Algal biofules production

1. Review : Current Status of
Algal Biofuels Production & Intensification
of the Production Process
Bandara W.B.M.A.C.
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World primary energy consumption

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4. • In 2040, The Crude-oil consumption, also expected to rise from
• World total oil reserves are now estimated at 1.64 trillion barrels.
• OPEC oil production is estimated to have declined 2.2% from a year
ago.
• But the demand for the energy is growing worldwide, especially in
rapidly developing countries such as in china and India.
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90 million barrels /day 104 million barrels /day

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• world will add
1 trillion tons of carbon dioxide
to the atmosphere
between now and 2040.
by burning fossil fuel.
(world energy outlook,2014)
• Fossil fuels is a Depleting resource
burning causes the
accumulation of greenhouse gases
in the environment
that have already exceeded the
“dangerously high” threshold of
450 ppm CO2.

6. Environmental and Economic sustainable production
processes
Not only renewable, but also capable of
Sequestering atmospheric CO2.
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Biofuel is the fuel which is produced from organic
products and wastes.

8. • Also called conventional biofuels. It includes sugar, starch, or
vegetable oil
• known as advanced biofuels and can be manufactured from
different types of biomass. The biomass contains lignocellulosic
material like wood, straw and waste plastic
• Extract from algae mostly marine algae
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Classification of Biofuels
1st Generation Biofuels
2nd Generation Biofuels
3rd Generation Biofuels

9. • In recent years,
biodiesels produce from oil (triglycerides) of raw materials such as
sunflower, soybean, etc
• Use of Food-based crops,
lead to several environmental & societal issues
such as land pollution, reduce of agricultural land cause to world
hunger and deforestation
• 3rd generation bio fuels are better,
they are carbon neutral, or they reduce atmospheric CO2 as they are
carbon negative
Ex : Soybean like 1st generation biodiesel only induces a net reduction of
GHG emissions by 41%
To produce ton of microalgal biomass
It is estimate that 1.8 tons of CO2 would be consumed 180% reduction
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10. • Found in a variety of aquatic habitats.
Ex : freshwater, brackish, marine and hypersaline
aquatic environments
evenreported in desert crust communities
• Tolerate temperature extremes and low water availability
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Algae
Microalgae
Macroalgae
• Have anatomical structures resembling leaves, stems,
and roots of higher plants

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• Rapidly growing and have a higher solar conversion efficiency
Botryococcus braunii or Schizochytrium sp. contain up to 80%
lipids of their dry weight
yield 770 times higher than oleaginous plants per acre
• Multiply rapidly.
Microalgae can double from 1 to 3 times in 24 hours
• Can be harvested (batch-wise or continuously) almost all year round.
• Non-productive, non-arable land can use
• Algae can utilize salt and waste water sources that cannot be used by
conventional agriculture.
Advantages of using microalgae as source
of biofuels

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• Due to use of waste CO2, has potential to mitigate the GHG
• Capable of fixing large amounts of carbon dioxide (CO2)
while contributing to approximately 40 % to 50 % of the
oxygen in the atmosphere
• Used to generate nontoxic, biodegradable biofuels industries
valuable co-products such as food, cosmetic, fertilizing and
many other
• Microalgae can use sustainably to generate diverse biofuels, which
are mainly:
Biomethane produced by anaerobic digestion
Biohydrogen by photobiological process
Bioethanol by fermentation
Liquid oil by thermal liquefaction
Biodiesel

13. Lipids yield of microalgae
Nutrient deprivation can lead to an increase in lipid content, but not for all
species of microalgae.
Ex : Microalgae Navicula (NAVIC1) had the highest lipid content,
which raised in exponential phase
from 22 to 49% (g lipid/g dry weight) in silicon (Si) deficiency
& increased to 58% (g lipid/g dry weight) when nitrogen was limited.
On the other hand, nutrient limitation (nitrogen or Si) limitation had
less or no significant effect on lipid content of microalgae
Amphora and Cyclotella
Studies found that P deprivation could have a positive effect on lipid
content.
Ex : Increasing the P concentration from 0.14 to 0.37 mg/L
Observed a raise of microalgae concentration from 0.14 to 0.37 g/L
while the lipid content decreased from 53 to 23.5% (g lipid/g dry weight).
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14. An osmotic shock might also stimulate the lipids production.
Ex : enhanced the sodium chloride (NaCl) concentration from 3.5 to 7 g/L
(0.5 to 1 mol/L) and found an increase in lipid production from 60 to 67% (g
lipid/g dry weight).
However,
these physicochemical treatments lead to synthesis of
polar lipids like phospholipids or glycolipids
associated with cell walls of the microalgae
such lipids are less interesting for biodiesel production
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Lipids yield of microalgae cont.

