Towards net-zero: Low CO2 cement production

With commitments to net-zero CO₂ cement production being made by producers across the board, Global Cement looks at the current status of low-CO₂ cement blends, novel production technology and CO₂ capture and storage.

While 2020 will forever be remembered for the Covid-19 pandemic, it also continued the 21st Century’s run of warming climate trends. Indeed, 2020 was the hottest year on record not to feature an El Niño climate event, which would likely have boosted temperatures even higher. The mean temperature in 2020 was 13.9°C, around 1.2°C above the 20th Century average of 12.7°C. This was recorded despite a 7% year-on-year fall in CO₂ emissions due to pandemic-related lockdowns, which did not prevent CO₂ concentrations hitting 417ppm in January 2021. Atmospheric CO₂ concentrations are now 50% higher than the pre-industrial 278ppm of the late 1700s and around 20% higher than in the early 1990s (~350ppm).

Build back better

As we emerge from the metaphorical rubble of the pandemic, construction activities, particularly cement and concrete, are increasingly under the spotlight of environmental campaigners, the wider public and national governments. There is good reason: Cement and concrete are responsible for ~7% of overall global CO₂ emissions. This is related to not only the use of fuel-derived CO₂ to heat the raw materials to 1400 - 1500°C, but also to the decarbonisation of calcium carbonate, the essential first step in the formation of clinker.

While the most forward-thinking producers can now point to a 30 year plus record of alternative fuels, clinker substitution, waste heat recovery and other efficiency gains, it is clear that the sector’s ‘traditional levers’ will be insufficient to reduce CO₂ to the low levels required by the UN Paris Climate Agreement. Indeed, in April 2018 a report by the CDP looking at some of the largest multinational cement producers concluded that producers needed to double their emissions’ reductions in order to meet the 2°C global warming target outlined in the Paris Agreement. The report, entitled ‘Building Pressure,’ analysed 13 large cement companies including LafargeHolcim, HeidelbergCement and Cemex.

Beyond traditional levers

As national and international governments ramp up their own CO₂ abatement targets with a view to meeting their obligations under the UN Paris Climate Agreement, cement producers have now set far bolder targets, both separately and jointly under the auspices of the sector’s two new international associations - the Global Cement & Concrete Association (GCCA) and the World Cement Association (WCA). Both of these were established in the late 2010s and each has a strong sustainability ethos.

Indeed, GCCA members, which represent 40% of the industry, have jointly committed to a low-carbon transition and the production of CO₂-neutral concrete by 2050. The association’s 2050 Climate Ambition document was launched in September 2020, with a full Roadmap to be published by the close of 2021. Speaking with Global Cement, the GCCA’s CEO Dinah McLeod said “It represents the first time that the industry has come together to jointly state such a bold and wide-ranging set of sustainability targets.”

The WCA meanwhile, also supports a sustainable cement industry and encourages technical development and other steps to achieve full decarbonisation with the aim of keeping global temperatures to less than 2°C and as close as possible to 1.5°C. It is extremely active through the dissemination of best sustainability practices across its membership network and professional committees, including with those outside of the sector.

Regionally, Cembureau, the European Cement Association, has set out its Roadmap to achieve net-zero CO₂ emissions along the cement and concrete value chain by 2050. Germany’s VDZ has done the same, its CEO Dr Martin Schneider noting that the potential for further gains from traditional sustainability measures is close to its limit, requiring a “Completely new approach to the production of cement and its use in concrete.” In North America, the Portland Cement Association has announced that it too will publish a Roadmap to carbon neutrality by 2050 by the end of 2021. Its Vice President for Sustainability Rick Bohan, said “Developing a roadmap to carbon neutrality by 2050 further demonstrates our industry’s commitment to be a part of the solution and tackle this global issue.”

Spain’s Oficemen recently announced that it would target a 43% emissions drop by 2030 across its entire value chain compared to 1990 levels. Finally, UK Concrete and the Mineral Products Association (MPA) have launched a roadmap for the concrete and cement industry in the UK to become net CO₂ negative by 2050. It plans to do this through decarbonised electricity and transport networks, fuel switching, greater use of low-carbon cements and concretes as well as carbon capture, use or storage (CCUS) technology.

Cement producers’ targets

In 2020 cement producers introduced their boldest ever sustainability targets. Those of the largest firms, plus other notable cases, are outlined below.

