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Calix circumvents concrete creation challenge


Redefining how concrete is manufactured, Calix has pioneered a new approach to concrete creation with the Leilac technology to enable businesses to reach net zero targets. Lewis Cross writes.

Contributing roughly eight per cent of carbon emissions worldwide, cement and concrete iare essential for modern living but have historically been damaging to the environment. 

Concrete, cement and other limestone products are formed through the heating of cement meal and other applicable aggregates.

To focus on the reduction of carbon dioxide (CO2) that is inevitably produced from the production of cement, Calix formed Leilac (Low Emissions Intensity Lime and Cement) to spread leading edge carbon capture technology worldwide.

The Leilac technology is being piloted with the world’s largest cement and lime companies, such as Adbri, Boral, Heidelberg Materials and Cemex, to mitigate their CO2 emissions dramatically, without significant use of energy or capital penalty.

Leilac chief executive officer Daniel Rennie explained to Quarry the benefits of the Leilac technology when it comes to carbon capture.

“Leilac was born from environmental technology company, Calix, who established global partnerships across industry, academia and government to develop this unique technology for the decarbonisation of cement and lime,” Rennie said.

The process to create cement requires heat to break apart the limestone and combine the crushed components of cement, which releases unavoidable CO2 emissions as part of the reaction.

Employing a unique carbon capture utilisation and storage (CCUS) approach that involves indirect heating allows Leilac to separate the product that is heated from the source that heats it.

“Our indirect heating approach uses a module of steel tubes to deliver radiative heat to limestone or cement meal,” Rennie said.

“By separating what we heat from how we heat it, the process emissions are largely pure CO2, as they remain uncontaminated by air or heating gases. Therefore, it does not require a conventional, energy intensive process of separating gases from gases. 

The result is a highly efficient, low cost solution, for the separation of process emissions as high purity CO2 ready for compression, transport or storage.

Leilac’s technology replaces part of the existing cement plant, rather than adding an additional process, which ensures that there are no additional chemicals or processes.

The Leilac technology can be retrofitted and integrated to an operational plant with minimal disruption.

There are two distinct types of emissions that are part of cement and lime decarbonisation: the process emissions that are unavoidably created when processing the limestone and cement meal, and the energy emissions that come from heating the limestone and cement meal.

One of the strengths of Leilac’s technology is its ability to be used in multiple settings.

“Leilac’s technology is designed to be energy agnostic and electrification ready,” Rennie said. “We are working on flexible and economical solutions to decarbonise energy consumption in the industry. These solutions will include the use of low-cost alternative fuels, renewable electricity or green hydrogen for carbon neutral cement and lime. 

“Leilac’s technology has the potential for strong synergies with other capture technologies that can capture fuel emissions. The combination has the potential for creating the lowest cost route to carbon negative cement and lime.”

Traditional carbon capture technologies can employ sorbents or other chemical applications to absorb CO2 released from the process of cement creation. 

However, these approaches require additional energy, which call for emitters to account for any carbon emissions that occur from the use of additional energy, as Rennie explained.

In contrast, the CCUS approach from Leilac is a novel approach as it re-engineers an existing process to optimise and draw as much benefit with as little penalty to energy usage as possible.

“Leilac’s approach is different. We simply re-engineer the process flows of a traditional calciner to separate high purity CO2 from limestone, with minimal energy penalty.” 

One of Leilac’s partners currently undertaking engineering studies to install the Leilac technology is Adbri.

A spokesperson from Adbri highlighted the importance of CCUS solutions in a 2022 announcement of the partnership released by Calix.

“As a leading Australian producer of lime aspiring to be net zero by 2050, we recognise it is a difficult manufacturing process to abate,” Adbri said.

“Transformative technology-led partnerships like this one with Calix form a key part of our own pathway to net zero by 2050, reducing our emissions profile while supporting the decarbonisation of our end-market customers.”

The benefits for this style of CCUS technology is appealing, not just from an emissions reduction standpoint, but also from a financial standpoint.

This is particularly the case where policy settings incentivise CO2 abatement, such as in the “EU ETS and CBAM policies, the US Inflation Reduction Act’s changes to Q45, and  the announced changes to the Safeguard Mechanism being discussed in Australia,” as Rennie said.

Calix’s technology is being piloted with the world’s largest cement and lime companies.

Environmental concerns

With the global use of cement being essential to modern society, considerations need to be made on the environmental impact it has worldwide. 

