Flue Gas Pre-Treatment and CO₂ Separation at the Industrial Interface
The first engineering challenge in any CCUS retrofit is bringing hot, contaminant-laden flue gas to a state compatible with CO₂ separation. Industrial flue gases from combustion units contain dust particles, nitrogen oxides, sulfur oxides, moisture, trace elements, and CO₂ — a complex matrix that must be treated before efficient CO₂ capture is possible. A combined decontamination and dust removal unit typically forms the first stage, after which CO₂ is routed to a dedicated capture unit where it can be stored as a supercritical fluid for downstream conversion, as demonstrated in a 2022 patent from Green Carbon Nanotech (Jiangsu) Co. Ltd.
A central problem is how to cool high-temperature flue gas without diluting its CO₂ content. Air injection — the conventional approach — increases volumetric flow and reduces CO₂ partial pressure, making downstream purification more expensive and energy-intensive. Air Liquide’s 2022 patent proposes controlled cooling to 100–600°C followed by recirculation of either a fraction of the pre-treated flue gas or purified CO₂ from the CCUS unit itself as the cooling medium, avoiding CO₂ dilution while enabling particle removal, desulfurization, and denitrification in the pre-treatment stage.
Air Liquide’s flue gas treatment patent proposes controlled cooling to 100–600°C followed by recirculation of pre-treated flue gas or purified CO₂ as the cooling medium — a technique that avoids the CO₂ concentration penalty of conventional air injection while enabling particle removal, desulfurization, and denitrification.
Post-combustion amine absorption remains a primary separation technology at the flue gas interface. General Electric Technology GmbH (2013) describes a system in which a CO₂-loaded amine solution is pressurized in a regeneration unit, generating a high-pressure CO₂ stream that is expanded through a turbine to recover energy, partially offsetting the parasitic power penalty of the capture process. However, amine-based aerosol formation is an emerging operational concern: a 2025 patent from Zhejiang Feida Environmental Technology identifies amine aerosol escape from absorption towers as a key bottleneck limiting large-scale deployment, proposing a downstream condenser combined with sintered plate or carbon fiber filter stages to intercept sub-micron aerosol droplets that bypass conventional mist eliminators.
Sub-micron amine aerosol droplets escape conventional mist eliminators in post-combustion capture towers. These droplets reduce real-world capture efficiency and create secondary pollution. Zhejiang Feida’s 2025 sintered-plate and carbon fiber filter solution specifically targets this gap, which the patent identifies as a critical constraint on large-scale CCUS deployment.
Cryogenic and pressure-swing approaches offer alternatives to amine scrubbing. Praxair Technology (2011) discloses a process where flue gas and a CO₂-rich recycle stream are co-compressed, dried over sorbent beds, and subjected to cryogenic separation, with liquid CO₂ expansion providing the refrigeration duty — eliminating the need for external refrigerant circuits. Bright Energy Storage Technologies (2023) further refines this approach with a self-referential thermal loop: liquid CO₂ pre-cools incoming flue gas in a first stage, the cooled gas is compressed, CO₂ melting enthalpy drives a second cooling stage, and a final expansion step produces solid CO₂ that subsequently melts to regenerate liquid CO₂ — avoiding the external refrigerant capital costs identified as a weakness of competing amine and external-cooling approaches.
Retrofit Integration with Power Generation and Industrial Facilities
Integrating CCUS into operating power plants requires careful attention to steam extraction, auxiliary power demands, and the mechanical interfaces between the existing flue gas train and new capture equipment. The dominant Western strategy — pre-installing heat exchangers, steam extraction points, and flue gas expanders before committing to a specific capture technology — is designed to manage retrofit risk without costly full plant re-engineering or shutdowns.
PFBC Environmental Energy Technology, Inc. (US, 2014) discloses an interface architecture for pressurized fluidized bed combustion facilities that uses a gas-to-water heat recovery steam generator to cool flue gas and produce steam for the existing turbine cycle, while a variable-frequency drive motor and flue gas expander coupled to the combustion air compressor allow the facility to be energized with minimal disruption. Critically, the expander is synchronized via an SSS-clutch to the compressor, enabling the interface to condition flue gas in preparation for future addition of CO₂ capture technology — a “capture-ready” design philosophy. ALSTOM Technology Ltd. (EP, 2018) addresses the same challenge by designing its steam cycle to maintain high efficiency whether or not the CO₂ capture system is extracting steam, allowing operation in capture mode, non-capture mode, and a future-retrofit-ready mode without requiring full plant re-engineering.
“A clear trend emerging from the 2023–2026 filings is the consolidation of CCUS into multi-function integrated systems that simultaneously perform carbon capture, energy storage, grid peak-shaving, and chemical production — contrasting sharply with the earlier generation of standalone post-combustion capture units added to plants as parasitic loads.”
