Thermal Energy Storage Patent Landscape 2026
Thermal Energy Storage Patent Landscape in 2026
The thermal energy storage patent field spans 4,580 patent families and is entering a maturity phase, with annual filings plateauing near their 2022 peak. Panasonic Holdings leads a moderately concentrated field dominated by heat-exchange apparatus technology, while challengers such as Rondo Energy show accelerating momentum in industrial-scale thermal power applications.
Panasonic leads a moderately concentrated field with a two-tier competitive structure
Panasonic Holdings Corp holds the top position with 372 patent families, nearly doubling the count of second-ranked Rondo Energy Inc at 176 patent families. The top five filers together account for 21% of the combined output of the hundred largest filers, indicating a moderately concentrated but not locked-down competitive landscape.
A clear tier gap separates Panasonic from the next tier: Rondo Energy (176), Rocky Research (148), Octopus Energy Heating (119), and Mitsubishi Electric (118) form a dense second tier with counts roughly one-third to one-half of the leader. Below rank five, the field opens into a long tail of academic, national-lab, and specialist entrants.
| # | Applicant | Patent families | Share |
|---|---|---|---|
| 1 | Panasonic Holdings Corporation | 372 | |
| 2 | Rondo Energy Inc | 176 | |
| 3 | Rocky Research Inc | 148 | |
| 4 | Octopus Energy Heating Ltd | 119 | |
| 5 | Mitsubishi Electric Corporation | 118 | |
| 6 | French Alternative Energies and Atomic Energy Commission (CEA) | 97 | |
| 7 | IFP Energies Nouvelles | 94 | |
| 8 | Hitachi Ltd | 94 | |
| 9 | Siemens Gamesa Renewable Energy A/S | 94 | |
| 10 | Rolls-Royce North American Technologies Inc | 83 |
| # | Applicant | Patent families | Share |
|---|---|---|---|
| 11 | Kubota Corporation | 81 | |
| 12 | University of Dayton | 77 | |
| 13 | Toshiba Corporation | 74 | |
| 14 | Yazaki Energy System Corporation | 74 | |
| 15 | SCHUMANN SASOL GMBH & CO KG | 71 | |
| 16 | Daikin Industries Ltd | 71 | |
| 17 | Dow Global Technologies LLC | 66 | |
| 18 | Panasonic Electric Works Co Ltd | 66 | |
| 19 | German Aerospace Center (DLR) | 65 | |
| 20 | Siemens AG | 64 |
Panasonic’s scale reflects decades of heat-exchange and phase-change material work; however, the presence of pure-play start-ups such as Rondo Energy and Octopus Energy Heating in the top five signals that incumbent scale is no longer a prerequisite for competitive positioning in emerging sub-segments.
Filings from approximately 2024 onward are subject to publication lag and are likely under-counted; apparent softness in those years should not be read as a fundamental slowdown. Longer-window growth, applicant concentration, and technology-route coverage are therefore more reliable signals than the latest-year bar alone.
Filing activity plateaued at its 2022 peak; heat-exchange apparatus dominates the technology mix
Annual filing volume and technology-class composition together reveal a field that has moved from rapid expansion into a consolidation phase, with the dominant IPC class commanding an outsized share of activity.
Annual filing trend
Filings climbed from 496 in 2017 to a peak of 651 in 2022, then stepped down toward 490 in 2023 and 442 in 2024. The 2025 and 2026 bars are truncated by publication lag and do not represent real decline. On a multi-year basis, the corpus has grown, but the annual run-rate has eased from the 2022 peak, consistent with the maturity life-cycle stage.
↗ Hover for values · click a bar to ask EurekaTechnology composition
F28D (heat-exchange apparatus) is the dominant IPC class, reflecting the centrality of thermal storage media and exchanger design. F25B (refrigeration and heat pumps) and C09K (phase-change materials) form a strong secondary layer. Further out, F24D (domestic heating), F24F (air conditioning), F01K (steam and thermal power plants), and F24S (solar heat collectors) represent meaningful but smaller clusters, indicating that the field spans grid-scale industrial systems and building-level applications in roughly equal measure.
↗ Hover for values · click a bar to ask EurekaHighly cited patent families surfaced by the query
Citation-heavy patent families returned by the query. Use this section as citation context, not as a curated list of the most topic-specific patents.
