Cryogenic Air Separation for Oxyfuel Combustion 2026
Cryogenic Air Separation for Oxyfuel Combustion
Cryogenic ASUs are the dominant oxygen supply technology for oxyfuel combustion, producing 95–99.5% purity O₂ to enable concentrated, sequestrable CO₂ flue gas. Patent activity spans 35 years of innovation from foundational process designs to renewable-coupled architectures.
Cryogenic ASU Architecture and Oxyfuel Integration
Cryogenic air separation for oxyfuel combustion involves fractional distillation of atmospheric air below −170°C to produce a high-purity oxygen stream (95–99.5% O₂) supplied to combustion systems in place of air. Eliminating nitrogen from the oxidizer produces flue gas composed primarily of CO₂ and water vapor, making carbon capture dramatically simpler — water is condensed and CO₂ is compressed for storage or utilization.
The core technical architecture consistently identified in retrieved records comprises five components: multi-stage feed air compression, pre-cooling and drying, cryogenic rectification in a double-column cold box, liquid oxygen storage and buffering, and integration of oxygen output with combustion systems. Oxygen delivery pressure is a critical design variable, driving a distinct sub-field of high-pressure ASU patents centered on closed CO₂ power cycles.
Key sub-domains in retrieved records include ASU-combustion process integration, thermal energy management within the ASU, CO₂ purification downstream of oxyfuel combustion, and load-flexible ASU operation for grid-connected power plants. The dataset spans literature and patents from 1989 to 2025, covering both foundational process designs and recent energy-integration innovations including renewable-powered compression and LNG cold energy recovery.
In this dataset, 8 Rivers Capital, LLC is the most prolific assignee with at least 13 distinct patent records across US, CA, EP, AU, IN, HK, and WO jurisdictions. Air Liquide, Praxair Technology, and GE Energy represent the other principal concentrated positions in retrieved records, collectively covering load-flexible buffering, warm turbine recycle architectures, and ASU-gasifier integration.
Filing Trends and Technology Cluster Distribution
Analysis of retrieved patent records reveals a clear multi-decade innovation arc with distinct waves of activity: foundational process architectures (1989–2000), pilot-scale integration patents (2000–2012), high-pressure cycle-integrated ASU patents (2012–2020), and emerging renewable and LNG integration filings (2020–2025).
Patent Records by Technology Cluster — Cryogenic ASU Oxyfuel (Dataset Snapshot)
In this dataset, the high-pressure oxygen ASU cluster (Allam cycle integration) holds the largest share of distinct patent records, driven primarily by 8 Rivers Capital’s multi-jurisdiction family spanning 2012–2020.
↗ Click bars to explorePatent Filings by Decade — Cryogenic ASU Oxyfuel (Dataset Snapshot)
In this dataset, the 2010–2019 decade shows the highest concentration of filings, driven by 8 Rivers Capital’s multi-jurisdiction Allam cycle patent family and CO₂ capture method patents.
↗ Click bars to exploreKey Application Domains for Cryogenic ASU Oxyfuel Combustion
Cryogenic ASU oxyfuel combustion spans multiple industrial sectors, from utility-scale coal and natural gas power generation to oil sands steam production, refinery FCC units, and emerging mobile and aviation propulsion contexts. Each domain presents distinct oxygen pressure, purity, and delivery requirements.
Callide Oxyfuel Project, Australia
IHI’s Callide Oxyfuel Project in Australia, documented in 2013 literature, advanced oxy-coal combustion to grid-connected demonstration scale. Air Liquide and Babcock & Wilcox demonstrated oxy-coal systems at 30 MWth pilot scale, reporting a 20% reduction in ASU separation energy specific to coal-fired plants. Techno-economic analyses indicate oxyfuel coal plants achieve approximately 2 percentage points higher net efficiency than MEA post-combustion capture plants at full load.
Coal Power GenerationAllam Cycle Natural Gas Plants
8 Rivers Capital’s patent family (2012–2020) specifically serves the Allam cycle, where cryogenic ASU oxygen at high pressure integrates with a supercritical CO₂ working fluid turbine for near-zero-emission natural gas and coal power. Techno-economic literature from 2021 identifies the Allam cycle as having the best thermal efficiency among oxy-fuel combustion cycles analyzed. Patents span US, CA, EP, AU, IN, HK, and WO jurisdictions, reflecting a broadly protected multi-jurisdictional IP position.