For coal-fired plants, Dongfang Electric’s 2025 integrated system connects the boiler flue gas duct directly to an adsorption separation tower module, inserting multiple heat exchangers between the flue duct and both the compressor and the high-pressure CO₂ storage vessel. In the zero-power-supply operating mode — when the coal unit participates in grid balancing by reducing load to minimum — the system diverts all remaining output beyond plant auxiliary consumption to drive the compressor at elevated speed, enabling continuous CO₂ liquefaction without shutting down the boiler. A parallel 2025 patent from Dongfang Electric further couples a low-pressure adsorptive CO₂ storage sub-system in parallel with the main high-pressure liquid storage circuit, significantly reducing footprint and capital cost relative to conventional high-pressure tank farms.
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Explore CCUS Patents in PatSnap Eureka →For refinery applications, IFP Énergies Nouvelles (2013) describes an integrated fluid catalytic cracking (FCC) unit and amine capture process in which a back-pressure steam turbine drives both the cracking gas compressor and the regeneration blower, achieving a utility balance with net surplus high-pressure and low-pressure steam — enabling the combined FCC/amine capture unit to produce near-zero or even negative CO₂ emissions relative to the uncaptured baseline. This demonstrates how existing process steam infrastructure can actively power the capture system rather than penalizing plant efficiency.
Siemens Energy International (2025) discloses a CO₂ provision facility in which the separated CO₂ is pre-heated before entering a multi-stage compressor; after each compression stage, the high-temperature CO₂ passes through a steam generator that produces steam fed back to the amine separation facility for solvent regeneration, creating a thermal self-sufficiency loop. Condensed water from the final compressor stage is separated and removed, delivering pipeline-ready dense-phase CO₂. According to IEA analysis, thermal integration of this kind is central to reducing the energy penalty that has historically made CCUS economically challenging for existing industrial facilities.
Dongfang Electric’s 2025 coal-fired plant CCUS system uses a zero-power-supply operating mode in which all plant output beyond auxiliary consumption is diverted to drive the CO₂ compressor at elevated speed, enabling continuous CO₂ liquefaction without shutting down the boiler — eliminating large energy losses associated with conventional stop-start operation.
CO₂ Utilization Pathways: From Energy Storage to Enhanced Recovery
Once CO₂ has been captured and separated from industrial flue gas, the disposition of that CO₂ — storage, utilization in energy systems, or injection into geological formations — determines the economic viability of the overall CCUS project. The patent data reveals three major utilization clusters: CO₂-coupled energy storage, enhanced hydrocarbon recovery, and conversion to chemical products.
CO₂-Coupled Energy Storage
Multiple patents develop the concept of using captured CO₂ as the working fluid in compressed-gas energy storage systems co-located with power plants. The Institute of Engineering Thermophysics, CAS (2022) presents a CCUS and supercritical CO₂ energy storage coupling system in which the CCUS chain is augmented with compression storage segments — using salt cavern or depleted reservoir storage — and expansion power generation segments. CO₂’s critical temperature of 304.2 K and critical pressure of 7.28 MPa make the supercritical state relatively easy to achieve, and the stored high-pressure CO₂ can provide grid load balancing as well as eventual geological sequestration. Bairan New Energy (2025) integrates an amine absorption carbon capture sub-system with a CO₂ phase-change energy storage sub-system: lean solvent exiting the desorption tower with residual heat serves as the evaporation heat source for liquid CO₂ in the power release unit, while high-temperature heat transfer fluid in the energy storage thermal cycle provides the heat to regenerate the solvent — achieving bidirectional thermal integration that reduces both capture energy penalty and storage system operating costs.
CO₂’s critical temperature of 304.2 K and critical pressure of 7.28 MPa make the supercritical state relatively easy to achieve, enabling captured CO₂ from industrial flue gas to serve as a working fluid for grid load balancing in compressed-gas energy storage systems co-located with power plants.
Enhanced Hydrocarbon Recovery
China University of Petroleum (East China, 2018) describes a CCUS system built around gas-lift oil recovery, in which CO₂ produced from the oil-gas separation process and CO₂ from the on-site gas generator exhaust are jointly reinjected into the well group for gas-lift operations, substantially increasing CO₂ re-utilization rates and reducing direct atmospheric release. Hebei Shengjia Technology (2024) applies CCUS to oilfield thermal operations via a two-stage separation system: a first separator performs gas-liquid separation and pressure reduction, while a second separator cools the mixed gas to –30°C at 2 MPa to fractionate CO₂ from natural gas, with a heat pump providing both the heating and cooling duties. The recovered CO₂ is reinjected for reservoir pressure maintenance. Anhui Lanqing Energy Technology (2025) extends this approach to coal seam methane via CCUS-ECBM (Enhanced Coal Bed Methane) displacement, injecting CO₂ through angled horizontal drill paths positioned between multiple methane extraction wells to maximize contact area and displacement efficiency. According to IEA, enhanced oil recovery remains one of the most commercially mature CO₂ utilization pathways globally.