China’s cement producers, many of which are ultimately controlled by the state, were committed en masse by President Xi’s commitment to reach a net zero CO₂ economy by 2060 in September 2020. Data from the Centre for International Climate and Environmental Research (CICERO) shows that the Chinese cement industry emitted an estimated 782Mt CO₂ in 2018 compared to 37.1Gt CO₂ from all anthropogenic sources. This means that Chinese cement plants were responsible for a staggering 2% of all CO₂ emissions in that year. If realised, this target would represent one of the larger pieces of the global zero-CO₂ puzzle.

LafargeHolcim signed the Science-Based Targets initiative (SBTi) Business Ambition for 1.5°C pledge in September 2020. This commits it to net-zero CO₂ emissions by 2050. It also committed to a 20% reduction in its CO₂ intensity by 2030 against a 2018 baseline. This interim target, to hit 475kg of CO₂ per tonne of cementitious material, will be partly backed up by a Euro850m sustainability-linked bond with a coupon of 0.5% that matures in 2031. Investors will be entitled to a higher coupon should the company not meet its emissions target.

HeidelbergCement has brought forward its former CO₂ emissions target for 2030 of 525kg of CO₂ per tonne of cement to 2025 as part of its Beyond 2020 programme. If achieved, this would represent a 30% decrease from 752kg of CO₂ per tonne in 1990. Its new goal for 2030 is ‘below 500kg’. Its targets to 2030 have been successfully assessed against the Science Based Targets initiative’s (SBTi) criteria.

HeidelbergCement has also strengthened its climate neutrality commitments by joining the Stiftung 2° support group, a network of private companies lobbying for climate goals. The group says that it wants to ‘Develop cross-sector approaches and concepts for Germany and Europe in order to make climate protection a sustainable and successful business model.’

Cemex announced that Carbon Trust had validated its roadmap to decarbonise global operations in line with the Sectoral Decarbonisation Approach 2°C scenario developed by the International Energy Agency (IEA), in October 2020. It also aims to reduce its net CO₂ emissions by 30% by 2030.

Dalmia Cement commited to below zero CO₂ emissions by 2040 in 2019. In 2020 it joined five leading companies of other sectors in signing the Near-Zero pledge, an industry charter targeting near-zero CO₂ emissions by 2050.

Sumitomo Osaka Cement has formulated a set of medium-term goals and long-term policies in order to enable it to achieve carbon neutrality by 2050, in line with the Japanese government’s target. These include a 30% reduction in energy-derived CO₂ emissions intensity between 2005 and 2030 and efforts toward carbon neutrality in energy and process-derived emissions by 2050.

Cementir Holding has set a CO₂ emissions reduction target less than 500kg per of CO₂ per tonne of cement by 2030.

Buzzi Unicem aims to reach a target of 662kg of CO₂ per tonne of cement in 2022.

Taiheiyo Cement will reduce specific CO₂ emissions by 80% between 2000 and 2050.

Vicem, the largest cement producer in Vietnam, and Danish cement sector supplier FLSmidth have announced a cooperation agreement with the aim of radically reducing the greenhouse gas emissions from Vicem’s activities, including an aim to use 100% alternative fuels.

Grupo Cementos de Chihuahua (GCC) has committed to setting scientifically-verified greenhouse gas reduction targets by joining the SBTi.

How can we do this?

The commitments above will be met using a combination of approaches. These include, but are not limited to, the increased use of biomass alternative fuels, waste heat recovery, process efficiency gains, automation, lower clinker cements, renewable power generation, novel fuels / heating systems, recarbonisation of concrete and CCUS. Many of the above have been covered previously, so this article will focus on four main areas:

1. Ultra-low CO₂ mixtures;

2. Renewable power, including storage;

3. Novel fuels and heating technologies;

4. CO₂ capture and utilisation / storage.

The content relates predominantly to the production of binder systems based on calcium carbonate. Note that the limited space available means that it will not be possible to include all examples and case-studies.

Ultra-low CO₂ cement blends

The inclusion of supplementary cementitious materials, clinker extenders and other additives to substitute for a portion of the clinker in a cement blend is an extremely well established practice. However, many traditional blends remain far from the 60% clinker factor required by the Cement Sustainability Initiative’s (CSI) 2DS. This has led to the development of ultra-low CO₂ cement blends, including ternary blends and those that do away with clinker altogether.

