Carbon Capture Is Emerging in the Cement Industry: Part 1

The cement industry is part of what are often referred to as the hard-to-abate sectors. Per the World Economic Forum, the hard-to-abate designation refers to heavy industry (such as cement, steel, chemicals, and aluminium) and heavy duty transport (shipping, long-distance trucking, and aviation). Figures vary, but heavy energy-intensive industries constitute around 20% of global CO2 emissions. Though commentary on carbon capture utilization and storage technologies often revolve around hard-to-abate sectors, the technology is certainly not limited to them. This three-part blog begins with an exploration of the background of the cement industry, why the decarbonization of this sector matters, and where in the process CO2 is generated, and introduces possible decarbonization strategies.

Why the Cement Industry?

Altogether, the global cement industry is said to be the source of around 7%-8% of global anthropogenic CO2 emissions. Cement is necessary for the production of concrete, the most widely used construction material in the world with no readily available replacement on that scale. This reality underlies the importance of the decarbonization of cement. Looking at the breakdown of global greenhouse gas emissions by sector for the 2016 from Our World in Data, cement takes up 3% of the global total. That the figure represents the CO2 produced directly from the cement production process. There are also emissions related to the necessary energy inputs of the process and supply chain-related emissions. 

Particulars of the Production Process 

The total CO2 emissions from cement production can be thought of in two parts: emissions from the calcination of limestone and emissions from the combustion of fuel to heat a kiln. Around half of total cement emissions come from the calcination stage where limestone is decomposed into lime and CO2 in the kiln. Many other raw materials go into the production of cement, such as clay, iron ore, and fly ash (as part of the popular dry process in cement production). A new substance called clinker is eventually formed as the main ingredient of cement. The clinker is then grinded and mixed with gypsum and limestone to form cement. 

With the calcination of limestone, such a significant volume of emissions are released from a set chemical reaction that it becomes difficult to reduce emissions beyond improvements to overall process and material efficiencies (such as the clinker-to cement ratio) and fuel switching. The assortment of materials in the kiln is heated to temperatures around 1,450°C, generating emissions from the related combustion of fuel. For example, in the Australian cement and concrete sector, such thermal emissions accounted for 26% of emissions of the overall production and transportation process.

To reduce emissions further, researchers at Imperial College, London, have suggested that the deployment of carbon capture technology together with fuel switching away from conventional fossil fuels to carbon-neutral biomass (and possibly municipal waste) has the potential to result in big emissions reductions in this industry. The world’s first commercial-scale cement carbon capture and storage deployment is to be at Norcem cement factory (owned by HeidelbergCement) with 0.4 megatons of capture capacity to commence operations by 2024. The carbon is to be eventually stored in saline formations offshore. Part 2 of this blog series looks closer at various active cement decarbonization projects around the world.