Green Hydrogen & Water Electrolysis Patent Landscape
Green Hydrogen & Water Electrolysis Patent Landscape in 2026
The green hydrogen and water electrolysis patent field has expanded significantly on a multi-year basis, with three-year filing volume up 111% versus the prior window, though annual output eased from its 2023 peak. Activity is moderately concentrated: the leading filer holds a substantial share, and the top five ranked applicants together account for a majority of leading-filer combined volume, with electrolytic compound production (C25B) dominating the technology mix.
Haldor Topsoe leads a moderately concentrated field of 13,802 patent families
Haldor Topsoe (Topsoe A/S) ranks first with 593 patent families, placing it well ahead of the second-ranked French Atomic Energy Commission (CEA) at 354 and De Nora Electrodes (formerly Permelec Electrode) at 353. The corpus covers 13,802 patent families in scope.
The top five ranked filers — Topsoe, CEA, De Nora Electrodes, Asahi Kasei, and Toshiba — together account for 62% of the leading filers’ combined total, indicating meaningful concentration among the front runners but leaving substantial room for challengers. A clear tier gap exists between the top three and the next group.
| # | Applicant | Patent families | Share |
|---|---|---|---|
| 1 | Topsoe A/S (Haldor Topsoe) | 593 | |
| 2 | French Alternative Energies and Atomic Energy Commission (CEA) | 354 | |
| 3 | De Nora Electrodes Ltd. (Permelec Electrode) | 353 | |
| 4 | Asahi Kasei Corporation | 307 | |
| 5 | Toshiba Corporation | 270 | |
| 6 | Panasonic Intellectual Property Management Co., Ltd. | 252 | |
| 7 | Siemens Energy International GmbH | 247 | |
| 8 | De Nora Industries S.p.A. | 230 | |
| 9 | Bloom Energy Corporation | 225 | |
| 10 | Honda Motor Co., Ltd. | 195 |
Topsoe’s position reflects deep focus on electrolytic hydrogen production and downstream inorganic chemistry (C25B, C01B). The presence of a national research agency (CEA) and two Japanese industrial firms (Asahi Kasei, Toshiba) in the top five signals both government-backed and corporate industrial programs as primary drivers.
Rankings and corpus total are measured in patent families. Branch, jurisdiction, and route-matrix figures are at the patent-record level — one family can carry multiple IPC classes or be filed in multiple offices, so those counts can exceed the family total and are not directly comparable to family figures. The most recent 18–24 months are under-counted due to publication lag.
Multi-year growth remains strong despite easing from the 2023 peak; C25B dominates the technology mix
The annual filing trend and IPC technology composition together reveal a field in sustained expansion with a clear technical core. The trend chart shows momentum built over multiple years; the composition chart shows where the intellectual property is concentrated and where adjacent branches attract lower activity.
Annual filing trend
Annual filings grew steadily from 697 records in 2017 to a peak of 2,758 in 2023, representing a multi-year growth rate of 111% comparing recent versus prior three-year windows. Volume dipped to 2,104 in 2024 and 1,340 in 2025, but these figures are further understated by publication lag and should not be read as a real decline. The 2026 figure of 45 reflects only the earliest published applications of that year and is not meaningful as an annual count.
↗ Hover for values · click a bar to ask EurekaTechnology composition
C25B (Electrolytic production of compounds) dominates at the patent-record level, reflecting the core electrolyzer technology. C01B (Non-metallic elements and inorganic compounds, primarily hydrogen) and H01M (Batteries, cells and fuel cells, including PEM components) are the next largest branches, together anchoring the electrochemical hydrogen production cluster. Branches such as B01J (catalysis), B01D (separation), C07C (acyclic compounds), C02F (water treatment), and C10G (hydrocarbon refining) have noticeably lower record counts, indicating relatively sparser coverage of adjacent process and downstream conversion technologies.
↗ Hover for values · click a bar to ask EurekaFoundational and most-cited patents
The most-cited families that anchor this space. Hover a row and click to open it in Eureka.
HYDROGEN PRODUCTION UNIT HAVING SOLID OXIDE ELECTR…
A green hydrogen production unit may have at least one solid oxide electrolyzer cell (SOEC) to generate hydrogen gas from water by electrolysis. A green power supply may be coupled to the at least one SOEC. A green back-up power supply may be coupled to the at least one SOEC. (excerpt from the patent abstract)
| # | Patent | Citations |
|---|---|---|
| 1 | Electrochemical production of ozone and hydrogen p… | 586 |
| 2 | Selective adsorption process | 575 |
| 3 | Electrolytic cell for hydrogen peroxide production… | 409 |
| 4 | Low cost bipolar current collector-separator for e… | 349 |
| 5 | Optimizing photovoltaic-electrolyzer efficiency | 323 |
| 6 | Deposition of catalytic electrodes on ion-exchange… | 284 |
| 7 | Methods and devices for the production of Hydrocar… | 265 |
| 8 | Polymer electrolyte membrane, and process for the … | 256 |
Ranked by total forward citations. Citation counts accrue over time, so this list favours older, broadly-cited patents and may include general-purpose work beyond the specific topic; treat it as foundational context rather than a current-activity ranking.
