Technology at it's Best
With petroleum reserves dwindling, the search is on to replace gasoline with a cleaner, greener alternative.
The increased emphasis on renewable fuels has attracted new interest in a potentially rich source of biofuels: algae. Most research has been
centered on ethanol from corn and biodiesel from soybeans, the biofuel that looks more likely to replace petroleum on a large scale comes from a most unlikely place: pond scum.
Algae, like corn, soybeans, sugar cane and other crops, grows via photosynthesis (meaning it absorbs carbon dioxide) and can be processed into fuel oil. However, the slimy aquatic organisms yield 30 times more energy per acre than land crops such as soybeans, according to the US Department of Energy. The reason: They have a simple cellular structure, a lipid-rich composition and a rapid reproduction rate. Many algae species also can grow in saltwater and other harsh conditions -- whereas soy and corn require arable land and fresh water that will be in short supply as the world's population expands.
If you replaced all the diesel in the U.S. with soy biodiesel, it would take half the land mass of the U.S. to grow those soybeans, On the other hand, the Energy Department estimates that if algae fuel replaced all the petroleum fuel in the United States, it would require 15,000 square miles, which is a few thousand miles larger than Maryland.
Yield comparison for different feedstocks:
Gallons of Oil per Acre per Year
Corn . . . . . . . 18
Canola . . . . . . 150
Soybeans . . . .50
Safflower. . . . . 83
Sunflower . . . 102
Rapeseed. . . 127
Oil Palm . . . . 650
Micro Algae . .5000-15000
Algaculture is a form of aquaculture involving the farming of species of algae.
The majority of algae that are intentionally cultivated fall into the category of microalgae (also referred to as phytoplankton, microphytes, or planktonic algae). Macroalgae, commonly known as seaweed, also have many commercial and industrial uses, but due to their size and the specific requirements of the environment in which they need to grow, they do not lend themselves as readily to cultivation.
Another bonus: Because algae can be grown just about anywhere in an enclosed space, it's being tested at several power plants across the nation as a carbon absorber. Smokestack emissions can be diverted directly into the ponds, feeding the algae while keeping greenhouse gases out of the atmosphere.
A Little History
The Aquatic Species Program launched in 1978. The U.S. research program, funded by the U.S. DoE, was tasked with investigating the use of algae for the production of energy. The program initially focused efforts on the production of hydrogen, however, shifted primary research to studying oil production in 1982. From 1982 through its culmination, the majority of the program research was focused on the production of transportation fuels, notably biodiesel, from algae. In 1995, as part of the over-all efforts to lower budget demands, the DoE decided to end the program. Research stopped in 1996 and staff began compiling their research for publication. In July of 1998, the DoE published the report "A Look Back at the U.S. Department of Energy's Aquatic Species Program: Biodiesel from Algae"
The National Renewable Energy Laboratory (NREL) has identified approximately 300 species of algae, as varied as the diatoms (genera Amphora, Cymbella, Nitzschia) and green algae (genera Chlorella in particular) as potentially good sources of oil from algae. Diatoms, or Bacillariophytes, are unicellular, microscopic algae. These organisms are widespread in salt water where they constitute the largest portion of phytoplankton biomass. There exist approximately 100,000 known species around the world. More than 400 new specimens are described each year.
What are algae comprised of? Algae are made up of eukaryotic cells. These are cells with nuclei and organelles. All algae all have plastids, the bodies with chlorophyll that carry out photosynthesis. But the various lines of algae can have different combinations of chlorophyll molecules; some have just Chlorophyll A, some A and B, and other lines, A and C. All algae primary comprise of the following, in varying proportions: Proteins, Carbohydrates, Fats and Nucleic Acids. While the percentages vary with the type of algae, there are algae types that are comprised up to 40% of their overall mass by fatty acids. It is this fatty acid (oil) that can be extracted and converted into biodiesel. Table 1 - Chemical Composition of Algae Expressed on A Dry Matter Basis (%) Strain Protein Carbohydrates Lipids Nucleic Acid Scenedesmus obliquus Scenedesmus quadricauda Scenedesmus dimorphus Chlamydomonas rheinhardii Chlorella vulgaris Chlorella pyrenoidosa Spirogyra sp. Dunaliella bioculata Dunaliella salina Euglena gracilis Prymnesium parvum Tetraselmis maculata Porphyridium cruentum Spirulina platensis Spirulina maxima Synechoccus sp. Anabaena cylindrica
Source: Becker, (1994)
50-56
10-17
12-14
3-6
47
-
1.9
-
8-18
21-52
16-40
-
48
17
21
-
51-58
12-17
14-22
4-5
57
26
2
-
6-20
33-64
11-21
-
49
4
8
-
57
32
6
-
39-61
14-18
14-20
-
28-45
25-33
22-38
1-2
52
15
3
-
28-39
40-57
9-14
-
46-63
8- 14
4-9
2-5
60-70
13-16
6-7
3-4.5
63
15
11
5
43-56
25-30
4-7
-
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