Advanced Power CyclesCanadian Oil Sands SAGD Operations
Literature from 2011 documents the CO₂ Capture Project — involving Praxair, Devon Canada, Cenovus Energy, and Statoil — applying oxyfuel combustion to once-through steam generators (OTSGs) in Canadian oil sands SAGD operations. Each OTSG produces up to 250 kt/yr CO₂, making oxy-combustion with cryogenic ASU oxygen a high-impact CCS pathway for heavy oil production. This application demands reliable oxygen supply integrated with steam generation at variable load conditions.
Oil Sands Steam GenerationPetrobras FCC Oxy-Combustion Retrofit
Petrobras demonstrated oxy-combustion retrofit on a large pilot-scale fluid catalytic cracking (FCC) unit as part of CO₂ Capture Project Phase 3, with literature from 2013 and a 2020 review documenting the transition from air to oxy operation in FCC regenerators. FCC units can represent 25–35% of refinery CO₂ emissions, making this a high-impact application domain. Cryogenic ASU oxygen supply enables carbon capture at a process unit historically resistant to post-combustion CCS integration.
Refinery FCC RetrofitKey Patent Assignees in Cryogenic ASU Oxyfuel Combustion (Retrieved Records)
In this dataset, 8 Rivers Capital, LLC accounts for the single largest concentration of distinct patent records with at least 13 filings across seven jurisdictions, all directed to high-pressure ASU integration with closed CO₂ cycles. Praxair Technology, L’Air Liquide, and GE Energy are the other principal named assignees in retrieved records, each holding 3–4 records covering complementary ASU architectures and process domains.
Top Assignees by Patent Record Count — Cryogenic ASU Oxyfuel (Dataset Snapshot)
↗ Click bars to explore8 Rivers Capital, LLC
8 Rivers Capital holds at least 13 distinct patent records in this dataset spanning US, CA, EP, AU, IN, HK, and WO jurisdictions, covering the cryogenic ASU method providing high-pressure oxygen for closed-cycle CO₂ power production. Their foundational US patent was filed in 2012, with a distinct high-pressure variant filed in WO in 2018 and granted in the US in 2020. Active patents across multiple jurisdictions cover elimination of inter-cooling between air compression stages and thermodynamic integration with a supercritical CO₂ working fluid turbine.
United StatesPraxair Technology, Inc.
Praxair Technology holds 4 patent records in this dataset across US, IN, EP, and CA jurisdictions, covering warm turbine recycle ASU architectures (CA, 1998), high-pressure oxygen production (US, 2004), and near-zero-emission CO₂ purification technology for oxyfuel streams. Praxair is also cited in 2011 literature for applying oxyfuel combustion to once-through steam generators in Canadian oil sands SAGD operations, documenting up to 250 kt/yr CO₂ capture per OTSG unit. Their CO₂ purification work is documented in a 2011 literature publication on near-zero emissions oxy-combustion CO₂ purification technology.
United StatesNew Technology Vectors in Cryogenic ASU Oxyfuel Combustion
The most recent filings and publications in the dataset (2022–2025) point to four distinct emerging directions: renewable-powered ASU compression, LNG cold energy integration, cryogenic CO₂ recovery from mobile engine exhaust, and cryogenic ASU enhancement of aircraft gas turbines.
Renewable-Powered ASU Compression
A 2025 GB patent by Moghales (Mohamed Amin Abdulkader) claims solar- or wind-powered compressors integrated directly with ASUs for oxyfuel applications, targeting at least 9% reductions in fuel consumption and emissions. ASU compression is the largest single energy cost in oxyfuel systems, so coupling variable renewable energy to ASU operation represents an important system-level efficiency and decarbonization shift. This patent signals the intersection of renewable energy integration with cryogenic process engineering.
LNG Cold Energy Integration with ASU
A 2025 IN patent by UPES, Dehradun proposes using LNG regasification cold energy to drive air liquefaction in the ASU, combined with Direct Expansion Cycle (DEC) and Organic Rankine Cycle (ORC) sub-systems for in-situ power generation. This represents a significant energy efficiency opportunity for LNG-import terminal co-location with oxyfuel power plants. The dual DEC-ORC configuration enables recovery of both cryogenic cold energy and compression waste heat within the same integrated system.
