Oxyfuel: a climate-neutral cement production is getting closer

innovation | Sustainability and climate protection | #greenminded is when you capture and process greenhouse gases where they come from. This sustainable idea is particularly important in cement production: seven percent of global CO2 emissions are caused by the constantly growing industry alone. The good news is that thyssenkrupp's Oxyfuel allows the harmful greenhouse gas CO2 to be separated in concentrated form and made usable. Currently, thyssenkrupp is further developing the innovation in groundbreaking research projects. Social and political developments in 2019 also point even more clearly in the direction of tackling climate change.

In recent years, the cement industry has done a great deal to reduce its pollutant emissions. Nevertheless, large quantities of CO2 are still emitted during cement production. 60 percent of this is produced in the intermediate calcination step alone, when limestone is deacidified – in other words, CO2 is separated from the calcium carbonate and processed into cement clinker. This is an unavoidable consequence, as the gas exits directly from the limestone and does not result from the fuel burned.

At World Environment Day 2018, thyssenkrupp showed a way to minimize and theoretically completely eliminate precisely this CO2 emission with the Oxyfuel process – by capturing it in highly concentrated form before it reaches the atmosphere. The collected CO2 can then be used as a raw material for the production of chemical products. Especially in times of “Fridays for Future”, unmistakable messages from science and the increasingly environmentally conscious society, the Oxyfuel technology can thus make an important contribution to meeting Paris’ climate targets.

Oxyfuel: More relevant and efficient than ever before

What has happened in the project one year later, on World Environment Day 2019? In a nutshell: a lot! This is not stated by just anyone, but by someone who needs to know – Jost Lemke, process engineer at the thyssenkrupp Research Center for Cement Technology. “The interest of industry and politics in CO2 capture in cement production has once again grown significantly in recent months,” says Jost Lemke. “With our latest generation of the Oxyfuel process, we are in a position to significantly reduce the resource and energy requirements for CO2 capture compared with the concepts discussed so far.”

Patent pending, ready for first field trials

An important step in this direction was the invention and patent application for the process, now called “polysius® pure oxyfuel”. In addition, the team is currently planning to participate in numerous advanced research projects, both nationally and internationally. Jost Lemke highlights the “West Coast 100” project. The central topic of the real laboratory for the successful energy system transformation on the North German coast of Schleswig-Holstein is to jointly research technologies for the production of green hydrogen and decarbonization on an industrial scale.

Process engineer Jost Lemke is delighted that the topic of climate protection is becoming more and more relevant for many people. This is one of the reasons why the Oxyfuel project continues to progress.

Process engineer Jost Lemke is delighted that the topic of climate protection is becoming more and more relevant for many people. This is one of the reasons why the Oxyfuel project continues to progress.

Step by step towards CO2 reduction – with an eye on the industrial demonstration project

One thing is clear: Jost Lemke and his colleagues will continue to work tirelessly to bring their technology to market maturity. “We will continue to develop our CO2 capture processes, and we have a lot planned for next year.” That is why a project roadmap for an industrial demonstration project would be another milestone for the expert – but it is not yet possible to say whether this will actually happen. “Things are in motion. At the moment, a lot depends on how the political conditions for the economic implementation of CO2 capture develop. In my opinion, however, the issue of climate protection is finally on the right path to achieving the necessary significance.”

At a glance: How the Oxyfuel process works

“Oxyfuel” is composed of “Oxy” for oxygen and “fuel” for fuel. And this is exactly what the core of the innovative technology is all about: in the process, the clinker production combustion process is not operated with ambient air as usual, but with pure oxygen. As a result, hardly any nitrogen enters the combustion process – highly concentrated CO2 is produced. The gas is finally separated and not released into the atmosphere. Thanks to its purity and other technologies, the greenhouse gas can then be converted into a raw material, thus forming the basis for the production of, for example, fuels, plastics and fertilizers. Another plus: Oxyfuel can be retrofitted into existing cement plants – an argument not to be underestimated, since cement plants are usually designed for a service life of 30 to 50 years.

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