Conversion to Chemical Products
Lanzatech (2023) provides a process in which CO₂ from industrial gas streams is first cleaned of contaminants and then fed to a CO₂-to-CO conversion system — including reverse water-gas shift, thermocatalytic, electrocatalytic, partial combustion, or plasma conversion units — to regenerate CO for gas fermentation reactors that produce fuels and chemicals. M2X Energy Inc. (CA, 2023) specifically targets flare gas at oil production sites, using an air-breathing engine reformer to produce a syngas intermediate that is converted to methanol, with a CO₂ separator channeling the CO₂-rich fraction toward EOR or geological storage. Dongfang Electric’s methanol-production variant (2025) routes captured CO₂ through a CCUS reduction device heated by compressed CO₂ waste heat, then combines it with green hydrogen to synthesize methanol — substituting conventional CO₂ liquefaction and cold-chain storage with direct chemical utilization, a route that eliminates cryogenic logistics costs while generating revenue from the methanol product stream. As noted by WIPO, CO₂ utilization patents have grown substantially as industrial operators seek to convert a cost centre into a revenue-generating asset.
Lummus Technology’s 2025 patent (WO) introduces the concept of using existing CO₂ pipeline infrastructure as the high-pressure reservoir for a charge/discharge energy storage cycle — eliminating dedicated storage vessel capital by repurposing already-deployed CO₂ transport infrastructure. This represents a significant reduction in marginal CCUS infrastructure cost for regions with existing CO₂ transport networks.
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Analyse CO₂ Utilization Patents in PatSnap Eureka →Key Players and Innovation Trends Across the Patent Landscape
Based on filing frequency and technical breadth in the dataset of more than 60 patents, a clear hierarchy of innovation leadership emerges at the CCUS–flue gas interface, with Chinese institutions dominating the most recent filing cohort and Western firms holding foundational capture-ready and thermal integration patents.
Dongfang Electric Group is the most prolific Chinese assignee in the power-plant integration space, with multiple 2025 patents covering both coal-fired flue gas capture and CO₂ adsorptive energy storage, including a methanol synthesis variant that routes captured CO₂ through a reduction device heated by compressed CO₂ waste heat before combining with green hydrogen. Bairan New Energy Technology holds multiple patents on CO₂ energy storage systems coupled to amine capture sub-systems, reflecting a strategy of incremental refinement of the same core thermal integration architecture. The Institute of Engineering Thermophysics, CAS contributes foundational coupling architectures including the CCUS and supercritical CO₂ energy storage coupling system (2022) and a supercritical CO₂ and spray packed-bed fire storage coupling system (2024), emphasizing large-scale grid-balancing applications.
On the Western side, PFBC Environmental Energy Technology, Inc. holds the most complete “capture-ready” interface architecture in the Western patent literature, with active patents in Canada and the United States. ALSTOM Technology Ltd. (now part of GE) is represented by patents in both EP and JP jurisdictions addressing retrofit-ready fossil-fired power plants with explicit focus on maintaining steam cycle efficiency across capture-on and capture-off operating modes. China University of Petroleum, through both its Beijing and East China campuses, leads in subsurface CCUS integration, including gas-lift oil recovery, CCUS pipeline source-sink matching optimization, and CO₂ pipeline hydraulic-thermal simulation. According to EPO patent data, CCUS-related filings have grown significantly across all major jurisdictions since 2020, with China representing the fastest-growing national applicant base.
Lummus Technology LLC’s 2025 PCT patent introduces using existing CO₂ pipeline infrastructure as the high-pressure reservoir for a charge/discharge energy storage cycle, eliminating dedicated storage vessel capital by repurposing already-deployed CO₂ transport networks — a novel approach that reduces marginal CCUS infrastructure cost for regions with existing CO₂ pipelines.
Lummus Technology LLC (WO, 2025) introduces the novel concept of utilizing existing CO₂ pipeline infrastructure for energy storage, where the pipeline itself serves as the high-pressure CO₂ reservoir for a charge/discharge energy storage cycle — eliminating dedicated storage vessel capital by repurposing already-deployed CO₂ transport infrastructure. Multi-dimensional retrofit optimization tools are also emerging as a necessary complement to hardware innovation: Beijing Guodian’s CCUS retrofit path optimization method (2026) and Dalian University of Technology’s source-sink matching evaluation apparatus (2023) reflect the recognition that hardware-level innovation must be matched by GIS-integrated, multi-scenario techno-economic assessment frameworks to enable cluster-scale deployment. The IEA has similarly emphasized that source-sink matching and infrastructure planning tools are among the most critical gaps in current CCUS deployment capability. PatSnap’s R&D and innovation intelligence platform provides the patent analytics infrastructure needed to track these rapidly evolving technology clusters across jurisdictions.
A clear trend emerging from the 2023–2026 filings is the consolidation of CCUS into multi-function integrated systems that simultaneously perform carbon capture, energy storage, grid peak-shaving, and chemical production. This contrasts sharply with the earlier generation of standalone post-combustion capture units that were added to plants as parasitic loads. PatSnap’s Insights blog continues to track the patent landscape as these integrated architectures mature toward commercial deployment.