Algaculture
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2008-07-17T02:12:39Z
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Reverted 1 edit by [[Special:Contributions/74.130.212.162|74.130.212.162]]; Spam. ([[WP:TW|TW]])
[[Image:Spirulina farm.jpg|thumb|200px|left|An open pond [[Spirulina]] farm]]
{{aquaculture topics}}
'''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 on a large scale as microalgae and are most often harvested wild from the ocean.
Some of the commercial and industrial purposes of algae cultivation are for production of [[bioplastics]], [[dyes]] and [[colorants]], feedstock, [[pharmaceuticals]], [[pollution control]], and for possible future food and [[algae fuel]] sources.
==History and uses of algae==
[[Image:Dulce.JPG|thumb|Dulse is one of many edible algae.]]
Presumably, the first use of algae was food. One example is the wrapper on a [[sushi]] roll. Other species are edible as well, such as [[Spirulina (dietary supplement)|Spirulina]] and dulse (''[[Palmaria palmata]]''). [[Dulse]] is a red species sold particularly in [[Ireland]] and Atlantic [[Canada]]. It is eaten raw, fresh, dried, or cooked like spinach.
[[Spirulina (dietary supplement)|Spirulina]] is a blue-green microalgae with a long history as a food source in East Africa and pre-colonial Mexico. As it is high in protein and other nutrients it is currently used as a food supplement and as a treatment for malnutrition.
[[Chlorella]], another popular microalgae, has similar nutrition and is an ingredient of "Chlorella Growth Factor," a nutritional supplement which makes the unsubstantiated claim that it can increase growth in animals and children.<ref>{{cite web|url=http://www.naturalways.com/chlorella-growth-factor.htm|title=Chlorella Growth Factor, nutritional supplement.}}</ref> Chlorella, particularly a transgenic strain which carries an extra mercury reductase gene, has been studied as an agent for the environmental remediation due to its ability to reduce Hg2+ to the less toxic elemental mercury. <ref>{{cite journal |author=Huang C |title=Expression of mercuric reductase from Bacillus megaterium MB1 in eukaryotic microalga Chlorella sp. DT: an approach for mercury phytoremediation. |journal=Appl Microbiol Biotechnol. |volume=72 |issue=1 |pages=197-205 |year=2006 |pmid=16547702}}</ref> As a nutritional supplement it is touted as a method of reducing mercury levels, supposedly by chelation of the mercury to the cell wall of the organism. However, what little scientific study there is on this topic, appears to contradict this claim.
<ref>{{cite web|url=http://www.autismwebsite.com/ari/dan/heavymetals.pdf|title=Treatment Options for Mercury/Metal
Toxicity in Autism and Related Developmental Disabilities:
Consensus Position Paper}}</ref> Chlorella is very popular in [[Japan]] and is currently one of the most prescribed supplements in that country{{Fact|date=February 2007}}.
Purple laver (''[[Porphyra]]'') is also collected and used in a variety of ways. In [[Wales]], for example "[[laverbread]]" is a traditional food, and in [[Ireland]] it is collected and made into a jelly by stewing or boiling. Preparation also can involve frying or converting to a pinkish jelly by heating the fronds with a little water and beating with a fork. It is also harvested along western coast of [[North America]], from [[California]] to [[British Columbia]] and by [[Native Hawaiians]] and the [[Māori]] of [[New Zealand]].
Irish moss (''[[Chondrus crispus]]''), often confused with ''[[Mastocarpus stellatus]]'', is the source of [[carrageenan]] for the stiffening of instant puddings, sauces, and dairy products such as ice cream. Irish moss is also used by brewers as a [[fining]] agent; the addition of Irish moss to the wort 15 minutes before the end of the boil produces a clearer beer{{Fact|date=February 2007}}.
[[Sea lettuce]] (''Ulva lactuca''), is used in [[Scotland]] where it is added to soups and salads. Dabberlocks or badderlocks (''[[Alaria esculenta]]'') is eaten either fresh or cooked in [[Greenland]], [[Iceland]], Scotland and Ireland.
For centuries [[seaweed]] has been used as fertilizer. It is also an excellent source of [[Potassium]] for manufacture of [[potash]] and [[potassium nitrate]].
There are commercial uses of algae, such as [[agar]].<ref name="SeaweedUses">{{cite journal | author= | title=Seaweeds and their Uses | journal=Methuen & Co. Ltd., London | year= | volume= | issue= | pages= }}</ref><ref name="PorphyraAsfood">{{cite journal | author=Mumford, T.F. and Miura, A | title=Porphyra as food: cultivation and economics | journal=In Lembi, C.A. and Waaland, J.R. (Ed.) Algae and Human Affairs | year=1988 | volume= | issue= | pages= 87–117}}</ref><ref name="SeaweedInEurope">{{cite journal | author=Guiry, M.D. and Blunden, G. | title=Seaweed Resources in Europe: Uses and Potential. | journal=John Wiley and Sons Ltd. | year=1991 | volume= | issue= | pages= }}</ref>
==Growing, harvesting, and processing algae==
===Algae monoculture===
Often it is desired to grow just one species of algae in each growing vessel. With mixed cultures, one species tends to dominate over time and if a non dominant species is believed to have particular nutritive value for some larval animal, it is necessary to obtain pure cultures in order to cultivate this species. Individual species cultures are also needed for research purposes.