Low-CO₂ producers

Several companies have been established specifically as low-CO₂ cement producers:

Ecocem’s products are based on ground granulated blast furnace slag (GGBS), with the Irish firm claiming specific CO₂ emissions as low as 12kg/t for its non-clinker containing ‘Ecocem’ product. It also produces CEM III / A, which contains >50% GGBS, and Ecocem Superfine, an additive with a specific area of 7000-8000cm2/g. The company makes these in Ireland, France and the Netherlands.

Hofman Green Cement, based in France, makes a range of low-CO₂ from a variety of materials. H-P2A is a geopolymer binder made by mixing flash-calcined clay and silicates that are combined with Hofmann’s proprietary activators. H-EVA is an alkali-activated ettringite technology that combines flash-calcined clay, byproduct gypsum and Hofmann’s activators. H-UKR is a GGBS-based blend, which Hofmann claims has a CO₂ footprint 80% lower than traditional concrete.

The company is in the process of building a new 0.25Mt/yr plant at the site of its existing Bornezeau 50,000t/yr plant in France’s Vendée region and a second 0.25Mt/yr plant in the region surrounding Paris, which will come online in 2024.

DB Group markets CemFree, an ultra-low CO₂ cement alternative that reduces emissions by up to 80% compared to conventional mix, in the UK. CemFree is a proprietary alkali-activated cementitious material that activates pozzolanic materials such as ground granulated GGBS and pulverised fly ash. The company launched Wolfenden Concrete, which has CO₂ emissions 62% lower than traditional concrete, with its partner Wolfenden Concrete in February 2021.

Celitement, now 100%-owned by Schwenk Zement, makes its eponymous product by heating calcium carbonate and silica-bearing minerals in a steam-saturated autoclave at a relatively cool 150-300°C. This produces a stable C-S-H rich ‘raw meal’ that can be activated by grinding. Celitement’s lower CO₂ footprint is achieved predominantly through its lower process temperature.

BIGBOSS Cement, based in the Philippines, uses volcanic lahar material as a raw material, enabling it to produce cementitious binders that have a CO₂ footprint around 50% of that of OPC.

Concrene is a UK-based nanotechnology firm that has developed the use of graphene (thin sheets of carbon atoms) in concrete products. The properties of graphene lead to a faster cure, 15 - 20% higher flexural and compressive strength, reduced cracking and very high hydrophobicity. The lower CO₂ emissions of Concrene are derived from using less clinker to achieve the same strength.

Marta Abreu University in Cuba began the production of LC3 cement consisting of clinker, calcined clay, limestone and gypsum at a 1460t/yr pilot cement plant in Las Villas in October 2020.

Low-CO₂ products

Many established cement producers have now brought low- or net-zero-CO₂ cement and / or concrete products to market:

LafargeHolcim has introduced its EcoLabel to highlight products with at least 30% lower than average CO₂ emissions or more than 20% recycled content. It has also launched of ECOPact green concrete products in Canada, Colombia, Ecuador, France, Gemany, Mexico, Switzerland, the UK and the US. These allow CO₂ emissions reductions of 30-100% compared to using CEM I. For the range 70 - 100% the company uses offsetting schemes to compensate for the necessary CO₂ released during clinker production. The company has also launched its Susteno cement product in Europe, which it claims is the only cement product that contains fine mixed granulate from demolished buildings as an additive.

Cementir Holding has developed its FutureCemTM technology, which uses clinker, calcined clay and limestone. This allows it to remove more than 40% of clinker from the blend and reduce CO₂ emissions by 30%. It has been used at full-scale in infrastructure projects in Europe.

Cemex is currently rolling out its net-zero CO₂ Vertua® concrete product worldwide following its release in Europe. The product, which has already found use in infrastructure projects in Europe, uses a geopolymer binder solution created by Cemex’s Research and Development Center in Switzerland. This solution has a reduced CO₂ footprint of up to 70%. The compensation of the remaining CO₂ is achieved by participating in reforestation projects, among other initiatives.

HeidelbergCement has developed i.tech 3D, a low-CO₂ concrete blend developed specifically for the 3D printing of buildings. This is currently being used to construct Europe’s largest ever 3D printed structure in Bavaria, Germany. Its Hanson subsidiary markets GGBS-based binders in the UK under its Regen brand. In February 2021 its Lehigh Hanson subsidiary launched EcoCem Plus, which is made at its Edmonton cement plant in Alberta, Canada. The product is a blended Portland Limestone Cement (PLC) that comprises clinker, fly ash, limestone and gypsum, with CO₂ emissions 22% lower than for standard cement.

