The photo is sourced from heidelbergcement.com
To capture CO2, amine-based solvents will be used. As an example of the use of this technology, we can take Norcem, the Norwegian subsidiary of HeidelbergCement, planning to install some CCS facilities at its cement plant in the city of Brevik by 2024, with the capacity of 400,000 tons of carbon dioxide per year (the volume comparable to the annual emissions of 180,000 passenger cars).
The exhaust gases from cement production are sent, first, to a cooling tower for their purification from sulfur dioxide by adding sodium hydroxide. Then, the gases cooled from 100 to 30 degrees Celsius are sent to an absorber partially filled with amine solvent, which will absorb the CO2. After that, the carbon dioxide-enriched solution is pumped into a desorber where the mixture is heated to 120 degrees, allowing the CO2 to separate from the amine molecules – this energy-intensive process will use the residual heat energy not used in cement production.
The extracted CO2 is fed to a compressor plant for cooling, and then converted from a gaseous state to a liquid one under the pressure increase (from 1.7 to 70 bar), after that the pressure will lower to 16 bar. Finally, at the last stage, the liquefied CO2 is sent to a transit storage facility for onward marine transportation.
The cement industry is one of the most carbon-intensive. According to McKinsey, its share of the global industrial emissions mix is second only to steelmaking (20% vs. 26%), but ahead of oil and gas production (15%) and the chemical (12%) and coal (6%) industries and all the other ones (20%). This is partially why cement imports to the EU will fall under the Carbon Border Adjustment Mechanism (CBAM) to start its operation in 2023.
This is also the reason for growing popularity of CO2 capture projects among cement producers. For example, cement giant CEMEX, together with power generation company Enertrag and Sasol ecoFT, the company specialising in production of synthetic hydrocarbons, are going to start joint production of sustainable jet fuel using carbon dioxide and green hydrogen. They plan to use the Fischer-Tropsch process to convert the oxide carbon and hydrogen into liquid hydrocarbons when a catalyst is added.
