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Algal Oil Yields
From Oilgae.com Oil from Algae (So whats the Oilgae story?)
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Nature gave us oil from algae; perhaps we should try Natures way again
You are at: Oilgae Home > About Algae > Algae Oil > Oil Yields from Algae
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Algal Oil Yields
Microalgae contain lipids and fatty acids as membrane components, storage products, metabolites and sources of energy. Algal strains, diatoms, and cyanobacteria (catagorised collectively as "Microalgae") have been found to contain proportionally high levels of lipids (over 30%). These microalgal strains with high oil, or lipid content are of great interest in the search for a sustainable feedstock for the production of biodiesel. As could be seen from Table 1, algae contain anywhere between 2% and 40% of lipids/oils by weight.
Lipid accumulation in algea typically occurs during periods of environmental stress, including growth under nutrient-deficient conditions. The lipid and fatty acid contents of microalgae vary in accordance with culture conditions. In some cases, lipid content can be enhanced by the imposition of nitrogen starvation or other stress factors. Biochemical studies have also suggested that acetyl-CoA carboxylase (ACCase), a biotin-containing enzyme that catalyzes an early step in fatty acid biosynthesis, may be involved in the control of this lipid accumulation process. Therefore, it may be possible to enhance lipid production rates by increasing the activity of this enzyme via genetic engineering.
The key question in everyones mind is: which is the best species of algae for biodiesel? The decades-long research undertaken by NREL of USA called the Aquatic Species Program (see a copy of the Aquatic Species Program Research notes here, but please remember it is a large PDF file!) did in-depth research on this topic and in the end has said that there is no one strain or species of algae that can be said to be the best in terms of oil yield for biodiesel. However they did conclude that the diatoms and secondly green algae were the most promising.
The following species listed are currently being studied for their suitability as a mass-oil producing crop, across various locations worldwide.
· Neochloris oleoabundans - Neochloris oleoabundans is a microalga belonging in the class Chlorophyceae · Scenedesmus dimorphus - Scenedesmus dimorphus is a unicellular algae in the class Chlorophyceae. While this is one of the preferred species for oil yield for biodiesel, one of the · Euglena gracilis · Phaeodactylum tricornutum - Phaeodactylum tricornutum is a diatom · Pleurochrysis carterae - Pleurochrysis carterae is a unicellular coccolithophorid alga that has the ability to calcify subcellularly. It is a member of the class Haptophyta (Prymnesiophyceae) · Prymnesium parvum - Prymnesium parvum is a toxic algae · Tetraselmis chui - Tetraselmis chui is a marine unicellular alga · Tetraselmis suecica Isochrysis galbana - Isochrysis galbana is a microalga. Nannochloropsis salina This is also called Nannochloris oculata. In the same group are Nannochloris atomus Butcher, Nannochloris maculata Butcher, Nannochloropsis gaditana Lubian, and Nannochloropsis oculata (Droop) Algal strains such as Botryococcus braunii can produce long chain hydrocarbons representing 86% of its dry weight. The green alga Botryococcus is unique in the quality and quantity of the liquid hydrocarbons it produces. Some scientists consider the ancestors of Botryococcus to be responsible for many of the world's fossil fuel deposits. Dunaliella tertiolecta - This strain is reported to have oil yield of about 37% (organic basis). D. tertiolecta is a fast growing strain and that means it has a high CO2 sequestration rate as well. Nannochloris sp. Spirulina species The strains of Algae most favoured by the NREL researchers were Chlorophyceae (green algae). Green algae tend to produce starch, rather than lipids. Green algae have very high growth rates at 30oC and high light in a water solution of type I at 55 mmho/cm. The other favoured algae (by NREL researchers) is Bacilliarophy (diatom algae). However, the diatom algae needs silicon in the water to grow, whereas green algae requires nitrogen to grow. Under nutrient deficiency the algae produced more oils per weight of algae, however the algae growths also were significantly less. While certain green algae strains are very tolerant to temperature fluctuations, diatoms have a fairly narrow temperature range.
See also: Biodiesel Now Forum on Algal Strains
Research on Oil Yield from Algae
· Research into cloning the gene that encodes ACCase from the eukaryotic alga Cyclotella cryptica has been undertaken, by isolating this gene. Research found that the amino acid sequence of ACCase deduced from this gene exhibited a high degree of similarity to the sequences of animal and yeast ACCases in the biotin carboxylase and carboxyltransferase domains, but less similarity exists in the biotin carboxyl carrier protein domain. Comparison of the genomic nucleotide sequence to the sequences of cDNA clones has revealed the presence of two introns in the gene. Research teams are currently constructing expression vectors containing this gene and developing algal transformation protocols to enable over-expression of ACCase in C. cryptica and other algal species.
More articles & news on algal oil yield: Visitors may kindly have a look at the Oilgae Blog Directory for relevant blog articles.
