Pumped Thermal Energy Storage 2026 — PatSnap Eureka
Pumped Thermal Energy Storage Technology Landscape 2026
PTES — also called Pumped Heat Energy Storage or Carnot Battery — converts electricity into thermodynamic potential stored in hot and cold reservoirs, then recovers it via a heat engine. This report maps patent clusters, key actors, round-trip efficiency benchmarks, and emerging innovation directions as of 2026.
How Pumped Thermal Energy Storage Works
PTES systems store electricity as a temperature differential between a high-temperature (hot) reservoir and a low-temperature (cold) reservoir, mediated by a working fluid circulating through a closed thermodynamic cycle. During the charging phase, electrical work drives a compressor-based heat pump that raises the hot reservoir temperature while cooling the cold reservoir. During discharge, the temperature gradient drives a heat engine — turbine or expander — to regenerate electricity.
The system is analogous in concept to pumped hydroelectric storage, but replaces elevation potential energy with thermodynamic potential energy stored in thermal mass. This makes PTES location-independent, a critical advantage over pumped hydro, which requires specific geographic conditions. Thermal reservoirs span solid packed beds, liquid sensible storage (molten salts, synthetic and vegetable oils), and latent heat phase-change materials (PCMs). Learn more about long-duration storage technology at PatSnap Analytics.
Three dominant thermodynamic cycle architectures are identified in this dataset: Brayton-cycle systems (using noble gases such as argon or air), Organic Rankine Cycle (ORC)-based systems (using refrigerants such as R1233zd(E)), and supercritical CO₂ (sCO₂) systems. The International Renewable Energy Agency (IRENA) identifies long-duration storage as essential for achieving net-zero grids, and IEA projections underscore the urgency of scaling non-geographic alternatives to pumped hydro.
Four Phases of PTES Development: 2015–2025
From foundational techno-economic studies to active commercialisation and emerging Chinese market entry, the PTES innovation timeline reveals a technology approaching grid-scale viability.
Conceptual & Analytical Phase. Foundational techno-economic studies (2015–2017) evaluated PTES against competing storage technologies. First LCOS benchmarking vs. batteries and CAES. ORC requirements formulated, predicting RTE up to 70%.
Early Patent Activity. Malta Inc. emerges as earliest prominent patent filer (priority 2018–2020). Echogen Power Systems files foundational US patents on sCO₂-based PTES. Thermo-economic comparison with LAES anchors PTES in the competitive landscape.
Demonstration & Scale-Up. World’s first grid-scale PHES demonstration (150 kWe, Hampshire UK) completes commissioning. Malta Inc. files across US, WO, CA, AU, IN. Supercritical Storage Company establishes three-reservoir architecture.
Commercialisation Push. Most recent filings target waste heat integration, hybrid low-temperature reservoirs, dual-powertrain architectures, and direct-contact thermal storage — all targeting improved RTE and reduced capital cost.
Four Core PTES Architecture Clusters
Patent and literature analysis identifies four distinct thermodynamic architecture clusters, each with different performance profiles, application targets, and IP ownership structures.
Brayton Cycle with Sensible Heat Reservoirs
The dominant PTES architecture in academic literature uses a closed Brayton cycle with noble gas or air working fluids (argon, nitrogen, air) and solid or liquid sensible heat stores. Air was identified as the most cost-effective working fluid, achieving 1–7% cost reductions over argon. Packed beds and liquid tanks serve as the thermal storage medium. This architecture is positioned as a substitute for pumped hydro in geographically unconstrained deployments. Research published on US DOE programmes supports noble-gas cycle development.
Air: 1–7% cost reduction vs argonHeat Pump + ORC Carnot Battery Systems
A second architecture pairs a vapour-compression heat pump (charging) with an Organic Rankine Cycle (discharging), connected through a thermal storage buffer. Targeted at small-to-medium-scale applications, this cluster enables integration with low-grade heat sources. Refrigerant R1233zd(E) has been studied as a dual-use working fluid. Systems frequently incorporate thermal integration (TI-PTES), whereby waste heat or ground-source heat feeds into the heat pump to increase effective COP and apparent RTE. The PatSnap Chemicals platform supports working fluid patent searches.