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Biodiesel production from microalgae
Cultivation
Harvesting
Extraction of Oil
Transesterification
Biodiesel

16. Culture of microalgae
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Open pond systems (Race way)
Open pond systems are shallow ponds in
which algae are cultivated.
Nutrients can be provided through
runoff water from nearby land areas.
The water is typically kept in motion by
paddle wheels or rotating structures

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Photo bioreactors
Closed systems in which algae are
cultivated
Water, necessary nutrients and CO2 are
provided in a controlled way, while oxygen
has to be removed.
 Algae receive sunlight either directly
through the transparent container walls or
via light fibers.
concentration of microalgae up to 6.7 g/L
• Production cost is about 100 $ US/kg

18. Harvesting of microalgae
• Centrifugation
• Flocculation
• Gravity sedimentation
• Filtration
• Screening
• flotation
• electrophoresis techniques
As microalgae are floating in pond at a concentration less than 0.5 g/L
the harvesting costs can represent 20 to 30% of the industrial microalgae
biomass production cost of 2.95 and 3.80 $US/kg biomass
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Different harvesting methods

19. Extraction techniques
Far the most commonly used method
but less effective when microalgae are still wet
Consequently, for laboratory scale extraction of lipids freeze-drying is a
popular method but
spray-drying
oven-drying
vacuum-evaporation
have also been used to dry microalgae.
However,
Drying microalgae prior to lipid extraction
could require 2.5 times more energy than a process without drying,
which makes a process using a prior drying unprofitable
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Chemical solvents extraction

20. In laboratory scale studies,
from a heterotrophic microalgae, Chlorella protothecoides
Other less toxic solvents like alcohols (ethanol, octanol) have been
tested,
but the yield of fatty acid methyl ester (FAME)
obtained was up to 5 times lower than with n-hexane extraction
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17% (g lipid/g dry weight)chloroform-methanol
hexane
(less polar solvent /low
toxicity)
25% (g lipid/g dry weight)
For microalgae lipid extraction on an industrial scale,
Soxhlet extraction is not recommended due to high energy requirement

21. • Not toxic
• Easy to recover
• Usable at low temperatures (less than 40˚C)
Constrains - Requires expensive equipment
huge amount of energy to reach high pressures
Ex :
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Supercritical carbon dioxide extraction
26% (g lipid/g dry weight)Nannocloropsis sp.
Botryococcus sp. 28.6% (g lipid/g dry weight)
Both results are higher than the corresponding hexane
Soxhlet extraction
60˚C & 30 MPa

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Supercritical carbon dioxide extraction cont.
In opposition to chemical solvent extraction,
supercritical CO2 lipid extraction can be stimulated by the
presence of water in the blend of microalgae
Chlorococcum sp. (dry mass) 5.8 and 3.2% (g lipid/g dry weight)
Chlorococcum sp. (wet mass) 7.1% (g lipid/g dry weight)

23. can be used for microalgae cell disrupting in order to recover lipids
Using microwave or bead-beating seems to be the most promising
techniques to increase the lipid yield.
Ex : Botryococcus sp. in water phase increased the lipid extraction yield from
7.7 to 28.6% (g lipid/g dry weight) using a 5 min microwave pretreatment.
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Physicochemical extraction
• Freeze-drying
• French Press
• Grinding
• Sonication
• Microwave
• Autoclaving
• Osmotic Shock
• Beadbeating
• Homogenization

24. Offer low-tech and low-cost methods of harvesting and lipid
extraction.
Ex : Using a 72 h cellulase hydrolysis pretreatment of the
Chlorella sp.
lipids yield has increased from
52 to 54% (g lipid/g dry weight).
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Biochemical extraction

25. Transesterification
The direct use of crude vegetable oils in diesel engines could lead
to numerous technical problems.
Because of their characteristics,
• High viscosity
• High density
• Difficulty to vaporize in cold conditions
Cause deposits in the combustion chamber
risk of fouling and an increase in most emissions .
To overcome all these inconveniences, the transformation of microalgae
lipids in
corresponding esters is essential
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The reaction reduces the,
• Molecular weight
• Viscosity
• Increases the
• Volatility of microalgae lipids.
Transesterification Cont.