A common method of obtaining pure cultures is serial dilution. A wild sample or a contaminated lab sample of algae containing the desired algae is diluted with filtered water and small aliquots are introduced into a large number of small growing containers. The dilution is done following a microscopic examination of the source culture to a degree that leads one to expect on average there will be a few of the growing containers with only one cell of the desired species. Following a suitable period on a light table, microscopic examination then selects out the successful growing containers and they are used to start larger cultures.
===Growing algae===
[[Image:Spirulina drying.jpg|thumb|right|Drying of harvested Spirulina]]
When cultivating algae, several factors must be considered, and different algae have different requirements. The water must be in a temperature range that will support the specific algal species being grown. Nutrients must be controlled so algae will not be "starved" and so that nutrients will not be wasted. Light must not be too strong nor too weak.
Algae can be mainly cultured in open-ponds (such as [[raceway pond|raceway-type ponds]] and lakes) and [[photobioreactor]]s. Raceway ponds may be less expensive.{{Fact|date=July 2008}}
==== Open-ponds ====
[[Raceway pond|Raceway-type ponds]] and lakes <ref name="spirulina1">{{cite web |last = |first = | year = | url = http://www.spirulinasource.com/earthfoodch6a.html#tour |title = How spirulina is ecologically grown | work = |publisher = spirulinasource | accessdate = 2006-08-28}}</ref> are open to the elements and so sometimes called "open-pond" systems. They are much more vulnerable to contamination by other microorganisms, such as invasive algal species or bacteria. Because of these factors, the number of species successfully cultivated in an "open-pond" system for a specific purpose (such as for food, for the production of oil, or for [[pigments]]) are relatively limited. In open systems one does not have control over water temperature and lighting conditions. The growing season is largely dependent on location and, aside from tropical areas, is limited to the warmer months. A major benefit to this type of system are that it is one of the cheaper ones to construct, in the very least only a trench or pond needs to be dug. It can also have some of the largest production capacities relative to other systems of comparable size and cost. This type of culture can be viable when the particular algae in question requires (or is able to survive) some sort of extreme condition that other algae can not survive. For instance, Spirulina sp. can grow in water with a high concentration of sodium bicarbonate and Dunaliela salina will grow in extremely salty water. Open culture can also work if there is a simple inexpensive system of selecting out the desired algae for use and to inoculate new ponds with a high starting concentration of the desired algae. Some chain diatoms fall into this category as they can be filtered from a stream of water flowing through an outflow pipe. A "pillow case" of a fine mesh cloth is tied over the outflow pipe and most algae flow right through. The chain diatoms are held in the bag and used to feed shrimp larvae (in Eastern hatcheries) and to inoculate new tanks or ponds.
A variation on the basic "open-pond" system is to close it off, to cover a 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 grown, it allows the species that are being grown to stay dominant, and it extends the growing season, only slightly if unheated, and if heated it can produce year round.
==== Photobioreactors ====
Algae can also be grown in a [[photobioreactor]] (PBR). A PBR is a [[bioreactor]] which incorporates some type of light source. Virtually any [[translucent]] [[container]] could be called a PBR, however the term is more commonly used to define a closed system, as opposed to an open tank or pond. Because these systems are closed, all essential nutrients must be introduced into the system to allow algae to grow and be cultivated. Essential nutrients include [[CO2 sequestration|carbon dioxide]], water, minerals and light (the basic reaction is carbon dioxide + water + light energy = glucose + oxygen + water <ref>http://www.coolclassroom.org/cool_projects/lessons/biology/resources.html</ref>). A pond covered with a [[greenhouse]] could be considered a PBR. A PBR can be operated in "[[batch]] mode", but it is also possible to introduce a [[continuous]] stream of sterilized water containing nutrients, air, and carbon dioxide. As the algae grows, excess culture overflows and is harvested. If sufficient care is not taken, continuous bioreactors often collapse very quickly, however once they are successfully started, they can continue operating for long periods. An advantage of this type of algae culture is that algae in the "[[log phase]]" <!-- dear author/editor: please define "log phase", or link to a definition --> is produced which is generally of higher nutrient content than old "[[senescent]]" algae. It can be shown that the maximum productivity for a bioreactor occurs when the "exchange rate" (time to exchange one volume of liquid) is equal to the "doubling time" (in mass or volume) of the algae.
