A 323% patent surge: what the filing data reveals about thermal energy storage momentum
Thermal energy storage patent applications climbed from 48 filings in 2017 to 203 in 2025 — a 323% increase in eight years — driven by the twin pressures of industrial decarbonization mandates and the need to integrate variable renewable electricity into continuous heat-intensive manufacturing. The global TES market is projected to reach USD 53.4 billion by 2030, according to market intelligence cited by GlobeNewswire, making it one of the fastest-growing segments within the broader clean energy transition.
The patent landscape reveals a pronounced geographic concentration: South China University of Technology leads all applicants with 21 patents — 53.8% of the top-10 applicant portfolio — focused on thermal conductivity enhancement and high energy density solutions for 80–300°C industrial applications. Beijing University of Technology holds 8 patents (20.5%), emphasising compact heat exchanger designs and system integration for waste heat recovery, while Zhejiang University contributes 3 patents (7.7%) targeting molten salt composition optimisation and corrosion resistance.
Thermal energy storage patent applications grew from 48 filings in 2017 to 203 in 2025, representing a 323% increase, with South China University of Technology leading all applicants with 21 patents (53.8% of the top-10 portfolio).
Notably, Rondo Energy is the only U.S. startup appearing in the top applicant cohort, signalling that while Chinese academic institutions dominate filing volume, Western commercial players are beginning to establish positions — particularly in high-temperature brick-based and pumped-heat architectures targeting cement and steel industries.
The analysis covers 884 thermal energy storage patents filed between 2017 and 2026. European and Japanese innovation may be underrepresented in the dataset, and thermochemical storage patent coverage is sparse (3 patents retrieved), reflecting early-stage technology maturity rather than an absence of industrial R&D activity.
Molten salt storage: commercially proven, industrially underdeployed
Molten salt thermal energy storage has reached TRL 9 for concentrated solar power applications, with more than 10 GW deployed globally and 8–15 hour storage duration capability demonstrated at GWh scale. For direct industrial process heat, the technology sits at TRL 7–8, with 5–10 demonstration projects operational or under construction as of 2025. The 300–565°C operating range matches approximately 40% of industrial heat demand — spanning chemicals, food processing, and paper manufacturing — making molten salt the nearest-term commercial option for high-temperature industrial decarbonization.
Commercial molten salt systems operate across a 500°C–1000°C range. Ternary and quaternary salt mixtures (NaNO₃-KNO₃-LiNO₃ systems) extend the effective operating window to 150–600°C while reducing corrosion rates by 40–60% versus binary salt formulations. Round-trip efficiency for waste heat recovery applications reaches 85–92%.
Recent patent activity has concentrated on three innovation vectors. First, dual-tank and thermocline system design: a 2024 Korean patent (KR1020240030377A) demonstrates a dual-container architecture improving energy efficiency by 18–25% through optimised thermal stratification. Second, corrosion mitigation: electrochemical purification methods (US20190376192A1) reduce oxygen and moisture content in the salt circuit, extending system lifetime from 20 to 30+ years. Third, modular deployment: patent WO2016057404A1 covers modular molten salt solar towers enabling combined electricity and process steam generation while reducing installation time by 30–40%.
On the commercial side, Rondo Energy is developing a brick-based thermal storage “Heat Battery” targeting cement and steel industries, backed by $60M in Series B funding raised in 2023, with pilot deployments in California cement plants. Hyme Energy has commissioned its first 100 MWh facility in 2024 using molten hydroxide technology operating at 1,200°C for industrial steam generation. Malta Inc. combines molten salt hot storage with cryogenic cold storage in a pumped-heat architecture, achieving 50–60% round-trip efficiency for 8–100 hour durations.
“The 300–565°C temperature range of molten salt storage matches approximately 40% of global industrial heat demand — the largest addressable market of any single TES technology route.”
Two technology gaps constrain faster deployment. Freeze protection — salt solidification at 220–240°C requires continuous heat tracing, adding 8–12% parasitic load to system energy balance. And high-temperature corrosion above 600°C limits containment materials to specialised nickel alloys, increasing capital expenditure by 35–50% compared with conventional pressure vessels. Closing these gaps through protective coatings or corrosion inhibitors enabling lower-cost stainless steel use up to 650°C could deliver a 20–30% system cost reduction and open 600–800°C industrial processes to molten salt integration.
