What HTL is and why it matters in 2026
Hydrothermal liquefaction (HTL) is a thermochemical conversion process that subjects wet organic feedstocks — including biomass, sewage sludge, algae, plastics, and lignocellulosic materials — to elevated temperatures (typically 250–420°C) and pressures (90–300 bar) in an aqueous medium to produce an energy-dense bio-crude oil. The defining commercial advantage over conventional pyrolysis is that HTL does not require feedstock drying: water at elevated temperature and pressure acts simultaneously as reaction medium, acid-base catalyst, and hydrogen donor, breaking down complex biopolymers — lipids, proteins, carbohydrates — into smaller hydrocarbon molecules that coalesce into bio-crude.
The technology is gaining strategic relevance as a pathway toward renewable fuels and circular waste valorisation, according to patent filings analysed by PatSnap’s innovation intelligence platform. A parallel strand of innovation extends HTL methodology to fossil feedstocks: Saudi Arabian Oil Company has filed on supercritical water upgrading of heavy crude and whole crude oil, operating at conditions directly analogous to biomass HTL but targeting petroleum quality improvement — demonstrating how a single thermochemical principle spans both the renewable energy and conventional refining sectors.
Operating conditions in the retrieved dataset span from subcritical conditions (240–310°C, as referenced in the Eni Group patent filed in China in 2024) through to near-supercritical regimes (350°C+ at pressures of 220+ barg, as described by TotalEnergies OneТech in a 2025 Indian filing). The choice of regime affects product yield, bio-crude quality, and energy input requirements.
Hydrothermal liquefaction (HTL) converts wet organic feedstocks into energy-dense bio-crude oil at temperatures of 250–420°C and pressures of 90–300 bar using subcritical or near-critical water as both reaction medium and catalyst, eliminating the need for energy-intensive feedstock drying required by conventional pyrolysis.
From proof-of-concept to commercial maturity: the HTL innovation timeline
The earliest directly relevant HTL filing in this dataset dates to 2010, when Saudi Arabian Oil Company filed a Korean patent on supercritical water upgrading of whole crude oil. A cluster of biomass-to-biocrude systems appeared between 2015 and 2019 — including the Phycofeeds Limited HTL reactor (India, 2019) and the Bond/Cody solar-hybrid HTL system (PCT, 2015; EP, 2016) — signalling a transition from proof-of-concept to engineered systems. The most recent filings span 2023 to 2025 and reflect commercialisation-oriented innovation across multiple organisations and geographies.
Circlia Nordic’s decentralised, centrally controlled multi-unit biocrude production network (PCT, 2023) signals a shift toward scale-out rather than scale-up thinking. Overall, the field in this dataset spans approximately 2010–2025, with the most recent cohort of filings — from Battelle Memorial Institute (EP, 2025), Reliance Industries (India, 2025), TotalEnergies OneТech (India, 2025), and UPM-Kymmene Corporation (EP, 2023) — all oriented toward commercialisation challenges: residence time management, charring reduction, downstream fractionation, and novel energy input mechanisms.
“The center of gravity of active HTL filings is shifting markedly toward 2022–2025, consistent with a technology approaching early commercial maturity.”
The earliest directly relevant hydrothermal liquefaction patent filing in the PatSnap dataset dates to 2010 (Saudi Arabian Oil Company, Korea), with 8 of 16 surveyed filings concentrated in the 2023–2025 period — a distribution consistent with HTL approaching early commercial maturity.
Four technical clusters driving HTL patent activity
HTL patents in the retrieved dataset cluster around four core technical domains: continuous-flow tubular and pressurised reactor systems; integrated multi-stage and hybrid process systems; supercritical water upgrading of fossil feedstocks; and distributed and modular HTL architectures. Each cluster represents a distinct engineering challenge and competitive IP position.
Cluster 1: Continuous-flow tubular and pressurised reactor systems
This is the dominant technical cluster. These patents cover reactor configurations designed to maintain feedstock slurries at reaction temperature and pressure through the full HTL conversion cycle, with emphasis on heat recovery and product separation. Battelle Memorial Institute’s 2025 EP filing describes a staged two-pump, two-heat-exchanger system that incrementally pressurises and heats a biomass slurry to HTL conditions — addressing the technical challenge of pumping viscous or particle-laden slurries to supercritical-adjacent pressures. TotalEnergies OneТech introduces ohmic (resistive) heating as a novel energy delivery mechanism within a single tubular reactor, achieving heating rates of at least 10°C/minute to reach 350°C+ at 220+ barg. Reliance Industries’ 2025 Indian filing focuses on improving residence time management and reducing charring through system design, with a multi-feed preparation arrangement enabling simultaneous processing of multiple feedstock types while reducing equipment count and OPEX.