While algae is often grown in [[monoculture]]s using [[microbiological]] techniques to [[purify]] the desired strain, another approach has been used very successfully to produce algae feed for the cultivation of a variety of [[mollusk]]s. Sea water is passed through filters to remove algae which are too large for the [[larvae]] being cultivated. Tanks in a green house, sometimes on a [[balcony]] in the mollusk house, are filled with the partially filtered water and nutrients are added. The tanks may be aerated and the water is used after only a day or two of growing. The resulting thin soup of mixed algae has been shown to be an excellent food source for larval mollusks. An advantage of this method of algaculture is the low maintenance requirements.
Different types of PBRs include:
* tanks provided with a light source
* [[polyethylene]] sleeves or bags
* glass or plastic tubes.
==== Light supply ====
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 1/10th 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, thus circulating the algae so that it does not remain on the surface, which would cause it to be over-exposed. [[Paddle wheel]]s can be used to circulate the water in a pond. [[Compressed air]] can be introduced into the bottom of a pond or tank to agitate the water, bringing algae from the lower levels up with it as it makes its way to the surface.
Apart from agitation, another means of supplying light to algae is to place the light ''in'' the system. [[Glow plate]]s are sheets of plastic or glass that can be submerged into a tank, providing light directly to the algae at the right concentration.
==== Odor prevention ====
The odor associated with [[bogs]], [[swamps]], or any stagnant waters that have been taken over by algae, is due to oxygen depletion in the water caused by the decay of deceased [[algal bloom]]s. Under anoxic conditions, the bacteria inhabiting algae cultures break down the organic material and produce [[hydrogen sulfide]] and [[ammonia]] which causes the odor. This condition, called [[hypoxia (environmental)|hypoxia]], often results in the death of all aquatic animals. In a system where algae is intentionally cultivated, maintained, and harvested, neither [[eutrophication]] nor [[hypoxia (environmental)|aquatic hypoxia]] are likely to occur. Living algae does not emit objectionable odors.
===Harvesting of algae===
Algae can be harvested using microscreens, by [[centrifugation]], or by [[flocculation]].<ref name="FlocculationMicroalgae">{{cite web |last = D. Bilanovic, A. Sukenik, G. Shelef (PDF) |first = | year = 1988 | url = http://www.bemidjistate.edu/dbilanovic/FlocculationIonicStrength.pdf |title = Flocculation of microalgae with cationic polymers. Effects of medium salinity. | work = |publisher = Elsevier Science Publishers Ltd, England | accessdate = 2006-08-28}}</ref> Froth flotation is another method to harvest algae whereby the water and algae are [[Aerated waters|aerated]] into a froth, with the algae then removed from the water.<ref name="FrothingAlgaeHarvest">{{cite web |last = Gilbert V. Levin, John R. Clendenning, Ahron Gibor, and Frederick D. Bogar. (PDF) |first = | year = 1961 | url = http://www.pubmedcentral.gov/picrender.fcgi?artid=1057831&blobtype=pdf |title = Harvesting of Algae by Froth Flotation | work = |publisher = Research Resources, Inc, Washington, D.C. | accessdate = 2006-08-28}}</ref> [[Alum]] and [[ferric chloride]] are chemical flocculants used to harvest algae. A commercial product called "Chitosin", commonly used for water purification, can also be used as a flocculant. The shells of [[crustaceans]] are ground into powder and processed to acquire [[chitin]], a [[polysaccharide]] found in the shells, from which chitosin is derived. Water that is more [[brackish]], or saline requires additional chemical flocculant to induce flocculation. Harvesting by chemical flocculation is a method that is often too expensive for large operations. Interrupting the [[carbon dioxide]] supply to an algal system can cause algae to flocculate on its own, which is called "autoflocculation". [[Ultrasound]] based methods of algae harvesting are currently under development, and other, additional methods are currently being developed.<ref name="UltrasoundAlgaeHarvest">{{cite web |last = Rouke Bosma, Prof. dr.ir J.Tramper, Dr. ir. R.H. Wijffels (PDF) |first = | year = 1961 | url = http://ospt.tnw.utwente.nl/pdf/posterbook/posters/WU-Boom-Bosma.pdf |title = ULTRASOUND A new technique to harvest microalgae? | work = |publisher = Universiteit Twente | accessdate = 2006-08-28}}</ref><ref name="AlgaeHarvestNewMethods">{{cite web |last = |first = | year = | url = http://www.freepatentsonline.com/6524486.html |title = Microalgae separator apparatus and method, United States Patent 6524486 | work = |publisher = United States Patent Department | accessdate = 2006-08-28}}</ref>
===Oil Extraction===
Algae oils have a variety of commercial and industrial uses, and are extracted through a wide variety of methods. The simplest method is mechanical crushing. Since different strains of algae vary widely in their physical attributes, various press configurations (screw, expeller, piston, etc) work better for specific algae types. Often, mechanical crushing is used in conjunction with chemicals (see below). Estimates of the cost to extract oil from microalgae vary, but are likely to be around $1.80/kg (compared to $0.50/kg for palm oil).<ref name="chisti">{{cite journal |last = Chisti |first = Y. |title = Biodiesel from microalgae |journal = Biotechnology Advances |volume = 25 |pages = 294–306 |date = 2007 |doi = 10.1016/j.biotechadv.2007.02.001}}</ref>
