For Students
Engineering Design in Oregon Science Classrooms
Page 1 of 6
Data Worksheet for Biofuel from Algae
INTRODUCTION
Plankton Power, a biofuel company, wants to build a machine that maximizes indoor algae growth so that they can make a profit selling algae
as biofuel. To facilitate the engineering process they have been conducting research on machine prototypes to determine the optimal conditions for
algae growth. Below is a list of research questions they are attempting to answer:
1. What intensity of light (3400 lumens, 2300 lumens, 1800 lumens) is best for algae growth?
2. What species of algae (Scenedesmus, Selenastrum, or Spiropgyra) grows best in the machine?
3. What temperature range (22°C-23°C or 24°C-25°C) is best for algae growth?
4. What amount of light (12 hours/day or 24 hours/day) is best for algae growth?
5. What concentration of fertilizer maximizes algae growth?
6. What ratio of nitrogen: phosphorus: potassium for fertilizer is best for algae growth?
Researchers measured algae growth indirectly
by collecting data on the turbidity of the samples.
Turbidity is a measure of the cloudiness caused by
solid particles suspended in a liquid. If these particles
are too tiny to see with the naked eye, they stay
suspended, discoloring the liquid. In these experiments.
algae discolored the water solution growth medium
green. A greater concentration of algae made a greener
solution as determined by cross-referring the turbidity
data below with microscope cell counts (see Data
Collection Methods Handout for a complete
explanation as to how the data in the tables below was
determined).
For Students
Engineering Design in Oregon Science Classrooms
PREDICTIONS
Predict the answer for each of the five research questions listed above. Be sure to explain your predictions.
A) What intensity of light (3400 lumens, 2300 lumens, 1800 lumens) is best for algae growth?
B) What species of algae (Scenedesmus, Selenastrum, or Spiropgyra) grows best in the machine?
C) What temperature range (22°C-23°C or 24°C-25°C) is best for algae growth?
D) What amount of light (12 hours/day or 24 hours/day) is best for algae growth?
E) What concentration of fertilizer maximizes algae growth?
Page 2 of 6
For Students
Engineering Design in Oregon Science Classrooms
Page 3 of 6
DATA TABLES
Key
Genus
Fertilizer Solution, MiracleGro:Water
SCE = Scenedesmus
FS1 = 1 Tbsp: 1 Gallon
SES = Selenastrum
FS2 =
SPI = Spirogyra
FS3 =
Experiment #1
Algae
Sample
Description
Light
Change in
Turbidity
(ml)
K
A
100 ml SCE
400 ml Water
24 hours
1900 Lumens
-19.5
L
B
200 ml SCE
300 ml Water
24 hours
1900 Lumens
-22
M
C
100 ml SCE
400 ml FS1
24 hours
1900 Lumens
-21.5
D
200 ml SCE
300 ml FS1
24 hours
1900 Lumens
-25.5
E
100 ml SCE
400 ml FS2
24 hours
1900 Lumens
-30.5
F
200 ml SCE
300 ml FS2
24 hours
1900 Lumens
G
100 ml SCE
400 ml FS3
24 hours
1900 lumens
-39.5
H
200 ml SCE
300 ml FS3
24 hours
1900 lumens
-28.5
R
I
100 ml SCE
400 ml Water
24 hours
2300 lumens
-31.5
S
J
100 ml SCE
400 ml FS1
24 hours
3400 lumens
-35.0
N
O
P
-18.5
Q
T
Narrow Bottle
100 ml SCE
400 ml FS2
Narrow Bottle
100 ml SCE
400 ml FS3
Narrow Bottle
200 ml SCE
300 ml Water
Narrow Bottle
200 ml SCE
300 ml FS1
Narrow Bottle
200 ml SCE
300 ml FS2
Narrow Bottle
200 ml SCE
300 ml FS3
Narrow Bottle
100 ml SCE
400 ml Water
Narrow Bottle
