Biodiesel From Algae Is It Feasible Biology Essay

As the menace of fossil fuel depletion is approaching the hunt for alternate renewable resources has ne’er been greater. Algae are simple photosynthesising unicellular/milticellular beings which produce high degrees of lipoid. There is a great involvement affecting microalgae and biodiesel production due to their high oil content, there are legion methods to cultivate, pull out and treat the biomass produced. The taking cultivation methods are raceway pools and photobioreactors, although the photobioreactor is the taking system. Raceway pools are less efficient as they are unfastened system intending vaporization of the batch biomass is possible every bit good as taint with other micro-organisms, perchance some which feed on algae. The method of which biodiesel is produced is through transesterification, this involves triacylglycerols ( TAGs ) and intoxicant to organize fatty acerb methyl esters ( biodiesel ) and glycerin. The methods to pull out the biomass are as follows flocculation, centrifugation, filtration and eventually desiccation. In comparing with workss grown for biodiesel suction as rapeseed, thenar or soy, algae produce much higher content per land country unit and flourish in aqueous environments hence would non be in competition with land harvests grown for nutrient.

2. Introduction

These yearss crude oil and Diesel are used more than of all time to fulfill the universe ‘s demand. Oil militias are drying up rapidly and there is increasing demand to happen options to fossil fuel. Fossil fuels are besides a job as they create green house gases such as CO2, NO2 and methane fouling the environment, which increase the rate of planetary heating along with consuming woods ensuing in devastation of home grounds. With turning involvement in biofuel many different ways of extraction from different beginnings has arisen with oil made from workss, carnal fats or recycled fats. Most late microalgae have been a hot subject for research workers ; it is found that algae are a low cost option which produces higher outputs of oil in comparing with harvests and seeds. In this article this subject will be discussed in farther item and whether biodiesel from algae is executable.

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2.1 Background Theory

Interest in algae in usage for commercial intents has been under research for many old ages. One of the first large-scale cultivation of Chlorella, in the 1960 ‘s was produced in Japan by Nihon Chlorella. Interest in biodiesel specifically began in the 1970 ‘s during the first oil crisis. In the Unites States the National Renewable Energy Laboratory ( NREL ) utilizing the Aquatic Species Program ( ASP ) began funding plans affecting research into renewable fuels. This undertaking lasted for many old ages ( 1978-1996 ) until it was terminated due to miss of financess. In these experiments the lipid production biochemistry and physiology of microalgae were studied to obtain cognition about their composing. The concluding decision deducted was at low costs biodiesel from microalgae is executable, nevertheless to have high outputs much more research and development in the country must be investigated. [ 1 ]

3. Categorization of Algae

Algae can be classified in the paraphyletic group as a big group of beings from different phyletic groups. Similar to workss in many ways but differ in the fact they are really simplistic unicellular/multicellular beings. Largely microscopic, some species such ( e.g. seaweed ) range vast sizes up to 50m and turn in saltwater or fresh water and by and large muffle, moist or wet conditions. Algae contain a membrane edge karyon and encompass chloroplasts hence can photosynthesise. Algae produce more O than workss are of import factor in the nutrient concatenation, many little species such as runts feed on them therefore they are at the underside of the nutrient concatenation. Excluding Cyanobacteria ( procaryotic ) most algae are eucaryotic. They were considered eucaryotic until late were moved their cell construction resembles that of bacteriums and they photosynthesise in the cytol instead. [ 2, 3, 4 ]

3.1 Algae Phylum

The chief algae phyla are Cyanophyta ( bluish green algae/ Cyanobacteria ) , Rhodophyta ( ruddy algae ) , Chrysophyceae ( aureate algae ) , Phaeophyceae ( brown algae ) and Chlorophyta ( green algae ) other phyla include Bacilloriophyta ( diatoms ) , Dinophyta ( Dinoflagellates ) , Haptophyta, Prochlorophyta etc. [ 5, 6 ]

3.2 Strain Efficiency

The optimal strain would be able to bring forth efficient biomass ( high oil content ) and fast growing rate and a temperature between 20 – 30oC. The job that occurs with this is algae that grow at a fast gait normally produce low oil content about 30 % , taking merely a twosome of hours to split. Algae bring forthing high oil content of 80 % grow at a slow gait perchance up to 10 yearss and split merely one time during that period. A technique enabling algae to turn expeditiously and bring forth high oil content is alimentary famishment such as nitrogen famishment, although this is besides slows growing.