Cementos Argos announced the completion of work on a new 0.45Mt/yr calcined clay production line at its Rio Claro plant in Colombia in February 2020. it will enable Cementos Argos to produce ternary cement blends with CO₂ emissions 38% lower than for OPC. Energy consumption is also cut by 30%, which provides secondary benefits in terms of reduced off-site CO₂ emissions.

Cimpor Global Holdings is in the process of building a clay calcination plant at its new integrated Kribi cement plant in the Port of Kribi in South Cameroon. The system, supplied by thyssenkrupp Industrial Solutions, will calcine clay at 800°C. This is then substituted for a third of the clinker in CEM I, lowering the finished cement’s clinker factor by up to 40%.

OYAK Group, the Turkish owner of Cimpor, announced in early 2020 that it planned to invest in pozzolan extraction in Cape Verde, where Cimpor has grinding plant assets.

Using SCMs more effectively

Reducing the amount of clinker in cement and concrete mixtures represents a low-cost and relatively low-research option to lower overall CO₂ emissions, compared to other technologies. In his October 2020 article in Global Cement Magazine, cement consultant John Kline highlighted that, in addition to securing SCM supplies to use in low-CO₂ products, producers should pay careful attention to the availability of the active calcium silicate hydrate component of the cement blend. Both the calcium oxide and silica need to be in a reactive form. All components, aggregates, sand, SCMs and cement must have carefully-controlled particle size distributions to fully allow reactions to take place and avoid the wastage of active ingredients. This effect can be seen with relation to the surprisingly high strength, and hence potential CO₂ savings, of ternary blends that contain clinker, limstone and calcined clay. When particle sizes are not already optimised, Kline suggests that lower CO₂ emissions can be achieved through separate grinding of clinker and individual SCMs.

Renewable energy

Due to the high demand for thermal energy and the nature of the clinker production process, electrical emissions from cement plants can often be sidelined. However, the CO₂ emissions associated with power generation still account for around 10-15% of the overall total. Minimising this is thus essential for producers seeking net-zero CO₂ emissions.

In many markets, electricity from wind and solar power is now cheaper than that made using fossil fuels, nuclear energy and geothermal plants in terms of cost per MWh. In recent years this has tipped the balance in favour of investment for numerous cement plants seeking quick and low-capex CO₂ reduction. Solar panels or turbines can be installed in former quarry areas, on roofs or in other parts of the plant. Alternatively, producers can agree renewable energy supply agreements with utility suppliers. Projects and contracts dating from January 2020 to February 2021 are shown in Table 1.

Table 1: Summary of solar (top) and wind power (bottom) projects / contracts announced by cement producers from January 2020 to February 2021. Source: Global Cement website news.

LH = LafargeHolcim.
HC = HeidelbergCement.
GCC = Grupo Cementos Chihuahua.
U/C = Under construction.
Cont. = Contract.

* = Floating.
** = Total size of supplier’s solar farm.
*** = Split between wind and solar installations.

Storage solutions

Despite their advantages in cost and sustainability, wind- and solar-generated electricity supplies are considerably less predictable than conventional sources. This leads to mismatches between demand and supply at the plant, forcing it to buy and sell power at different times.

This is a practical solution but one that will become increasingly unsatisfactory as the proportion of renewable energy increases. To provide more independence while ensuring that the CO₂ benefits of renewable energy stay with the cement plant, there has been significant research in the field of intermediate energy storage, especially over multi-day timeframes. Potential solutions include:

• Batteries of various sizes and chemistries;
• Gravity storage: A heavy object is lifted using electrical power and later undergoes a controlled descent, regenerating electricity;
• Thermal batteries: Heat is transferred to high-capacity concrete blocks, ceramic blocks, pebbles or aluminium ingots;
• Kinetic storage, including flywheels.
• Electrolysis of water using renewable electricity to produce hydrogen and oxygen. These are stored and later combusted to provide heat.

While they are broadly hypothetical at the moment, the combination of such storage systems connected to industrial users and captive power generation facilities, the system as a whole is known as a microgrid. These can either be independent from or linked to the wider power network. In the cement sector they remain a concept, with storage the final piece of the puzzle. In the period to 2050, such systems could become widespread, expanding to provide power for electric site vehicles and quarry machinery, as well as delivery fleets.