100 ml SCE
400 ml FS1
Narrow Bottle
100 ml SCE
400 ml FS2
Narrow Bottle
100 ml SCE
400 ml FS3
24 hours
3400 lumens
-43
24 hours
3400 lumens
-43.5
24 hours
3400 lumens
-32
24 hours
3400 lumens
-27
24 hours
3400 lumens
-29
24 hours
3400 lumens
-29
24 hours
3400 lumens
with reflector
24 hours of
3400 lumens
with reflector
24 hours of
3400 lumens
with reflector
24 hours of
3400 lumens
with reflector
-51
-46
-46.5
-48.5
For Students
Engineering Design in Oregon Science Classrooms
Page 4 of 6
Experiment #2
Change of
Turbidity
(ml)
Algae
Solution
Description
Light
(Lumens)
A
100 ml SEC
400 ml FS2
3400
12 hours
22ºC Lights off
23 ºC Lights on
-7
B
100 ml SEC
400 ml FS2
3400
12 hours
Reflector
22ºC Lights off
23 ºC Lights on
-14
C
100 ml SEC
400 ml FS2
2300
12 hours
22ºC Lights off
23ºC Lights on
-3
D
100 ml SEC
400 ml FS2
2300
12 hours
Reflector
22ºC Lights off
23ºC Lights on
-8
Temperature
Experiment #3
Algae Solution
Description
A
5 ml SEC
500 ml FS2
B
5 ml SEL
500 ml FS2
C
5 ml SPI
500 ml FS2
Light
3400
12 hours
Reflector
3400
12 hours
Reflector
3400
12 hours
Reflector
Temperature
Change in turbidity after
1 week (ml)
Change in turbidity
from week 1 to week
2 (ml)
Total change in
turbidity after 2
weeks (ml)
22ºC Lights off
23 ºC Lights on
-39
-14
-53
22ºC Lights off
23 ºC Lights on
-78
-3
-82
22ºC Lights off
23 ºC Lights on
0
0
0
For Students
Engineering Design in Oregon Science Classrooms
Experiment #4
Change in
turbidity after 1
week (ml)
Algae
Solution
Description
Light
(Lumens)
A
100 ml SCE
400 ml FS1
3400
12 hours
Reflector
22ºC Lights off
23 ºC Lights on
-35
B
50 ml SCE
450 ml FS1
3400
12 hours
Reflector
22ºC Lights off
23 ºC Lights on
-62
C
100 ml SCE
400 ml FS1
3400
12 hours
Reflector
D
100 ml SEL
400 ml FS1
E
50 ml SEL
450 ml FS1
F
100 ml SEL
400 ml FS1
Temperature
24ºC Lights off
25ºC Lights on
-20
22ºC Lights off
23ºC Lights on
-24
3400
12 hours
Reflector
22ºC Lights off
23ºC Lights on
-10
3400
12 hours
Reflector
24ºC Lights off
25ºC Lights on
-40
3400
12 hours
Reflector
ANALYSIS
Graph
Create a graph in the space provided to the right, illustrating the change in turbidity by its temperature, light, or concentration.
Page 5 of 6
For Students
Engineering Design in Oregon Science Classrooms
Page 6 of 6
Analysis Questions
1. Which species of algae had the highest total growth rate? Use the data from the tables above to support your answer.
2. Were the growth rates of Scenedesmus and Selanstrum constant over the course of two weeks? What happened to growth rate after the first week?
3. What factors might have affected the growth rate of algae during the second week of the experiment?
4. What might have caused the Spiropgyra to show no change in turbidity? Does this mean the algae did not grow over the course of the two weeks?
a) Algae grow better under higher lumen light. Explanation: Different species prefer different light intensities for photosynthesis. This
species of algae happens to prefer a high light intensity. Follow-up experiment: Would even higher intensity make for more
photosynthesis and growth?
b) Algae grow better when surrounded by reflectors. Explanations: Reflectors reduce shadowing from nearby bottles and helps ensure the
bottle receives more light. More light of course means more photosynthesis, which means more cell growth and division.