Cluster 2: Integrated multi-stage and hybrid process systems
These patents combine HTL with upstream feedstock preparation, downstream upgrading, or co-processes such as anaerobic digestion or Fischer-Tropsch synthesis to maximise carbon and energy recovery. UPM-Kymmene Corporation (EP, 2023) converts lignocellulosic feedstock via a two-temperature HTL sequence (290–340°C, 90–120 bar), followed by thermal upgrading of the separated oil phase and optional fractionation to produce light and heavy renewable product fractions. Eni Group’s 2024 Chinese filing describes a subcritical HTL process (240–310°C) integrated with multi-stage anaerobic digestion of the aqueous phase to co-produce bio-oil and biogas. Bond/Cody (PCT, 2015) discloses hybrid energy supply using concentrated solar thermal energy and/or biogas from anaerobic digesters co-processing municipal biosolids, grease, and food waste — enabling energy-neutral or energy-positive HTL operation, as documented by WIPO in its PCT filings database.
Cluster 3: Supercritical water upgrading of fossil feedstocks
A distinct subset applies near-HTL thermochemical conditions (supercritical water, 374°C+) to petroleum feedstocks rather than biomass. Saudi Arabian Oil Company’s 2018 Singapore PCT filing combines a supercritical water reactor with flash drum, aqueous reforming unit, and downstream hydrotreating/hydrocracking stages to upgrade heavy oil while co-generating hydrogen from the aqueous reforming step. An earlier 2010 Korean filing established the use of supercritical water contact with whole crude oil combined with a recovery fluid to reduce metal and nitrogen impurities and produce high-value refinery feedstocks. This represents a non-biomass application of thermochemical water-mediated conversion at HTL-equivalent conditions, and is relevant to organisations assessing freedom-to-operate under EPO or PCT patent coverage.
Cluster 4: Distributed and modular HTL architectures
Circlia Nordic ApS (PCT, 2023) discloses a network of decentralised HTL units each with local control systems, communicatively coupled to a central controlling facility that manages a first subset of operational parameters while local systems retain exclusive control over a second subset. This architecture enables distributed biocrude production from geographically dispersed biomass sources — a form factor suited to aggregated waste streams such as sewage, agricultural residues, and food waste.
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Explore HTL patents in PatSnap Eureka →UPM-Kymmene Corporation’s 2023 European patent describes a two-temperature hydrothermal liquefaction sequence operating at 290–340°C and 90–120 bar for lignocellulosic feedstocks, followed by thermal upgrading and optional fractionation to produce distinct light and heavy renewable fuel fractions.
Assignee and jurisdictional landscape: who is filing and where
Innovation in the HTL dataset is distributed across a relatively small number of assignees, with no single organisation dominating the biomass HTL space. Saudi Arabian Oil Company is the clearest concentrated actor, holding 3 directly relevant filings — but exclusively in the petroleum supercritical water upgrading sub-domain. Eni Group holds 2 relevant filings for biomass HTL processes filed in China. The remaining active assignees — TotalEnergies OneТech, Battelle Memorial Institute, Reliance Industries, UPM-Kymmene Corporation, Circlia Nordic, and Phycofeeds Limited — each hold a single filing in the dataset.
Among directly HTL-relevant patents in this dataset, India accounts for 3 of the most recent active filings — from Reliance Industries, TotalEnergies OneТech, and Phycofeeds Limited. This makes India a notable emerging destination for both biomass HTL and petroleum upgrading patent activity. IP strategists should monitor Indian assignee activity and freedom-to-operate implications in that geography, particularly given the Indian Patent Office‘s growing role in technology-sector filings.
Jurisdictional distribution across the dataset spans India (3 filings), EP (2 filings), PCT/WO (2 filings), Korea (3 filings for petroleum supercritical water), and China (2 filings for biomass HTL). The EP filings from Battelle Memorial Institute and UPM-Kymmene Corporation, combined with PCT filings from Circlia Nordic and Bond/Cody, indicate that biomass HTL innovators are seeking broad international coverage — consistent with the global nature of renewable fuel markets tracked by organisations such as the IEA in its bioenergy outlook reports. The concentration of recent filings in India reflects both the country’s growing domestic refining and bioenergy sector and the strategic importance of the Indian market for multinational energy companies.
Saudi Arabian Oil Company holds the largest number of directly relevant hydrothermal liquefaction patent filings in the dataset (3 filings: Singapore PCT 2018, Korea 2010, Korea 2019), but all three are concentrated in petroleum supercritical water upgrading rather than biomass-to-biocrude conversion.