Novel fuels and heating methods

The environmental benefits of using materials that would otherwise go to waste as cement plant fuels include the avoidance of landfill, lower production costs and, for biomass-derived fuels such as paper/card, waste wood and agricultural byproducts, lower CO₂ emissions. These advantages have led alternative fuels to take hold in many European countries. They are also used to a lesser extent in North and South America and are gaining a foothold in most parts of Asia, the Middle East and Africa.

However, the proportion of fossil fuels used by the 21% of cement producers that submitted data to the GCCA’s Getting the Numbers Right (GNR) database in 2018 remained stubbornly high at 81.5%. Between them, petcoke and coal contributed 69.4% of the thermal energy used. Alternative fossil-based materials, for example waste plastics and oils, accounted for 12.1%, with biomass fuels contributing just 6.4% of the necessary thermal energy. There clearly remains a lot to be achieved using this particular traditional lever.

Very alternative fuels

The atmosphere doesn’t care if a cement plant burns oil straight from the ground or oil that was converted into a plastic bottle first, so even when a plant does reach an alternative fuel substitution rate of 100%, it may still have a lot of work to do to lower its CO₂ emissions. Therefore, several approaches are being developed to optimise the combustion process or replace it with another process, while retaining clinker as the product. Some aim to eliminate fuel-based CO₂ emissions entirely, while others clean up the gas flow to enable cheaper and easier CCS. Prominent examples include:

With fuels

Catch4Climate is a project comprising four cement producers: Buzzi Unicem subsidiary Dyckerhoff, HeidelbergCement, Schwenk Zement and Vicat. The consortium intends to build and operate its own oxyfuel demonstration plant on a semi-industrial scale. Oxyfuel combustion uses an enhanced O2 atmosphere, rather than ambient air, to increase combustion efficiency and simplify CO₂ capture. In the future, the captured CO₂ will be used to produce so-called ‘reFuels’, climate-neutral synthetic fuels such as kerosene for air traffic, with the help of renewable electrical energy. The project is now planning a pilot plant at Schwenk Zement’s Mergelstetten cement plant.

The European Cement Research Academy (ECRA) has selected HeidelbergCement’s Colleferro plant in Italy and LafargeHolcim’s Retznei plant in Austria as demonstration plants for two oxyfuel combustion projects. The costs of the test phase will be around Euro80m.

Hanson Cement’s Ribblesdale plant in North Yorkshire, UK is the subject of a study in the use of biomass and hydrogen fuels coordinated by the Mineral Products Association (MPA), with the aim of achieving 100% fossil-fuel-free operation. The Euro7m project, due to be completed by the end of March 2021, is being funded by the UK Department for Business, Energy and Industrial Strategy (BEIS) and has been awarded through the MPA. It follows a BEIS-funded feasibility study in 2019, which found that a combination of 70% biomass, 20% hydrogen and 10% plasma energy could be used to eliminate fossil fuel CO₂ emissions from cement manufacturing entirely.

AC2OCem, a project coordinated by the University of Stuttgart, will conduct pilot-scale experiments and analytical studies to advance key components of oxyfuel cement plants with the aim of reducing the time to market of the oxyfuel technology in the cement sector. Its current funding period runs from November 2019 to the autumn of 2022.

The Westküste100 green hydrogen project intends to produce green hydrogen, transport it in the gas network, use it in industrial processes and to interlink different material cycles within the existing infrastructure in Germany. The consortium brings together 10 partners: Holcim Deutschland, EDF Deutschland, OGE, Ørsted Deutschland, Raffinerie Heide, Heide’s municipal utility, Thüga and ThyssenKrupp Industrial Solutions, along with the Region Heide development agency and the Westküste University of Applied Sciences.

“An electrolysis plant with a capacity of 700MW. This is our vision and the next milestone in implementing the development targets laid down in the national hydrogen strategy by 2030,” said Jürgen Wollschläger, managing director of Raffinerie Heide and coordinator of the Westküste100 project.

Without fuels

Cemex announced the signing of a collaboration agreement with Switzerland-based alternative fuel specialist Synhelion in October 2020. The pair aims to develop the use of solar power as an alternative heat source to fuel in clinker production. In Synhelion’s process, a classic solar tower configuration focuses radiation on a single point from a large number of reflectors, where it heats a mixture of CO₂ and H2O gases trapped in a chamber, heating the mixture to 1550°C. In the project with Cemex, this hot gas mixture will be fed to the calciner, where it will heat the raw meal in the same way as a flame, just in the absence of any fuel. Pilot testing of Synhelion’s technology at an as-yet unannounced Cemex plant is slated for late 2022.

