Beyond emissions

What are the options available for cement producers to reduce their impact on global warming?

Firstly, it is important to understand where the greenhouse gases associated with cement production come from. The calcination process that takes place during clinker production releases CO₂ from limestone (calcium carbonate). The production of clinker also requires high temperatures and the combustion of fuels to provide energy for the process. So, these are the primary sources of emissions within cement production.

As a first step to find a more efficient and feasible way to fight the global warming impact associated with cement production, players often start out by investigating alternative fuels. By moving from fossil fuels to biomass or waste-derived fuels, the overall fossil carbon footprint of the process can be reduced. Aside from looking into substitute fuels, it also makes sense to consider energy efficiencies that can be made to reduce the energy consumption of the clinker production. This includes optimising kiln operations, improving heat recovery systems, and minimising energy waste. Both options are already available and relatively cheap to implement.

Some players also consider substituting some of the cement with other cementitious materials, such as for example fly ash, slag, or calcined clay, to ensure that the product itself becomes less carbon intensive.

But to truly slash carbon emissions, it gets more CAPEX intensive. The technology itself would need to be changed to use some of the more drastic changes, such as oxyfuel combustion, and / or carbon capture as the very effective mitigation options.

It is widely recognised that there are different types of carbon capture – which are relevant for cement production?

Yes, that is true. The types of carbon capture on the market today can be divided into two groups: the solvent-based carbon capture methodologies and those based on cryogenics. To really strip down the description of these methods, I can describe them like this: the solvent-based carbon capture washes out the CO₂ from the flue gases after cement processing, whereas the cryogenic method freezes out the CO₂ from the flue gases.

Both methods are widely available today and are different in terms of the way they are integrated into the cement plant and their energy profile.

We have prepared a more technical article that examines the different ways the cement industry can reduce emissions, and here you can learn a lot more about the technical differences within the different carbon capture methods.

Why do you believe CCS is the most effective option for cement producers to significantly reduce emissions?

In terms of feasibility and affordability, the most efficient options are investigating alternative fuels and implementing optimisations to the clinker production. But these options do not bring a cement plant all the way on their decarbonisation journey. To make a significant impact, carbon capture is really the ultimate option. As around 60% of cement production CO₂ emissions are unavoidable and cannot be mitigated, it is only carbon capture that can reduce those emissions to almost zero.

Although there are many different technologies available for carbon capture, the ones with the most references and potential today are the solvent-based and cryogenic capture technologies. These are commercially available and can be retrofitted to an existing cement plant. Hopefully, some of the other technologies will see implementation on a large scale in the future.