Table 1 – [ 21 ]

Optimum storage triacylglycerols TAG ( s ) concatenation length would sooner necessitate to be to the full saturated or monounsaturated, as this increases oxidative stableness ( storage stableness ) and combustion public presentation of the oil, they should incorporate concatenation length of myristic or oleic acid C14 to C18 severally. Fatty acids with medium to long concatenation length with concentrated or monosaturated dual bonds are ideal nevertheless algae incorporating these concatenation lengths are either slow turning strains or hard to turn. [ 8, 9 ]

Researchers presents are looking into methods to bring forth efficient algae strains and one manner is through familial alteration. It would be valuable to be able to command concatenation length of fatty acids every bit good as dual bond formation, and it can be achieved through familial technology. Assays carried out on Chlamydomonas reinhardtii in Roessler Et. All and Dunahay research how cistrons can be extracted from algae within the same phyletic group and introduced into C. reinhardtii. [ 8, 9, 10 ]

3.3. Chlamydomonas reinhardtii

The diatom Cyclotella cryptica has been utilised to analyze how a recombinant cistron can be expressed in a host cell. The synthesis of fatty acids in the cell is controlled by Acetyl-CoA Carboxylase ( ACCase ) , hence in Roessler Et. all ‘s research this was the mark cistron to be extracted. The cistron was removed from C. cryptica and cloned utilizing polymerase concatenation reaction ( PCR ) . [ 8, 9, 10 ]

The host used was Chlamydomonas reinhardtii, the method involves the remotion of the cell wall by enzymatic digestion ( autolysin – cell wall degrading enzyme ) go forthing energids. As the cell is now exposed, in order for the Deoxyribonucleic acid to be absorbed the cell could be treated with electroporation or polythene ethanediol. This is a hard process and sometimes unsuccessful, some strains contain sporopollenin which is immune to enzymatic digestion. [ 8, 9, 10 ]

A method to foment the cell is DNA- coated gold atoms, the manner in which they are placed in the cell is through pressurised He gas ( biolistics ) . Another method is through agitation of C. reinhadtii with silicone carbide fibers ( SiC ) . This combined with rapid generation of algal exponential growing could potentially give rise to a species which is perfect for biodiesel production. [ 8, 9, 10 ]

3.4 Speciess Used for Biomass Production

The most common species used are the Chlorella species, other popular algae utilised are Chlamydomonas reinhardtii, Hematococcus Pluvialis, Arthrospira ( Spirulina ) platensis etc. The tabular array below gives illustrations of these. [ 1 ]

Table 2 – [ 21 ]

4. Photosynthetic Algae

The diagram below shows a speedy overview of photosynthesis, utilizing the two photosystems in photosynthesising algae:

Fig 1 – [ 7 ]

The overall reactions of photosynthesis are:

Internet: ( By 8 quanta )

Eqn 1 – [ 11 ]

4.1 Photosynthetic Pigments

Bluish green Algae

The bluish – green algae evolved from bacteriums hence they are procaryotic, presents are classed as bacteriums due to this. Their chief photosynthetic pigment is chl a absorbing at 680 nanometer in the ruddy and 440 nanometer in the bluish part. They are contained in the thylakoid membrane ( gill ) in the cytol. Major extra pigments are phycocyanin ( absorbing at 626nm ) , allophycocyanin ( absorbing at 650nm ) and phycoerythrin. [ 11 ]

4.1.1 Red Algae

Red algae contain the xanthophyll Lutein, besides phycoerythrin and this enables the soaking up of green visible radiation in deep H2O hence algae in deeper Waterss of course will hold more phycoerythrin nowadays. Phycoerythrin absorbs at 500, 540 and 566 nanometers and chl a at 440 and 670 nm the combination of these pigments allows a greater graduated table of wavelengths in the seeable portion of the spectrum to be covered. [ 11 ]

