Algae culture is a form of aquaculture involving the farming of species of algae for purposes of producing food or other products that can be extracted from the cultivated species. The examples and perspective in this article may not represent a worldwide view. ... A seaweed (Laurencia) up close: the branches are multicellular and only about 1 mm thick. ...

Cultivation methods

Algae can be cultured in raceway-type ponds and lakes [1] Due to the fact that these systems are "open" to the elements, sometimes called "open-pond" systems, they are much more vulnerable to being invaded by other algal species and bacteria. The number of species that have been successfully cultivated for a given purpose, (ie: as a food source, for oil production, or for pigments.), in an outdoor system, are relatively small. In open systems you do not have control over water temperature, and you have little control over lighting conditions. Depending on where you live the growing season is limited to the warmer months. Some of the benefits of this type of system are that it is one of the cheaper ones to produce - at the most basic you only need to dig a trench or pond. It also has one of the largest production capacities compared to other systems, and depending on how large it's made. A variation on the basic "open-pond" system is to close it off, to cover your pond or pool with a greenhouse. While this usually results in a smaller system, (for economic reasons), it does take care of many of the problems associated with an open system. It allows more species to be able to be grown, it allows the species that you are trying to grow to stay dominant, and it extends the growing season, only slightly if unheated, and if heated it can produce year round. A raceway pond is a long, relatively shallow open-pond made up of channels that wind around, sometimes in the pattern of an automotive raceway, though many ponds look like a very simple maze if looked at from above. ... In biology, pigment is any material resulting in color in plant or animal cells which is the result of selective absorption. ...

Algae can be grown in a photobioreactor. A photobioreactor is basically a bioreactor which incorporates some type of light source. While almost anything that it would be possible to grow algae in could technically be called a photobioreactor, the term is more commonly used to define a closed system, as opposed to an open tank, or pond. Because these systems are closed, when used to cultivate algae, everything that the algae need to grow, (carbon dioxide, nutrient-rich water and light), all must be introduced into the system. A pond covered with a greenhouse could be considered a photobioreactor. A bioreactor may refer to any device or system that supports a biologically active environment. ...

Different types of photobioreactors include:

• Tanks provided with a light source.[2]
• Polyethylene sleeves or bags.
• Glass or plastic tubes.

• www.ornl.govOak Ridge National Laboratory, photobioreactor system using glow plates.
• [3] tubular photobioreactor
• [4]Greenfuels photobioreactor at M.I.T.
• www.aquasearch.comMethods of microalgae cultivation, photobioreactor.
• www.bgu.ac.il Use of polyethylene sleeves for outdoor cultivation, Glass-tube bioreactor.
• www.fao.org Algal production.
• www.dabney.com Closed-pond system.
• home.bt-webworld.com Algal cultivation supplies, tubular photobioreactor.
• [5] Photobioreactor using polyethylene and chicken wire.
• [6]
• www.variconaqua.com tubular photobioreactors

In most algal-cultivation systems, light only penetrates the top 3-4 inches of the water. This is because as the algae grow and multiply they become so dense that they block light from reaching deeper into the pond or tank. Algae only need about 1/10 the amount of light they receive from direct sunlight. Direct sunlight is often too strong for algae. In order to have ponds that are deeper than 4 inches algae growers use various methods to agitate the water in their ponds, exposing the algae below to light and keeping algae on the surface from being over-exposed. Glow plates are sheets of glass or plastic that glow, when light is supplied to one of its edges. ... MIT redirects here. ...

• Paddle wheels can be used to circulate the water in a pond.
• Compressed air can be introduced into the bottom of a pond or tank, bringing algae from the lower levels up to the top to receive its share of light.

Aside from agitation, another means of supplying light to algae is to place the light in the system.

• Glow plates are sheets of plastic or glass that can be submerged into the water of a tank, providing light directly to the algae at the right concentration.

The odour that many people assosciate with bogs or swamps, or stagnant ponds that have been taken over by algae is due to the depletion of oxygen in the water caused by the death of algal blooms that have been left to decay. Often the oxygen is depleted to the point where it kills all the fish, resulting in an even worse smell. In a system where algae is intentionally cultivated, maintained, and harvested, this situation should never arise, the air around an algal pond should actually be very fresh from all the oxygen produced. Glow plates are sheets of glass or plastic that glow, when light is supplied to one of its edges. ...

Harvesting

Algae can be harvested using microscreens, by centrifugation, or by flocculation. Centrifugation is a process that involves the use of the centrifugal force for the separation of mixtures. ... Flocculation refers to a process where a solute comes out of solution in the form of floc or flakes. The term is also used to refer to the process by which fine particulates are caused to clump together into floc. ...

Chitosin can be used as a flocculant. The shells of crustaceans are ground into powder and processed to aquire chitin, a polysaccharide found in the shells, from which Chitosin is derived. Chitosin is commonly used for water purification. Structure of chitin molecule In biology, chitin (pronounced keye-tin) is one of the main components in the cell walls of fungi, the exoskeletons of insects and other arthropods, and in some other animals. ... Polysaccharides (sometimes called glycans) are relatively complex carbohydrates. ...

