Ocean Thermal Energy Conversion Patents: Top Companies & Trends 2026
- 45.7% of all 776 records sit with just five assignees, so most of the working-fluid and heat-exchange claim space is already staked by a small group.
- F03G draws 44.5% of records far ahead of steam-cycle (F01K, 13.0%) and heat-exchange (F28D, 11.0%) classes, showing where claim density is heaviest.
- Filing fell 33% from 2021 to 2024 (27 to 18 records), the last span the data can call complete before publication lag understates the newest years.
Filing growth compares 2021 (27 records) with 2024 (18) — a three-year span. 2024 is the most recent year we treat as complete: publication lags filing by roughly 18 months, so 2025 onwards are still filling in and any growth rate that ends there would understate the field. Top-5 share is the combined record count of the five largest assignees divided by all 776 records in scope (CR5), not by the ranked leaders only.
What the OTEC patent record actually shows
Ocean thermal energy conversion turns the temperature gradient between warm surface water and cold deep water into usable power, typically through a working-fluid Rankine cycle. The patent record in scope spans 776 published records filed between 2015 and 2026, covering everything from cold-water pipe design to heat-exchanger geometry to onboard energy-conversion control. Filing activity peaked in 2019 at 53 records and has since cooled, though the most recent years are still being backfilled as publications catch up to filings.
The technology composition leans heavily toward mechanical and thermal-cycle hardware rather than control software: heat exchange, pipe fittings and marine-vessel integration all show meaningful density alongside the dominant motor/converter class. That split matters for anyone deciding where a new filing is likely to clear prior art versus where it will land in a crowded queue.
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Filing trends and technology composition
Two views of the same 776-record dataset: how filing volume moved year over year, and which IPC subclasses carry the claim density.
Filing trend, 2017-2026
Filings ran from 27 in 2017 to a peak of 53 in 2019, then declined; the 2021-to-2024 span shows a 33% drop (27 to 18 records). The 2025 and 2026 figures are undercounts, since publication typically lags filing by around 18 months.
Technology composition by IPC subclass
F03G (spring/weight & misc. motors) covers 44.5% of records, well ahead of F01K steam and thermal power plants (13.0%), F28D heat-exchange apparatus (11.0%) and F28F heat-exchanger details (10.2%). Because a record can carry several IPC classes, these shares add up to more than 100% of the 776 records in scope.
Shares are the percentage of the 776 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Ocean Thermal Energy Conversion Patent Landscape with Eureka
This page is one run against one query. Ask Eureka your own question about ocean thermal energy conversion patent landscape and every answer comes back with the patent numbers behind it.
Try EurekaMost-cited records and a representative filing
US8572967B1 — High efficiency OTEC system
A high efficiency OTEC system for the efficient and low-cost production of energy and potable water through ocean thermal energy conversion. The system utilizes a working fluid such as ammonia with a standard Rankine cycle, comprising a heat exchanger with a fluid transfer assembly, a pump, a first heater, a turbine and a generator. The fluid transfer assembly condenses working fluid by transferring it to the cold depths of the ocean before returning it to the warm surface through an insulated return conduit, where the fluid is vaporized before entering the turbine stage.Filed by Cowden, David H., published 2013-11-05.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US20110043160A1 | Ac connected modules with line frequency or voltage variation pattern for energy control | 150 |
| 2 | US4497342A | Flexible retractable cold water pipe for an ocean thermal energy conversion system | 133 |
| 3 | US20030012985A1 | Pressure energy conversion systems | 121 |
| 4 | US4170878A | Energy conversion system for deriving useful power from sources of low level heat | 114 |
| 5 | GB2383978A | Platform provided with a plurality of renewable energy converter systems | 111 |
| 6 | US4346561A | Generation of energy by means of a working fluid, and regeneration of a working fluid | 102 |
| 7 | US20090217664A1 | Submerged Geo-Ocean Thermal Energy System | 101 |
| 8 | US4781029A | Methods and apparatus for ocean thermal energy conversion using metal hydride heat exchangers | 99 |
| 9 | US5513494A | Ocean thermal energy conversion (OTEC) system | 84 |
| 10 | US20110083436A1 | Systems, apparatus and methods for thermal energy storage, coupling and transfer | 80 |
Citation counts favour older filings inside this corpus and should be read as a signal of influence, not of current commercial relevance.
Each row carries its publication number; clicking a row searches Eureka by that number.
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Browse MCP servers →What the numbers mean for a filing decision
Three read-outs from the dataset that matter more than the raw ranking table.
The field is top-heavy but not closed
Five assignees hold 355 of the 776 records in scope, with the leader alone at 171. That leaves more than half the field split across a long tail of single- and low-filing entrants, which is where a differentiated claim still has room to register.
Volume cooled after the 2019 peak
Filing ran from 27 records in 2021 down to 18 in 2024, the last span the data can treat as complete. That is a real decline in documented activity, not a data artefact, though 2025-2026 figures will keep rising as publications catch up.