27. Ultrasound Extractive-Transesterification
Method
• Apply of sound higher than the 20 KHz (ultrasonic) to the microalgae in
water is known as ultra-sonication. cavitation process is utilized to
disrupt the cell wall.
• Can apply high amount of energy within short time, by cavitation bubble
collapse.
• Due to the ultrasonic irradiation cell structures are disintegrated making
the micro bubbles to collapse for the oil extraction can be possible 27
Lipid Ultra sound
Ethanol
Algae

28. Direct method can deliver intensity 100 times higher than indirect method.
Low frequency ultrasound gives better results, compare with high
frequency.
Can increase the yeild by 50–500% with in short period.
By combining of N-Hexane and Ethanol chemical solvent transesterificaion
with ultrasonic extraction was able to reduced extraction time significantly.
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direct method - Ultrasonic probe
indirect method - ultrasonic bath
Ultrasound Extractive-Transesterification Method Cont.

29. Microwave Extractive-Transesterification
Method
For the commercial application Microwaves at a frequency of 2.45 GHz
are used. Microwave enhance the reaction due to ionic conduction and
dipole polarization mechanisms.
Microwave extractive-transesterification can be used to obtain higher
biodiesel yields.
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Microwave
Lipid
Ethanol

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Ex : 1g of crude dried Nannochloropis with methanol- chloroform
(1:2 v/v)
770 watts microwave irradiation for 5 minutes
same dose of mixture was added to 03 g of SrO for the
transesterification of microalgae lipids.
subjected to microwaves for2 minutes
For two step method he obtain 32.8% biodiesel yield and 37.1%
for direct transesterification

31. • With the increase of the price of crude oil , biodiesel appears a
sustainable solution to reduce the dependency on oil producing
countries.
• 1st generation of biofuels currently used could have economic,
environmental and social negative consequences.
To overcome these problems, producing biodiesel from microalgae
lipids seems to be a sustainable solution.
• Thus, more efforts must be made to reduce the process costs and to
increase the biodiesel quality
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Conclusion

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• Microalgae could be used to reduce the CO2
emissions from coal power plants or wastewater
pollution.
• Researchers are working to engineer super lipids
producing microalgae strain in order to increase the
yield of biodiesel.
• Ultrasonication, microwave like energy efficient
methods can successfully adopted to
intensify the production.

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References
Alptekin, E. & Canakci, M. (2008). Determination of the density and the viscosities of
biodiesel-diesel fuel blends. Renewable Energy, Vol.33, No.12, pp. 2623-2630
Altin, R.; Çetinkaya, S. & Yücesu, H.S. (2001). Potential of using vegetable oil fuels as fuel
for diesel engines. Energy Conversion and Management, Vol.42, No.5, pp. 529-538
Carvalho, A.P.; Meireles, L.A. & Malcata, F.X. (2006). Microalgal reactors: A review of
enclosed system designs and performances. Biotechnology Progress, Vol.22, pp. 1490-
1506
Grobbelaar, J.U. (2000). Physiological and technological considerations for optimising
mass algalcultures. Journal of Applied Phycology, Vol.12, pp. 201-206
Lee, J.; Yoo, C.; Jun, S.; Ahn, C. & Oh, H. (2010). Comparison of several methods for
effective lipid extraction from microalgae. Bioresource Technology, Vol.101, pp. 575-577
Miao, X. & Wu, Q. (2004). High yield bio-oil production from fast pyrolysis by
metaboliccontrolling of Chlorella protothecoides. Journal of Biotechnology, Vol.110, pp.
85-93

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