4.1.2 Brown Algae, Diatoms and Dinoflagellates

These obtain chl a, chl degree Celsius, the luteins: – fucoxanthin in brown algae, diatoms and peridinin in dinoflagellates. Both luteins absorb at 490 nanometers and chl degree Celsius around 460 and 640 nanometer. Although there is a 40nm displacement of peridinin and fucoxanthin when in their native province, perchance being attached to a protein. [ 11 ]

4.1.3 Green Algae and Higher Plants

The pigments contained in green algae and higher workss are chl a, chl B and chl degree Celsius, chl B holding a bluish soaking up of 470 nanometers and ruddy soaking up of 650 nanometers. Unlike the other categorizations of algae these do non obtain specialized pigments in order to absorb visible radiation in the part of 500 and 600 nanometer, hence reflecting those wavelengths and looking green. The major lutein is lutein and little sums of violaxanthin and neoxanthin. [ 11 ]

4.3 Chlorophyll Content

Table 1 – The distribution of photosynthetically active pigments in different algae/ workss:

Alga

Chl

a

Chl

B

Chl

degree Celsiuss

Phycoerythrin

Phycocyanin

I?-Carotene

Major Xanthophyll

Bluish green

+

+

+

+

Myxoxanthin

Red

+

+

+

+

Xanthophyll

Brown, Diatoms

+

+

+

Fucoxanthin

Dinoflagellates

+

+

+

Peridinin

Green, Higher Plants

+

+

+

Xanthophyll

Yellow-green

+

+

Violaxanthin ; Vaucheriaxanthin

Table 3 – [ 11 ]

4.4 Taxonomy

Fig 2 – [ 6 ]

5. Biomass Production

The production of biomass requires, visible radiation for photosynthesis, C dioxide, foods and inorganic salts. Normally contained in the growing medium for microalgae the foods needed are, phosphorus ( P ) , nitrogen ( N ) , Fe and in some instances silicone. This is based from the elements that compose the algal cell, the minimum nutritionary demands can be approximately determined utilizing the molecular expression of algae biomass, CO0.48H1.83N0.11P0.01. The algae depend on light energy so light demands to be freely available ignoring seasonal fluctuations. CO2 needs to be invariably fed into the system during the daylight about 100 metric tons of algal biomass holes around 183 metric tons of CO2. Fresh medium must be circulated through the system merely during the daylight and at the same clip the same measure of biomass removed. The algal biomass must ever be assorted even during the dark clip to forestall cleavage which slows down the rate of biomass production [ 12 ]

6. Oil Production

6.1 Transesterification

Biodiesel is produced through the procedure of transesterification ( alcoholysis ) . This is the reaction between a triglyceride and an intoxicant in the presence of a accelerator to organize glycerin and esters. This takes place measure by measure, foremost the triglycerides are converted to diglycerides so following monoglycerides and eventually to glycerol.

TAG + CH3OH ) a DAG + R1COOCH3

DAG + CH3OH ) a MAG + R2COOCH3

MAG + CH3OH ) a Glycerol + R3COOCH3

Eqn 2 – [ 26 ]

Normally used for the intoxicant is methanol as it is inexpensive and produced from this are methyl esters. As this reaction is in equilibrium to guarantee a greater output of methyl esters extra ethyl alcohol must be used, 6mol, for each mole of triglyceride used in industry, this ensures 98 % output of esters on the footing of weight. The accelerators which can be used in the reaction include acids, bases and lipase enzymes, nevertheless lipase enzymes are costly therefore non appropriate for industrial usage. In industrial procedures alkali is applied as it is 4000 times faster than acid catalysed reactions. Alkali ‘s presently used are sodium hydrated oxide ( NaOH ) and potassium hydrated oxide ( KOH ) at a concentration of 1 % by weight of oil, Na methoxide is a better accelerator and is progressively utilized. The reaction conditions at atmospheric force per unit area at 60oC ( as methyl alcohol furuncles at 65oC ) and is about 1hr and 30mins long. In order to forestall saponification, the intoxicant and oil must be dry and the oil must incorporate a minimal sum of free fatty acids. The methyl esters are so isolated by the remotion of glycerin and methyl alcohol with repeatedly rinsing with H2O [ 12, 14, 15 ]