What the competitive structure means for R&D investment decisions
Four structural observations — maturity stage, concentration, collaboration patterns, and geographic filing — shape where new R&D investment is likely to find differentiated space versus established incumbency.
Growth stage, easing from 2023 peak
The field is classified as Growth: the recent three-year filing window is 111% above the prior three-year window, confirming the field is still expanding on a multi-year basis. Annual volume has eased from the 2023 peak of 2,758 records, though publication lag accounts for part of the apparent softening in 2024–2025. New entrants can still establish positions, but core electrolyzer IP is maturing rapidly.
Growth stageTop five hold 62% of leading-filer volume
The top five ranked applicants collectively account for 62% of the leading filers’ combined patent family count. Topsoe’s lead of 593 families is roughly 68% larger than the second-ranked CEA at 354. This tier gap means challengers in ranks six through ten — including Siemens Energy International and Bloom Energy — face a material IP density disadvantage in core C25B electrolytic production claims but may find differentiation in adjacent branches.
High concentrationDe Nora Electrodes anchors the most active co-filing network
De Nora Electrodes (Permelec Electrode) is the most active co-filer, appearing in six of the ten observed collaboration pairs. Its most frequent partnerships are with Yokohama National University (125 co-filed families), Kawasaki Heavy Industries (56), Kyoto University (25), the National Institute of Technology (15), ThyssenKrupp Nucera (14), and Aquaex (11). CEA co-files with the National Polytechnic Institute of Toulouse (8) and TotalEnergies (7). Siemens Energy International co-files with Siemens AG (8). These pairings suggest that electrode technology and system integration are the primary axes of cross-sector collaboration.
Active co-filingUS and EPO dominate; Asia and emerging markets thin
At the patent-record level, the United States leads with 6,397 records, followed by the EPO at 4,465 and WIPO PCT at 3,623. Australia and Canada rank fourth and fifth. China shows only 564 records in this corpus, and Japan 224, which is low relative to the Japanese applicants’ prominence in the ranking and likely reflects filing strategy differences. South Korea (40 records) and India (137 records) are sparse, signaling limited defensive coverage in two large potential hydrogen markets.
US/EPO-centricGo beyond the landscape: Eureka’s TRIZ Solution agent breaks down an R&D problem and returns patented concept solutions, each with a technical approach and cited patent & literature evidence.
| Applicant | Collaborator | Co-filings |
|---|---|---|
| De Nora Electrodes Ltd. (Permelec Electrode) | Yokohama National University | 125 |
| Toshiba Corporation | Toshiba Energy Systems & Solutions Corporation | 109 |
| De Nora Electrodes Ltd. (Permelec Electrode) | Kawasaki Heavy Industries, Ltd. | 56 |
| De Nora Electrodes Ltd. (Permelec Electrode) | Kyoto University | 25 |
| De Nora Electrodes Ltd. (Permelec Electrode) | National Institute of Technology (KOSEN) | 15 |
| De Nora Electrodes Ltd. (Permelec Electrode) | ThyssenKrupp Nucera AG & Co. KGaA | 14 |
| De Nora Electrodes Ltd. (Permelec Electrode) | Aquaex Inc. | 11 |
| French Alternative Energies and Atomic Energy Commission (CEA) | Toulouse INP (National Polytechnic Institute of Toulouse) | 8 |
| Siemens Energy International GmbH | Siemens AG | 8 |
| French Alternative Energies and Atomic Energy Commission (CEA) | TotalEnergies Onetech SAS | 7 |
Co-filing pairs, ranked by the number of jointly-filed patent families.
Topsoe leads on volume; Siemens Energy International shows the sharpest recent momentum
The applicant ranking reveals distinct strategic postures: an incumbent volume leader with stable output, fast-accelerating challengers, and players pulling back. Technology emphasis and recent-period momentum together clarify where each firm is placing its bets.
Topsoe A/S
Topsoe A/S (Haldor Topsoe) holds the top position with 593 patent families. Its technology emphasis spans electrolytic compound production (C25B1, C25B9), inorganic hydrogen chemistry (C01B3), and electrolyzer cell design (C25B9), reflecting a full-stack electrolyzer and green ammonia/hydrogen strategy. Recent momentum is essentially flat at –1%, with 167 families in the most recent period, indicating a stable, mature portfolio build rather than acceleration.
families: 593Siemens Energy International
Siemens Energy International ranks seventh overall with 247 patent families but shows the strongest recent momentum among measured applicants at 7.1× versus the prior three-year period, with 185 families in the recent window. Its technology emphasis concentrates on electrolytic compound production (C25B1), operational and system-level IP (C25B15), and electrolyzer cell architecture (C25B9), suggesting a rapid scaling of PEM and alkaline electrolyzer system IP consistent with its large-scale project pipeline.