Heliogen, based in California, US, has developed concentrated solar-thermal plants (CSPs) with the ability to focus sunlight to generate temperatures over 1000°C by micro-adjusting mirrors using computer technology. It has now engaged Parsons Corporation to build arrays of its CSPs for installation in cement pre-calciners. Requiring temperatures of 900°C, these represent the largest part of the industry’s CO₂ output.
Heliogen CEO Bill Gross says that the installations will make CCS of the remaining CO₂ emissions from the conversion of limestone to lime easier by removing other pollutants. Heliogen is now targeting 1500°C from its CSPs, which would enable them to supersede cement fuels in kilns.

Cementa, HeidelbergCement Swedish subsidiary, and utility provider Vattenfall reported on the pilot stage results of their CemZero project in February 2019. These showed that the technical prerequisites exist for electrified cement production via the generation of high-temperature plasma. The study gives the green light to investigating how a pilot plant can be built.

CO₂ capture and utilisation / storage

All of the roadmaps discussed in the introduction make no secret of the fact that ‘novel technologies’ will be required to achieve a net-zero CO₂ cement sector. While some have been discussed in previous sections, the bulk of this task is likely to fall on CO₂ capture and utilisation / storage (CCU/S). Such technology is currently very expensive, but competition and scale-up should change with time, although incentives (see below) will remain important for some time to come.

CO₂ capture and utilisation (CCU)

CCU is where captured CO₂ emissions are used to form products that can be used by the cement plant or sold to another user. Examples include:

Buzzi Unicem’s Vernasca cement plant saw the inauguration of the pilot plant for the Cleanker project in October 2020. The plant uses calcium looping technology that captures CO₂ using raw meal as a sorbent.

Carmeuse has signed a joint development agreement with France-based energy transition specialist ENGIE and John Cockerill for a CCU project in Belgium. It will concentrate CO₂ from a novel lime kiln and combine it with renewably-generated hydrogen to produce ‘e-methane,’ which can be used by industrial users or as a transport fuel. Construction is due to begin in 2022, with commissioning to follow in 2025.

CarbonCure is a prominent Canadian company that sells technology to inject recycled CO₂ into fresh concrete, permanently mineralising it while adding strength. It sources some of its CO₂ ­from the Cementos Argos Roberta plant in Georgia, US.

Carbicrete, based in Canada, directly injects CO₂ into a wet GGBS-based concrete mixture, a process called carbonation activation. CO₂ is permanently sequestered.

Cemex is involved in a working group looking to implement FastCarb aggregates into concrete production. Administrated by the US-based International Research and Exchanges Board, FastCarb is developing a process to make aggregates from recycled concrete containing waste CO₂.

Vicat started using a CO₂ntainer system supplied by UK-based Carbon8 Systems at its Montalieu-Vercieu cement plant in November 2020. It uses captured CO₂ from the unit’s flue gas emissions to carbonate cement-plant dust, producing aggregates.

Solidia is a patented cement and concrete technology that uses two core principles: a reduction in reaction temperature and the use of CO₂ to cure the concrete.

Mitsubishi Group is researching the injection of CO₂ into concrete in a project alongside Kajima Corporation and Chugoku Electric Power. They aim to develop an existing approach towards the production of cast-in-place concrete sections.

Sumitomo Osaka Cement is working on CO₂ mineralisation research project with Yamaguchi University, Kyushu University and the New Energy and Industrial Technology Development Organisation. The partners are developing a process that captures CO₂ exhaust from cement and power plants and then mineralises it with calcium-containing waste materials, with the aim of commercial use by 2030.

Cemex is working with Canada-based Carbon Upcycling Technologies to improve the cementitious properties of residues such as fly ash and steel slag by physically processing them into more active nanomaterials using captured CO₂.

Lafarge Zementwerke, OMV, Verbund and Borealis have signed a memorandum of understanding for the joint planning and construction of a full-scale plant to capture CO₂ and process it into synthetic fuels, plastics or other chemicals by 2030. As part of the ‘Carbon2ProductAustria’ (C2PAT) project, the companies intend to build the unit at the integrated Mannersdorf cement plant and capture all of the 0.7Mt/yr of CO₂ emitted. The project aims to use hydrogen produced by Verbund to allow OMV to transform the captured CO₂ into a range of olefins, fuels and plastics.

