Innovation trends in electrolysers for hydrogen production

Executive summary
In a collaborative effort between the European Patent Office (EPO) and the International Renewable Energy Agency (IRENA), this patent insight report examines the global evolution of patent filings published between 2005 and 2020 in the domain of electrolysers used to produce hydrogen. When policymakers and researchers agree on a vision for an innovative, low-carbon, affordable and safe hydrogen industry that would help the world to combat climate change and restrict global warming, resources and funding become available to accelerate the process of developing innovative solutions to produce, store and transport hydrogen. One of the key technical components in the production of hydrogen is the electrolyser. In an ideal world, electrolysers would be built out of raw materials that are cheap and abundantly available and would use only renewable electricity and water. Currently, technology is being developed to make electrolysers more efficient, cheaper and scalable up to market needs.

The role of electrolysers in energy transition Climate change is widely acknowledged by the largest
economies and developing countries as a significant problem that needs to be tackled urgently. A growing number of countries are developing programmes and strategies on greenhouse gas mitigation and decarbonisation roadmaps to overhaul their energy systems and infrastructures within the next decades. Through a combination of renewables, energy storage, energy efficiency and smart grid technology, a large share of end-use applications will be decarbonised in the coming decades. As more countries foster deep decarbonisation strategies, green hydrogen produced from renewables via water electrolysis is expected to be at the very heart of energy transition as a key piece of the clean energy puzzle. IRENA’s 1.5°C scenario projects that hydrogen and derivatives will account for up to 12% of final energy consumption by 2050.

The process based on water electrolysis allows hydrogen to be produced using electricity and water as inputs. Electrolysis is a well-known chemical process that requires wider adoption to lower production costs. Therefore a reduction in electrolyser system costs is essential and technology innovation is crucial to this end. According to IRENA, investment costs for electrolyser plants can be reduced by 40% in the short term and 80% in the long term through key strategies such as improved electrolyser design and construction, economies of scale, replacing scarce materials with abundant metals, increasing efficiency
and flexibility of operations and learning rates with high technology deployment aligned with a 1.5˚C climate target. Electrolysers suffer from rapid degradation, meaning that development is also needed to increase both process efficiency and technology life cycle.

The use of water and land for electrolysis
Green hydrogen production depends on two key inputs: water as the main feedstock and renewable electricity as the energy source. According to the International Energy Agency (IEA), electrolysis currently corresponds to about 2% of global hydrogen production. However there is a significant momentum for electrolysis to replace fossil-fuel based hydrogen production. If all current demand for
hydrogen were produced via water electrolysis, this would lead to an electricity demand of 3 600 TWh and 617 million m3 of water. To put these numbers into perspective, this would amount to more than the annual electricity generation of the European Union and 1.3% of the water consumption of the global energy sector today, roughly twice the current water consumption for hydrogen production from natural gas.

About the study
The primary objective of this study is to examine the global evolution of patent filings in order to identify major trends in the uptake of new technologies to facilitate the further implementation of the large-scale use of hydrogen. The report provides useful insights for interested players in the
field and for policymakers to leverage actions and initiatives to further develop and deploy electrolyser-related technologies, thus enabling a wider uptake of hydrogen. For this purpose, the study uses various resources, including EPO patent databases and registers and other available public reports, and it benefits from the long standing technical expertise in the field of both IRENA and the EPO. By virtue of their respective missions and activities, the EPO and IRENA share a common interest in the study of patent filing statistics to improve understanding of trends affecting the transition to a sustainable energy future using renewable energy sources. In 2017, IRENA and the EPO signed a memorandum of understanding on bilateral co-operation to promote innovation in the field of renewable energy technologies. 10 This memorandum of understanding was extended in 2021 and a decision was made to publish regular patent landscape reports focusing on a specific technological area.

Methodology Using patent information
Patents are exclusive rights that can only be granted for inventions that are novel and inventive. 12 High-quality patents are assets which can help attract investment, secure licensing deals and provide market exclusivity. Patent owners pay annual fees to maintain patents in those countries that are of commercial value to them and protect their inventions from being used by competitors, for example. In
exchange for these exclusive rights, all patent applications are published, revealing the technical details of the protected inventions. This allows other researchers to build on the published inventions of other inventors and also avoid the mistake of investing in developing a solution for a problem that has already been solved by others.