Eqn 3 – [ 1 ]

6.2 Supercritical Transesterification

Transesterification of TAG ( s ) with an intoxicant is normally heterogenous. This reaction utilises methanol every bit good as supercritical conditions, alternatively of a two liquid stage reaction due to the conditions triacylglycerols have been subjected to a individual homogeneous stage this speeds up the reaction. An intoxicant molecule attacks the carbonyl of the TAG. The H bonding decreases form force per unit area hence methanol becomes a free monomer, fatty acid methyl ester and diglycerides are formed, farther transesterification of diglyceride signifiers methyl esters and monoglyceride and the concluding measure monoglyceride forms methyl ester and glycerin. [ 14 ]

7. Cultivation Procedures

7.1 Raceway Pond

This is a closed cringle go arounding channel system where this is about 0.3m deep which allows for visible radiation to perforate to the underside of the pool for maximal algal growing. The algae foods are fed continuously at the paddle wheel, ( located at the beginning of the raceway ) keeps the algae biomass circulating at all times. The raceway is built from concrete or compact Earth and lined with white plastic. This cringle continues in a circle until making the paddle wheel once more,

Fig 4 – [ 12 ] where behind it, the crop is collected. [ 12, 16 ]

To keep changeless temperature, chilling can merely be done through vaporization. This causes a job as CO2 is lost through vaporization and the algal biomass is ill assorted. Other jobs involved are unwanted algae and micro-organisms that feed on algae. Although raceway pools are cheaper and are easy maintained the algal productiveness is non that efficient in comparing with photobioreactors [ 12, 16 ]

7.2 Photobioreactors

Tubular photobioreactors

These are normally cannular, crystalline plastic round photobioreactors. These allow growing of individual celled species of microalgae and bring forth big measures of biomass. The

Fig 5 – [ 12 ]

breadth of the tubings are about 0.1m or less in diameter, this is done in order for visible radiation to perforate through the tubings wholly leting for maximal cultivation of the microalgae. The micro-algal stock is prepared in a reservoir called the degassing column this is so circulated through the cannular panels so back to the reservoir. The agreement in which the tubings are organised is horizontally lined on the land.

Fence-like Photobioreactors

The fence-like solar aggregators are lined parallel opposing one another. The solar tubings are oriented from north to south and the land underneath is painted white or covered with white sheets of plastic this is performed to increase coefficient of reflection enabling higher per centum of visible radiation to make the tubings.

Fig 6 – [ 12 ]

Helical Photobioreactor

Other methods of organizing the tubing may be around a supporting frame and the tubes spiral around this organizing a coiling photobioreactor, these are used for cultivation of a little sum of biomass. [ 12, 16 ]

In order for the photobioreactor to work expeditiously a changeless beginning of visible radiation must be applied during daylight hours, this can be created through unreal visible radiation instead than depending on fluctuations from sunshine. It is more dearly-won nevertheless to utilize this method, although it has been used in large-scale production. [ 12, 16 ]

In photobioreactors there are two types of pump that prevent deposit of algae in the solar tubings. The first is a mechanical pump, supplying a disruptive flow therefore may damage the biomass, the second is an airlift pump which is the gentler option and has been proven to be a success. The mechanical pump is flexible in comparing with the airlift pump, the airlift pump requires a supply of air. The photobioreactors must be cleaned sporadically to forestall deposit. [ 12, 16 ]

Oxygen is formed in the photobioreactors can be every bit much as 10g of O2 m-3min-1 which is debatable as the concentrated O2 slows down photosynthesis and at higher concentrations uniting with light strength can do photo-oxidative harm to the cells. The manner to take the extra O is to bubble air through the stock. This must be done at certain intervals the length of the tubings are limited and can non be longer than 80m in length depending on the system, e.g. light strength, concentration of O upon entry in the photobioreactor and sum of algae cultivated. [ 12, 16 ]

