Microalgae and Cyanobacteria as raw material for production of Biofuel in comparison to
terrestrial crops
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Executive Summary
Author’s Profile (31668482)
Background
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Hi there, welcome to my website. I’m Priyadarshinee Boojhawon. I am a third year undergraduate student
majoring in Biotechnology and Biomedical Sciences.
This unit involves the biotechnology of algae where recently I’ve been working on an experiment involving algae
which I find very interesting. I’ve been reading articles to get an idea how I can do my lab report and I came across
biofuel production from algae. I found research in the biofuel production to be very interesting and the use of
microalgae and cyanobacteria for the production of biofuel compared to terrestrial crops just caught my attention.
The world has been confronted with an energy crisis due to the depletion of finite resources of fossil fuel and they
are more likely to be scarce and costly and are considered to be unsustainable.
Methods to convert biomass to competitive liquid biofuels are increasingly attractive and are receiving increased
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attention.
The direct conversion of solar energy into liquid fuel using photosynthetic microorganisms such as microalgae and
cyanobacteria is an attractive alternative to fossil fuels and they have several advantages into using these
organisms.
Are Microalgae and Cyanobacteria the raw material for the production of biofuel compared to terrestrial crops?
Two scientific papers have been studied for a comparison and an answer to the question.
Microalgae and Cyanobacteria as raw material for production of Biofuel in comparison to
terrestrial crops
Author’s Profile
Papers of comparison
Papers of comparison
Executive Summary
Biofuels from algae for sustainable development
Background
Ayhan Demirbas., (2010), Use of algae as biofuel sources, Energy Conversion and
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Management. Volume 51, pp 2738-2749.
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Article 2
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Phostosynthetic production of fatty acid-based biofuels in genetically
engineered cyanobacteria
Lu Xuefeng. (2010), A Perspective: Phostosynthetic production of fatty acid-based biofuels
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in genetically engineered cyanobacteria, Biotechnology Advances.
Microalgae and Cyanobacteria as raw material for production of Biofuel in comparison to
terrestrial crops
Author’s Profile
Executive Summary
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Executive Summary
Comparisons of two scientific articles related to the production of biofuels from microalgae and
Background
cyanobacteria have been studied.
Both papers prove the same point that these photosynthetic microorganisms are theoretically a very
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promising source of biodiesel compared to terrestrial crops.
Microalgae appear to be a very good source of renewable biofuel that is capable of meeting the global
demand for transport fuels. It can be converted to biodiesel, bioethanol, bio-oil, biohydrogen and
biomethane via thermochemical and biochemical methods (Demirbas, 2011).
Industrial reactors for algal culture are open ponds, photobioreactors and closed system. Algae can be
grown almost anywhere.
Cyanobacteria are advantageous organisms for industrial applications.
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They are naturally transformable and have the potential to be genetically engineered for installing biofuel
producing chemical pathways cyanobacteria have been shown to be highly tolerant to the introduction of
foreign genes (Iara & Shota, 2012). Cyanobacteria has proved to be a very good source of biofuel
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References
production in contrast to terrestrial crops.
Microalgae and Cyanobacteria as raw material for production of Biofuel in comparison to
terrestrial crops
Background
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The term biofuel is referred to as solid, liquid, or gaseous fuels that are predominantly produced from
biorenewable feedstock. Biodiesel is produced through the chemical reactions transesterification and
esterification by chemically reacting lipids with an alcohol producing fatty acid esters. Biofuel can be
Executive Summary
produced from both microalgae and cyanobacteria.
Background
Microalgae are unicellular photosynthetic microorganism with growing requirements such as lights,
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sugars, carbon-dioxide, nitrogen, phosphorus and potassium. They have great capacity to convert
carbon-dioxide into lipids, protein and carbohydrates in large amounts over short period of time without
competing for arable land necessary for agricultural crops. These products can be processed into both
biofuels and useful chemicals.
Cyanobacteria are photosynthetic microbes, which can absorb solar energy and fix carbon dioxide. Direct
conversion of carbon dioxide to biofuels in photosynthetic cyanobacteria
can significantly improve the efficiency of biofuel
Production and other high value chemicals by modifying
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amino acid metabolic pathways by using protein
engineering and metabolic engineering and by building
non-native biosynthetic pathways.
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References
Figure 1 shows carbon fixation and main steps of algal
biomass technologies.
Microalgae and Cyanobacteria as raw material for production of Biofuel in comparison to
terrestrial crops
Author’s Profile
Article 1
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Biofuels from algae for sustainable development
Executive Summary
Background
Article 1
Article 1 contd
Ayhan Demirbas., (2010), Use of algae as biofuel sources, Energy Conversion and Management. Volume 51, pp 2738-2749.