Emerging directions: ohmic heating, multi-feedstock platforms, and distributed networks
The most recent filings (2023–2025) in this dataset reveal four forward-looking directions that are reshaping the competitive landscape of HTL innovation. These directions move beyond reactor design to address energy decarbonisation, feedstock flexibility, deployment architecture, and value-chain integration.
Ohmic and resistive heating for rapid thermal ramp-up
TotalEnergies OneТech’s 2025 Indian patent introduces electrical ohmic heating to achieve heating rates of at least 10°C/minute within a single tubular reactor, reaching 350°C+ at 220+ barg. This enables precise temperature control and potential integration with renewable electricity — representing a decarbonisation of the HTL process energy supply. The approach is distinct from conventional external heating by heat exchangers, and may offer advantages for modular or off-grid deployment scenarios.
Multi-feedstock flexibility and plastic co-processing
TotalEnergies OneТech’s 2025 filing explicitly covers plastics alongside biomass as HTL feedstocks. The Eni Group filings (China, 2024) cover a broad feedstock range including mixed biomass types. Reliance Industries’ 2025 filing introduces a multi-feed preparation arrangement enabling simultaneous processing of multiple feedstock types while reducing equipment count and OPEX. This convergence signals movement toward “omni-feedstock” HTL platforms capable of processing heterogeneous organic waste streams — a commercially significant capability as municipal and industrial waste management policies tighten globally, as tracked by bodies such as UNEP in its circular economy frameworks.
Distributed-network biocrude production
Circlia Nordic (PCT, 2023) introduces centrally coordinated but locally operable HTL networks — an architecture suited to decentralised biomass availability and enabling real-time operational adjustment from a central facility. This represents a significant departure from large centralised HTL plant concepts, and with only one retrieved filing directly addressing this architecture, the sub-domain represents a potential white space for technology developers targeting distributed waste processing at municipal or agricultural scale.
Downstream integration and bio-crude upgrading
UPM-Kymmene (EP, 2023) explicitly adds a thermal upgrading and fractionation step after HTL separation, producing distinct light and heavy renewable fuel fractions. Topsoe A/S (Brazil, 2025) and Eni Group’s process filings indicate growing attention to the HTL-to-refinery interface, including hydrodeoxygenation and co-processing with vegetable oils. These filings reflect maturation of the value chain beyond the HTL reactor itself — the rate-limiting IP challenges are now shifting from the HTL reactor to product quality and refinery co-processing compatibility.
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The HTL patent landscape as of 2026 presents a set of clear strategic signals for innovation teams, IP counsel, and technology investors monitoring the renewable fuels and waste valorisation sectors.
Feedstock diversification is a primary IP battleground. Recent filings from TotalEnergies OneТech, Eni Group, and Reliance Industries each push toward processing mixed or novel feedstocks (plastics, mixed biomass, algae), suggesting that feedstock-agnostic HTL reactor designs will be competitively differentiated IP assets. Organisations with narrow feedstock claims may face design-around pressure as the field matures.
Energy input innovation is a nascent but strategically important sub-field. Organisations filing in this space early — TotalEnergies OneТech with ohmic heating, and Bond/Cody with solar-hybrid and biogas integration — may establish dominant positions as the industry pivots toward electrically integrated and low-carbon HTL operations. This sub-field is particularly relevant as renewable electricity costs decline and corporate net-zero commitments tighten.
The modular and distributed architecture space is largely uncontested. With only one retrieved filing (Circlia Nordic, PCT 2023) directly addressing decentralised multi-unit HTL networks, this sub-domain represents a potential white space for technology developers targeting distributed waste processing at municipal or agricultural scale. Early filing activity in this space could establish strong positional IP before the architecture becomes mainstream.
Downstream upgrading and refinery integration are the critical scale-up bottleneck. The concentration of recent filings addressing bio-crude quality, charring, phase separation, and hydroprocessing integration — from UPM-Kymmene, Topsoe, Eni Group, and Reliance Industries — signals that the rate-limiting IP challenges are now shifting from the HTL reactor itself to product quality and refinery co-processing compatibility. Teams with expertise in hydrodeoxygenation, fractionation, and co-processing will find growing freedom-to-operate questions in this space.
“The modular and distributed HTL architecture space — with only one retrieved filing — represents a potential white space for technology developers targeting distributed waste processing at municipal or agricultural scale.”
As of the 2026 patent dataset, the distributed and modular hydrothermal liquefaction architecture sub-domain contains only one directly relevant filing (Circlia Nordic ApS, PCT 2023), representing a potential IP white space for organisations developing decentralised biocrude production networks from geographically dispersed biomass sources.