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CO₂ Capture Opens New Doors for Cement Plants to Mitigate Global Warming

Cement manufacturing plants are among the activities that contribute the most to global warming. Cement manufacturing is responsible for 8% of CO₂ emissions released into the atmosphere, followed by energy production and transportation, according to the International Energy Agency (IEA). However, this is one of the industrial sectors where decarbonisation is most difficult.

Cement manufacturing

Meanwhile, in this context, the first initiatives for the implementation of technologies aimed at capturing this CO₂, so it is no longer released into the atmosphere, are emerging. It seems like science fiction, but it is becoming less so.

The effort to decarbonise (eliminate these CO₂ emissions) will need to be enormous in the cement sector in the coming years. Climate protection policies and the sector’s own commitments set the ambitious goal of achieving net-zero emissions by mid-century.

High CO₂ emissions in these factories occur in two main areas of their production process. On one hand, conventionally, cement manufacturing uses fossil fuels to produce clinker (the base material for cement), which results in high emissions of CO₂ and other gases.

On the other hand, emissions are inherent in the production process when limestone (calcium carbonate) must be decomposed to extract CO₂ and produce clinker.

Emissions in this part of the process account for 60% of the total emitted by cement plants (the rest comes from combustion).

Two Sources of Emissions

One of the major drawbacks of the cement manufacturing process is that the gases from combustion come into contact with the limestone and release CO₂.

Additionally, another negative factor is that the kiln emits many other highly polluting gases (nitrogen oxides, volatile compounds, tyre residues, sulphur, carbon monoxide, dioxins, and furans), which are mixed and very difficult to separate from CO₂.

Thus, emissions from decarbonation and fuel combustion are combined, complicating the removal or separation of CO₂.

Leilac-1 cement plant

CO₂ Capture Arrives

To address the problem, one of the solutions being developed is technologies to capture and neutralise CO₂, preventing its release into the atmosphere.

Leilac is leading the way with a pioneering technology designed for the calcination phase that captures CO₂ emissions as a pure, recoverable stream.

In this process, calciner tubes transmit radiant heat to the limestone without contacting the combustion gases, keeping them separate.

Leilac technology explained

The result is that “the decarbonation process (the extraction of CO₂ from limestone) occurs in a clean environment, so the CO₂ is extracted in a pure form and can be handled later,” explains Luisa Serrano, a chemical and process engineer at Leilac, which promotes these technologies for integration into cement plants.

In a subsequent process, this CO₂ can be captured, stored, used in industry, or buried underground (a task in which Leilac does not directly intervene).

Another advantage of this calciner is that it is designed to use alternative fuels, such as renewable electricity (wind, solar). This specialist adds, “The need to use more fossil energy is avoided in case CO₂ must be separated from other gases after the process is completed.”

Its promoters point out that Leilac technology can be incorporated into a cement plant with minimal downtime, as it can be attached during regular maintenance shutdowns. “The modular design allows for flexible integration and adaptation options.”

Meanwhile, to complete the overall solution to the CO₂ problem, cement plants must continue working towards using other fuel sources (biomass, hydrogen) to reduce gas emissions from their kilns. “We aim to introduce electrification and low-carbon alternative fuels throughout the entire process,” say Leilac spokespersons.

Overcoming the Demonstration Phase

The limestone decarbonisation technology has successfully completed the pilot project phases Leilac I and Leilac II, and technical tests are ongoing at the Lixhe plant in Belgium. The next step will be to build a demonstration facility at the Ennigerloh cement plant in Heidelberg, aimed at validating a module that is replicable and adaptable for compatibility with renewable energy and alternative fuels for plants of any scale. All these projects are financially supported by the EU’s Horizon Europe 2020 programme and an industrial consortium.

At the Ennigerloh plant, we will have a facility capable of handling 40 tons of material per hour,”

says Serrano

Motivations to Act

One factor that could “motivate” cement companies to reduce their CO₂ emissions is the expected progressive increase in the cost of CO₂ emission rights, subject to the market for buying and selling these quotas.

This trend results from climate action policies. Cement plants must acquire emission rights at auction, which are gradually decreasing (allocated by the European Commission with increasingly restrictive criteria to drive decarbonisation); the forecast is that their costs could rise to 150-200 euros per ton. “If you have to add this emission cost to the cost of producing clinker, the processes can become unviable if emission reductions are not addressed,” warns Serrano.

For the Leilac engineer, another great advantage of this solution is that it acts preventively, so if the cement plant decides to install systems to separate the gases at the kiln outlet, the investment is lower because it has already acted in the decarbonisation phase.

Cement consumption decreased by 9% in 2022 in Catalonia, where exports also fell to the point that plants are operating at 60% of their potential.

The sector mainly complains about the competition from cement production in other countries (China or Turkey) where environmental costs are not assumed. Cement plants are subject to the emissions trading system, which means that in a few years, all plants must buy emission rights through auctions.

The Goal of Net-Zero Emissions by Mid-Century

Regarding the emergence of CO₂ capture technologies in cement plants, Salvador Fernández states that “there are several techniques that are not yet fully mature,” but “they are starting to see experiences” that will influence the sector.

Given the push the EU wants to give to these technologies, the president of Ciment Català calls for the central government to set specific support programmes to facilitate their progressive implementation. “The sector’s goal is to achieve a net-zero emissions balance by 2050. And in the period 2030-2050, most CO₂ reductions will come from direct CO₂ captures,” he tells this newspaper.

Leo Bejarano, director of the Catalan Climate Change Office, explains that “the sector is working hard” in the field of CO₂ capture and utilisation technology. “They are researching and innovating a lot, getting ready, there are prototypes, but there are still no large-scale initiatives; the leap needs to be made,” he explains to this newspaper.

“It’s a technology that interests us for eliminating process emissions that cannot be replaced by changing energy sources,” he adds. Bejarano maintains that in these cases “we will need to go to a CO₂ capture and utilisation system,” although “this does not mean storage,” but rather the reuse of this gas for other uses and processes.