When using IPC and CPC classification codes to extract patents for statistical analysis, readers must bear in mind that it is in the patent applicant’s interest to get the broadest possible scope of protection for the invention. Therefore a patent will not be restricted to the combination of elements in which the applicant is developing its technology. As a result, some aspects may be inaccurately attributed to a patent application in the sense that a technical aspect may be developed for a specific electrolysis process without being explicitly indicated in the patent application or reflected in the patent classification. The patents grouped under “electrocatalyst materials” provide an example of this as just over 50% of these are also flagged as being technologically relevant for water electrolysis. When looking at electrolyser technology, it is also clear that there is often no explicit reference to the electrolysis of water but rather to fuel cell stacks.

Patent trends in hydrogen production processes
In terms of real patent filings (left-hand chart in Figure 2), in 2017 the number of patent families linked to hydrogen production processes based on water electrolysis surpassed the number of filings based on electrolysis using liquid hydrocarbon sources. Liquid hydrocarbon patents remain at the same level even after 2017. This shows the incremental priority given to research focusing on electrolysis processes based on water rather than on liquid hydrocarbon. This shift is because water electrolysis has a higher level of adaptability to different sources of power, including solar and other renewable sources, which allows a reduction in the energy input and in the use of non-renewable sources for production via hydrocarbons.

The main source of this upswing is patents filed in China, mostly by exclusively Chinese applicants and their high focus on the domestic market (only about 3% of Chinese patents are international, see left-hand chart in Figure 3). In addition, detailed analysis shows that patents filed in China are often
utility models that do not have any further patent filings in other patent jurisdictions. Moreover, Chinese applicants often file patents for the same or similar inventions, which increases filing numbers. This is followed by Japan, the Republic of Korea, the United States of America, Germany and France. Europe’s rather minor position is an important finding in view of the strategic importance attributed to the “European Green Deal”, which identifies hydrogen as key to a clean and circular economy. However, we may assume that the effect of the European Union hydrogen strategy launched in 2020, 18 which bundles measures to promote a fast and targeted development of production capacities for green hydrogen, is not yet reflected in the current data on patent filings.

Japan and the USA are also the most important countries in terms of patent protection. Of the total international patent families, 24% were protected in the USA and 21% in Japan in the period 2005-2020 (chart on the left-hand side in Figure 4). A large home market can be seen by an applicant as an incentive to first file a patent in the patent office that covers an intended market. Applicants and inventors located in smaller countries can be expected to have a higher need to file their patent applications abroad. As the data in this graph covers international patent families, we may conclude
that this graph more accurately reflects the place where inventions are taking place, as the international aspect is covered by the sample selection. The portion of Japanese and American filings decreasing over time is partly compensated for by patent filings at other patent authorities such as Germany, the Republic of Korea and, more recently, China (chart on the right-hand side in Figure 4).

International patenting co-operation in water electrolysis and subtechnology areas
Analysis of international collaboration based on the location of the applicants shows that there is considerable involvement of the member states of the European Patent Organisation 19 in cross-country developments and subsequent patent applications. Most prominently, this applies to Germany, France, Great Britain, Switzerland, and the Netherlands having a high level of collaboration with the United States. Connections can also be observed between Canada, France, Switzerland and Belgium, which can probably be attributed to having French as a common Member states of the European Patent Organisation: Country pairs representing applicants from different countries (complete dataset without Q02 and Q03, having a minimum of four patent families). language. Strong co-operation with the United States is equally true for Japan, Canada and South Korea. Co-operation with China is marked by co-applicant filings with mainly Germany, Taiwan and South Korea. Overall, just over 2% of all patent families show indicators of international co-operation between the patent applicants, which is on a par with the average for the entire population of all patent families available in the PATSTAT database.

Cell operation conditions and structure
The electrochemical process takes place in the cell, which is the core of the electrolyser. In a drive for better efficiency, various electrolyser cell operating parameters such as temperature, pressure and the cell unit structure are being explored to make them more cost-effective over a wider range of operating conditions, such as voltage fluctuations.

On average across the seven categories analysed in Figure 8, 42% of the total patent filings were international. International patent filings accounted for about 70%, 65% and 49% in the divided zero gap (membrane electrode assembly or MEA), cell structure: divided and high temperature categories respectively.

