Algae Oil Extraction

In terms of the concept, the idea is quite simple: Extract the algea from its growth medium (using an appropriate separation process), and use the wet algae to extract the oil. (Note: The algae need not be dried before oil extraction) 

There are three well-known methods to extract the oil from oilseeds, and these methods should apply equally well for algae too:

1. Expeller/Press
2. Hexane solvent oil extraction
3. Supercritical Fluid extraction

Expeller/Press

Expression/Expeller press-When algae is dried it retains its oil content, which then can be "pressed" out with an oil press. Many commercial manufacturers of vegetable oil use a combination of mechanical pressing and Chemical Solvents in extracting oil.

While more efficient processes are emerging, a simple process is to use a press to extract a large percentage (70-75%) of the oils out of algae.

Hexane Solvent Method

Algal oil can be extracted using chemicals. Benzene and ether have been used, but a popular chemical for solvent extraction is hexane, which is relatively inexpensive. The downside to using solvents for oil extraction are the inherent dangers involved in working with the chemicals. Benzene is classified as a carcinogen. Chemical solvents also present the problem of being an explosion hazard.

Hexane solvent extraction can be used in isolation or it can be used along with the oil press/expeller method. After the oil has been extracted using an expeller, the remaining pulp can be mixed with cyclo-hexane to extract the remaining oil content. The oil dissolves in the cyclohexane, and the pulp is filtered out from the solution. The oil and cyclohexane are separated by means of distillation. These two stages (cold press & hexane solvent) together will be able to derived more than 95% of the total oil present in the algae.

Supercritical Fluid Extraction

This can extract almost 100% of the oils all by itself. This method however needs special equipment for containment and pressure

In the supercritical fluid/CO2 extraction, CO2 is liquefied under pressure and heated to the point that it has the properties of both a liquid and gas. This liquefied fluid then acts as the solvent in extracting the oil.

References for Supercritical fluid extraction – see here, here

Other Less Well-known Extraction Methods

Enzymatic extraction - Enzymatic extraction uses enzymes to degrade the cell walls with water acting as the solvent, this makes fractionation of the oil much easier. The costs of this extraction process are estimated to be much greater than hexane extraction.

References for Enzymatic Extraction – see here & here

Osmotic shock - Osmotic Shock is a sudden reduction in osmotic pressure, this can cause cells in a solution to rupture. Osmotic shock is sometimes used to release cellular components, such as oil.

Ultrasonic-assisted Extraction - Ultrasonic extraction can greatly accelerate extraction processes. Using an ultrasonic reactor, ultrasonic waves are used to create cavitation bubbles in a solvent material, when these bubbles collapse near the cell walls, it creates shock waves and liquid jets that cause those cells walls to break and release their contents into the solvent.

References for Ultrasonic-assisted extraction – see here, Ultrasound – A New Technique to Harvest Microalgae? (PDF), Sonochemistry – from Food Technology Centre, Ultrasonic Irradiation for Synthesis of Biodiesel Fuels

See also: www.cyberlipid.org, Soxhlet extraction, U.S. patent: Process for extracting lipids with a high production of long-chain highly unsaturated fatty acids

More articles & news on algal oil extraction: Visitors may kindly have a look at the Oilgae Blog Directory for relevant blog articles.

See also:

• A Discussion from Biodiesel Now Forums
• Imagine – from Algae to Biodiesel (PDF)
• Oil from Algae Yahoo Group
• Biodiesel from Algae – Groupee Community
• Biodiesel from Algae – US Dept of Energy (PDF)
• Algae Farms Make Case for Kyoto
• Turning Emissions into Fuel with Algae
• Micro-algae for CO2 Utilisation and Biofuel Production (PDF)
• US Dept of Energy’s Aquatic Species Program – Biodiesel from Algae (PDF)
• Biodiesel from Algae is Here
• Biodiesel from Marine Algae – from Hawaii Natural Energy Institute (PDF)
• Modelling & Simulation of the Algae to Biodiesel Fuel Cycle (PDF)
• Green Algae for Carbon Capture & Biodiesel
• Biodiesel from Algae – from the Imagine Project (PDF)
• GreenShift Licenses Bioreactor Technology
• SolaRoof OpenEco Wiki – Oil from Algae
• Biodiesel Created from Algae – Social Forge
• Industrial Photo Bioreactor for Commercial Production of Algae-based Biodiesel (PDF)
• Westfalia Separator – See Westfalia separator homepage & A brochure explaining decanter technology and its applications (PDF)
• Algae Oil Extraction Methods from Yahoo Groups Messages, also this, this
• Centrifuges for Algal Oil Extraction – Info from Phyco.org

Related Blogs

• Professor David Brune,Clemson University uses Brine Shrimp for algae oil extraction
• OriginOil Files Patent for Breakthrough Algae Oil Extraction Technique
• AlgaeLink has Developed a New Method of Oil Extraction for the Production of Algae Oil
• Quantum Fracturing Technology Patent from OriginOil
• Biodiesel from Scenedesmus Obliquus Algae
• Alabama Grant Furthers Cultivating Algae for Biofuel

Other Related Sections

Blue Green Algae, Red Algae, Green Algae, Marine Algae, String Algae, Pond Algae, Pond Algae Control, Algae Control

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About Oilgae - Oilgae - Oil & Biodiesel from Algae has a focus on Biodiesel production from algae while also discussing alternative energy in general. Algae present an exciting possibility as a feedstock for biodiesel, and when you realise that oil was originally formed from algae - among others - you think "Hey! Why not oil again from algae!"
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