Cement is the key ingredient in concrete and is the second most consumed substance on Earth, after water. It provides the foundations of modern society and economies as it is found in almost all buildings and infrastructure. 

In a similar vein, lime is a key material for many industries, including steel, paper and water.

However, the production of cement comes bundled with a high amount of CO2 emissions, that are unavoidable when processing limestone and contribute to climate change.

Ensuring the production methods for cement are sustainable and low-cost for the future, Rennie said that “Leilac is working urgently with industry to develop and provide solutions”. 

“Both cement and lime are widely available and affordable, thanks to highly optimised production methods. The cement and lime industries provide an essential, low cost, accessible product that forms the foundation of our society,” Rennie said.

“Additionally, the unique properties of cement make it a durable, high-performance material that will likely be essential for sustainable and climate resilient buildings and infrastructure.”

The main identifiable downside to this is the carbon intensity of traditional production methods, specifically the unavoidable release of CO2 when processing limestone. 

“As the global population heads towards 10 billion and becomes increasingly urbanised, it is essential that everyone can continue to benefit from available, low-cost and sustainable cement and lime. We must ensure that the just transition to a net zero economy balances social, economic and environmental sustainability.”

“As noted by the Intergovernmental Panel on Climate Change (IPCC), CCUS plays a major role in decarbonising the industry sector in the context of 1.5°C and 2°C pathways, especially in industries with higher process emissions, such as cement.”

Future-proofing the quarrying and aggregates industry

There is increasing pressure on all fronts for sustainable outcomes from industries, which currently already affects the quarrying and aggregates industry.

If carbon capture technology is not made available and is not robust in its application, these industries may face further difficulties. 

The Global Cement and Concrete Association (GCCA) predicts that even with significant savings from more efficient design and construction, as well as less carbon intensive cement and concrete production, CCUS will still be the dominant source of emissions reduction required for the industry to reach net zero. 

“This is due to the inherently carbon intensive process of cement production,” Rennie said, “where between 60-100 per cent of total CO2 emissions are released unavoidably from the processing of limestone.

“For these emissions, carbon capture, utilisation or storage is essentially the only solution.”

To avoid significant disruptions to the industries that use cement in their applications, industry standard cement such as Portland Cement, which is the backbone of the construction industry needs to be able to be made sustainably to avoid disruptions.

Looking towards containing emissions at the point of creation is paramount. With current global targets and obligations in place, attempting to capture the released emissions would be substantially less efficient.

“Even when we account for all other carbon saving measures, it is estimated that to reach net zero, 1.4 billion tonnes of CO2 will need to be captured from cement each year by 2050,” Rennie said.

“If the industry was to be unsuccessful in its decarbonisation efforts, and we – as a society – want to achieve our climate goals, then that 1.4 billion tonnes of CO2 will need to be captured and stored from the air. This would be a considerably less efficient and more costly option than capturing it at the source from the production plant.”

Recognising the need for these targets and understanding that they are unlikely to change is important for business moving forward, to ensure that they can get ahead of emissions regulation that might otherwise impact their business.


Though CCUS methods are the best way identified to reduce emissions from cement production, thought has been given to utilising low carbon alternatives in the formation of cement and looking at the reabsorption of CO2 in the air by concrete.

Though CO2 is reabsorbed and held by cement and concrete over time, in a process known as recarbonation, the GCCA estimates that “recarbonation will only account for around six per cent of the industry’s emissions by 2050”, according to Rennie.

“The recarbonation of CO2 to cement and concrete, over time, is a useful property of the material,” Rennie said. “Particularly if we can reduce the carbon intensity of its initial production.”

“Supplementary cement materials, including clinker substitutes such as calcined clay, offer potential low carbon alternatives. When used in blends such as LC3 cements, the resulting products can exhibit properties similar to that of Portland Cement.

“We are able – with the same underlying technology – to produce such substitutes cost efficiently, and it is an area that we are actively developing,” Rennie said.

Utilisations of lower carbon alternatives is an attractive solution, but one that is not going to address the larger problem.

“Substitutes, however, are likely to only get us so far on the journey to net zero, with the GCCA anticipating that they will contribute only nine per cent of the emissions reductions required by 2050.”

“Leilac believes that the efficient, low-cost capture of unavoidable emissions from limestone will be essential to enabling sustainable cement and lime in a carbon neutral world.”

Employing CCUS in conjunction with low-carbon cement material alternatives may be the best way for the industry to move forward to a sustainable and reliable future of cement production.