R1233zd(E) dual-use working fluidSupercritical CO₂ Three-Reservoir PTES
Supercritical Storage Company has built its patent portfolio around a PTES architecture using sCO₂ as the working fluid in a three-reservoir configuration: a high-temperature reservoir, a low-temperature reservoir, and a waste heat reservoir. A recuperator with balanced heat capacity flow rates on both sides is the defining thermodynamic feature. The system enables waste heat integration through a decoupled low-temperature thermal reservoir, raising apparent RTE above theoretical single-cycle limits. Three-reservoir architecture granted in the US (2022) with national phase entries in AU (pending, 2025).
Supercritical Storage Company — US, WO, AU, IL, CNMolten Salt / Solid Media + Cryogenic Cold-Side Brayton
Pioneered by Malta Inc., this cluster uses molten salt (analogous to concentrating solar power thermal storage) as the hot-side storage medium and a cold-side cryogenic or sub-ambient fluid, with a closed-cycle gas (air) Brayton system. The architecture enables integration with existing thermal power plant infrastructure. Siemens Energy has filed on a variant using conveyable bulk solid thermal media directly coupled to the working fluid — a novel direct-contact design that eliminates intermediate heat exchangers. Malta Inc. holds filings across US, WO, CA, AU, and IN jurisdictions.
Malta Inc. — US, WO, CA, AU, INKey PTES Performance and Filing Data
Visualising round-trip efficiency benchmarks and the geographic spread of patent filings from the two dominant PTES IP holders in this dataset.
RTE Benchmarks by Architecture
Brayton and ORC systems reach 70% idealised RTE; the Hampshire demonstration achieved 60–65%; waste heat integration enables apparent RTE above 100%.
Patent Jurisdiction Coverage by Key Filer
Malta Inc. leads in jurisdictional breadth (US, WO, CA, AU, IN); Supercritical Storage Company’s most active prosecution is in WO, US, AU, IL, and CN as of 2025.
Where PTES Technology Is Being Deployed
From utility-scale grid storage to industrial waste heat recovery and distributed energy communities, PTES addresses multiple distinct application domains with different scale and integration requirements.
Key Patent Holders in the PTES Space
Two US-headquartered companies dominate PTES-specific patent filings in this dataset, with emerging Chinese assignees signalling a new competitive dynamic.
| Assignee | Jurisdiction(s) | Key Technology Focus | Status (as of 2025) |
|---|---|---|---|
| Malta Inc. | US, WO, CA, AU, IN | Molten salt hot-side, cryogenic cold-side, Brayton cycle, thermal plant integration, dual-powertrain, direct-contact storage | Active grants + pending filings |
| Supercritical Storage Company, Inc. | US, WO, AU, IL, CN | sCO₂ three-reservoir architecture, waste heat integration, hybrid low-temperature reservoir | Most active prosecution in dataset (2025) |
| Echogen Power Systems (Delaware), Inc. | US | sCO₂-based electricity generation systems relevant to PTES | Active US patents (2020–2021) |
| Siemens Energy, Inc. | US | Conveyable solid thermal media direct-contact PTES variant | Active US patent (2019) |
| State Power Investment Group Yunnan | CN | Heat pump storage system architectures — domestic Chinese development | Emerging (2024) |
| Northeast Electric Power University | CN | Academic-origin CN filings on heat pump storage systems | Emerging (2024) |
Four Innovation Frontiers in PTES (2024–2025)
The most recently filed patents in this dataset reveal four distinct engineering directions targeting improved round-trip efficiency, reduced capital cost, and operational flexibility.
Waste Heat Integration as First-Class Design Feature
Supercritical Storage Company’s family (priority: February 2023, US provisional 63/443,775), published across WO, AU, IL, and CN in 2025, discloses a PTES architecture in which the low-temperature thermal reservoir used during charging is decoupled from the generating cycle’s cold reservoir — enabling waste heat at elevated temperature to be absorbed without degrading heat engine efficiency. This “decoupled low-temperature reservoir” concept is the most aggressively prosecuted emerging technical claim in this dataset.
Direct-Contact Thermal Storage
Malta Inc.’s November 2025 WO filing introduces direct contact between the working fluid and the cold-side thermal storage fluid — eliminating intermediate heat exchanger surfaces, reducing thermal resistance, and potentially improving round-trip efficiency and reducing capital cost. This represents a significant departure from conventional heat exchanger-mediated thermal storage designs.
