A new study entitled ’Towards a business case for CO2 mineralisation in the cement industry’ revealed that – through techno-economic modelling - the notoriously hard-to-abate cement industry could see a reduction in carbon dioxide equivalent (CO2e) emissions and additional profit by incorporating CO2 mineralisation.

According to best estimates, the cement industry is responsible for approximately 7% of anthropogenic CO2e emissions and, in 2015, the Paris climate agreement emphasised the need for signatories to limit CO2e emissions and strive for a temperature rise of 1.5C. 

The challenge of reducing these emissions in the cement industry stems from the majority (60%) of its emissions being process-inherent, meaning that to lower emissions either the entire process must be replaced by more sustainable alternatives or the emissions generated through the process must be captured and stored. 

A little-studied area of carbon capture and storage (CCS) lies in CO2 mineralisation – a technique that involves captured CO2 reacting with activated minerals within rocks or industrial wastes to form stable carbonate minerals. 

A rock containing olivine

A rock containing olivine

The reactions lead to long-term storage of CO2 within the minerals, creating a potential market for the CO2-filled products and generating a subsequent revenue stream. 

The study revealed that the mineralised CO2 product could be used in a range of applications from fillers, polymer additives, to be used in land reclamation or as supplementary cementitious materials (SCM) – creating revenues of Є14-700 per tonne of CO2 captured. 

In a world destined to witness ever-increasing sea levels as temperatures rise and ice caps melt, another application - as suggested by industrial gases expert Stephen B. Harrison during gasworld’s Europe CO2 Summit 2022 – could be sea defences. 

To make cement, limestone is required, and a huge amount of energy is needed to grind the limestone. Using mineralisation-produced calcium carbonate, industry can avoid the energy-intensive grinding process and reduce transportation and energy costs associated with conventional cement manufacture. 

Commenting on the use of serpentinite and olivine to help absorb CO2 during mineralisation, Harrison said, “These ultramafic rocks are interesting because they can help us to absorb CO2 to remove CO2 from the atmosphere.” 

“We can use these rocks to help decarbonise industrial processes.” 

The specific requirements of ideal natural rock feedstock include magnesium or calcium-rich silicates minerals present in olivine, serpentinite, and wollastonite. Other feedstocks include industrial wastes – less than ideal due to the potential for the waste to change composition over time.

According to the study, CO2 mineralisation could reduce the CO2e emissions from cement production by 8-33% while generating positive revenues providing two conditions are met: 

1) SCMccu (cement replacement quality of the carbonated product) must be widely accepted and standardised as cement replacement and;

2) The production of SCMccu must be eligible for EU Emissions Trading System (ETS) credits or similar.

The full paper can be accessed here.