* [[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. 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.<ref name="HexaneRisks">{{cite web |last = |first = | year = | url = http://www.healthfromthesun.com/HexaneFreePg.htm |title = Essential Fatty Acids and Herb FAQ's: What are the hazards of Hexane? | work = |publisher = Health From The Sun | accessdate = 2006-08-28}}</ref>
::[[Soxhlet]] extraction is an extraction method that uses chemical solvents. Oils from the algae are extracted through repeated washing, or [[percolation]], with an organic solvent such as [[hexane]] or [[petroleum ether]], under [[reflux]] in a special glassware.<ref name="AutoSoxhletExtraction">{{cite web |last = |first = | year = | url = http://www.cyberlipid.org/extract/extr0010.htm |title = AUTOMATIC SOXHLET EXTRACTION | work = |publisher = cyberlipid.org | accessdate = 2006-08-28}}</ref>
* [[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.<ref name="EnzymaticExtraction">{{cite web |last = |first = | year = | url = http://www.p2pays.org/ref/10/09365.htm |title = Aqueous Enzymatic Extraction of Oil from Rapeseeds | work = |publisher = Institute for Applied Environmental Economics | accessdate = 2006-08-28}}</ref> The enzymatic extraction can be supported by ultrasonication. The combination "sonoenzymatic treatment" causes faster extraction and higher oil yields. <ref name="SonoenzymaticExtraction">{{cite web |last = |first = | year = | url = http://www.hielscher.com/ultrasonics/algae_extraction_01.htm#Ultrasonic_Enzymatic_Extraction |title = Ultrasonically assisted enzymatic extraction | work = |publisher = hielscher.com | accessdate = 2007-11-06}}</ref>
* Expression/[[Expeller pressing|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]]/CO<sub>2</sub> extraction, [[carbon dioxide|CO<sub>2</sub>]] 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.<ref name="supercriticalfluids1">{{cite web |last = |first = | year = | url = http://www.supercriticalfluids.com/faqs.htm |title = How Do Supercritical Fluids Work? | work = |publisher = Supercritical Fluid Technologies | accessdate = 2006-08-28}}</ref><ref name="supercriticalfluids2">{{cite web |last = |first = | year = | url = http://www.phasex4scf.com/supercritical_markets/supercritical_fluids_nutraceuticals.htm |title = Nutraceuticals and Supercritical Fluid Applications: Production of Astaxanthin Concentrate | work = |publisher = Phasex | accessdate = 2006-08-28}}</ref>
* [[Ultrasonic]]-assisted extraction: Ultrasonic extraction, a branch of [[sonochemistry]], 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 causes those cells walls to break and release their contents into the solvent.<ref name="Sonochemistry">{{cite web |last = |first = | year = | url = http://www.gov.pe.ca/ftc/index.php3?number=1006554&lang=E |title = Sonochemistry | work = |publisher = Prince Edwards Island Government Food Technology Centre | accessdate = 2006-08-28}}</ref>
Other methods are still being developed, including ones to extract specific types of oils, such as those with a high production of long-chain highly unsaturated fatty acids.<ref name="UltrasoundAlgaeHarvest">{{cite web |last = Rouke Bosma, Prof. dr.ir J.Tramper, Dr. ir. R.H. Wijffels (PDF) |first = | year = 1961 | url = http://ospt.tnw.utwente.nl/pdf/posterbook/posters/WU-Boom-Bosma.pdf |title = ULTRASOUND A new technique to harvest microalgae? | work = |publisher = Universiteit Twente | accessdate = 2006-08-28}}</ref><ref name="AlgaeHarvestNewMethods">{{cite web |last = |first = | year = | url = http://www.freepatentsonline.com/6524486.html |title = Microalgae separator apparatus and method, United States Patent 6524486 | work = |publisher = United States Patent Department | accessdate = 2006-08-28}}</ref>
{| class="wikitable"
== Algae as an energy source ==
{{Main|Algae fuel}}
===Biofuels production===
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]], [[bioethanol]] and [[biobutanol]] may be the only viable method by which to produce enough automotive fuel to displace current world gasoline usage.<ref name="BiodieselFromAlgae">{{cite web |last = |first = | year = | url = http://www.eere.energy.gov/biomass/pdfs/biodiesel_from_algae.pdf |title = Biodiesel Production from Algae | work = |publisher = Department of Energy [[Aquatic Species Program]], National Renewable Energy Laboratory | accessdate = 2006-08-29}}</ref>
Microalgae have much faster growth-rates than terrestrial crops. The oil yield per unit area of algae is estimated to be 5,000 to 20,000 gallons per acre, per year (4.6 to 18.4 l/m<sup>2</sup> per year); this is 7 to 30 times greater than the next best crop, [[Chinese tallow]] (699 gallons).<ref name="Biodiesel">{{cite web |last = |first = | year = | url = http://en.wikipedia.org/wiki/Biodiesel |title = Biodiesel | work = |publisher = Wikipedia Biodiesel| accessdate = }}</ref>
The difficulties in efficient biodiesel production from algae lie 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. Additionally, a cost-effective way to extract the oil must be found.
