Capturing CO2 from ambient air - David Keith

List of Figures
1.1 Global CO2 emissions over time. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2.1 Example air capture system (top level process diagram). . . . . . . . . . . . . . . . . . . . 11
3.1 Diagram and photograph of prototype contactor. . . . . . . . . . . . . . . . . . . . . . . . 20
3.2 CO2 absorption by falling drops – comparison of theory and measurements. . . . . . . . . . 21
3.3 Outlet CO2 concentration during a typical trial. . . . . . . . . . . . . . . . . . . . . . . . . 22
3.4 CO2 absorption for several solution concentrations of NaOH and two nozzles. . . . . . . . . 23
3.5 Water loss measured in the prototype and calculated water loss in a full-scale system . . . . 25
3.6 Size distribution of sprays used in coalescence modeling. . . . . . . . . . . . . . . . . . . . 30
3.7 Total surface area of a parcel of spray over time in the contactor. . . . . . . . . . . . . . . . 31
3.8 Size distributions over time for model calculation in Figure 3.7. . . . . . . . . . . . . . . . 32
3.9 Initial and steady-state size distributions of spray in CFSTR model of coalescence. . . . . . 33
3.10 Spray surface area as a function of liquid flow rate . . . . . . . . . . . . . . . . . . . . . . 34
3.11 Spray surface area as a function of contactor height. . . . . . . . . . . . . . . . . . . . . . . 35
3.12 Surface area as a function of liquid flow rate for a smaller drop size distribution. . . . . . . . 36
3.13 Simple diagram of a horizontal flow contactor . . . . . . . . . . . . . . . . . . . . . . . . 46
3.14 Equilibrium speciation of carbonates. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
B.1 Dimensions, layout, and labeling of major components of the final prototype design. . . . . 70
B.2 Photograph of completed prototype structure. . . . . . . . . . . . . . . . . . . . . . . . . . 71
B.3 Lining the inside of the Sonotubes with PVC sheets. . . . . . . . . . . . . . . . . . . . . . 72
B.4 Photograph of the reaction chamber being lifted by crane. . . . . . . . . . . . . . . . . . . 73
B.5 Tower support structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
B.6 Flow diagram of liquid and air systems in the final prototype design. . . . . . . . . . . . . 76
B.7 Sampling points of CO2 concentration in air. . . . . . . . . . . . . . . . . . . . . . . . . . 79
B.8 Measured CO2 concentration during a portion of Trial 2. . . . . . . . . . . . . . . . . . . . 82
B.9 CO2 absorbed during Trial 2: comparison of two measurement methods. . . . . . . . . . . 83
B.10 Measured CO2 concentration during a portion of Trial 11. . . . . . . . . . . . . . . . . . . 84
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