Salt hydrate-based thermal energy storage material…
A phase change material composition for latent heat storage is provided. The composition includes a eutectic mixture of two or more salt hydrates, and at least one salt additive each selected from a bromide salt and a bromide salt hydrate. The mixture of salt hydrates has a melting temperature above room temperature. The at least one salt additive decreases… (excerpt from the patent abstract)
| # | Patent | Citations |
|---|---|---|
| 1 | Compressed air energy storage method and system | 486 |
| 2 | Orthopedic device having gel pad with phase change… | 384 |
| 3 | Phase change thermal control materials, method and… | 358 |
| 4 | Computing infrastructure | 351 |
| 5 | Thermally enhanced foam insulation | 308 |
| 6 | Phase change material thermal capacitor clothing | 292 |
| 7 | Thermal energy storage and delivery system | 279 |
| 8 | Phase change thermal control materials, method and… | 277 |
Ranked by total forward citations. Citation counts favour older and broadly cited patent families, and broad or adjacent patents may appear when they match the search scope. Treat this section as citation context, not as a curated list of the most topic-specific patents. Some patent titles may be shown in their original, non-English language where an accurate translation could not be guaranteed.
What the patent structure means for R&D investment decisions
The combination of a maturing filing curve, a moderate concentration ratio, a well-documented collaboration ecosystem, and strong US and Japanese jurisdictional presence shapes both the risk and the opportunity for new entrants.
Field has plateaued near its 2022 peak
The lifecycle evidence places thermal energy storage at the Maturity stage: annual filings have plateaued near their 2022 peak of 651, with the recent-window growth rate at -8%. This means incremental claims in well-covered sub-classes face a crowded prior-art environment. R&D investment is most defensible in either highly differentiated materials science (C09K) or system-integration sub-classes that remain relatively sparse.
Maturity stageModerate concentration leaves room for challengers
With the top five filers holding 21% of the hundred largest filers’ combined output, the field is moderately concentrated but not oligopolistic. Panasonic’s lead is substantial at 372 patent families, yet pure-play entrants Rondo Energy and Octopus Energy Heating have secured top-five positions, demonstrating that focused, application-specific filing strategies can achieve competitive standing. New entrants with differentiated technology can still build a credible position.
Moderate concentrationJapan’s AIST network is the most active co-filing hub
The most frequent co-applicant pairing is Japan’s Agency of Industrial Science and Technology (Director-General) with the National Institute of Advanced Industrial Science and Technology (AIST), with 21 joint filings. Mitsubishi Electric and Mitsubishi Electric Europe R&D are the most active corporate co-filers at 12 joint filings. Panasonic (Japan) co-filed with Japan Air Conditioning Systems on 6 families, and Rocky Research co-filed with Honeywell International on 6. These pairings suggest that industrial-academic consortia, particularly in Japan, are a primary engine of collaborative IP creation in this domain.
Japan-centric ecosystemUS and Japan lead; Europe and PCT pathways are robust
The United States is the leading filing jurisdiction, followed by Japan and the European Patent Office. The WIPO PCT route and Germany are also significant, and notable emerging-market presence can be observed in India and Australia. The US-Japan-Europe triad accounts for the bulk of activity, indicating that IP strategy should prioritize these three jurisdictions as core, with PCT as the primary route for multi-region protection.
US–Japan–Europe triadGo 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 |
|---|---|---|
| Director-General, Agency of Industrial Science and Technology (METI Japan) | National Institute of Advanced Industrial Science and Technology (AIST) | 21 |
| Mitsubishi Electric Corporation | Mitsubishi Electric Europe R&D Centre GmbH | 12 |
| Director-General, Agency of Industrial Science and Technology (METI Japan) | Daikin Industries Ltd | 7 |
| Panasonic Corporation (Japan) | Japan Air Conditioning Systems Co Ltd | 6 |
| Rocky Research Inc | Honeywell International Inc | 6 |
| Siemens AG | Siemens Concentrated Solar Power Ltd | 2 |
| Director-General, Agency of Industrial Science and Technology (METI Japan) | Fujikura Ltd | 2 |
| Director-General, Agency of Industrial Science and Technology (METI Japan) | Hisaka Works Ltd | 2 |
| Director-General, Agency of Industrial Science and Technology (METI Japan) | Toyobo Co Ltd | 2 |
| Director-General, Agency of Industrial Science and Technology (METI Japan) | Toyo Soda Manufacturing Co Ltd | 2 |
Co-filing pairs, ranked by the number of jointly-filed patent families.
Panasonic anchors the field; Rondo Energy and Octopus Energy Heating are accelerating fast
The leader and top challenger differ sharply in trajectory: the incumbent leads on volume while newer entrants are growing their filings at a rate that signals serious strategic intent.
Panasonic Holdings Corp
Panasonic Holdings holds 372 patent families, the largest position in the corpus by a wide margin. Its technology emphasis concentrates on F28D 20 (heat-exchange apparatus with 291 families), followed by F24H 7 (fluid and water heaters, 63 families) and C09K 5 (phase-change materials, 45 families), reflecting a broad thermal systems portfolio spanning household appliances and industrial storage. Momentum data is not available in the evidence for Panasonic’s recent filing trajectory, but its accumulated depth across three complementary technology classes points to a defensive, portfolio-broadening strategy.