Explore the full molten salt patent landscape — compositions, reactor designs, and applicant rankings — in PatSnap Eureka.
Analyse Patents with PatSnap Eureka →Phase change materials: versatile integration across the 80–400°C industrial band
Phase change materials have achieved commercial maturity in building HVAC (more than 500 MW installed globally at TRL 9) and are now transitioning to industrial applications, where MW-scale pilots are demonstrating 70–85% round-trip efficiency across the 80–400°C temperature range. The core challenge holding back GWh-scale industrial deployment is not technical performance but material cost: high-performance PCMs cost USD 5–15/kg versus USD 0.5–1/kg for molten salts, making large-scale deployment economically prohibitive without significant cost reduction.
The PCM material landscape spans four distinct categories, each suited to different industrial temperature bands. Salt hydrates (20–120°C, 150–250 kJ/kg energy density) serve low-grade waste heat recovery and cold chain logistics. Organic PCMs such as paraffins and fatty acids (30–90°C, 120–210 kJ/kg) are used in food processing and pharmaceutical manufacturing. Eutectic salts (200–600°C, 300–500 kJ/kg) address metal heat treatment and glass manufacturing. Metallic PCMs (400–1,200°C, 200–400 kJ/kg) target steel reheating furnaces and aluminium casting, with patent AU2020396795A1 demonstrating 95% latent heat efficiency in this range.
Phase change material thermal energy storage has more than 500 MW installed globally in building HVAC applications (TRL 9), while industrial PCM pilots in the 80–400°C range are demonstrating 70–85% round-trip efficiency at 10–50 MW scale as of 2024–2025.
Two encapsulation breakthroughs are accelerating industrial applicability. Metal oxide shell microencapsulation (US9493695B2) achieves 500+ thermal cycles without degradation, enabling PCM integration in high-shear industrial process flows. Coaxial polymer spinning methods (WO2024251391A1) produce 50–200 μm diameter fibers with 85% PCM loading and 12 W/m·K thermal conductivity — a threefold improvement versus bulk PCM — at manufacturable scale.
Heat transfer enhancement is the other critical lever. Adding graphene or carbon nanotube additives increases thermal conductivity from the 0.2–0.5 W/m·K baseline of organic PCMs to 3–8 W/m·K, reducing charging and discharging time by 60–75%. Expanded graphite matrices, as demonstrated in DE102021104769A1, deliver a 15-fold thermal conductivity improvement while retaining 88% of latent heat capacity. According to IDTechEx, these advances are enabling PCM systems to compete with molten salt for distributed industrial heat applications where installation space is constrained.
Industrial decarbonization applications span three primary use cases: batch process heat buffering in chemical reactors (reducing natural gas consumption by 25–40%); multi-stage waste heat cascading from kilns, dryers, and furnaces (70–85% recovery efficiency across 80–300°C exhaust streams); and grid-interactive thermal batteries enabling demand response participation with 4–8 hour discharge duration matching industrial shift patterns. The R&D priority for unlocking GWh-scale deployment is identifying low-cost eutectic salt or bio-based PCM candidates with 200+ kJ/kg latent heat and 500+ cycle stability — a breakthrough that could deliver 60–80% material cost reduction and enable cost parity with molten salt systems.
Thermochemical storage: the high-density frontier for long-duration industrial heat
Thermochemical energy storage offers 3–10× higher energy density than sensible heat storage such as molten salt (which delivers 0.3–0.8 GJ/m³), and stores energy indefinitely at ambient temperature in chemical bonds — eliminating the 1–3% daily standby losses that characterise molten salt systems. No commercial deployments have been identified as of 2026; most reaction pairs sit at TRL 3–5, with CaO/Ca(OH)₂ systems reaching TRL 5 in laboratory environments through 50–100 cycle demonstrations.