Open-pond methods have largely been abandoned for the cultivation of algae with high-oil content. Many believe that a major flaw of the [[Aquatic Species Program]] was the decision to focus their efforts exclusively on open-ponds. Algae in an open-pond environment are subject to wide swings in temperature and pH, and competition from invasive algae and bacteria. Open systems using a monoculture are also vulnerable to viral infection. The open-pond method makes the entire effort dependent upon the hardiness of the strain chosen, requiring it to be unnecessarily resilient (compared to a closed system) in order to withstand the environmental conditions. For a given amount of photosynthetic energy, an algae strain producing relatively high levels of oil will produce relatively less protein and/or carbohydrate, usually resulting in the species being less hardy, 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.
Some open sewage ponds trial production has been done in [[Marlborough, New Zealand]].<ref name="BiodieselAlgaeSeweragePonds">{{cite web |last = |first = | year = 2006| url = http://www.renewableenergyaccess.com/rea/news/story?id=44928 |title = Biodiesel Made from Algae in Sewerage Ponds | work = |publisher = Renewable Energy Access | accessdate = 2007-01-31}}</ref>
A feasibility study using marine microalgae in a photobioreactor is being done by The International Research Consortium on Continental Margins at the [http://www.iu-bremen.de/ International University Bremen].<ref name="MarineInternationalUniversityBremen">{{cite web |last = |first = | year = 2006| url = http://www.irccm.de/greenhouse/project.html|title = Greenhouse Gas Mitigation Project at the International University Bremen | work = |publisher = The International Research Consortium on Continental Margins | accessdate = 2007-01-31}}</ref>
Research into algae for the mass-production of oil is mainly focused on [[microalgae]]; organisms capable of photosynthesis that are less than 2 mm in diameter, including the [[diatoms]] and [[cyanobacteria]]; as opposed to macroalgae, e.g. 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 the raw materials for the system, such as CO<sub>2</sub> and nutrients; but it changes those wastes into resources.
The corporations Chevron, Honeywell, and Boeing are starting algae businesses. According to Boeing's technology leader for energy and emissions, Dave Daggett, 'In the past two years, we have changed from algae skeptics to proponents'. <ref name="Pond Power">{{cite web |last = |first = | year = 2007| url = http://www.businessweek.com/globalbiz/content/nov2007/gb20071121_358781.htm?chan=globalbiz_europe+index+page_top+stories |title = Here Comes Pond Scum Power | work = |publisher = BusinessWeek | accessdate = 2007-12-02}}</ref>
The development challenge is to reduce the cost of producing algae oil in commercial volumes, i.e. billions of gallons.
"'In Europe, refiners are producing 1.4 billion gallons a year from rapeseed, soy, and other plants. In all, the world consumed $1.7 billion worth of biodiesel last year. That should grow to $26 billion by 2020, says market researcher Global Insight.'"
<ref name="Pond Power">{{cite web |last = |first = | year = 2007| url = http://www.businessweek.com/globalbiz/content/nov2007/gb20071121_358781.htm?chan=globalbiz_europe+index+page_top+stories |title = Here Comes Pond Scum Power | work = |publisher = BusinessWeek | accessdate = 2007-12-02}}</ref>
These figures project an average growth of over 20% per year.
===SVO===
The algal-oil feedstock that is used to produce biodiesel can also be used for fuel directly as "[[Straight Vegetable Oil]]", (SVO). While using the oil in this manner does not require the additional energy needed for [[transesterification]], (processing the oil with an alcohol and a catalyst to produce biodiesel), it does require modifications to a normal diesel engine, whereas [[biodiesel]] can be run in any modern diesel engine, unmodified, that is designed to use [[ultra-low sulfur diesel]], the new diesel fuel standard for the United States of America that went into effect in the fall of 2006.
===Refining to traditional transport fuels===
There are processes for [[vegetable oil refining]] that can produce gasoline, diesel, propane, or kerosene from the oil extracted from algae.