CO2 is besides fed into the solar tubings through the degassing column pH is an index of how much CO2 is required. PH accountants step alterations in pH and where increased, CO2 is fed into the system. [ 12, 16 ]

Even with photobioreactors loss by vaporization through respiration of algae still occurs and chilling of the system is needed twenty-four hours and dark. This can be done by using heat money changers placed in the degassing Chamberss or in the cannular cringle and another method is to spray H2O on the tubings, which has proved to be a utile method in dry climes. [ 12, 16 ]

To compare both systems, photobioreactors are much more efficient in bring forthing a greater sum of biomass. When recovery of algae after cultivation is made, either through filtration and centrifugation that recovered from photobioreactors is 30 times the biomass concentration than that of raceway pools [ 12, 16 ]

7.3 Extraction

Suitable reaping methods to pull out biomass and retrieve this from the civilization include deposit, centrifugation, filtration, ultra-filtration and flocculation. Most normally used measure is flocculation which collects the algae cells and increases surface country which enables deposit, centrifugation and filtration. Another method of aggregation is with filter imperativenesss nevertheless this is better when used for cultivation of larger microalgae. To forestall the rupture of cell walls and devastation of cells the gentler methods to retrieve biomass is filtration or ultra-filtration ( although are dearly-won ) . [ 1, 19 ]

Dehydration of biomass is effectual as additions shelf life, current methods of desiccation are spray-drying, drum-drying, freeze-drying and sun drying. As algal biomass is wet, sun drying is uneffective, the same applies for spray drying. After desiccation the cells must be disrupted and this can be done through mechanical methods ( cell homogeniser, bead Millss, ultrasound, autoclave and spray drying ) and non-mechanical methods ( stop deading, organic dissolvers and osmotic daze and acid, base enzyme reactions ) . For lipids solvent extraction is applied through Lyophilisation ( breaks cells and turns to pulverize ) , this makes extraction easier and with less debasement of the dry biomass. Solvents used to pull out the Fig 7 – [ 1 ] fatty acids are hexane-ethanol which successfully extract 96 % . [ 1, 19 ]

8. Biodiesel Content and Acceptability

In order to be used as an efficient conveyance fuel or for other applications biodiesel should be composed of concentrated or monosaturated fatty acids, therefore the lower the sum of polyunsaturated fatty acids the higher the quality fuel. Oil from microalgae normally contain four or more dual bonds, two common illustrations are eicosapentaenoic acid ( EPA, C20:5n-3 ) , and docosahexaenoic acid ( DHA, C22:6n-3 ) , EPA incorporating 5 and DHA 6 dual bonds. The ground this is a job is that the dual bonds in unsaturated fatty acids are reactive and susceptible to oxidization ( auto-oxidation ) whilst in storage and go prone to organizing peroxides, hence high oxidative stableness is equal to long term storage stableness. Oxidation causes the chemical decomposition of oil and debasement of biodiesel. [ 12, 13, 17,18 ]

A trial to mensurate unsaturation degrees is the Iodine Value ( IV ) , it measures per 100g of oil the sum of Iodine absorbed, since the unsaturated bonds are sensitive to iodine, the higher the I value the greater sum of unsaturated fatty acids nowadays. A Peroxide Value is used to mensurate the sum of ROOH nowadays this method is used in the nutrient industry to mensurate the rancidity ( oxidization of oils ) . [ 12, 13, 17, 18 ]

In footings of ordinances set in EU ( Standard EN 14214 ) , most microalgal oils would non follow due to their high degrees of unsaturation, these criterions require the IV non to transcend 120/130g of I per 100g of oil. There is a 12 % ( mol ) value of the sum of linolenic acid methyl esters present in biodiesel in the EN14214 ordinances, linoleic ( C18:3n-6 ) and linolenic ( C18:3n-3 ) acid have a much higher oxidative stableness in comparing with DHA and EPA due to take down unsaturated fatty acid degrees, but are still under limitations in the EU in biodiesel oil. There is a manner to take dual bonds in fatty acids and this is through the partial catalytic hydrogenation of the oil, e.g. production of oleo from vegetable oils. [ 12, 13, 17,18 ]

