A revolutionary technology is cleaning up industry's act by transforming CO2 emissions into a manageable stream.
Imagine a world where the smoke rising from power plants and factories is no longer a threat to our climate, but a manageable stream ready for safe storage or even reuse. This is the promise of oxy-fuel combustion, a cutting-edge carbon capture technology poised to decarbonize the world's most emission-intensive industries. Unlike traditional methods that try to pluck carbon dioxide from a chaotic mix of flue gases, oxy-fuel combustion creates an environment where CO2 is the dominant product, dramatically simplifying its capture and bringing us closer to a net-zero future 2 7 .
Tonnes of CO2 captured annually by 2028
Projected market value by 2031
Oxygen concentration in experimental setups
This article explores the science behind this process, from its fundamental principles to a real-world experiment, illuminating how engineers are turning the tide on industrial carbon emissions.
To understand the power of oxy-combustion, it helps to first consider traditional combustion. When we burn fuel—like coal or natural gas—in ordinary air, the resulting flue gas is a complex mixture. It is mostly nitrogen (from the air), along with carbon dioxide, water vapor, and various pollutants. Capturing the CO2 from this dilute and contaminated stream is a challenging and energy-intensive process 2 .
Oxy-fuel combustion elegantly sidesteps the problem of dilute CO₂ by changing the combustion medium itself. Instead of using air, it burns the fuel in an atmosphere of nearly pure oxygen.
This simple substitution has a profound effect: the resulting flue gas is primarily composed of carbon dioxide and water vapor 2 6 . The water vapor can be easily removed through cooling and condensation, leaving behind a highly concentrated stream of CO2 that is ready for compression, transportation, and storage 7 .
Controls temperature and improves efficiency
Simple condensation process
Ready for transport and storage
A key part of making this process efficient is Recycled Flue Gas (RFG). Burning fuel in pure oxygen creates extremely high temperatures that could damage standard equipment. To control this, a portion of the CO2-rich flue gas is recycled back into the combustion chamber. This dilutes the oxygen concentration, moderates the temperature, and improves the overall efficiency of the system 3 6 .
While the principle is straightforward, implementing it requires meticulous research. A recent study provides an excellent example of how scientists are optimizing oxy-combustion for different fuels. This experiment investigated the co-combustion of wood pellets and plastic waste in a bubbling fluidized bed reactor, a system known for its fuel flexibility and efficient burning 6 .
The researchers designed their experiment to systematically analyze how different variables affect the combustion process. The key steps were:
The team used wood pellets (a common biomass) and polyethylene (PE) plastic. They first conducted proximate and elemental analyses to determine the exact chemical makeup and heating value of each fuel 6 .
Before the combustion tests, they used a TGA to heat small fuel samples and measure weight changes. This helped understand the thermal degradation behavior and activation energy required for combustion under different atmospheres 6 .
The core of the experiment involved a continuous-feed bubbling fluidized bed reactor. The researchers varied three key parameters:
During each test run, they monitored the temperature distribution inside the reactor and analyzed the gas emissions, particularly carbon monoxide (CO) and nitrogen oxides (NOx) 6 .
| Item | Function |
|---|---|
| Wood Pellets | Representative biomass fuel; low in sulfur and ash 6 |
| Polyethylene (PE) Plastic | High-calorific waste fuel; simulates co-processing of municipal waste 6 |
| Pure Oxygen (O₂) | Primary oxidizer instead of air; enables production of CO2-rich flue gas 6 |
| Bubbling Fluidized Bed Reactor | Provides efficient gas-solid mixing and stable combustion conditions for diverse fuels 6 |
| Secondary Oxygen Injection | Creates staged combustion to control temperature and suppress NOx formation 6 |
The experiment yielded valuable, actionable data:
The TGA results showed a significant synergistic effect when wood and plastic were burned together. The mixture had a lower ignition temperature and higher combustion stability than expected, meaning the two fuels burned better together than separately 6 .
Staging the oxygen injection (SOR) proved highly effective at reducing emissions. A higher SOR led to a marked decrease in NOx production by creating fuel-rich zones that limit nitrogen oxide formation 6 .
Increasing the oxygen concentration in the inlet gas improved the exergy efficiency—a measure of how effectively the fuel's energy is utilized. The 50/50 wood-plastic blend achieved the highest efficiency, outperforming wood alone 6 .
Note: Values are approximate and recreated based on the findings described in the source material 6 .
This experiment demonstrates that oxy-combustion is not a one-size-fits-all solution. It can be finely tuned for different fuel types—even waste products—to achieve optimal efficiency and minimal environmental impact.
The transition of oxy-combustion from a promising concept to a tangible climate solution is already underway. Major demonstration projects are being built across the globe. For instance, Holcim's Go4Zero project at its cement plant in Belgium will use oxy-fuel technology to capture 1.1 million tonnes of CO2 annually, with operations scheduled to begin in 2028 8 .
Global oxy-fuel market valued at US$589.89 million
Holcim's Go4Zero project operational, capturing 1.1M tonnes CO2 annually
Projected market value exceeds US$1.05 billion
The market for this technology is growing rapidly, driven by stringent environmental regulations and the urgent need for decarbonization in sectors like cement, steel, and power generation. The global oxy-fuel combustion technology market is projected to grow from US$589.89 million in 2024 to over US$1.05 billion by 2031 .
Innovations in air separation technology for more efficient oxygen production
Future advancements are focused on overcoming remaining challenges, primarily the energy cost of oxygen separation. Innovations like advanced membrane technologies for air separation and the development of redox-active metal-organic frameworks (MOFs) for more efficient gas separation are on the horizon 5 . Furthermore, the integration of artificial intelligence is accelerating the discovery of new materials and the optimization of combustion control systems 5 .
Oxy-fuel combustion represents a paradigm shift in how we approach industrial emissions. It is a powerful and practical technological pathway for capturing CO2 from existing infrastructure, giving hard-to-abate industries a fighting chance in the race to net-zero.
While it must be deployed in concert with renewable energy, energy efficiency, and other carbon removal strategies, its role is indispensable. By turning a waste product into a manageable stream, oxy-combustion is more than just a filter at the end of a pipe; it is a fundamental re-engineering of one of industry's core processes, offering a breath of clean air for our planet's future.
Projected growth of oxy-fuel combustion technology market
Concentrated CO₂ stream requires less processing
Can process various fuels including plastic waste
Suitable for cement, steel, and power plants