===Hydrogen production===
{{main|Biological hydrogen production (Algae)}}
Algae can be used as a [[Biological hydrogen production|biological]] source for the production of [[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 alga), would sometimes switch
from the production of oxygen to the production of
hydrogen.<ref name="WiredAlgae1">{{cite web |last = |first = | year = | url = http://www.wired.com/news/technology/0,1282,54456,00.html |title = Algae: Power Plant of the Future?
| work = |publisher = Wired News | accessdate = 2006-08-29}}</ref>
Gaffron never discovered the cause for this change and for many years other scientists failed in their
attempts at its discovery. In the late 1990s professor [[Anastasios Melis]], a researcher at the University
of California at Berkeley discovered that by depriving 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 presence 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.
===Biomass===
Algae can be grown to produce [[biomass]], which can then be harvested and burned in the same manner as wood, to produce heat and electricity.<ref name="ENERGYFROMALGAE">{{cite web |last = |first = | year = | url = http://www.accesstoenergy.com/view/atearchive/s76a5002.htm |title = ENERGY FROM ALGAE | work = |publisher = Access To Energy, Cave Junction, Oregon | accessdate = 2006-08-29}}</ref>
===Methane===
Through the use of algaculture grown organisms and cultures, various [[polymeric]] materials can be broken down into [[methane]].<ref name="MethanProductionFromAlgae">{{cite web |last = |first = | year = | url = http://www.fao.org/docrep/w7241e/w7241e0f.htm#TopOfPage |title = Methane production | work = |publisher = FAO, Agriculture Department | accessdate = 2006-08-29}}</ref>
==Commercial and industrial uses==
Algae are cultivated to serve many commercial and industrial uses.
* [[Algaculture#Bioplastics|Bioplastics]]
* [[Algaculture#Dyes and Colorants|Dyes and Colorants]]
* [[Algaculture#Feedstock|Feedstock]]
* [[Algaculture#Nutritional|Nutritional]]
* [[Algaculture#Pharmaceutical|Pharmaceutical]]
* [[Algaculture#Pollution Control|Pollution Control]]
:*CO<sub>2</sub> sequestration
:*Uranium/Plutonium sequestration
:*Fertilizer Runoff reclamation
:*Sewage treatment
===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 thrives in open systems and commercial growers have found it well-suited to cultivation. One of the largest production sites for Spirulina is [[Lake Texcoco]] in central Mexico.<ref name="KickingImp">{{cite web |last = |first = | year = | url = http://www.pathfinder.com/asiaweek/98/0731/feat_2.html |title = The Imp With a Mighty Kick | work = |publisher = Asia Week| accessdate = 2006-08-29}}</ref> The plants themselves produce a variety of nutrients and high amounts of [[protein]], and is often used commercially as a nutritional supplement.<ref name="sbalgae">{{cite web |last = |first = | year = | url = http://www.sbgalgae.com/afa.htm |title = Aphanizomenon Flos-Aquae Blue Green Algae | work = |publisher = Energy For Life Wellness Center| accessdate = 2006-08-29}}</ref><ref name="microalgaenutrition">{{cite web |last = |first = | year = | url = http://www.fao.org/DOCREP/003/W3732E/w3732e07.htm |title = Nutritional value of micro-algae | work = |publisher = United States Fisheries Department| accessdate = 2006-08-29}}</ref> Extracts and oils from algae are also used as additives in various food products.<ref name="algaeicecream">{{cite web |last = |first = | year = | url = http://ift.confex.com/ift/2005/techprogram/paper_31527.htm |title = Sensory properties of strawberry- and vanilla-flavored ice cream supplemented with an algae oil emulsion | work = |publisher = Dept. of Food Science, [[Pennsylvania State University]]| accessdate = 2006-08-29}}</ref> The plants also produce [[Omega-3]] and [[Omega-6]] [[fatty acids]], which are commonly found in [[fish oils]], and which have been shown to have positive medical benefits to humans.<ref name="ISBNews">{{cite web |last = |first = | year = | url = http://www.isb.vt.edu/news/2004/artspdf/jul0403.pdf |title = Transgenic Plants Produce Omega-3 and Omega-6 Fatty Acids | work = |publisher = School of Biology and Biochemistry, [[University of Bath]], England, UK| accessdate = 2006-08-29}}</ref>
===Pollution Control===
Much of the carbon dioxide that is released into the atmosphere is from the burning of fossil fuels. With concerns over global warming, new methods for the thorough and efficient capture of CO<sub>2</sub> are being sought out. An alternative to [[carbon capture and storage]], by attaching an algae pond, or photobioreactor to any fuel burning plant, the carbon dioxide produced during combustion can be fed into the algae system. Nutrients can be sourced from sewage, thus turning two pollutants into resources for the production of biodiesel, with a land requirement much smaller than other crop sources.<ref name="SmokestackGasTank">
{{cite journal
| last = McKenna
| first = Phil
| authorlink =
| coauthors =
| title = From smokestack to gas tank
| journal = New Scientist
| volume = 192
| issue = 2572
| pages = 28–29
| publisher = Reed Business Information
| date = 7 October 2006
| url =
| doi =
| id = ISSN: 1032 1233
| accessdate = }}</ref>
===Future food source===
Large scale algaculture of the oceans, as well as similar culture of other [[plankton]], is proposed as a future [[food source]] in order to support a growing [[world population]]. Currently, however, it has limited application, since e.g. technologies of the [[green revolution]] has resulted in that land-based food production so far has increased faster than the demand of the growing world population.{{Fact|date=April 2008}}
== Algal Culture Collections ==
Specific algal strains can be acquired from algal culture collections.