Schwenk Zement announced plans for the production of sustainable aviation fuel from the waste CO₂ from its Allmendingen plant in Baden-Württemberg in 2020.

Dalmia Cement will install large-scale CCU at its Ariyalur plant in Tamil Nadu, India in 2022 at the latest. An agreement was signed with UK-based Carbon Clean Solutions Limited to use its technology for a 0.5Mt/yr facility in 2019. The partnership has explored how CO₂ from the plant can be used, including direct sales to other industries and using the CO₂ as a precursor in manufacturing chemicals.

CO₂ capture and storage (CCS)

CCS is where large volumes of CO₂ are permanently stored underground. Examples include:

HeidelbergCement’s Brevik plant in Norway is home to arguably the best-known CCS project in the cement sector. Now 10 years in development, the 1.2Mt/yr plant will be fitted with Aker Solutions’ amine-based CCS technology to sequester ~0.4Mt/yr of CO₂ under the sea as part of the Norwegian government’s Longship demonstration project and the Northern Lights project for permanent storage. It is expected to be in operation by 2024.

LafargeHolcim and CO₂ capture technology firm Svante are developing a full-scale CCS solution at the Holcim Portland plant in Florence, Colorado, US as part of the CO₂MENT project. Svante has developed an extremely high surface area metal-organic framework (MOF), which traps CO₂ directly from industrial exhaust streams. It is expected that the project will be commissioned in 2024-2025. The partners are also developing the technology at the Lafarge Canada plant in Richmond, British Columbia, Canada.

HeidelbergCement’s Lixhe plant in Belgium has been a key part of the Low Emissions Intensity Lime And Cement (LEILAC) consortium as a test-bed for Calix’s Direct Separation Reactor (DSR) since 2018. The DSR separates fuel and process gas streams during the cement production process. This simplifies the process of condensing and storing the process CO₂. Following strong results from Lixhe, a second demonstration plant, LEILAC 2, will be installed at HeidelbergCement’s Hanover plant in Germany.This will capture 20% of the cement plant’s capacity, corresponding to around 100,000t/yr of CO₂. Including design, construction, commissioning and extensive testing, the overall project is expected to be completed by 2025. Cemex is also a participant in the consortium.

Lehigh Cement (HeidelbergCement) and the International CCS Knowledge Centre are conducting a CCS feasibility study at its Edmonton, Alberta cement plant to find out whether capturing 90-95% of the plant’s CO₂ is viable. Completion of the study is scheduled for the autumn of 2021.

Cemex subsidiary Cemex Ventures is working with US-based CCS specialist Carbon Clean toward the development of a CCS solution for under US$30 per tonne of CO₂ captured. Cemex is also working with Membrane Technology & Research’s membrane CCS product at its Balcones plant in Texas, US.

Oficemen, the Spanish cement association has announced that it is working with the Spanish Technological Platform for CO₂ (PTECO₂) to identify potential locations for storing CO₂ captured from cement plants.

C-Capture, from the UK, has developed a non-amine solvent for use in CCS. The mechanism by which it absorbs and releases CO₂ means it breaks down less easily than amines. C-Capture’s says that its technology uses 40% less energy than other available technologies.

Concluding remarks

The development of a net-zero CO₂ cement and concrete sector is a daunting task, one that will continue to fill issues of this publication for decades to come. The many products, projects, case-studies and opportunities discussed above highlight the vast array of innovative solutions that the cement sector and its partners are bringing to the fight against climate change... ...and they are just the start.

No single country, company or technology will provide ‘the answer,’ alone. In their quest towards net-zero-CO₂, companies must coordinate their efforts and draw on each others’ experience, a strategy that goes against decades of traditional business practice. In this regard the sector’s associations - GCCA, WCA, Cembureau, PCA and others - will play an increasingly important role in coordinating collaboration on sustainability issues, while keeping their members free to compete in the business of selling cement.

International associations also have an important role to communicate the cement sector’s needs to policy makers, and coordinate sustainability efforts with those outside of the sector. As the examples above show, assistance from waste processors, iron and steel manufacturers, gas handling experts, renewable energy, battery manufacturers and besides will inform and shape the cement industry of the future.