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Global cement production produced 1.6 billion metric tons of CO2 in 2022

It is said that if the cement industry were a country, it would be the third or fourth largest emitter of carbon dioxide (CO2) in the world. As highlighted in a report by Eris Driva on economix.gr, global cement production produced 1.6 billion metric tons of CO2 in 2022 – the latest year for which data is available – an amount corresponding to approximately 8% of total emissions. Reducing the amount of carbon emitted by cement production plays a critical role in meeting global climate goals. At the same time, however, cement is a key component of concrete. So an obvious solution would be to reduce the amount of concrete the world needs. Things, however, are not that simple as concrete is the second most widely used material after water, as reported by the World Economic Forum. Its global annual production is projected to increase from 14 billion m³ today to 20 billion m³ by 2050 as human societies urbanize and demand for infrastructure increases.
If this trend continues it will see CO2 emissions in the cement industry skyrocket to 3.8 billion tonnes per year. Unlike other sectors, where the largest share of emissions are energy-related, in cement and concrete production, more than half of emissions are process-related, according to a new report completed by the World Economic Forum’s First Movers Coalition, in collaboration with with Deloitte. The industry, therefore, requires either new solutions in a sector that spans millennia or the significant enhancement of carbon sequestration practices.
Here are four key directions for the decarbonisation of the cement and concrete industry and the innovative solutions they include.
Replacement of clinker
Clinker is the main component of cement and is “responsible” for 90% of total emissions. Its replacement with lower intensity supplementary cementitious materials (SCM) is expected to directly address the issue of high emissions associated with the process. The bad news is that there are currently no solutions that can completely replace clinker on a large scale. However, there are several proven ways to significantly reduce the amount of clinker needed to produce cement and concrete, and one of the most promising solutions is called LC3 – Limestone, Calcined Clay Cement – ​​which can reduce CO2 emissions by around 40% in compared to conventional cement. LC3 addresses both sources of carbon emissions from clinker production. First by replacing half the clinker with fired clay and ground limestone, neither of which release carbon when heated like limestone. Second, the clay is heated to a much lower temperature, which reduces the amount of fuel required and means that electricity can be used instead of fossil fuels. Also, scientists at the University of Cambridge have developed a “zero emissions” technique to produce cleaner clinker. The alternative process involves reusing cement paste from demolished buildings. According to the scientists, this process could save up to three gigatons of CO2 per year.
Limestone replacement
Heating limestone for clinker production accounts for 50% of emissions in cement production. Therefore their replacement in the clinker production process provides an important way to reduce emissions. American company Brimstone has developed a process to make cement from carbon-free calcium silicate rock – which can be found in abundance on the surface of every continent in the world – instead of limestone. The company says the process also removes CO2 from the air because its rocks contain magnesium that can passively and permanently bind atmospheric carbon dioxide.
Sublime Systems uses calcium silicate minerals or industrial waste to produce cement using an electrochemical process rather than heat. Cemvision has piloted the production of mineral-free cement made entirely from recycled materials. The Swedish company recycles mining and steel by-products, which require less energy and create no waste. The company has designed its cement to be “drop-in”, meaning it can be incorporated into existing buildings alongside conventional cement, to enable rapid adoption.
Fuel switching and electrification
Fuel switching and electrification are critical to reducing energy-related emissions. Heating part of the kiln used to make clinker with a carbon-free electricity source and replacing fossil fuels with low-carbon alternative fuels for the rest can help phase out carbon. CoolBrook, SaltX and Rondo Energy have developed electric or thermal alternatives to kilns and calciners – a stage that preheats the limestone before it enters the kiln.
Another approach to achieving the very high temperatures required is concentrated solar energy, which has been tested by start-ups such as Synhelion – in partnership with Cemex – and Heliogen. Low-carbon fuel alternatives are also common in other industries and range from short-term solutions such as biomass to longer-term solutions such as “green” hydrogen.
Carbon sequestration
In this process carbon is sequestered at the source of emission, such as power plants and industrial facilities, and stored to prevent its release into the atmosphere. It is a key method of reducing emissions in the cement and concrete industry. Forecasts by the World Cement and Concrete Association show that carbon capture, use and storage (CCUS) could reduce emissions by 36%, making the industry the biggest driver of emissions reductions.
The city of Brevik in Norway has become the first region in the world to have a cement plant with carbon capture and storage (CCS) technology. Installation of the 100-meter-high CCS system at Heidelberg Materials’ cement plant began in August and is expected to be completed by the end of 2024. It will trap CO2 from the clinker production process, preventing it from being emitted into the atmosphere, and then store it safely underground in the North Sea.
Net zero cement production
At COP28 in Dubai, the Cement and Concrete Breakthrough initiative was agreed, which aims to establish and increase near-zero emission cement production in every region of the world by 2030. To make this goal a reality, it will be necessary to widespread adoption of innovative cement and concrete production processes such as the four mentioned above.