Table 4 – [ 21 ]

8.1 Power Plant CO2 Utilisation

Operating photobioreactors is dearly-won, including disbursals of edifice and running the system the cost of foods and CO2 will besides necessitate to be incorporated. In order to cut down this value flue CO2 from power workss provides the solution. Other pollutants such as NOx and SOx can besides be recycled and applied as foods.

A system design given by Brune Et. all, suggests a conjectural appraisal of the costs which would be involved in using power works CO2. The scenario presents a semibase-load ( end product of power works over a period of clip ) with an electrical production of 18h/day in 8 months. The electrical capacity is 50MW hence giving 216 million kMh/ season. The generated CO2 from this is calculated to be 30.3million kg-C/ season, with such a high measure of CO2 the power works nowadayss adequate CO2 for a photobioreactor to use. For CO2 to be used successfully it depends on several factors, the rate of CO2 transportation from power works to reactor and the sum of algae adult each clip CO2 is madee. CO2 transportation ranges from 85-95 % and even lower cut downing to 60-80 % .There a high recovery value of 15-50 % of algal C. If the overall production of biomass from algae is on mean 20g-m2/day at a CO2 efficiency of 70 % and including 30.3 million kg-C/season ( 126,450 kg-C/day ) of CO2 the production of algae will be: [ 20 ]

( 126,450 kg-C/day ) ( 2g VS/g-C ) ( 0.70 ) = 177,030 kg-VS/ twenty-four hours

Ten ( 240 yearss ) = 42.4million kg-VS/season [ 20 ]

Flue CO2 flow rate ( at 6 % CO2 ) is around 322,000 kg/h. Algal productiveness, presuming the norm cell completes a full rhythm in 3 yearss, is 20g VS/m2 -day or C arrested development of 10g-C/m2 -day. To civilization the algae the surface country therefore is:

( 176,030 kg-VS/day ) ( 1,000 g/kg ) / ( ( 20 g VS/m2 -day ) x ( 10,000 m2/ha ) ) = 880 hour angle ( 2,147 estates ) [ 20 ]

The 880 hour angle can be placed as 4 photobioreactors made of 220 hour angle. The system hypothesised by Brune Et. all shows that power workss generate 126,450 kg-C/day plenty to bring forth 4 photobioreactor systems of 880ha. However the cost to construct these particularly with such a big surface country would be really costly and impractical. The electrical capacity to run the installation must besides be considered. [ 20 ]

9. Economic Value

9.1 The World ‘s Situation

The International Energy Agency ( IEA ) reported the universe ‘s primary energy, which is considered to be fossil fuels as they provide 84 % of the universe ‘s overall demand, will turn by 55 % from 2005 to 2030 yearly at rate of 1.8 % . In studies from energy and capital a drastic addition of up to 60 % will hit by 2025. Two of the biggest consumers are China and India with one-year growing rate amounting to 7.5 % and 5.5 % severally. If policies do non alter by 2030 there will be an addition of 60 % greater demand for oil, both China and India history for 45 % of this. At the rate dodo fuels will be exhausted in around 45 old ages clip. [ 21, 22 ]

9.2 Consumption Costss

Harmonizing to Chisti ( 2007 ) if it is assumed CO2 is non included in the cost, the disbursal for bring forthing a kg of biomass is $ 2.95 for photobioreactors and $ 3.80 for raceways. If the biomass contained 30 % oil by weight a liter of oil would hence amount to approximately $ 1.40 for photobioreactors and $ 1.81 for raceways. Oil recovery costs sum are of import as these save disbursals and lend 50 % to the cost of the concluding recovered oil. In the US during 2006, if revenue enhancements and distribution are excluded the monetary value of petrodiesel was $ 0.49/L ( 73 % rough oil, 27 % refinement ) . Biodiesel produced from palm oil