372 patent familiesRondo Energy Inc
Rondo Energy Inc holds 176 patent families and is the fastest-growing named applicant in the evidence, with a filing rate approximately 5.5 times higher in the recent three-year window versus the prior three years. Its focus is concentrated on F28D 20 (heat-exchange apparatus, 173 families), F01K 3, and F01K 15 (steam and thermal power plants, 141 and 136 families respectively), indicating a deliberate specialization in high-temperature industrial heat storage and power-cycle integration. This trajectory, combined with deep coverage of steam-plant IPC classes, positions Rondo as the primary patent challenger to established incumbents in grid-scale thermal storage.
176 patent families| Applicant | Recent (3 yrs) | Trend |
|---|---|---|
| Rondo Energy Inc | 126 | ▲ 5.5× vs prior 3-yr |
| Rocky Research Inc | 6 | ▼ -83% |
| Mitsubishi Electric Corporation | 14 | ▲ new entrant |
| Octopus Energy Heating Ltd | 99 | ▲ new entrant |
| French Alternative Energies and Atomic Energy Commission (CEA) | 9 | ▼ -36% |
Under-served branches adjacent to the dominant heat-exchange core
The whitespace analysis identifies IPC classes that appear in the corpus but hold a smaller share of filings relative to their technical relevance; these are observations of relative sparsity, not validated opportunities, and should be evaluated against a team’s specific technical capabilities.
F25B · Refrigeration & heat pumps integrated with thermal storage
F25B holds the second-largest record count in the corpus yet accounts for only 8% of the top-branch share, indicating that the intersection of refrigeration and heat-pump cycles with dedicated thermal storage media is under-patented relative to pure heat-exchange work. The technical value is plausible: heat-pump-coupled thermal storage can shift grid demand and improve COP in both heating and cooling modes. A realistic entry path exists through novel working-fluid or cycle-configuration claims that bridge F25B and C09K phase-change material classes.
Search this in Eureka →C09K · Advanced phase-change and heat-transfer materials
C09K (materials for miscellaneous applications, including heat-transfer and phase-change materials) represents 7% of the top-branch share, a comparatively sparse position given the centrality of materials science to storage performance. While some incumbents such as Panasonic, Rocky Research, and the former Sunaptic entity do file under C09K, the class remains thinly covered relative to F28D apparatus claims. Teams with expertise in novel PCM formulations, encapsulation techniques, or thermochemical storage materials could build differentiated positions here with relatively limited prior-art friction.
Search this in Eureka →How leading applicants differ by technology route
Strength of each leader across the main technology routes.
| Player | F28D 20 · Heat-exchange apparatus | C09K 5 · Materials for misc. applications | F24F 5 · Air conditioning & ventilation | F01K 3 · Steam & thermal power plants | F28D 17 · Heat-exchange apparatus |
|---|---|---|---|---|---|
| Panasonic Corporation (Japan) | Strong · 291 | Emerging · 45 | Absent | Absent | Emerging · 17 |
| Rondo Energy Inc | Strong · 173 | Absent | Absent | Strong · 141 | Absent |
| Siemens AG | Strong · 117 | Absent | Absent | Moderate · 44 | Moderate · 27 |
| Director-General, Agency of Industrial Science and Technology (METI Japan) | Strong · 91 | Absent | Absent | Absent | Moderate · 32 |
| IFP Energies Nouvelles | Strong · 94 | Absent | Absent | Absent | Moderate · 19 |
| Octopus Energy Heating Ltd | Strong · 95 | Absent | Absent | Absent | Absent |
Frequently asked questions
The in-scope corpus contains 4,580 patent families, spanning global filings over the last decade.
Panasonic Holdings Corp leads with 372 patent families. Rondo Energy Inc (176), Rocky Research Inc (148), Octopus Energy Heating Ltd (119), and Mitsubishi Electric Corp (118) form the next tier.
The field is at a maturity stage. Annual filings peaked at 651 in 2022 and have eased since, reaching 490 in 2023 and 442 in 2024. The multi-year corpus has grown, but the annual run-rate has plateaued. Figures for 2025 and 2026 are incomplete due to publication lag.
The United States is the leading filing jurisdiction, followed by Japan and the European Patent Office. Germany, India, and Australia are also notable. A US–Japan–Europe strategy, supplemented by PCT for multi-region coverage, captures the majority of the active landscape.
Rondo Energy Inc shows the strongest momentum among named applicants, with a filing rate approximately 5.5 times higher in the recent three-year window versus the prior three years. Octopus Energy Heating Ltd and Mitsubishi Electric Corp are both classified as new entrants in the momentum data, indicating rapid recent accumulation from a low prior base.
F25B (refrigeration and heat pumps integrated with thermal storage) and C09K (advanced phase-change and heat-transfer materials) are the most prominent under-served adjacent branches relative to their technical relevance. F24D (domestic heating systems) and F24F (air conditioning coupled storage) are also comparatively sparse and may merit further investigation depending on a team’s application focus.
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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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