FLSmidth Opinion - 16/February/2021

Clay cement can cut up to 3% of global CO2 emissions

Replacing limestone with clay in cement production can cut global CO2 emissions by up to 3%. But there is significant investment tied up in the "old" ways of doing things, and it will be necessary to use a range of incentives—as well as technological advancements—to change the status quo, writes Fleming Voetmann, vice president at FLSmidth

The views expressed are those of the author and do not necessarily reflect the position of FORESIGHT Climate & Energy

New processes are essential to reduce emissions from a vital sector

Cement is the world’s second most used resource, surpassed only by water. We cannot do without cement when cities need to be maintained and expanded, when infrastructure needs to be created and when the living conditions of millions of people need to be improved.

Unfortunately, there are staggering CO2 emissions associated with cement production. If the cement industry was a country, it would be the world’s third-largest emitter of CO2 surpassed only by the United States and China. Cement production stands for 7% of total global emissions.

Around 56% of those emissions come from the release of CO2 that is embedded in the limestone, which is the basic substance used in cement. However, replacing limestone with clay, which has no embedded CO2 is both a simple and genius solution. If this technology is adopted by cement producers around the world, we can potentially remove 3% of the world’s CO2 by this exercise alone.

We have been working on the replacement of clinker with clay, or in engineering terms, “clay calcination” and the results are promising. How will this influence the finished product, one may ask? The late strengths and colour of the cement will not be changed significantly, however minor adjustments in the recipe with regards to water requirement and early strength might be needed. This is subject to ongoing research.

Pricing-wise the clay-based cement is actually the cheaper option, as less energy is needed to activate the clay. This is encouraging because if this more sustainable cement can gain in global popularity, it will result in a significant contribution to the fight against climate challenge by cutting down CO2 emissions.


The problem is that the cement industry and the construction industry are traditional and not easy to change. Most changes require significant outlay in machinery and equipment and, even if this is supported by a long-term business case, it takes courage to make this kind of investment in the short term. It is clear, however, that the cement industry can reduce emissions considerably and that the technology and knowhow to create more sustainable cement is available.

Currently, we have just over 70% of the technology needed to fulfil our promise of zero emissions by 2030. We are confident that research and development over the coming years will provide the final 30%. But it will be all for nothing if the new green technology is just left on the shelf and does not reach the end-users—the world’s cement factories. Here, politicians, legislators and regulators must play a part.


It is important to create incentives to promote sustainable development. One way to do this, for instance, would be to create a set of requirements for the CO2 footprint of newly constructed infrastructure projects and buildings.

Additionally, there is an opportunity to influence development through large publicly-funded construction projects. Here, one could stipulate that 30-50 %—or even 100%—of the project is constructed using the most sustainable materials available. That would make a huge difference and give all players in the industry an incentive to invest in lower-carbon solutions.

We will welcome and encourage all debate on the subject and will do what we can to secure that the cement industry will move from a traditionally black industry to a much greener future. We know it is possible from a technological perspective. The rest is up to the players in the cement industry to make it happen through progressive decision making and stronger environmental prioritisation.

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