Oxycombustion (TRL 6)

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Category: Carbon capture (innovations) Subcategory: Physical separation Combustion type: Oxy

DESCRIPTION

The oxy-combustion process (or oxy-fuel combustion) is a carbon capture method that involves burning fossil fuels in an oxygen-rich (or pure oxygen) environment instead of air, resulting in flue gas that is primarily CO2 and water vapor, making it a promising technology for reducing greenhouse gas emissions from power plants and other industrial sources. In this process, an air separation unit (ASU) is generally used to separate air into oxygen and nitrogen. Then the fuel is burned in a mixture of oxygen and recycled flue gas instead of regular air. This approach reduces nitrogen oxide (NOx) emissions and enhances the efficiency of CO2 capture. The water vapor is condensed, leaving behind a highly concentrated CO2 stream, which can be purified and compressed using a CO2 processing unit (CPU) to pipeline specifications.

Oxy-fuel Combustion Carbon Capture

TECHNICAL ASPECTS (all % are volume-based)

Point sources: Power plants1,2, iron and steel, cement factories3, chemical plants, waste-to-energy plants4.

CO2 concentration range: Oxy-fuel combustion produces CO2 at various concentrations depending on oxygen purity and flue gas recycling.

CO2 capture efficiency: 90-99%3,5,6

CO2 purity: 80-85%3 (from combustion in cement kiln – requires further purification), 99.9%6 (after conditioning)

Min. feed gas pressure: 1.3 bar7 (feed pressure of oxygen from ASU)

Max. feed gas temperature: 70 °C7 (feed temperature of oxygen from ASU)

Typical scale: Medium to Large (> 100,000 tCO2/yr) 3,7

Primary energy source: Fuel (fossil or biomass)

Impurity tolerance: Co-capture of SOx and NOx is possible in the CPU.1

FUNCTION IN CCU VALUE CHAIN

  • Producing nearly pure CO2, simplifying capture, utilization, and storage.
  • Reduces (or removes) NOx emissions since nitrogen is removed before combustion, eliminating the need for the NOx removal step.

LIMITATIONS

  • High energy requirement for oxygen separation in the air separation unit.1
  • Retrofit challenges for existing point sources due to modified combustion conditions.

ENERGY

  • Electricity is primarily consumed by ASU to produce oxygen and CPU for purification and compression.
  • If an organic Rankine cycle (ORC) is employed to recover energy, some electricity can be generated.8

CONSUMABLES

  • Cooling water is used to manage and recover heat from the process.
  • Pure oxygen produced by an ASU is used for combustion to create an oxygen-rich environment.
Energy and Consumables
Parameter Value
Heat duty (GJ/tO2) 0.058 7 *
Electricity (kWh/tO2) 226 7,9 *
Cooling duty (GJ/tO2) 0.57 7 *
Oxygen (t/tCO2) 0.31 7 **
Electricity CPU (kWh/tCO2) 122 7 ***

* Required by ASU per ton of O2 produced at 95% purity.

** O2 required for a cement plant.

*** Additional energy is required for the CPU to purify and bring CO2 to pipeline specifications (110 bar).

COSTS

CAPEX: 15 €/tCO2 8

Main CAPEX: Air separation unit (ASU), CO2 processing units (CPU), and organic Rankine cycle (ORC).

OPEX: 21 €/tCO2 8

Main OPEX: electricity, cooling water.

CO2 capture cost:  36 €/tCO2 8

CO2 avoidance cost: 42 €/tCO2 avoided 10

                                   39 – 41 €/tCO2 avoided 3

                                   26 €/tCO2 avoided 6

8 Cement plant; calculation includes only retrofitting CAPEX and additional OPEX than reference plant; capture rate – 90%; plant lifetime – 25 yrs; CO2 capture capacity – 0.8 MtCO2/yr; discount rate – 8%; 2014 euros; electricity price – 58 €/MWh.

3 Cement plant; low range – retrofit; upper range – new installation; capture rate – 90%; plant lifetime – 25 yrs; cement capacity – 1.36 Mt/yr; CO2 capture capacity – 0.75 MtCO2/yr; discount rate – 8%; 2013 euros; electricity price – 80 €/MWh.

6 Air Liquide lignite oxyfuel plant (1000 MWe gross) with 42% LHV efficiency, heat integration on ASU and CO2 cryogenic purification unit.

ENVIRONMENTAL

CO2 footprint: Electricity source dependent.

Spatial footprint: ASU - 4000 m2 for 90 tO2/h; CPU – 3000 m2 for 234 tCO2/h 11

(Require space for only ASU/CPU, recirculation piping, and additional equipment (organic ranking cycle and condenser). The burner, coolers, and preheaters undergo redesign, so no additional space is required.

