Cement

Reducing CO₂ emissions while producing enough cement to meet demand will be challenging. Demand growth is expected to resume as the slowdown in Chinese activity is offset by expansion in other markets. Moreover, the emissions intensity of production has increased since 2015, largely due to a higher global clinker-to-cement ratio – although the rate of increase has been slowing more recently.  

Key strategies to cut carbon emissions in cement production include improving energy efficiency, switching to lower-carbon fuels, promoting material efficiency (to reduce the clinker-to-cement ratio and total demand), and advancing innovative near zero emission production routes. The latter two contribute the most to direct emission reductions in the Net Zero Scenario. Aligning with that scenario will require the development and deployment of technology that is not currently available. As that may take time, appropriate investment over the next decade will be critical to getting cement emissions on track with the Net Zero Scenario.  

Globally, the thermal energy and electricity intensities of cement production have gradually declined over the past decades as dry-process kilns – including staged preheaters and precalciners (considered state-of-the-art technology) – replace wet-process kilns, and as more efficient grinding equipment is deployed. The global thermal energy intensity of clinker is estimated to have remained relatively flat over the past five years, at 3.4-3.5 GJ/t.  

In the Net Zero Scenario the thermal energy intensity of clinker production declines by slightly less than 1% per year to a global average of around 3.3 GJ/t, and the electricity intensity of cement production as a whole fall to less than 95 kWh/t (relative to about 105 kWh/t today), excluding additional energy required for emission reduction technologies such as carbon capture and storage (CCS). 

Fossil fuels continue to provide the majority of energy in the cement sector, with bioenergy and biomass-based wastes accounting for only about 4% of thermal energy used in 2021. The share of bioenergy and renewable waste grows considerably to 14% in 2030 in the Net Zero Scenario. Meanwhile, the share of fossil-based waste (such as plastics, waste oil and fossil-based industrial wastes) remains at about 5% of fuel use, roughly where it was in 2021. 

Approximately 4 300 Mt cement was produced in 2021, as the industry recovers from a small slump in 2020. China was the largest contributor to global production, accounting for about 55% of the total, followed by India at 8%. 

Production is likely to decline in China in the long term, but increases are anticipated in India, other developing Asian countries and Africa as these regions develop their infrastructure. These increases are projected to more than offset the decline in China, resulting in growth in global cement production to 2030 under a baseline trajectory.  

This diverges from the Net Zero Scenario, in which global cement production stays relatively flat to 2030 owing to more efficient material use and alternative building materials. Actions to reduce cement demand include optimising the use of cement in concrete mixes, using concrete more efficiently, minimising waste in construction, and maximising the design life of buildings and infrastructure.  

Clinker is the main ingredient in cement, and the amount used is directly proportional to the CO₂ emissions generated in cement manufacturing, due to both the combustion of fuels and the decomposition of limestone in the clinker production process. From 2015 to 2020, the global clinker-to-cement ratio is estimated to have increased at an average of 1.6% per year, reaching an estimated 0.72 in 2020; this rise was the main reason for the increase in direct CO₂ intensity of cement production over the period. 

Conversely, the clinker-to-cement ratio falls 1.0% per year to a global average of 0.65 by 2030 in the Net Zero Scenario, owing to greater use of blended cements and clinker substitutes. In the long run, clinker replacements made from widely available materials – such as calcinated clay in combination with limestone – will become more important, as decarbonisation of other sectors reduces the availability of industrial by-products currently used as alternatives, such as fly ash from coal power plants and ground granulated blast furnace slag from the steel sector.  

The other technology that sees wide deployment in the Net Zero Scenario is CCS. Capturing around 0.1 Mt of cement emissions today, CCS deployment needs to increase drastically over the decade, capturing almost 180 Mt in 2030.  

Technological innovation is needed to reduce cement process emissions. CCS is likely to play a critical role in decarbonising cement, as it would enable the capture of process emissions. Alternatives might involve making clinkers from non-carbonate sources to avoid these emissions altogether. Developments from the past year include the following: 

• The LEILAC-2 project, which aims to use direct-separation CCS technology at a cement manufacturer in Hanover, has been awarded EUR 16 million funding by the EU Horizon programme, and is currently on track to become operational in 2023. Other CCS projects continue to progress, including Norcem Brevik – using chemical absorption – which aims to be operational by 2024. 
• Progress has been made using electric kilns for clinker production, with 2022 seeing deployment of the first large prototype from VTT Decarbonate.  
• Brimstone – a US-based start-up – has announced the development of a new cement-making process sourcing lime from calcium silicate rocks instead of limestone, which would avoid the generation of process emissions in the calcination process and produce a magnesium-based waste product that can even absorb emissions from fuel combustion. The company reports that the process would be cheaper than traditional production techniques and chemically identical to ordinary Portland cement clinker. The process is in the relatively early stages of development – about 1 kg has been produced in the laboratory – but in 2022 they announced plans to build a first-of-a-kind demonstration plant in the United States. 

To get on track with the Net Zero Scenario, near zero emission cement production technologies should be commercialised before 2030. In the current energy context, it is more important than ever to advance innovation towards reducing energy use in near zero emission technologies, such as minimising the energy needs for capturing CO₂. 

