Carbon Capture and Storage (CCS) is a technology for separating carbon dioxide from industrial process streams and storing it permanently in deep geological formations. In cement production, CCS targets both combustion emissions from fuel use and process emissions from limestone calcination, which accounts for approximately 50 % of total CO₂ emissions in cement manufacturing.
Capture Methods
Three primary capture approaches are used in cement plants: post-combustion capture from flue gases (typically 85–95 % CO₂ purity), oxy-fuel combustion with air separation units (90–99 % purity), and pre-combustion decarbonization. Post-combustion capture using chemical solvents or solid sorbents is most compatible with existing facilities. Capture rates in cement production typically achieve 85–95 % efficiency of the available CO₂ stream, though this varies by technology and operating conditions.
Storage and Utilization
Captured CO₂ is compressed to 8–15 MPa for transport via pipeline, ship, or truck. Geological storage in saline aquifers, depleted oil and gas reservoirs, or deep unmineable coal seams provides permanent sequestration at depths exceeding 800 m, where CO₂ remains in supercritical state. Storage capacity in suitable European formations is estimated at 150–200 Gt CO₂. Alternatively, captured CO₂ can be utilized in chemicals, beverages, building materials, or enhanced oil recovery (CCUS), though utilization typically locks carbon for shorter periods than geological storage.
Emission Reduction Potential
CCS integration can reduce process-specific CO₂ emissions by up to 90 % when applied to both kiln exhaust and calcination streams. For a typical cement plant producing 1 million tonnes of cement annually, CO₂ emissions of approximately 800–900 kg per tonne can be reduced to 80–180 kg per tonne, depending on capture technology and scope. Full lifecycle reduction is lower due to energy requirements for capture, compression, and transport (typically adding 0.2–0.4 t CO₂ per tonne cement captured).
Energy Demand and Economics
CCS retrofits require 150–250 kWh of electricity per tonne of CO₂ captured, depending on technology maturity and optimization. Capital expenditure for post-combustion capture in cement plants ranges from €50–150 per tonne of annual capture capacity. Operational costs are approximately €60–120 per tonne of CO₂ captured and stored. Economic viability depends on carbon pricing mechanisms, industrial subsidies, and CO₂ transport infrastructure availability.
Regulatory Context
CCS deployment in cement is recognized under the EU ETS as a means to reduce mandatory emissions reductions targets. National building regulations increasingly accept lower-carbon cement from CCS-equipped plants for compliance with embodied carbon limits. ISO 14644 series standards govern storage integrity monitoring and verification.