Environmental issues: Additional CO2 emissions if electricity for oxygen separation comes from fossil fuel.

ENGINEERING

Maturity: Demonstration (TRL 6-8)4

Oxy-fuel combustion maturity varies depending upon the application.

Retrofittability: Challenging

Retrofitting is generally challenging than the new plants, mainly due to the complexity of integration with existing systems and major modifications to operate with nearly pure oxygen.3

Scalability: Moderate

Oxy-fuel combustion has moderate scalability due to the high energy demand for oxygen production, complex flue gas recycling, and expensive retrofitting. Additional ASUs can be added at a later stage.

Process type: Non-chemical oxygen-based fuel combustion.

Deployment model: Centralized or decentralized.

Centralized: only if one ASU and one CPU are used for one oxy-fuel combustion process.

Decentralized: when one ASU and one CPU are used for multiple oxy-fuel combustion processes at different locations.

Technology flexibility: Moderate

Oxy-fuel combustion can be hybridized with other CO2 capture technologies, such as post-combustion capture, chemical looping combustion, and membrane-based oxygen separation, to reduce energy penalties and improve scalability.12

TECHNOLOGY PROVIDERS

INNOVATIONS

  • Membrane-based oxygen separation to replace energy-intensive cryogenic air separation units.13
  • Chemical looping combustion eliminates the need for direct oxygen separation by using oxygen carriers.14
  • Pressurized oxycombustion improves thermal efficiency and reduces the equipment size.15

CONTACT INFO

Mohammed Khan (mohammednazeer.khan@vito.be)

Miet Van Dael (miet.vandael@vito.be)

ACKNOWLEDGEMENT

This infosheet was prepared as part of the MAP-IT CCU project funded by VLAIO (grant no. HBC.2023.0544).

REFERENCES

1.    Fu C, Gundersen T. Techno-economic analysis of CO2 conditioning processes in a coal based oxy-combustion power plant. Int J Greenh Gas Control. 2012;9:419-427.

2.    IEAGHG. Oxy-Combustion Turbine Power Plants 2015/05.; 2015.

3.IEAGHG. Deployment of CCS in the Cement Industry.; 2013. https://www.globalccsinstitute.com/archive/hub/publications/162743/deployment-ccs-cement-industry.pdf

4.    Barlow H, Shahi SSM. State of the Art: CCS Technologies 2024.; 2024.

5.    GCCA. Oxyfuel. 2025. Accessed April 3, 2025. https://gccassociation.org/cement-and-concrete-innovation/carbon-capture-and-utilisation/oxyfuel/

6.    Perrin N, Dubettier R, Lockwood F, et al. Oxycombustion for carbon capture on coal power plants and industrial processes: Advantages, innovative solutions and key projects. Energy Procedia. 2013;37:1389-1404.

7.    Voldsund M, Gardarsdottir SO, De Lena E, et al. Comparison of Technologies for CO2 Capture from Cement Production—Part 1: Technical Evaluation. Energies. 2019;12(3):559.

8.    Gardarsdottir SO, De Lena E, Romano M, et al. Comparison of Technologies for CO2 Capture from Cement Production—Part 2: Cost Analysis. Energies. 2019;12(3):542.

9.    IEAGHG. Oxy Combustion Processes for CO2 Capture from Power Plant.; 2005. https://ieaghg.org/docs/General_Docs/Reports/Report 2005-9 oxycombustion.pdf

10.  Anantharaman R, Berstad D, De Lena E, et al. CEMCAP Comparative Techno-Economic Analysis of CO2 Capture in Cement Plants.; 2019.

11.  Berghout N, Kuramochi T, Broek M van den, Faaij A. Techno-economic performance and spatial footprint of infrastructure configurations for large scale CO2 capture in industrial zones: A case study for the Rotterdam Botlek area (part A). Int J Greenh Gas Control. 2015;39:256-284.

12.  Davidson R. Hybrid Carbon Capture Systems.; 2012.

13.  Singh R, Prasad B, Ahn YH. Recent developments in gas separation membranes enhancing the performance of oxygen and nitrogen separation: A comprehensive review. Gas Sci Eng. 2024;123:205256.

14.  Khan MN, Chiesa P, Cloete S, Amini S. Integration of chemical looping combustion for cost-effective CO2 capture from state-of-the-art natural gas combined cycles. Energy Convers Manag X. 2020;7:100044.

15.  Chen S, Zhou N, Xiang W. Pressurized oxy-fuel combustion with sCO2 cycle and ORC for power production and carbon capture. Case Stud Therm Eng. 2024;60(May):104697.

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