Table 5 – [ 12 ]

costs $ 0.66/L amounting to a sum of 35 % excess cost in comparing with petrodiesel. For biodiesel from palm oil to vie with petrodiesel the cost of biodiesel should be $ 0.48/L the same logic applies to biodiesel produced from algae. This requires the $ 2.80 current production costs to diminish to $ 0.48. [ 12 ]

Byung-Hwan Um states that tests in ideal conditions aggressive micro-algae output 1800-2000 gallons/acre yearly of oil, whereas soybean 50 gallons, rapeseed 130 gallons and ~650 gallons palm oil. The land required to reap algae is minimum since land country of photobioreactors or raceway pools are much smaller in comparing with that of harvests and surface country of cultivation is larger as solar panels are compact. The microalgae would non be viing with nutrient harvests as they are grown in aqueous conditions and it is possible to cultivate algae in sewerage and H2O intervention workss. Oil produced from 20-40M estates of land could replace full US supply of imported oil therefore leting for 450M estates for nutrient production. Algal biodiesel can be produced utilizing photobioreactors at $ 4.54 per gallon. However this would hold to drastically cut down to ?1.81 per gallon ( 2006 ) in order to vie with petrodiesel. This is taking into history that 71 % of the costs are from get downing stuffs and refinement of fuels. [ 8, 24 ]

9.3 Industrial Costss

To compare the two procedures of extraction, the cost to run raceway pools yearly is much less compared with that of photobioreactors, photobioreactors are complex and sophisticated systems which require in the scope of $ 60-100/m2. The entire cost per annum per hectare ( hour angle ) of a photobioreactor closed system is $ 200,000. The comparing of disbursals for unfastened pool system is $ 125,000 – $ 150,000 per hectare per annum accordingly the photobioreactor costs more to run. [ 23 ]

10. Future Prospects

Companies presently researching biodiesel from microalgae and perfecting civilization techniques include ExxonMobil, Solazyme, GreenFuel Technologies, Solix and Livefuels. Possible future chances would be to place the optimum therefore a strain of algae with fast exponential growing rate, high lipid content and light impregnation factor could be engineered. Of class the problem with this theoretical account would be the harm that this strain could enforce on the environment and could potentially harm the eco-system and niches of micro-organisms within it. The research into low cost photobioreactors must be delved into farther, every bit good as lower costs to run the system. Further development should be conducted into using flue CO2 from power workss every bit good as the application of foods from effluent systems this country is of huge importance with the possible to cut down pollution and GHG. [ 23 ]

11. Decision

Biodiesel from algae seems to be a really promising country with changeless new R & A ; D in this field. Algae have high oil content, photosynthesise quickly bring forthing big measures of biomass in a short sum of clip doing them ideal for biodiesel production. Algae can last in rough conditions and are non high care they may merely obtain foods from effluent and CO2 from flue gas. They have been successfully cultivated at a big graduated table by raceway pools and photobioreactors and in competition with biodiesel from workss they produce a higher content of oil without viing with harvests grown for food.The cost to construct and run this machinery is expensive and presently for algal oil from raceway pools are estimated to be $ 1.40, photobioreactors at $ 1.81 per L and $ 2.80 for oil recovery from lower cost biomass, excepting the cost for CO2. The cost for petrodiesel in 2006 was $ 0.49/L. If potentially there is an addition in production of biomass to 100,000t the cost per kg would cut down to $ 0.47 and $ 0.60 for photobioreactors and raceways severally. However presently petrodiesel is still the easiest and cheapest option to bring forth and sell fuel. Biodiesel from microalgae is executable although non cost effectual at present, it has the possible to replace fossil fuels hence research into cutting the cost of edifice photobioreactors is required besides the cost of CO2 and foods. The cost of CO2 and foods could potentially be made through the usage of fluke gas from power workss and foods such as N at effluent workss or the usage of low-priced fertilizers. This will besides cut down the sum of green house gases released in the ambiance cut downing pollution and the rate of planetary heating. [ 1 ]