Biomedical Engineering Reference
In-Depth Information
10000
9000
8000
7000
6000
5000
4000
3000
2000
1000
1950
1960
1970
1980
1990
2000
2010
Year
FIGURE 15.8
Global CO
2
emission rate from fossil burning, cement manufacturing, and gas flaring. Data from
Carbon Dioxide Information Analysis Center.
underneath earth. By virtue, using fossil energy is not a sustainable process.
Fig. 15.8
shows
the global fossil CO
2
emission, while
Fig. 15.9
shows the CO
2
concentration in atmosphere.
Fig. 15.8
shows that the emission rate of CO
2
(log scale) into atmosphere due to fossil energy
use increases exponentially with two distinctive periods: from 1950 to 1978 and then from
1982 to 2007. The exponential pace of CO
2
rate increase is lower at the later period. The
net rate of CO
2
emission (as a source) is alarming.
Fig. 15.9
shows that the concentration
of CO
2
(log scale) in atmosphere increases monotonously when seasonal effect is taken
out. The seasonal change is due to the equilibrium concentration change with temperature
change in the oceans (water) and soil. The concentration change in the atmosphere can be
estimated by a mass balance
r
e;
CO
2
YF
CO
2
=
X
m
max
C
CO
2
d
C
CO
2
d
t
K
CO
2
þ C
CO
2
XS
B
¼ðV
At
þ V
W
S
WA
Þ
(15.7)
where
YF
CO
2
=
X
is the yield factor of CO
2
on plant biomass,
m
max
is the average maximum
specific overall growth rate of plant biomass,
K
CO
2
is the Monod saturation coefficient
of CO
2
for the average growth of plant biomass, X is the standing (plant) biomass, S
B
is the area of earth surface on which plant biomass grows, V
At
is the effective volume
of atmosphere,
V
W
is the effective volume of the water bodies, S
WA
is the effective CO
2
saturation in water,
is the net emission rate of CO
2
,and
C
CO
2
is the concentration
of CO
2
in atmosphere. One can observe that the increase in CO
2
in the atmosphere since
1970 is exponential except a short period of time between 1992 and 1994 as expected from
the corresponding CO
2
emission data in
Fig. 15.8
. However, the CO
2
emission from fossil
r
e;
CO
2
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