According to studies in this article, microalgae appear to be the only source of renewable biodiesel that
is capable of meeting the global demand for transport fuels.
Industrial reactors for algal culture are open ponds, photobioreactors and closed system.
Microalgae contain oils or lipids and fatty acid. The algal oil is converted into biodiesel through
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transesterification. The algae are harvested from tanks through processes including concentration
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through different processes. Oil extracted from the algae is mixed with alcohol and an acid or a base to
produce fatty acid methylesters that make up the biodiesel.
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The oil content from microalgae exceeds 80% of dry weight of algae biomass. About 50% of their weight
is oil. The yield of oil per unit area is estimated to be from 19,000 to 57,000 L per acre per year, and is
200 times greater than plant/vegetable oils and can produce 30-100 times more energy per hectare
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compared to terrestrial crops. The calculated cost per barrel would be only $20 while currently a barrel
Personal Comments
of oil in the US Market is over $100.
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Microalgae and Cyanobacteria as raw material for production of Biofuel in comparison to
terrestrial crops
Author’s Profile
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Different microalgae can produce different amount of product and different biofuel types as shown in
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Table 1.
Biodiesel produced from microalgae is more beneficial compared to conventional crops since it produces
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more oil, consume less space and can be grown on any land even those that are not suitable for
agriculture.
However one disadvantage of microalgae for production of biofuel is the low biomass concentration. But
the high growth rate of microalgae makes it possible to satisfy the high demand on biofuels.
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The advantages and disadvantages of biofuel production using microalgae are shown in table 2.
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Table 1
Table 2
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Microalgae and Cyanobacteria as raw material for production of Biofuel in comparison to
terrestrial crops
Article 2
Author’s Profile
Phostosynthetic production of fatty acid-based biofuels in genetically engineered cyanobacteria
Papers of comparison
Lu Xuefeng. (2010), A Perspective: Phostosynthetic production of fatty acid-based biofuels in genetically engineered cyanobacteria, Biotechnology Advances.
Executive Summary
This article demonstrate how cyanobacteria can be exploited for biofuel production. The cyanobacterium
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Synechococcus elongatus PCC7942 has been reported to produce the isobutyraldehyde which is used
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primarily as a chemical intermediate to produce plasticizers, glycols, essential amino acids, polymers,
insecticides and isobutanol, a higher alcohol, produced via a keto acid pathway.
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Coupled with this, microbial production of isoprene, a high volatile hydrocarbon, has been recently
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demonstrated by an engineered Synechocystis sp. PCC 6803 strain.
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Moreover, another higher chain alcohol of interest as a biofuel is 1-butanol is produced by S.elongatus
and it can be used as a solvent for extraction of essential oil. 1-butanol is proposed to be used as a
substitute for diesel and gasoline because of its low hygroscopicity and energy content.
Higher energy such as C5-C8 and C4-C8 can be produced by Escherichia coli.
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Furthermore, biodiesel is made by transesterification of triglycerides purified from plant oils, yielding
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fatty acid methyl esters and fatty acid esters. Fatty acid can be produced from cyanobacteria. For
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example, Escherichia coli can be engineered to be an efficient producer of fatty acids. The free fatty acid
can be converted into biodiesel by esterification, and to alkanes and alkenes. Hence this concept has
been applied to production and secretion of fatty acids leading to production of biodiesel using
cyanobacteria.
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Microalgae and Cyanobacteria as raw material for production of Biofuel in comparison to
terrestrial crops
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Author’s Profile
Figure 2 shows the proposed biosynthetic pathways for production of fatty acid-based biofuels including
Papers of comparison
fatty acid esters, fatty alcohols and fatty alkanes directly from solar energy and carbon dioxide in
Executive Summary
cyanobacteria.
A theoretical calculation shows that the productivity of ethanol in photosynthetic organism can reach
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19,800 L/acre/year. Algeno Biofuels Inc. has developed an innovative cyanobacteria-based technology
and is reported to produce ethanol at a rate of 22,680 L/acre/year. In contrast annual yield of ethanol
from corn is 1,213 L/acre/year, from sugar cane it is 2,748 L/acre/year andfrom switchgrass it is 1,247 –
3,062 L/acre/year. Clearly, ethanol production from cyanobacteria is significantly more efficient than
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from plant feedstocks.
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So, according to this article compared to general
eukaryotic microalgae, cyanobacteria are more
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amenable to genetic manipulation for
installing biofuel producing chemical pathways.
