The contribution of the cement and concrete sector to carbon removals
CEMBUREAU’s 2050 Carbon Neutrality Roadmap “Cementing the Green Deal” (see link) sets out the technological and innovation pathways to achieve carbon neutrality by 2050 in the cement industry. These pathways span the full value chain and assess the CO2 reduction potential in both the manufacturing part of the business (clinker and cement manufacturing) as in the production, use and end-of-life of the end product, concrete, which is a key enabling building material for tomorrow’s sustainable built environment thanks to its durability, strength, recyclability and its carbonation potential. The CEMBUREAU Roadmap puts forward intermediate CO2 reduction targets of 30% (cement) and 40% (over the value chain) by 2030.
Achieving the CO2 reduction targets requires significant investments that, on their turn, are preconditioned by a stable and facilitating regulatory framework that guarantees viable investment projects with proper returns on investment.
Such regulatory framework is key notably for carbon uptake in our industries (cement, precast concrete, ready-mix concrete, concrete admixtures, aggregates) which occurs via two main streams: Carbon Capture, Utilisation and Storage (CCUS) and carbon uptake in concrete.
1. Carbon uptake in cement with CCUS
With two thirds of its CO2 emissions related to the manufacturing process (calcination of limestone), the cement industry strongly focuses on carbon capture as its key technology representing 42% of is CO2 emission reduction efforts by 2050. Carbon capture and storage (CCS), which will make cement carbon neutral can even become carbon negative when biomass waste is used as alternative fuel. A significant number of carbon capture and storage and use (CCUS) projects are currently under development by the European industry1. The viability of the technology hinges on the way the CO2 captured is recognized and accounted for under the regulatory framework. Given the geographic spread of cement kilns across Europe, CO2 utilisation is an essential avenue to explore for the sector.
As the European Commission acknowledges, the EU will still need carbon by 2050 and beyond as a feedstock to produce sustainable synthetic fuels, plastics, chemicals and advanced materials2. The sustainable character of each of these uses requires a proper accounting of the CO2, a fact that CEMBUREAU does not contest. The core question in this debate is where the CO2 will be accounted for.
|Policy ask: in CEMBUREAU’s view, CO2 must be accounted for at the point in time where the CO2 is released into the atmosphere. In concrete terms, when the capturing installation transfers the CO2 to a third party for either permanent storage, mineralisation or use in further products, including synthetic fuels, there is no release into the atmosphere at the point of capture. Therefore, the capturing installation should be allowed to deduct the CO2 from its emissions. Absent a clear rule allowing such deduction, an investment into a capture installation is simply not economically viable.|
2. Concrete as carbon sink
Cement is made by heating limestone to very high temperatures (>1450°C) allowing the limestone to be broken down in calcium oxide, the key ingredient of cement, and carbon dioxide (CO2). Part of the CO2 released during manufacturing is reabsorbed during the lifetime of a built structure as well as at the demolition stage where the concrete is exposed to the air. This reabsorption process, which is in fact the reverse from what happens in cement manufacturing, is a natural process which mineralises mortar and concrete and returns it to its stone-like properties.
Carbonation in the cement and concrete sector contributes to carbon removals through 3 main processes:
a) Enhanced carbon uptake in cement and concrete production
Some alternative raw materials in cement production and cement itself could be cured with captured CO2 at the cement plants. The same process could also apply to the production of ready-mix and precast concrete. This way the absorbed CO2 is permanently captured in the mineral structure of the new cement and concrete. Furthermore, the CO2 curing accelerates the setting of the concrete and enhances its strength.
|Policy ask: in order to incentivise CO2 utilisation for curing and mineralisation, which allows for a permanent capture, the European Union should include enhanced CO2 uptake in cement and concrete in its coming carbon removal certificates.|
b) Naturally throughout the lifetime of the building infrastructure
The absorption of CO2 turns the built environment into carbon sinks and this natural carbonation effect has been recognized in the Full Sixth Assessment Report of the Intergovernmental Panel on Climate Change3. Proper attention should be given to the recognition of the carbonation potential for mortar and concrete to be included in the estimation of negative emissions. In particular, it is critical that the EU fully recognises carbonation alongside other carbon sinks. The cement and concrete industry is engaging in research projects that seek to enhance this process and has commissioned a study4 to calculate the CO2 uptake in cement-containing products to support improved calculation methods within the IPCC and national greenhouse gas calculations. CEMBUREAU estimates that the potential carbonation volume is 16 million tonnes CO2 per year in the EU27.
|Policy ask: all Members States and the European Union should recognise carbonation alongside other carbon sinks, and include carbonation in MS and EU greenhouse gas calculations. The UNFCCC acknowledges the carbonation of concrete in national GHG inventories.|
c) At the end of life
At the end of life, concrete should be re-used and/or recycled into aggregates. At this life stage, the carbon uptake can be enhanced by crushing it and leaving it exposed to air for a period of time in order to maximise carbonation. In addition, some producers are also working on enhancing carbon uptake in recycled aggregates to lower the CO2 content of new concrete5.
Click here to download the position paper in pdf!
3 Please see https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_Full_Report.pdf, page 1171