CO2 Sequestration through Deep Saline Injection and ...

A good estimate for the saturation light intensity is 30 to 45 W/m 2 or 140 to 210 uE/m 2 /s [31, 35-
37]. The saturation light intensity is a specific property of each individual photosynthetic
organism and can be experimentally determined by collecting data of specific growth rate vs
luminous intensity. The light intensity at which growth becomes non-linear with respect to
luminous intensity is the saturation light intensity. A value of 45 W/m 2 was used in the design.
The energy equivalent of the algae will have to be determined experimentally by calorimetric
experiments. A reasonable estimate is 23.1 kJ/g dry weight, resulting in K=0.156 g dry
weight/h/W [31].
The ratio of g dry weight to g of carbon could be measured by combustion and GCMS. A typical
composition is 49% carbon, which results in a G of 2.04 [31].
The respiration rate is a function of cellular concentration and would have to be carefully
measured under the growth conditions. Figure 6 shows the respiration rate of Scenedesmus
obliques [31].
CO2 Evolution (gC/g dry weight/h)
0.009
0.008
0.007
0.006
0.005
0.004
0.003
0.002
0.001
0.000
0 0.5 1 1.5 2 2.5 3 3.5
Cell Concentration (g dry weight/L)
Figure 6
Respiration Rates as a function of Cellular Concentration [31]
The data from Figure 6 was entered into a spreadsheet program and a hyperbolic function of the
form / ( )
d
a b+ C + e was used to fit the function using a minimization of sum of squared error
method. The constants were found to be: a=1.854, b=2.582, d=5.819, e=0.002715. This
function was used to calculate the respiration rate for the final design. The fit to the data is
shown as the pink line in Figure 6.
Finally, the parameters used in the modified Beer-Lambert’s law need to be measured. This can
be done using a quantum sensor and a several optical cells of varying path lengths. These
16