Leilac-1, at the Heidelberg Materials plant in Belgium, is capable of capturing 25,000 tonnes of CO2 per annum.

Scalability of CCUS 

A primary issue that exists within CCUS technology is the requirement for another system to contain the emitted CO2, which typically require emissions to be created, and diminishes the impact on capturing the emitted carbon from the process of cement creation.

The Leilac technology innovates within its field, exploring the possibility of no energy penalty when compared with existing production methods.

 “Efficiency is at the heart of the Leilac technology,” Rennie said. “Our process modification approach has, in theory, no energy penalty compared with existing production methods.

“Even when retrofitted to an operational cement plant, the energy penalty is expected to be minimal. This efficiency is enabling us to develop the potentially lowest cost carbon abatement solution for the industry.”

The energy penalty is a significant factor of the success observed with the Leilac CCUS, as when renewable energy becomes more widely used and accessible for industrial applications, emissions can be then further reduced.

“The minimal energy penalty of the technology also means that, unlike other capture solutions that require significant energy to power additional processes, the technology can simply and economically scale to capture 100 per cent of the process emissions from any plant,” Rennie said.

“Our pilot plant, Leilac-1, located at the Heidelberg Materials plant in Lixhe, Belgium, consists of a single steel tube capable of capturing 25,000 tonnes per annum of CO2, or five per cent of a typical cement plant’s throughput. 

“Leilac-2, our demonstration scale plant, will be retrofitted to Heidelberg Materials’ operational plant in Hanover, Germany. 

With a target CO2 capture capacity of 100,00 tonnes per annum, or 20 per cent of a typical cement plant, Leilac-2 aims to develop a replicable modular array of steel tubes that can then be multiplied to a full-scale, low-cost commercial CO2 abatement solution at any scale – for eventual deployment and construction by local firms using design blueprints.”

“In support of this, engineering is already occurring (with multiple clients across the world) to understand how this design could be applied to capture all the unavoidable process emissions from a variety of different plants.”     

The retrofit capability of the Leilac plants is a major strength of the CCUS, as it enables businesses to capture emissions, without large restructuring needed on behalf of the owners and operators of the plant.

Adoption of CCUS

Active adoption and use of CCUS is important for the industry, because this technology is being designed in conjunction with cement production facilities.

GCCA member companies are responsible for 40 per cent of global cement production and have collectively set a target for net zero emissions by 2050, mirroring global commitments under the Paris Agreement. 

The sooner companies can adopt CCUS solutions, the quicker those emissions targets can be met, for a lower overall cost to business.

“With cement being responsible for around eight per cent of global CO2 emissions,” Rennie said, “every single method, technology and means of reducing our emissions needs to be pursued as quickly and as thoroughly as possible.”

“We believe that Leilac has reimagined carbon capture. Our technology is purpose built for – and in active collaboration with – the cement and lime industries. 

“It is not a legacy technology developed for another industry, but instead uses a first principles approach to develop the most efficient capture solution for unavoidable process emissions.”

The technology Calix developed is technology which has been expressly designed for the carbon capture of emissions from cement production.

Businesses have the chance to develop and aid in lowering emissions in an active way, by taking part and adopting these CCUS options for their operations. 

“Leilac’s flexibility on fuel sources provides pathways to carbon neutral and even carbon negative cement and lime. It aims to future-proof production methods as we transition towards electrification and renewable energy. As such, we are doing everything that we can to work with industrial players, and collaboratively enable an efficient and compelling case for carbon-capture at all sites globally.”

Future outlook

Carbon capture technology – such as CCUS – is an important component of the quarrying and aggregates industry moving forward.

Both as suppliers of limestone and other materials used to create concrete and operations that produce concrete, looking to methods that lower emissions in line with global CO2 reduction goals is essential for the longevity of the industry.

The Leilac technology, developed by Calix, is a solution which is tooled to provide lower emissions as the need to decarbonise intensifies and the future of renewable energy continues to advance.

“The Leilac technology’s optionality on fuel source and its potential for grid load balancing in an increasingly renewably powered energy grid, offers a future proof solution for the industry,” Rennie said.

“As penalties for emitters increase across the world, decarbonising is not only a matter of environmental responsibility for producers: it is a matter of survival. 

“Affordable CO2 abatement solutions will enable producers to take urgent action against climate change and protect their industries’ jobs and prosperity.” 

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