Claim density sits in the conversion hardware, not the cycle chemistry
F03G-class filings (motors and misc. energy converters) outnumber the steam/thermal-cycle class F01K by more than three to one. Working-fluid and cycle-chemistry claims (F01K, F28D, F28F) are comparatively less crowded than the mechanical conversion hardware around them.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to ocean thermal energy conversion patent landscape, with the prior art for and against each one.
Who is filing, and where the field is still open
The ranked leaders account for just over half of all activity; recent-year momentum has thinned even among the largest historical filers.
One filer holds a clear lead
The top assignee's 171 records outsize the fifth-place holder's 18 by nearly tenfold, indicating a long-running, deliberately built portfolio rather than a recent land-grab.
The drop-off past the leader is steep but not a cliff
Fifth place holds 18 records and tenth place 13, a gentler slope than the gap to the leader suggests. This is where competitive-intelligence teams should watch for consolidation or acquisition activity.
Recent-year activity has gone quiet even among historic leaders
Several of the largest historical assignees show zero filings in the latest year, while the most active recent filer logged just one. That is consistent with the broader 2021-2024 decline rather than a single company pulling back.
| Assignee | Recent year | YoY |
|---|---|---|
| NOVEK ETHAN J | 1 | — |
| Lockheed Martin Corp | 0 | — |
| Abell Foundation Inc | 0 | — |
| CarbonTrack (Aust) Pty Ltd | 0 | — |
| SHAPIRO LAURENCE JAY | 0 | — |
| COLE BARRY R | 0 | — |
| Marine Power Systems | 0 | — |
| EDWARDS DOUGLAS | 0 | — |
Where to take this next
The dataset points to a field with a concentrated top and a thinning recent pipeline. The next steps depend on whether the goal is freedom-to-operate, acquisition targeting, or new filing strategy.
Run a freedom-to-operate check against the top assignee
With 171 of 776 records held by one filer, any new working-fluid or heat-exchanger claim should be screened against that portfolio before drafting.
Explore assignee claims in EurekaMap the under-claimed branches to a first-claim draft
Biofouling-resistant piping and hybrid desalination integration show thinner filing density than the core conversion-hardware classes.
Draft claim scope in EurekaTrack recent-year momentum before it resolves
2025-2026 filings are still being published; revisit the trend once the publication lag closes to see whether the 2021-2024 decline continues.
Set up monitoring in EurekaCommon questions about OTEC patents
One assignee leads the ranked list with 171 records, well ahead of the fifth-place holder at 18. That gap indicates a long-built, deliberate portfolio rather than a recent surge of filings from a single company. The next four positions in the top five combine with the leader for 355 records, or 45.7% of all 776 records in scope, so the field is concentrated at the top but still leaves a large tail of smaller filers.
Filing peaked in 2019 at 53 records and has declined since; the last span the data can treat as complete, 2021 to 2024, shows a 33% drop from 27 to 18 records. Figures for 2025 and 2026 are still partial because publication typically lags filing by around 18 months, so it is too early to call the most recent years a continuation of that decline. Anyone tracking this should revisit the trend in a year or two once those filings have published.
The IPC subclass F03G, covering spring/weight and miscellaneous energy converters, appears in 44.5% of the 776 records in scope, far ahead of steam and thermal power plant claims (F01K, 13.0%) and heat-exchange apparatus (F28D, 11.0%). Because a single record can carry multiple IPC classes, these percentages add up to more than 100% of the total; they describe density, not a share of a fixed pie. Marine-vessel integration (B63B) and water treatment (C02F) also show meaningful activity, suggesting OTEC patents increasingly cover system integration alongside core conversion hardware.
US8572967B1 describes a high-efficiency OTEC system using an ammonia working fluid in a standard Rankine cycle, with a heat exchanger, pump, heater, turbine and generator arranged around a cold-water condenser conduit and an insulated warm-water return conduit. It is a useful reference point for the overall system architecture, but it does not close off adjacent variations such as different working fluids, alternative pipe insulation methods, or hybrid desalination integration. A freedom-to-operate review should treat it as one data point in a crowded F03G/F28D claim space, not as a single blocking patent.
The under-claimed branches sit adjacent to the dense conversion-hardware classes rather than within them: biofouling-resistant cold-water pipe coatings, ammonia working-fluid leak detection, modular floating platform mooring, hybrid OTEC-desalination heat integration, and low-grade heat-flux sensor arrays for resource assessment all show comparatively thinner filing density. These are narrower than the core F03G motor/converter space but sit close enough to it to be commercially relevant. A first claim in one of these areas is more likely to clear prior art than a broad Rankine-cycle or heat-exchanger claim.
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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.
Nothing on this page constitutes an exhaustive prior-art, novelty, freedom-to-operate, or validity search, nor does it constitute legal, financial, investment, or professional advice, and it should not be relied upon as such. Any patent, commercial, or strategic decision should be verified independently and reviewed with qualified patent, legal, and domain professionals. Patsnap makes no warranties, express or implied, as to the accuracy, completeness, or fitness for any particular purpose of the information presented.
Machine translation. Assignee and organisation names originally recorded in Chinese, Japanese or Korean have been rendered into English by an AI translation step so that the tables stay readable. These renderings are best-effort and may not match a company’s registered English name; the original name is what the underlying patent record carries, and it is what any Eureka query launched from this page uses.