Fig. 1: The system boundary diagram depicting the 13 processes, which were accounted for when determining the net CO2 benefit of CCU concrete.
From: Carbon dioxide utilization in concrete curing or mixing might not produce a net climate benefit
The processes required to produce CCU concrete are highlighted in gray and green. The processes required to manufacture conventional concrete are highlighted in gray and red. The CO2 emissions, which is utilized in the curing or mixing of CCU concrete (φCCU in kg), is captured from a power plant. The energy penalty from capturing φCCU (Ep kWh) is compensated by an external power plant. When conventional concrete is produced, there is no carbon capture during electricity generation and the CO2 from generating Ep in the power plant is completely emitted. The functional unit—1 m3 of concrete with 1 MPa strength and Ep kWh of electricity—is common across the CCU and conventional concrete production pathways. The CO2 emissions from each of the CCU and conventional concrete production process is quantified in Eqs. 1 and 5.