IP Strategy and Commercial Outlook for PTES
Malta Inc. and Supercritical Storage Company have established strong IP moats in the PTES space across multiple jurisdictions. New entrants must design around the core Brayton-cycle + molten salt / sCO₂ + three-reservoir architectures. The most defensible white space lies in alternative working fluids (e.g., CO₂ blends), novel cold-side reservoir concepts, and control system innovations not yet claimed.
Waste heat integration is becoming a key commercial differentiator. The ability to achieve apparent RTE >100% by coupling PTES to industrial waste heat streams transforms the value proposition from pure electricity arbitrage to an industrial energy efficiency product — broadening the addressable market significantly and improving project economics in cost-sensitive jurisdictions. The PatSnap Analytics platform enables IP landscape mapping across these emerging white spaces.
Round-trip efficiency of 60–70% remains the primary performance gap versus electrochemical alternatives. Academic literature consistently identifies turbomachinery isentropic efficiency, thermal store effectiveness, and heat leakage as the dominant loss mechanisms. R&D investment targeting high-efficiency axial or radial turbomachinery optimised for noble gas working fluids represents the highest-leverage engineering lever. The US EPA and IEA both identify long-duration storage as critical infrastructure for decarbonisation.
Thermal plant integration — co-location with existing fossil fuel or nuclear Rankine cycle assets — is the most immediately deployable pathway to commercial viability. By avoiding the capital cost of a dedicated discharge turbine and generator, co-located PTES can achieve competitive levelised cost of storage at smaller scale and shorter lead times than greenfield installations. Explore customer case studies at PatSnap Customers.
China represents an emerging competitive threat. Current CN filings are early-stage, but the combination of domestic manufacturing scale, aggressive grid storage procurement targets, and demonstrated ability to industrialise energy technologies rapidly means that Chinese PTES competitors could reach commercial scale within 5–7 years. IP strategists should file defensively in CN jurisdiction ahead of this inflection point. PatSnap Open API enables automated CN patent monitoring.
- Design around Brayton + molten salt and sCO₂ three-reservoir core claims
- Target CO₂ blends and novel cold-side reservoirs as white-space opportunities
- Waste heat integration broadens addressable market beyond electricity arbitrage
- Thermal plant co-location is the fastest path to commercial viability
- File defensively in CN jurisdiction ahead of Chinese market inflection
Pumped Thermal Energy Storage — key questions answered
PTES converts electrical energy into thermal energy during charging via a heat pump cycle, stores it in hot and cold thermal reservoirs, and recovers electricity via a heat engine cycle during discharge. It is analogous to pumped hydroelectric storage but replaces elevation potential energy with thermodynamic potential energy stored in thermal mass.
Literature from 2017–2023 benchmarks PTES round-trip efficiency (RTE) at 60–70% under idealised conditions. The first grid-scale demonstration (150 kWe, 600 kWh, Hampshire, UK) achieved 60–65% RTE as reported in commissioning results.
Malta Inc. and Supercritical Storage Company, Inc. dominate PTES-specific patent filings. Malta Inc. has filings across US, WO, CA, AU, and IN jurisdictions. Supercritical Storage Company has the most recently active prosecution activity, with waste heat integration patents pending in WO, US, AU, IL, and CN as of 2025.
Three dominant thermodynamic cycle architectures are identified: Brayton-cycle systems (using noble gases such as argon or air), Organic Rankine Cycle (ORC)-based systems (using refrigerants such as R1233zd(E)), and supercritical CO₂ (sCO₂) systems.
By integrating freely available industrial waste heat into the charging cycle, PTES systems can bypass the need for a second thermal storage unit and achieve apparent RTE greater than 100%. This transforms the value proposition from pure electricity arbitrage to an industrial energy efficiency product.
Thermal plant integration (co-location with existing fossil fuel or nuclear Rankine cycle assets) is the most immediately deployable pathway to commercial viability. By avoiding the capital cost of a dedicated discharge turbine and generator, co-located PTES can achieve competitive levelised cost of storage at smaller scale and shorter lead times than greenfield installations.
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