families: 247| Applicant | Recent (3 yrs) | Trend |
|---|---|---|
| Topsoe A/S (Haldor Topsoe) | 167 | ▬ -1% |
| French Alternative Energies and Atomic Energy Commission (CEA) | 85 | ▲ +85% |
| De Nora Electrodes Ltd. (Permelec Electrode) | 28 | ▼ -67% |
| Asahi Kasei Corporation | 57 | ▼ -47% |
| Toshiba Corporation | 123 | ▲ 3.2× vs prior 3-yr |
| Panasonic Intellectual Property Management Co., Ltd. | 72 | ▼ -41% |
| Siemens Energy International GmbH | 185 | ▲ 7.1× vs prior 3-yr |
| De Nora Industries S.p.A. | 93 | ▲ +102% |
Under-served branches adjacent to core electrolysis IP
Several IPC classes appear at lower record counts relative to the dominant C25B cluster, despite plausible technical and commercial links to green hydrogen production. These are observations of relative sparsity; entry-path viability depends on the applicant’s existing capabilities and commercial context.
B01D · Separation processes
Separation processes (filtration, membrane separation, gas purification) carry 1,774 patent records — roughly one-tenth the density of C25B. For green hydrogen, downstream gas purification and hydrogen/oxygen separation are direct process requirements, yet the patent record here is sparse relative to electrolyzer core IP. Teams with membrane or PSA (pressure-swing adsorption) capabilities may find less crowded IP space in hydrogen-specific separation system claims. Entry would require linking separation chemistry to electrolyzer output streams.
Search this in Eureka →C02F · Water & wastewater treatment
Water treatment for electrolysis feed carries 1,145 patent records, making it one of the sparser branches directly upstream of the electrolysis process. High-purity water supply is a critical operational requirement for PEM electrolyzers, yet this branch has notably lower coverage than the core C25B cluster. The technical link is clear: feed-water quality directly affects membrane lifetime and current efficiency. Organizations with water-treatment or industrial water management expertise may find differentiated IP space in integrated electrolyzer feed-water conditioning systems.
Search this in Eureka →How leading applicants differ by technology route across C25B sub-classes
Strength of each leader across the main technology routes.
| Player | C25B 1 · Electrolytic production of compounds | C25B 9 · Electrolytic production of compounds | C25B 15 · Electrolytic production of compounds | C25B 11 · Electrolytic production of compounds | C01B 3 · Non-metallic elements & inorganic compounds |
|---|---|---|---|---|---|
| Topsoe A/S (Haldor Topsoe) | Strong · 463 | Moderate · 214 | Moderate · 206 | Absent | Strong · 269 |
| De Nora Electrodes Ltd. (Permelec Electrode) | Strong · 207 | Strong · 200 | Moderate · 108 | Strong · 216 | Absent |
| French Alternative Energies and Atomic Energy Commission (CEA) | Strong · 249 | Strong · 285 | Strong · 154 | Absent | Absent |
| Asahi Kasei Corporation | Strong · 177 | Strong · 247 | Strong · 130 | Moderate · 108 | Absent |
| Panasonic Intellectual Property Management Co., Ltd. | Strong · 183 | Strong · 211 | Moderate · 77 | Moderate · 105 | Moderate · 83 |
| Toshiba Corporation | Strong · 201 | Strong · 193 | Strong · 123 | Strong · 119 | Absent |
| Bloom Energy Corporation | Strong · 175 | Strong · 168 | Strong · 131 | Absent | Absent |
Frequently asked questions
The corpus covers 13,802 patent families globally. The most recent 18–24 months are under-counted due to publication lag, so the true current total is likely higher.
Topsoe A/S (Haldor Topsoe) leads with 593 patent families, ahead of the French Atomic Energy Commission (CEA) at 354 and De Nora Electrodes at 353.
The field is in the Growth stage. Recent three-year filing volume is 111% above the prior three-year window. Annual volume peaked in 2023 and has eased since, though publication lag accounts for part of the apparent decline in 2024–2025.
The United States leads at 6,397 patent records, followed by the EPO at 4,465 and WIPO PCT at 3,623. Australia and Canada follow. These are record-level counts; a single family filed in multiple offices contributes to each.
Siemens Energy International shows the sharpest acceleration at 7.1× versus the prior three-year period (185 recent families). Toshiba grew at 3.2×. CEA grew at +85% and De Nora Industries at +102%. De Nora Electrodes and Asahi Kasei declined, at -67% and -47% respectively.
De Nora Electrodes and Yokohama National University are the most frequent co-filers with 125 joint families. Toshiba and Toshiba Energy Systems account for 109. De Nora Electrodes also co-files actively with Kawasaki Heavy Industries (56), Kyoto University (25), and ThyssenKrupp Nucera (14).
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Disclaimer. This page is generated from PatSnap Eureka data drawn from a limited snapshot of global patent and scientific-literature records, and is provided for general information and reference only.
Patent data carries inherent limitations: recent filings (typically the most recent 18–24 months) are under-counted due to standard publication lag; counts may be reported at either a patent-family or a patent-record basis and are not always directly comparable; classification, applicant-name, and citation data may contain errors, duplicates, or omissions; and the underlying search query defines and constrains the scope shown. As a result, the analysis may be incomplete or inaccurate and may not reflect the full technology landscape.
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