Beyond emissions

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.

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.