As CSS is likely to play a major role in reducing emissions from cement production, governments must make plans for the construction of infrastructure to transport and store captured CO₂, as a lack of supporting infrastructure could significantly delay technological deployment and effectiveness. Pipelines are already the most common way to transport CO₂, and this is likely to continue. An important early step for governments will be gaining public support for building these pipelines, as well as CO₂ storage facilities, to ensure that later deployment can proceed without delay. As fossil fuel use is projected to decline in the Net Zero Scenario, governments with significant oil and gas infrastructure may also want to study the feasibility of repurposing pipelines for the transport of CO₂.  

Many states have introduced policies addressing industrial emissions as a whole, discussed at further length on the IEA's tracking page for industry. Important developments for cement include the following:  

Cement emissions are being addressed by pricing schemes in a number of jurisdictions, including the European Union (along with the European Free Trade Association), Canada and Korea. Most recently China – responsible for producing well over half of the world’s cement in 2020 – has announced it will be putting a price on cement emissions, possibly as soon as 2023. 

The European Union is in the process of developing a carbon border adjustment mechanism for industries, including cement, which would apply tariffs on emissions-intensive goods from foreign jurisdictions with weak or absent emissions policy in an effort to limit carbon leakage and incentivise stronger emissions measures in foreign countries. 

France and Japan recently released roadmaps for decarbonising the cement sector, setting out specific decarbonisation targets, and laying out concrete steps for the decarbonisation of their cement sectors. The French plan calls for emission reductions of 35% by 2030. The United Kingdom released its decarbonisation roadmap for cement in 2015. 

Policy makers are increasingly coordinating their work to address the challenges that face the decarbonisation of the cement and concrete industry, including the threat posed by carbon leakage and the need for more investment in developing and deploying clean technology. A major development in 2021 was at COP26, where the United Kingdom and India led the push for the Clean Energy Ministerial’s Industrial Deep Decarbonization Initiative to encourage the public procurement of low-emission steel and concrete in order to create a market for these goods. 

A number of organisations have released roadmaps to reach net zero by 2050. Most notable is the Global Cement and Concrete Association (GCCA) – whose member companies are responsible for 40% of global cement production (80% outside of China) – setting a target for net zero emissions by 2050. there are The European Cement Association has released an emissions roadmap of its own, joined by several national associations including the United Kingdom, India, Brazil, and in the United States the Portland Cement Association.  

Programmes are in place to help improve energy efficiency in cement production on the road to the arrival of breakthrough technology, including the Plant Evaluation Gap Analysis and Support Service (PEGASUS) Programme and the Global Cement and Concrete Association’s GNR reporting database for use in benchmarking. Other programmes target innovation, such as the GCCA's Innovandi programmes.  

Climate Group's ConcreteZero initiative, which launched on 5 July 2022 with 17 member firms, brings together leading businesses to create a market for near zero concrete, with members committing to procure 30% low-emission concrete by 2025 and 50% by 2030. The First Movers Coalition – a group of companies using their purchasing power to create early markets for innovative clean technologies – also plans to launch their initiative for decarbonising concrete at COP27 in Egypt.  

As with industry overall, the decarbonisation of cement will require multiple measures, including:  

• Adopting mandatory CO₂ policies covering industry, preferably with international co-operation. Domestically this might include carbon prices and tradeable low-emission standards, while carbon border adjustments or international sectoral agreements might be considered to limit carbon leakage. 
• Managing existing assets and near-term investment in order to create a smooth energy transition (mandating refurbishment to near zero emission technology to avoid stranded assets). 
• Maximising energy productivity by accelerating progress in energy efficiency, recycling and material efficiency. Deployment of best available technologies and material efficiency strategies can facilitate this. 
• Increasing investment and finance for R&D and deployment for low-carbon technologies essential to decarbonising process emissions from industry, including investment in CCS and clinkers based on alternative raw materials in the case of cement. Both direct support and mechanisms that mobilise private finance are important. 
• Investing in and planning for supporting infrastructure, including for CO₂ transport and storage. 
• Improving data collection, tracking and classification systems, where industry participation and government co‑ordination are both important. 

Greater uptake of alternative fuels can be facilitated by redirecting waste from landfills to the cement industry and by coordinating the supply of sustainably sourced biomass across sectors to enable cost-competitive access for cement production.  

In the long term, clinker substitutes and supplementary cementitious material replacements that are widely available – such as calcined clay in combination with limestone – will become more important, as the decarbonisation of power generation and iron and steelmaking will reduce the availability of these industrial by-products. Governments should review and revise related building codes, procurement policies and standards to ensure that prescriptive requirements are not a barrier to maximising uptake of clinker substitutes.  

Creating demand for near zero emission cement will be crucial. Cement has a specific need for policies that incentivise the use of near zero emission clinker, as opposed to broader policies that might instead encourage switching to different materials or using cement with only incremental emission reductions, and thus not laying the groundwork for near zero emission production in the longer term. This is important as substantial amounts of clinker will be needed in a net zero world, since cement is very difficult to recycle, clinker substitutes can only constitute up to about half of cement for most applications, and alternative binding agents that could wholly substitute clinker are either in the very early stages of development or can only be used in particular applications.  

Furthermore, considerable hurdles remain to developing the required technologies, building out production plants and building up supply chains for clinker production, so targeted support is needed. Examples would be public procurement policies that specifically designate that a portion of cement must come from near zero emission clinker production or advanced market commitments that guarantee the purchase of near zero emission cement. Carbon contracts for difference could also play a role.