people to pause for thought – as evidenced by Hyundai’s reassuring sales pitch that “Hydrogen Fuel Cell Electric Vehicles (FCEVs) are not hydrogen bombs on wheels”. Hydrogen is often perceived as a dangerous gas, not least because of the 1937 Hindenburg disaster. Overcoming society’s prejudices against hydrogen will be another problem for the industry to solve.
Further cost reduction and efficiency improvements use will no doubt help achieve widespread acceptance of the technology over time. Such advances will be achieved in no small part by technology innovations yet to come across the hydrogen lifecycle.
The underlying properties of hydrogen suggest that it is a resource that is inevitably going to have a valuable role to play in our economy at some point. Currently hydrogen finds itself in a complex position. It will be fascinating to see where hydrogen technology finds the most growth in the coming years, as well as the technological innovations that come along to fuel it.
Chris Mason Senior Associate
Kealan Fallon Trainee Patent Attorney