• www.pubmedcentral.gov harvesting of algae by froth flotation(pdf)

Oil Extraction

• Chemical solvents-Algal oil can be extracted using chemicals. Benzene and Ether have been used, oil can also be separated by Hexane extraction, which is widely used in the food industry and is relatively inexpensive. [7]. The downside to using solvents for oil extraction are the dangers involved in working with the chemicals. Care must be taken to avoid exposure to vapors and direct contact with the skin, either of which can cause serious damage. Benzene is classified as a carcinogen. Chemical solvents also present the problem of being an explosion hazard.
• 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. [8]
• 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.
• 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.
• Supercritical fluid-In supercritical fluid/CO2 extraction, CO2 is liquefied under pressure and heated to the point that it has the properties of both a liquid and a gas, this liquified fluid then acts as the solvent in extracting the oil. [9]
• Ultrasonic-assisted extraction- Ultrasonic extraction, a branch of sonochemistry, can greatly accelerate extraction proccesses. Using an ultrasonic reactor, ultrasonic waves are used to create cavitation bubbles in a solvent matireal, when these bubbles collapse near the cell walls, it creates shock waves and liquid jets that causes those cells walls to break and release their contents into the solvent.[10]

www.cyberlipid.org Soxhlet extraction A substance is soluble in a fluid if it dissolves in the fluid. ... Benzene, also known as C6H6, PhH, and benzol, is an organic chemical compound that is a colorless and flammable liquid with a pleasant, sweet smell. ... Ether is the general name for a class of chemical compounds which contain an ether group — an oxygen atom connected to two (substituted) alkyl groups. ... R-phrases , , , , , , S-phrases , , , , , , , Flash point −23. ... In pathology, a carcinogen is any substance or agent that promotes cancer. ... Fractional distillation is the separation of a mixture of compounds by their boiling point, by heating to high enough temperatures. ... Osmotic pressure or turgor (also called turgor pressure) is the pressure produced by a solution in a space that is enclosed by a differentially permeable membrane. ... A supercritical fluid is any substance at a temperature and pressure above its thermodynamic critical point. ... A supercritical fluid is any substance at a temperature and pressure above its thermodynamic critical point. ... Carbon dioxide is an atmospheric gas composed of one carbon and two oxygen atoms. ... In chemistry, the study of sonochemistry is concerned with understanding the effect of sonic waves and wave properties on chemical systems. ... A schematic representation of a Soxhlet extractor A Soxhlet extractor is a type of laboratory glassware invented in 1879 by Franz von Soxhlet. ...

Algae as an energy source

Biodiesel production

www.eere.energy.govDepartment of Energy Aquatic Species Program; Biodiesel Production from Algae. (pdf)

Currently most research into efficient algal-oil production is being done in the private sector, but if predictions from small scale production experiments bear out then using algae to produce biodiesel may be the only viable method by which to produce enough automotive fuel to replace current world gasoline usage. The per unit area yield of oil from algae,(estimated to be from between 5,000 to 20,000 gallons per acre, per year), is 7 to 31 times greater than the next best crop, palm oil(635gal). Algal-oil processes into biodiesel as easily as oil derived from land-based crops. The difficulties in efficient biodiesel production from algae lie not in the extraction of the oil, which can be done using methods common to the food-industry such as hexane extraction, but in finding an algal strain with a high lipid content and fast growth rate that isn't too difficult to harvest, and a cost-effective cultivation system (ie, type of photobioreactor) that is best suited to that strain. Open-pond systems for the most part have been given up for the cultivation of algae with high-oil content. The energy that a high-oil strain invests into the production of oil is energy that is not invested into the production of proteins or carbohydrates, usually resulting in the species being less hearty, or having a slower growth rate. Algal species with a lower oil content, not having to divert their energies away from growth, have an easier time in the harsher conditions of an open system. Research into algae for the mass-production of oil is mainly focused on microalgae, (which is a term generally referred to as organisms capable of photosynthesis that are less than 2mm in diameter), as opposed to macroalgae, (ie. seaweed). This preference towards microalgae is due largely to its less complex structure, fast growth rate, and high oil content- (for some species). Some commercial interests into large scale algal-cultivation systems are looking to tie-in to existing infrastructures, such as coal power plants or sewage treatment facilities. This approach not only provides for the needs of the system, such as CO2 and nutrients, which, if the facility were built independently, would have to be otherwise acquired, but in addition it remediates waste. Biodiesel sample Biodiesel refers to any diesel-equivalent biofuel usually made of vegetable oils or animal fats. ... Biodiesel sample Biodiesel refers to any diesel-equivalent biofuel usually made of vegetable oils or animal fats. ... Biodiesel sample Biodiesel refers to any diesel-equivalent biofuel usually made of vegetable oils or animal fats. ... R-phrases , , , , , , S-phrases , , , , , , , Flash point −23. ... Figure 1: Structure of a Lipid. ... Microalgae are the most primitive form of plants. ...

