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Pure OxyfuelHow CO2 capture is decarbonizing the cement industry
The cement industry is one of the world’s largest industrial CO2 emitters. A significant share of these emissions is an unavoidable result of clinker production and cannot be eliminated through renewable energy alone. This is precisely where pure oxyfuel from thyssenkrupp Calvion comes in: the technology enables highly concentrated CO2 capture directly within the production process, thereby supporting the decarbonization of the cement industry.
How does Pure Oxyfuel work?
“Cement production generates the harmful greenhouse gas CO2 during both calcination and combustion,” explains Jost Lemke. CO2 emissions are unavoidable in the production of cement clinker because the gas results not only from the combustion of the fuels used, but primarily from limestone, which is essential for cement production and releases CO2 during calcination.
The innovation behind Pure Oxyfuel is that the CO2 is not simply emitted, but separated, concentrated and made available for further use.
In the conventional clinker burning process, oxygen from the ambient air is used. The oxygen content of air is around 21%. At the same time, the air introduces mainly nitrogen into the process, which means that the CO2 concentration in the exhaust gas is only around 25% to 30%.
Pure Oxyfuel by thyssenkrupp Calvion is a carbon capture technology that supports the decarbonization of the cement industry.
“By supplying pure oxygen in the pure oxyfuel process, nitrogen from the air is eliminated from the clinker burning process. This significantly reduces the gas volume and results in a high concentration of CO2 in the exhaust gas, allowing the carbon dioxide to be captured in an almost completely concentrated form,” explains Jost Lemke. “This also eliminates the need for the complex gas recirculation required in first-generation oxyfuel processes. As a result, the pure oxyfuel process offers lower investment and operating costs,” Lemke adds.
Instead of being released into the atmosphere, the CO2is separated and can either be stored permanently or used as a feedstock. For example, the captured CO2 can be combined with renewably produced hydrogen to manufacture methanol or synthetic fuels. Another advantage is that the process is suitable both for new cement plants and for modernizing existing facilities. In this way, Pure Oxyfuel helps cement producers significantly reduce their CO2 emissions and make their plants future-proof.
From development to industrial application
To further expand the potential of Pure Oxyfuel, the engineers at thyssenkrupp Calvion are continuously developing the technology.
Since the initial idea, we have developed numerous new approaches to make the pure oxyfuel process more efficient and even easier to integrate into the overall cement production system.
Pure Oxyfuel: capturing CO2 where it is generated
Cement clinker production generates CO2 emissions from two sources: fuel combustion and, above all, the calcination of limestone. These process-related emissions cannot be completely avoided, even through the use of renewable energy. Carbon capture technologies therefore play a key role on the path toward more climate-friendly cement production.
With pure oxyfuel, thyssenkrupp Calvion aims to provide the resulting CO2 in the highest possible concentration. Rather than releasing it unused into the atmosphere, the carbon dioxide is regarded as a valuable feedstock. It can, for example, be stored permanently or combined with renewably produced hydrogen to manufacture methanol or synthetic fuels.
A key milestone is the CI4C (Cement Innovation for Climate) research project. Together with the cement manufacturers Buzzi Unicem/Dyckerhoff, Heidelberg Materials, SCHWENK Zement and Vicat, a demonstration plant has been successfully built and commissioned at the Mergelstetten site. The technology is being tested there under real-world conditions and continuously refined. The plant provides valuable insights into the industrial-scale deployment of pure oxyfuel and helps further advance CO2 capture in the cement industry.
An important building block on the path to net zero
Decarbonizing the cement industry requires a combination of different technologies. Pure Oxyfuel is an important building block because it enables highly concentrated CO2 capture directly within the production process, thereby laying the foundation for carbon capture and the utilization or storage of CO2. Together with industry partners, thyssenkrupp Calvion is continuously developing pure oxyfuel and helping drive the cement industry’s transformation toward more climate-friendly production.