Lecture 17

Question 1

When did algae form

Answer 1

1.8 billion years ago (in the Proterozoic Eon)

Question 2

What allowed early eukaryotic cells to harvest light energy

Answer 2

Incorporation of photosynthetic cyanobacteria (endosymbiotic theory)

Question 3

What helped generate the oxygen levels needed for life to emerge

Answer 3

Cyanobacteria and algae

Question 4

Do algae use photosynthesis

Answer 4

Yes

Question 5

Algae photosynthesis

Answer 5

Use photosynthesis to generate organic carbon from CO2 and the energy of light (O2 is a byproduct)

Question 6

Can algae produce lipids/oils

Answer 6

Yes, under certain conditions

Question 7

What percent of their dry weight can algae produce in oil

Answer 7

70%

Question 8

Other compounds that can be produced by algae

Answer 8

Butanol, hydrogen, etc.

Question 9

Genera common for bioenergy purposes

Answer 9

Chlorella
Botryococcus
Dunaliella
Nannochloropsis
Scenedesmus

Question 10

Growth conditions that algae can have

Answer 10

Phototrophic
Heterotrophic
Mixotrophic

Question 11

Phototrophic growth

Answer 11

Requires light energy and inorganic carbon

Question 12

Heterotrophic growth

Answer 12

Requires an organic carbon source for energy (e.g. glucose, glycerol)

Question 13

Mixotrophic growth

Answer 13

Combination of light energy, organic carbon, and inorganic carbon (rarely used)

Question 14

Nutrients required by algae

Answer 14

Nitrates, phosphates, potassium, calcium, zinc, iron, magnesium, manganese, molybdenum, copper, etc.

Question 15

Why is it so expensive to grow algae for biodiesel

Answer 15

The need for nutrients

Question 16

Strategy to keep the cost low for algae biodiesel

Answer 16

Use of human wastewater as a source of nutrients

Question 17

Requirements of algaeal farms

Answer 17

Sunlight
Carbon dioxide
Moderate temperatures
Water
Nutrients
Land
The appropriate algael strain

Question 18

Main types of algael farms

Answer 18

Open
Closed

Question 19

Types of open system farms

Answer 19

Ponds
Raceways

Question 20

Downside to open system farms

Answer 20

Less control of nearly every parameter

Question 21

What type of system is more expensive to build and operate: open or closed?

Answer 21

Closed

Question 22

Main types of closed system farms

Answer 22

Columns
Tubes

Question 23

Control over closed system

Answer 23

Great control over parameters

Question 24

What does the choice between open and closed systems usually come down to

Answer 24

How much you have to invest

Question 25

Harvesting

Answer 25

Separating mature algae from water

Question 26

Harvesting methods

Answer 26

Centrifugation
Flocculation
Sedimentation
Filtration

Question 27

Centrifugation

Answer 27

Spinning at high speeds

Question 28

Flocculation

Answer 28

Algae aggregate and clump (auto and induced)

Question 29

Sedimentation

Answer 29

Gravity will cause algae to settle over time

Question 30

Filtration

Answer 30

Use fine screens to separate algae from the water

Question 31

Physical extraction of lipids from algae methods

Answer 31

Mechanical disruption
Electric pulse
Sonication
Osmotic shock
Expeller press

Question 32

Chemical and biochemical extraction of lipids from algae methods

Answer 32

Solvent (hexane)
Enzymatic

Question 33

Algae produces ____ that can be used to make biodiesel

Answer 33

Triacylglycerides

Question 34

___ of algal lipids leads to FAMEs

Answer 34

Transesterification

Question 35

Is the overall process of algae biodiesel production affordable

Answer 35

No

Question 36

Cost per gallon of algae diesel

Answer 36

$8 per gallon