Load-Flexible Liquid O₂ Buffering vs. High-Pressure ASU Integration
Click any row to explore further.
| Dimension | Load-Flexible Liquid O₂ Buffering | High-Pressure ASU Integration (Allam Cycle) |
|---|---|---|
| Primary Patent Holder | L’Air Liquide (WO, AU, 2007–2008) | 8 Rivers Capital, LLC (US, EP, CA, AU, IN, HK, WO, 2012–2020) |
| Core Innovation | Dynamic liquid oxygen tank buffering to accommodate variable oxygen demand from power plants | Elimination of inter-cooling between air compression stages; high-pressure O₂ delivered directly to supercritical CO₂ working fluid turbine |
| Oxygen Delivery Pressure | Near-atmospheric pressure (conventional ASU output) | Elevated pressure required by Allam cycle and similar supercritical CO₂ oxy-combustion cycles |
| Primary Application | Grid-connected oxyfuel coal and gas power plants requiring variable oxygen supply | Allam cycle natural gas and coal power generation with inherent CO₂ capture |
| Efficiency Benefit | Energy arbitrage by decoupling ASU steady-state operation from boiler oxygen demand | Thermodynamic synergies from CO₂ working fluid closed cycle; Allam cycle identified as best thermal efficiency among oxy-fuel cycles (2021 literature) |
| Jurisdiction Coverage | WO, AU (L’Air Liquide); US (Ha, Bao 2007) | US, CA, EP, AU, IN, HK, WO (8 Rivers Capital, active through 2020) |
| Technology Maturity | Pilot-scale demonstrated (30 MWth oxy-coal, Babcock & Wilcox / Air Liquide, 2009 literature) | Commercial scale under development; foundational patents filed 2012, high-pressure variant granted US 2020 |
| Energy Penalty Reduction | 20% ASU separation energy reduction for oxy-coal reported by Air Liquide (2009 literature) | 6–9% waste heat absorption cooling improvement documented in 2021 literature; additional gains from closed-cycle thermodynamic integration |
Frequently Asked Questions: Cryogenic ASU for Oxyfuel Combustion
Cryogenic air separation units produce a high-purity oxygen stream typically in the range of 95–99.5% O₂ for supply to oxyfuel combustion systems, based on the technology description in the dataset.
In this dataset, 8 Rivers Capital, LLC is the most prolific assignee with at least 13 distinct patent records across US, CA, EP, AU, IN, HK, and WO jurisdictions, all directed to high-pressure cryogenic ASU method integrated with closed-cycle CO₂ power production (the Allam cycle).
Liquid oxygen buffering decouples ASU operation from boiler oxygen demand. During periods of low demand, the ASU produces excess oxygen stored as liquid; during peak demand, stored liquid oxygen is vaporized and supplied. This enables energy arbitrage and allows the ASU to operate efficiently at steady state while the power plant varies output. L’Air Liquide filed a key patent on this approach in 2007 (WO jurisdiction).
The dataset documents a 20% reduction in ASU separation energy specific to coal-fired oxyfuel applications reported by Air Liquide in 2009 literature, and 6–9% improvements through waste heat absorption cooling documented in 2021 literature. A 2025 GB patent by Moghales claims at least 9% reductions in fuel consumption through renewable-powered ASU compression.
Retrieved records from 2022–2025 identify four emerging directions beyond conventional power generation: (1) LNG cold energy integration at import terminals (UPES Dehradun, 2025 IN patent); (2) renewable-powered ASU compression (Moghales, 2025 GB patent); (3) cryogenic CO₂ recovery from mobile combustion engines (LGE IP Management, 2022 WO / 2024 US pending); and (4) cryogenic ASU enhancement of aircraft gas turbines (RTX Corporation, 2024 EP and US filings).
The flue gas from oxyfuel combustion is composed primarily of CO₂ and water vapor. Water is condensed and removed, and then CO₂ is compressed and purified for storage or utilization using a Compression and Purification Unit (CPU). The CPU must account for impurities including SOx, NOx, Hg, and Ar carried over from the combustion process. Praxair published a 2011 literature record specifically on near-zero-emission CO₂ purification technology for oxyfuel streams, and Air Liquide is cited for CPU development for the FutureGen 2.0 project.
Data and insights on this page are based on a limited patent and literature dataset and are for reference only. Figures may not represent the complete technology landscape.