Biomedical Engineering Reference
In-Depth Information
energy resources, this swamp area is to be managed for biomass, which consisted of wetland
grass and bushes. The cost of harvesting biomass can be approximated by
H
C
¼ aX þ b
(E15-4.1)
where a and b constants pending biomass species and terrain, and X is the biomass density. To
harvest the biomass from the swamp, the coefficients are a
$
m
2
.
Because of the high cost in harvesting swamp biomass and its low productivity, it is
decided to replace the swamp with an algae field. The carrying capacity of algae under
consideration is 0.09 kg
$
m
2
but has a higher productivity of 1.25 kg
$
m
2
10
3
¼
$0.02/kg and b
¼
$1
$
year
1
. The
10
4
$
m
2
. Determine
cost of harvesting algae is estimated by a
¼
$0.01/kg and b
¼
$4
the net benefit of converting the swamp to an algae field.
Solution. The conversion of the swamp to algae field causes a shift in sustainability from
a diverse swamp (wetland system) to a single (biomass) species field. This is the significant
change. Apart from this sustainability change, there is the change of productivity. We can
estimate the productivity according to the data given. If the swamp remained as swamp,
the frequency of harvesting is
year
1
That is, we need to harvest 0.4 times a year. If the biomass is grown to 80% of full carrying
capacity before harvesting, the cost of harvesting each year is given by
2 year
1
:
=
¼ 0:4
0
8
10
3
m
2
$
year
1
0132m
2
$
year
1
H
CS
¼
$
ð
0
:
02
0
:
8
2
þ
Þ
0
:
4
=ð
Þ¼
$0
:
$0.020625 kg
1
.
If the swamp was converted to an algae field, the frequency of harvesting is
0.8) kg
1
which translates to $0.0132/(0.8
¼
year
1
That is in every year, we need to harvest 13.89 times. If algae are grown to 80% of full capacity
before harvesting, the cost of harvesting each year is given by
year
1
1:25=0:09
¼ 13:89
10
4
1056m
2
year
1
H
CS
¼
$
ð
0
:
01
0
:
8
0
:
9
þ
4
Þ
13
:
89
¼
$0
:
$0.10556 kg
1
.
Therefore, the conversion of swamp to algae increases biomass production by (1.25
1.25) kg
1
which translates to $0.1056/(0.8
¼
0.8)/
0.8
¼
56.25%. However, the unit cost of biomass is increased by (0.10556
0.020625)/
0.020625
411.8%. A combination of lower unit cost of harvesting and higher productivity
does not make out to be beneficial in this case due to the much lower standing biomass
of algae.
¼
15.5. WO
ODY BIOMASS USE AND DESIRED SUSTAINAB
LE STATE
Low-carbon fuel standard (LCFS) is a rule enacted to reduce carbon intensity in transpor-
tation fuels. Its aim was to reduce the amount of fossil genic CO
2
into the atmosphere. This
can be rather confusing as to how the LCFS carbon intensity can be measured for biomass.
The plantation, harvesting, and processing of biomass all require energy input. Are the
production and processing energy renewable? Even the conversion or change of land use
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