Also, the genetic engineering platform
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for cyanobacteria is well established and
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cyanobacteria have been shown to be highly tolerant
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to the introduction of foreign genes.
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Figure 2
Microalgae and Cyanobacteria as raw material for production of Biofuel in comparison to
terrestrial crops
Author’s Profile
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Demirbas shows that microalgae are very rich in oil. Algae are among the fastest growing plants and 50%
Executive Summary
of their weight is oil.
He also mentioned that microalgae have much faster growth rates than terrestrial crops and that the unit
Background
area yield of oil is 7-31 times greater than crops.
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Moreover the author also compared the chemical compositions of algae from different species and he
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added that different species of algae may be suited for different types of fuel.
He also added that the yield of oil per unit area is estimated to be from 19,000 to 57,000 L per acre per
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year and is 200 times greater than plant/vegetable oils and can produce 30-100 times more energy per
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hectare compared to terrestrial crops. Also, the cost would be 5 times cheaper than the current price.
(See Article 1 & Article 1 contd)
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Lu Xuefeng showed that using cyanobacteria to produce chemicals and biofuel is a very good method.
Genetic manipulation has permitted engineering of cyanobacteria to produce non-natural chemicals
typically not produced by photosynthetic microorganisms. Cyanobacteria can be engineered to install
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biofuel chemical pathways.
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He also added that productivity of ethanol in cyanobacteria can be 19,800-22,680 L/acre/year while in
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plants/terrestrial crops it is very low. (See Article 2 & Article 2 contd)
Microalgae and Cyanobacteria as raw material for production of Biofuel in comparison to
terrestrial crops
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Figure 3 shows the routes to biofuels, where biodiesel in microalgae is labelled as green line and novel
Executive Summary
biofuels in cyanobacteria is labelled by red line and traditional biofuels by blue arrows.
To summarise, both papers show that microalgae and cyanobacteria produces more biofuel per year
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compared to terrestrial crops since they have a rapid growth rate, CO2 fixation ability and production of
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fatty acids.
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Figure 3
Microalgae and Cyanobacteria as raw material for production of Biofuel in comparison to
terrestrial crops
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Executive Summary
Background
Article 1
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Ayhan Dermibas did a study on the use of algae for biofuel production and showed how it is very
beneficial compared to terrestrial crops. The claim was sufficiently supported by evidences. The use of
different industrial reactors yield to different amount of oil. Also, the cost is 5 times cheaper to the
current cost.
The study carried out by Lu Xuefeng provided evidences about the oil yield in terrestrial crops as well as
few species of cyanobacteria. More importantly he also proved how cyanobacteria proved to be the
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most suitable as raw materials for biofuel production compared to terrestrial crops. The claims were
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supported by evidences.
Both research articles provided evidences and they were relevant enough to prove the point of
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microalgae and cyanobacteria being the most important raw material for biofuel production compared
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to terrestrial crops.
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Microalgae and Cyanobacteria as raw material for production of Biofuel in comparison to
terrestrial crops
Author’s Profile
Papers of comparison
Personal Comments
Executive Summary
Background
Article 1
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Article 2
The research made on the two articles and the evidences provided were fair enough to
conclude that microalgae and cyanobacteria are better raw material for biofuel production
compared to terrestrial crops. The benefits of biofuel over traditional biofuel that is from
terrestrial crops and plants include greater energy security, reduced environmental impact,
foreign exchange and greenhouse effect issues.
In contrast the competition with land use for crops results in increased food cost, biofuel
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production from terrestrial crops can cause great environmental cost, for example
deforestation to clear land crops caused emission of large amount of greenhouse gases.
The two articles were an answer to the question whether or not microalgae and cyanobacteria
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are a raw material for production of biofuel compared to terrestrial crops.
Microalgae and Cyanobacteria as raw material for production of Biofuel in comparison to
terrestrial crops
Author’s Profile
Reference
Papers of comparison
Executive Summary
Background
• Ayhan Demirbas. (2010), Use of algae as biofuel sources., Energy Conversion and Management.
Volume 51, pp 2738-2749
Article 1
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Article 2
• Iara M.P. Machado, Shota Atsumi. (2012), Cyanobacterial biofuel production., Journal of
Biotechnology, volume 162, pp 50-56.
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• Lu Xuefeng. (2010), A Perspective: Phostosynthetic production of fatty acid-based biofuels in
Paper Comparison
genetically engineered cyanobacteria, Biotechnology Advances.
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References
• M. Fatih Demirbas., (2011), Biofuels from algae for sustainable development, Applied Energy. Volume
88, pp 3473-3480.