In the high pressure category (Figure 10) 25% of the applications were filed by the top 12 applicants. The total number of applicants filing in this area was about 600 from 2005 to 2020, which shows that research is dispersed, with many applicants only having one or a few patent families in their portfolio.

Japan and the United States of America are the two most active countries focusing on electrocatalyst materials (Figure 12). On average the number of their international patent filings accounts for about 42% of the total across the three categories. Germany comes third in the categories noble metals incl. oxides and organic, diamond, non-diamond, and fourth in the category non-noble metal alloys, ceramics after the Republic of Korea. Italy, France and the United Kingdom also appear in the top 5, while China ranks fifth for non-noble metal alloys and ceramics.

The pie chart on the left in Figure 15 shows that Japan, the United States of America, the Republic of Korea and Germany are the top countries with the highest number of international patent filings on the subject of inorganic separator membranes, and together they account for about 77% of the total patenting activity in the period 2005-2020. Japan alone accounts for about 37% of the total international
inventions in the polymer (organic) separator membranes category (see Figure 15, right-hand side). Combined with the contribution of the next three countries (United States of America, Republic of Korea and Germany), the top countries owned about 81% of the total inventions from 2005 to 2020.
The trend of polymer (organic) patents analysed in Figure 14 above is linked to the activity of Japan. In the period 2011-2017, Japan developed about 142 new patents a year on average, with a 14% annual increase. However, between 2018 and 2020 this activity decreased in Japan, while in other countries it increased: the average annual production of international patents increased by 45%, 76% and 67% in
the United States of America, the Republic of Korea and Germany respectively.

Among the top 20 patenting entities in stack technology (Figure 19), only three had at least one patent filed between 2005 and 2011: the French Alternative Energies and Atomic Energy Commission (CEA) and the Japanese Honda Motor and Chlorine Engineers. The first rising trend in the 2012-2014
period is a result of higher interest in the stackability of electrolysers, involving more players. The number of patenting entities increased from 55 in the period 2005-2011 to 87 in the period 2012-2014, many of whom had not previously been active. Together with the CEA, the German company Siemens registered the highest number of new patents. The period from 2015 to 2018 is when the stack type
category shows its largest increase in the number of international patents. In this period, Japanese companies took the lead in developing new patents: 8 of the top 10 patent entities were from Japan and they averaged about 10 international filings each. Toshiba ranked first with 28 international patents, followed by the CEA (with 18) and \Asahi Chemical Industry (with 12). In the last two years
analysed, 2019 and 2020, Japanese companies reduced their number of new patents, indicating a lower focus on this category of stack for electrolysers. Interestingly, four Japanese companies that were active in the previous period (2015-2018) did not file any patents between 2019 and 2020. In contrast, European companies remained active in these last years, or became active for the first time, as was the
case with the Danish company Hymeth, which entered the top 20 due only to its recent activity.


Water photoelectrolysis, using semiconductor photoelectrodes, is a sustainable and clean approach to
the production of hydrogen. Sunlight is used as the energy source to split water in a photoelectrochemical cell. This process of electrolysis of water produces dihydrogen which
in turn can be stored, used to produce electricity or even delivered to fuel cells to generate electricity and heat. It can also be used in a combined-cycle gas turbine to produce larger quantities of centrally produced electricity or burned to run a combustion engine.

Water electrolysis is an enabling chemical process that can make hydrogen technology play a crucial role in global energy transition. Thanks to hydrogen technology, several energy-intensive industries and sectors can be decarbonised, especially if hydrogen production is powered by renewable energy sources. From this perspective, electrolysers have become the key component in empowering the shift toward
a hydrogen-based energy system. This report has analysed patent trends and statistics in electrolysers, digging into key parts and components that are receiving higher attention. In 2016, patenting activity related to water electrolysis surpassed the activity related to liquid hydrocarbon feedstocks (mostly coal- and oil-based sources), which is reducing over time. This follows national and international strategies, where a global consensus exists on the necessity to spur technological development in the field of water
electrolysis. Countries such as Japan, the United States, Germany, France and China are frontrunners in such an effort, boosted by R&D activity in companies, universities and research institutions.


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