Comparison of average oil yields from algae with that from other oilseeds
The table below presents indicative oil yields from various oilseeds and algae. Please note that there are significant variations in yields even within an individual oilseed depending on where it is grown, the specific variety/grade of the plant etc. Similarly, for algae there are significant variations between oil yields from different strains of algae. The data presented below are indicative in nature, primarily to highlight the order-of-magnitude differences present in the oil yields from algae when compared with other oilseeds. ( see also: Vegetable Oils Yields & Characteristics from Journey to Forever)
Yield of Various Plant Oils
Crop Oil in Liters per hectare
Castor 1413 Sunflower 952 Safflower 779 Palm 5950 Soy 446 Coconut 2689 Algae 100000
Reference: Chemistry & Structure of Fixed Oils
Fixed oils from seeds, nuts & vegetables are typically composed of triglyceride molecules (also known as triacylglycerol or triacylglyceride). A triglyceride is a glyceride in which the glycerol is esterified with three fatty acids - a triglyceride is typically composed of a 3-carbon alcohol (glycerol) plus three 18-carbon (or 16-carbon) fatty acids. The 18-carbon fatty acids are Linoleic acid, Stearic acid & Oleic acid.
The fatty acids may be saturated (with all single bonds), mono-unsaturated (with one double bond) or polyunsaturated (with 2 or more double bonds). Plant fatty acids are usually unsaturated and liquid at room temperature, with one or more double bonds between the carbon atoms (mono-unsaturated and polyunsaturated). A notable exception is the palm fatty acid palmitin which is saturated and contains 16 rather than 18 carbon atoms. Since the plant fatty acids are unsaturated, the plant oils it is liquid at room temperature.
See also: Triglycerides from Wikipedia, Linoleic Acid from Wikipedia, Stearic Acid from Wikipedia, Oleic Acid Physical & Chemical Properties, Fats, Oils, Fatty Acids, Triglycerides Chemical Structure, See also: Food, Fats & Oils from ISEO (PDF), Determining the Contents of Oilseeds (PDF)
Cis & Trans Fatty Acids
Fatty acid isomers containing double bonds may have the cis or trans configuration. In cis fatty acids, all the hygrogen atoms adjacent to the double bonds are on the same side of the longitudinal carbon axis. In trans fatty acids, the hygrogen atoms adjacent to the double bonds occur on alternate sides of the main axis.
The trans configuration is chemically more stable. It is typically produced during partial hydrogenation of polyunsaturated vegetable oils.
Trans fatty acids tend to raise the level of low density lipoproteins (LDLs = bad) and lower the level of high density lipoproteins (HDLs = good). These changes in blood lipids (cholesterol levels) may increase the risk of heart disease (atherosclerosis) in some people. Dieticians generally recommend the use of mono-unsaturated, unhydrogenated oils and the avoidance of trans fatty acids found in french fries, cookies and crackers.
Unsaturated fatty acids found in plant oils and seeds are typically omega-6 fatty acids, in which the first double bond is located on the sixth carbon atom, counting backwards from right to left. Omega-3 fatty acids in which the first double bond in on carbon #3 - are prevalent in fish oils and flax seeds.
Oil Content of Fixed Oils
Cereals only contain about 2% by weight oil, compared to oilseeds that contain much higher levels. The oil content of oilseeds varies widely from one type to the other. It is about 20% in soybeans and as high as 50% in some new Australian varieties of canola (The oil content of canola seed varies from 35 to 50%, and is usually considered to be averaging 40%). Sunflower has one of the highest oil contents among oilseeds about 55%. Castor seeds have about 45-50% comprised of oil. Safflower has about 40% of its contents as oil, and cottonseed has about 20% of its weight as oil. Hemp has 30-35% oil content. Copra, the dried coconut meat, has about 60% (sometimes close to 65%) oil content. Peanuts contain approximately 50% oil on a dry weight basis. Palm kernel has about 50% oil. Corn has only 5-10% of its dry weight as oil. The average oil content of mustard is about 40% - yellow mustard have only about 27% while brown mustard have about 36% oil; some oriental mustard have upto 50% oil. Flaxseed has about 45% oil content. For jatropha, the oil content is 35-40% in the seeds and 50-60% in the kernel
Oil content (% of dry weight) average values
Soy - 20 Canola/rapeseed - 40 Sunflower - 55 Castor - 45 Safflower - 40 Hemp - 30 Copra (Dry Coconut) - 60 Peanuts/Groundnuts - 50 Palm Kernel - 50 Corn - 7 Mustard - 40 Flaxseed - 45 Jatropha seed - 40 Jatropha kernel - 55 Algae (for comparison)- 15-40% Olive Oil? Sesame Oil?
See also: Vegetable Oil Yields & Characteristics from Journey to Forever
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