Thermochemical energy storage systems offer 3–10× higher energy density than molten salt sensible heat storage (0.3–0.8 GJ/m³), can store energy indefinitely at ambient temperature with no standby losses, and are capable of delivering heat at 50–150°C above the charging temperature — but remain at TRL 3–5 as of 2026 with no commercial deployments.
The most advanced reaction pair is CaO/Ca(OH)₂, operating at 450–550°C with an energy density of 3.3 GJ/m³. Patent CN116123908A (2023) demonstrates a kettle reactor design achieving 85% conversion efficiency over 50 cycles and 92% thermal utilisation. MgO/Mg(OH)₂ systems operate at 250–350°C (2.8 GJ/m³), while metal hydride pairs such as MgH₂/Mg reach 300–400°C with the highest demonstrated energy density of 4.5 GJ/m³. For lower-temperature applications, salt hydrate pairs — MgCl₂·6H₂O (115–150°C, 2.1 GJ/m³) and SrBr₂·6H₂O (80–120°C, 1.8 GJ/m³) — are better suited to district heating and pharmaceutical drying.
A 2025 patent (US20250297813A1) presents a thermochemical salt hydrate system enabling inter-seasonal energy storage with six-month charge retention and 180 Wh/kg energy density — a capability no other TES technology can match. Zeolite-based adsorption systems (DE102012006311A1) deliver 2.5–3.0 coefficient of performance in 50–150°C temperature lift applications, relevant to industrial heat pumping.
Slow reaction kinetics limit power density to 50–200 W/kg (versus 500–2,000 W/kg for PCM systems). Material sintering and agglomeration after 20–100 cycles reduce reactivity by 30–60% with no cost-effective regeneration demonstrated. No proven path exists from 1–10 kg laboratory reactors to 10–100 tonne industrial reactors. Hydration reactions require precise humidity control (40–80% RH), adding integration complexity at industrial sites.
The most compelling long-term industrial application is cement kilns: the CaO/CaCO₃ reversible calcination reaction allows CaO to serve simultaneously as storage medium and cement feedstock, capturing 800–1,450°C waste heat while displacing virgin limestone input. Steel reheating furnaces represent a second high-value target, where MgO/Mg(OH)₂ systems could displace 30–50% of natural gas consumption in billet reheating. According to WIPO patent trend data, thermochemical storage filings remain sparse relative to molten salt and PCM, suggesting significant white space for early movers willing to invest in reactor scale-up research.
Map thermochemical storage white space and identify emerging patent clusters with PatSnap Eureka’s AI-powered landscape analysis.
Explore Patent Landscape in PatSnap Eureka →Economics of decarbonization: LCOH, carbon pricing, and the break-even calculus
Industrial process heat accounts for 74% of global industrial energy consumption — approximately 11,000 TWh per year — with 60% currently supplied by fossil fuels including natural gas, coal, and fuel oil. This makes industrial heat decarbonization one of the largest and most difficult emissions reduction challenges, and it is precisely the economic gap between TES-plus-renewables and incumbent fossil fuel heating that determines deployment pace.
On a levelised cost of heat basis over a 20-year project life (2026 estimates in USD/MWh thermal), natural gas boilers deliver heat at USD 25–40/MWh with a CO₂ intensity of 200 kg/MWh. Molten salt combined with renewable electricity costs USD 45–70/MWh at 5–15 kg CO₂/MWh. PCM-plus-renewable systems cost USD 55–85/MWh. Thermochemical systems, based on laboratory cost models, are estimated at USD 80–120/MWh — though commercial costs remain uncertain.
The break-even carbon price analysis is instructive for investment timing. At USD 50/tonne CO₂, molten salt achieves parity with natural gas for high-utilisation applications running more than 5,000 hours per year. At USD 75/tonne CO₂, PCM systems become competitive for medium-utilisation processes (3,000–5,000 hours/year). Thermochemical systems require either USD 100+/tonne CO₂ or a 50% CAPEX reduction to reach competitiveness. Carbon pricing regimes in the EU (currently above USD 60/tonne) already place molten salt TES within the competitive window for certain industrial applications, as tracked by the EPA and European climate policy bodies.