{{main|List of algal culture collections}}
== See also ==
* [[List of algal culture collections]]
* [[Algal bloom]]
* [[Algal nutrient solutions]]
* [[Algology]]
* [[Aquatic Species Program]]
* [[Biological hydrogen production (Algae)]]
* [[Biofuel]]
* [[Bio Fuel Systems]]
* [[Biotechnology]]
* [[Carbon sequestering]]
* [[Green crude]]
* [[GreenFuel Technologies Corporation]]
* [[Probiotics]]
* [[SERI microalgae culture collection]]
== References ==
<div class="references-small">
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<references/>
</div>
== External links ==
{{Too many links}}
* {{dmoz|Science/Agriculture/Aquaculture/Algaculture|Algaculture}}
'''Algal cultivation'''
* [http://www.sas.org/tcs/weeklyIssues/2004-10-15/feature2/ www.sas.org] How to Rear a Plankton Menagerie (home grow micro algae in soda bottles)
* [http://www.spirulinasource.com/earthfood.html www.spirulinasource.com] an informative online book on Spirulina
* [http://perso.wanadoo.fr/petites-nouvelles/manuel/grow.htm perso.wanadoo.fr] GROW YOUR OWN SPIRULINA
* [http://www.fao.org/DOCREP/003/W3732E/w3732e0b.htm#TopOfPage www.fao.org] Isolation of pure algal strains by the agar plating technique
* [http://io.uwinnipeg.ca/~simmons/ysesp/contents.htm io.uwinnipeg.ca] breeding algae in batch and continuous flow systems on small scale
* [http://www.talkingreef.com/forums/podcast-episodes/557-culturing-phyto-video-podcast-episode-39-a.html www.talkingreef.com] Full How-To video on culturing your own Live Phytoplankton
* [http://www.melevsreef.com/phytoplankton.html www.melevsreef.com]Culture your own Live Phytoplankton
* [http://www.qsl.net/w2wdx/aquaria/diyco2.html www.qsl.net] A Treatise on DIY CO<sub>2</sub> Systems for Freshwater-Planted Aquaria
* [http://kywater.org/watch/ALGAE.HTM kywater.org] general info, including collection technique
* [http://www.marinebio.net/marinescience/02ocean/swcomposition.htm Seawater Composition]
* [http://www.teachingboxes.org/upwelling/lessons/lesson2_activity1.jsp Making Algae Grow]
* [http://www.spirulinasource.com/cultivez.html How to growing algae] (in French)
'''Harvesting'''
* [http://www.lapes.ufrgs.br/ltm/pdf/over.pdf www.lapes.ufrgs.br] Overview of flotation as a wastewater treatment technique '''(pdf)'''
* [http://www.dep.state.fl.us/water/watersheds/docs/ptpac/HydromentiaPresentation.pdf www.dep.state.fl.us] Large-Scale Algal Turf Scrubber Pollutant Recovery System '''(pdf)'''
* [http://www.freepatentsonline.com/6524486.html Patent for microalgae separator apparatus and method].