• biodieselnow.com biodiesel production-biodiesel from algae
• groups.yahoo.com oil from algae
• europa.eu.int Biofuels production from microalgae after heterotrophic growth.(pdf)

Hydrogen production

Algae can be grown to produce hydrogen. In 1939 a German researcher named Hans Gaffron, while working at the University of Chicago, observed that the algae he was studying, Chlamydomonas reinhardtii (a green-algae), would sometimes switch from the production of oxygen to the production of hydrogen.[11] Gaffron never discovered the cause for this change and for many years other scientists failed in their attempts at its discovery. In the late 1990's professor Anastasios Melis a researcher at the University of California at Berkeley discovered that if you deprive the algae of sulfur it will switch from the production of oxygen (normal photosynthesis), to the production of hydrogen. He found that the enzyme responsible for this reaction is hydrogenase, but that the hydrogenase will not cause this switch in the pressence of oxygen. Melis found that depleting the amount of sulfur available to the algae interrupted its internal oxygen flow, allowing the hydrogenase an environment in which it can react, causing the algae to produce hydrogen. [12] Chlamydomonas moewusii is also a good strain for the production of hydrogen. [13] General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... Binomial name Chlamydomonas reinhardtii Chlamydomonas reinhardtii or Green yeast is a single celled green alga about 10 micrometres in diameter which swims with two flagella. ... Leaf. ... Ribbon diagram of the catalytically perfect enzyme TIM. An enzyme is a protein that catalyzes, or speeds up, a chemical reaction. ... A hydrogenase is an enzyme that catalyses the reversible oxidation of molecular hydrogen (H2). ...

• pmb.berkeley.edu
• www.fuelcellsworks.com
• www.autoblog.com
• www.theregister.co.uk
• www.bionik.tu-berlin.de (german)

Biomass

Ethanol

Methane

Industrial Uses

• [14]

Dyes and Colorants

• [15]

Nutritional

There are many algae that are cultivated for their nutritional value, either for supplemental use, or as a food source. Spirulina(Arthrospira platensis) is a blue-green algae(cyanobacteria) that is quite nutritious, this species does very well in open systems and commercial growers have found it well-suited to cultivation. One of the largest production sites for Spriulina is Lake Texcaco in central Mexico. Species Spirulina corakiana Spirulina crispum Spirulina labyrinthiformis Spirulina laxa Spirulina laxissima Spirulina major Spirulina meneghiniana Spirulina nordstedtii Spirulina princeps Spirulina subsalsa Spirulina subtilissima Spirulina platensis Spirulina tenerrima Spirulina weissii Spirulina is a genus of filamentous cyanobacteria (commonly called blue-green algae), with a coil-like shape. ... Orders The taxonomy of the Cyanobacteria is currently under revision. ...

Astaxanthin is commercially produced by overexposing the algal-species Haematococcus pluvialis to direct sunlight causing it to produce astaxanthin in defense. Astaxanthin is a carotenoid that has the ability to pass between the blood and the brain, carotenoids such as lycopene and beta-carotene can not. Astaxanthin Salmon roe at the Shiogama seafood market in Japan Astaxanthin is the chemical that gives krills, lobsters, shrimp, and some crabs their red color when they are cooked. ... Carotenoids are organic pigments naturally occurring in plants and some other photosynthetic organisms like algae, some types of fungus and some bacteria. ...

cantaxanthin Chlorella

• [16]
• [17]

Plastics production from algae

• www.biomatnet.org Algae as raw material for production of bioplastics and biocomposites.
• www.patentstorm.us U.S. patent for algal plastics
• www.feasta.org

Rowell et al. "Emerging Technologies for Materials and Chemicals from Biomass" American Chemical Society Symposium Series, vol. 476, Chapters 3, 12, 13 and 18, Aug. 1990.

Pollution control

• [18]
• Greenshift corporation

Algal cultures available for purchase

• www.bio.utexas.edu/
• www2.carolina.com (algae) (cyanobacteria)
• Algal cultures

Algal cultures are strains of algae that have been collected, identified, and preserved or stored in some way. ...

External links

• biodieselnow.com biodiesel production-biodiesel from algae
• www.phyco.org; a wiki-based site that is focused on energy production from algae.

• www.spirulinasource.com an informative online book on Spirulina
• perso.wanadoo.fr GROW YOUR OWN SPIRULINA
• www.io-warnemuende.de The IOW-Picture Gallery of Baltic microalgae
• www.sas.org how to home grow micro algae in soda bottles
• www.melevsreef.comCulture your own Live Phytoplankton
• http://www.sjwilson.net/reef/phytosteps.html/ 10 step phytoplankton culture
  

• www-cyanosite.bio.purdue.eduA Webserver for Cyanobacterial Research

Phycology groups

• http://www.intphycsoc.org/ International Phycological Society
  
• http://www.psaalgae.org/ Phycological Society of America
  
• http://www.schweizerbart.de/j/algological-studies/ Algological Studies is an international journal of phycology which publishes peer reviewed scientific papers of international significance from the entire field of algology (phycology)