Under an aggressive 2030 deployment scenario — 150 GWh of TES capacity — the technology could decarbonize 250–350 TWh/year of industrial heat, abating 50–70 Mt CO₂/year and displacing 25–35 billion cubic metres of natural gas annually. The moderate scenario (50 GWh deployed) projects 16–24 Mt CO₂/year abatement. Realising the aggressive scenario requires renewable electricity costs of USD 20–30/MWh to enable low-cost resistive heating or heat pump charging, combined with carbon pricing at USD 50–100/tonne CO₂ and process redesign to accommodate 4–12 hour charging and discharging cycles.
Industrial process heat accounts for 74% of global industrial energy consumption (approximately 11,000 TWh per year), with 60% currently supplied by fossil fuels. At a carbon price of USD 50 per tonne CO₂, molten salt thermal energy storage combined with renewable electricity achieves cost parity with natural gas boilers for industrial applications running more than 5,000 hours per year.
Commercialization roadmap and R&D priorities: what needs to happen before 2035
The three TES technology routes follow divergent commercialization trajectories through 2035. Molten salt is projected to reach 500–1,000 MW of industrial deployments in 2026–2028 and 2–5 GW cumulative by 2029–2031, with costs falling to USD 15–25/kWh through manufacturing scale-up. PCM industrial applications are expected to reach 100–300 MW pilots by 2028, achieving TRL 8–9 for 100–400°C applications by 2031 and potentially 5+ GW by 2035 if material costs fall 30–40%. Thermochemical systems face the longest path: 1–10 MW laboratory and pilot reactors through 2028, 50–100 MW demonstrations if reactor scale-up succeeds by 2031, and 500+ MW in niche applications (seasonal storage, high-density sites) by 2035.
Five R&D gaps are critical to closing. Molten salt corrosion above 600°C restricts containment to expensive nickel alloys, inflating CAPEX by 35–50%; protective coatings enabling lower-cost stainless steel to 650°C could deliver a 20–30% system cost reduction. PCM heat transfer enhancement — scaling graphene-enhanced or metal foam composite manufacturing to achieve 3–8 W/m·K conductivity — could reduce system volume by 50–70%, enabling retrofits in space-constrained facilities. Thermochemical reactor scale-up requires fluidised bed or moving bed designs with continuous material circulation achieving 500+ W/kg power density. PCM material cost reduction targeting low-cost eutectic salt or bio-based candidates with 200+ kJ/kg latent heat and 500+ cycle stability could deliver 60–80% cost reduction. Finally, model predictive control frameworks co-optimising TES charging and discharging with electricity prices, process schedules, and demand response opportunities could improve economic returns by 15–25%.
For industrial end-users, the near-term action priority (2026–2028) is piloting molten salt systems for high-temperature (above 400°C), high-utilisation (above 5,000 hours/year) processes where payback can be achieved in 5–7 years under current carbon pricing, while assessing PCM opportunities for 100–300°C waste heat recovery targeting 25–40% natural gas displacement. Engaging in demonstration programmes with vendors such as Rondo Energy, Hyme Energy, and Malta Inc. to secure early-adopter pricing is recommended before 2028. The IEA has identified industrial heat decarbonization as among the hardest emissions reduction challenges, and TES is increasingly recognised as a core enabling technology in roadmaps for 2050 net-zero industrial production. PatSnap’s IP analytics platform enables R&D teams to monitor competitor patent activity across all three TES routes in real time.
“With aggressive policy support and technology cost reductions, thermal energy storage could displace 250–350 TWh per year of fossil fuel-based industrial heat by 2030 — abating 50–70 Mt CO₂ annually.”
Policy levers are equally critical. Carbon pricing at USD 50–100/tonne CO₂ closes the economic gap for molten salt and PCM systems. Investment tax credits of 30–40%, modelled on the U.S. IRA Section 48C or the EU Innovation Fund, de-risk early projects. Regulatory mandates requiring large industrial emitters (above 100,000 tonnes CO₂/year) to evaluate TES integration in decarbonization plans would accelerate adoption. And dedicated R&D funding of USD 500M–1B over five years for thermochemical storage, PCM cost reduction, and system integration demonstrations would compress the timeline to commercial viability for next-generation technologies.