'''General'''
* [http://www.cae.cn/english/others/content.jsp?id=663 www.cae.cn] general info on microalgae
* [http://www.io-warnemuende.de/research/en_galerie.html www.io-warnemuende.de] The IOW-Picture Gallery of Baltic microalgae
* [http://www-cyanosite.bio.purdue.edu/ www-cyanosite.bio.purdue.edu]A Web server for Cyanobacterial Research
* [http://www.greenfuelonline.com/news/algaefuel.pdf www.greenfuelonline.com]An algae based fuel'''(pdf)'''
* [http://gcep.stanford.edu/pdfs/energy_workshops_04_04/biomass_benemann.pdf gcep.stanford.edu] Stanford University Biomass Energy Workshop: Photosynthesis, Algae, CO<sub>2</sub> and Bio-Hydrogen'''(pdf)'''
* [http://europa.eu.int/comm/research/energy/pdf/36_qingyu_wu_en.pdf europa.eu.int] Biofuels production from microalgae after heterotrophic growth.('''pdf''')
* [https://kb.osu.edu/dspace/bitstream/1811/5981/1/Modeling+and+Simulation+of+the+Algae+to+Biodiesel+Fuel+Cycle+-+Sazdanoff+undergrad+thesis.pdf kb.osu.edu]Modeling and Simulation of the Algae to Biodiesel Fuel Cycle ('''pdf''')
* [http://www.kluyvercentre.nl/content/documents/Verslag3biodieselmaurickcollege.pdf www.kluyvercentre.nl] algae to biodiesel project study('''pdf''')
* [http://igitur-archive.library.uu.nl/geo/2005-0622-145912/UUindex.html igitur-archive.library.uu.nl] Distribution of aliphatic, nonhydrolyzable biopolymers in marine microalgae ('''pdf''')
* [http://www.fao.org/ag/ags/Agsi/MICROALG.htm www.fao.org] lists lipid content of a few species of algae
* [http://oakhavenpc.org/cultivating_algae.htm oakhavenpc.org] Cultivating Algae for Liquid Fuel Production
* [http://www.google.com/u/BenGurionUniversity?q=cache:bXyL056zhGUJ:www.bgu.ac.il/IAR/cv_lib/iaab_ephraim_cohen_profile.doc+microalgae&hl=en&ie=UTF-8 www.bgu.ac.il] Use of polyethylene sleeves for outdoor cultivation, Glass-tube bioreactor.
* [http://www.freepatentsonline.com/5659977.html Patent for integrated microalgae production and electricity cogeneration]
* [http://www.ifremer.fr/aquaculture/en/algae/microalgae.htm www.ifremer.fr] microphytes
* [http://biodiesel.infopop.cc/groupee/forums/a/frm/f/1501000031 biodiesel.infopop.cc] Algae biodiesel forum
* [http://www.needfulprovision.org/projects/biodiesel.php www.needfulprovision.org]
* [http://www.azte.com/Documents/AnIndustrialPhotobioreactorforCommercial_002.pdf www.azte.com] An Industrial Photobioreactor for Commercial Production of AlgaeBased Biodiesel'''(pdf)'''
* [http://www.ecogenicsresearchcenter.org/biodiesel.htm www.ecogenicsresearchcenter.org] pictures of algal-biodiesel
* [http://www.salt.org.il/geo.html www.salt.org.il] Dunaliella Algae - Solar ponds
* [http://www.hielscher.com/ultrasonics/biodiesel_transesterification_01.htm www.hielscher.com] ultrasonication for enhanced biodiesel conversion
* [http://www.algoil.com/ Algoil.com] ALGOIL -Indian project focused on biodiesel production from algae
* [http://www.desertlake.com www.desertlake.com] harvesting wild algae from a lake
* [http://www.americanscientist.org/template/AssetDetail/assetid/53356?&print=yes www.americanscientist.org] Would the widespread adoption of biomass-derived transportation fuels really help the environment?
* [http://www.unu.edu/unupress/unupbooks/80434e/80434E0f.htm www.unu.edu] Indian experience with algal ponds
''' Analysis '''
* [http://www.hedykling.com/ Algal Taxonomy]
'''Photobioreactors'''
* [http://library.wur.nl/wda/dissertations/dis3423.pdf Photobioreactors : Scale-up and optimisation] PhD thesis Wageningen UR.
* [http://wwwscieng.murdoch.edu.au/centres/algae/BEAM-Net/BEAM-Appl4a.htm wwwscieng.murdoch.edu.au] large-scale algal culture systems
* [http://www.bioprodukte-steinberg.de/english/index.HTML www.bioprodukte-steinberg.de] tubular photobioreactor
* [http://www.ornl.gov/sci/hybridlighting/poster1txt.htm www.ornl.gov]Oak Ridge National Laboratory, photobioreactor system using [[glow plate]]s.
* [http://news.com.com/Photos+Betting+big+on+biodiesel/2009-1043_3-5714336.html Greenfuels photobioreactor] at [[M.I.T.]]
* [http://www.malawicichlidhomepage.com/aquainfo/greenwater1.JPG Photobioreactor using polyethylene and chicken wire].
* [http://www.variconaqua.com/bioreactors.htm www.variconaqua.com Tubular photobioreactors]
* [http://www.uni-kiel.de/ftzwest/ag2/projekte/rpbr-e.shtml www.uni-kiel.de] photobioreactor
* [http://www.igv-gmbh.de/englisch/bt/bt_pbr.html www.igv-gmbh.de Photobioreactors: production systems for phototrophic microorganisms]
* [http://www.pubmedcentral.gov/picrender.fcgi?tool=pmcentrez&blobtype=pdf&artid=1056974 www.pubmedcentral.gov] Studies on the Mass Culture of Various Algae in Carboys and Deep-Tank Fermentations'''(pdf)'''
{{fisheries and fishing}}
[[Category:Algae]]
[[Category:High lipid content microalgae]]
[[Category:Aquaculture]]
[[es:Alguicultura]]