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Algae Oil: A Sustainable Renewable Fuel of Future

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  • Vellore Institute of Technology

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A nonrenewable fuel like petroleum has been used from centuries and its usage has kept on increasing day by day. This also contributes to increased production of greenhouse gases contributing towards global issues like global warming. In order to meet environmental and economic sustainability, renewable, carbon neutral transport fuels are necessary. To meet these demands microalgae are the key source for production of biodiesel. These microalgae do produce oil from sunlight like plants but in a much more efficient manner. Biodiesel provides more environmental benefits, and being a renewable resource it has gained lot of attraction. However, the main obstacle to commercialization of biodiesel is its cost and feasibility. Biodiesel is usually used by blending with petro diesel, but it can also be used in pure form. Biodiesel is a sustainable fuel, as it is available throughout the year and can run any engine. It will satisfy the needs of the future generation to come.
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Review Article
Algae Oil: A Sustainable Renewable Fuel of Future
Monford Paul Abishek, Jay Patel, and Anand Prem Rajan
SchoolofBioSciencesandTechnology,VITUniversity,Vellore,TamilNadu632014,India
Correspondence should be addressed to Anand Prem Rajan; aprdbt@gmail.com
Received  February ; Accepted  March ; Published  May 
Academic Editor: Triantafyllos Roukas
Copyright ©  Monford Paul Abishek et al. is is an open access article distributed under the Creative Commons Attribution
License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly
cited.
A nonrenewable fuel like petroleum has been used from centuries and its usage has kept on increasing day by day. is also
contributes to increased production of greenhouse gases contributing towards global issues like global warming. In order to
meet environmental and economic sustainability, renewable, carbon neutral transport fuels are necessary. To meet these demands
microalgae are the key source for production of biodiesel. ese microalgae do produce oil from sunlight like plants but in a
much more ecient manner. Biodiesel provides more environmental benets, and being a renewable resource it has gained lot
of attraction. However, the main obstacle to commercialization of biodiesel is its cost and feasibility. Biodiesel is usually used by
blending with petro diesel, but it can also be used in pure form. Biodiesel is a sustainable fuel, as it is available throughout the year
and can run any engine. It will satisfy the needs of the future generation to come. It will meet the demands of the future generation
to come.
1. Introduction
Oil depletion is the degradation in oil production of a well
or oil eld. A  study published in the journal, Energy
Policy by researchers from Oxford University, predicted that
demand would surpass supply by , unless forced by
strong recession pressures caused by reduced supply or gov-
ernment interference []. It relates to long-term degradation
intheavailabilityofpetroleum.Onanaverage,humanutilizes
fossil fuels which results in the release of  gigatonnes
CO each year. ese gures point towards Hubbert’s peak
theory according to which peak oil is the point in time when
the maximum rate of petroleum extraction is reached, aer
which the rate of production is expected to enter terminal
decline []. is critical situation has led to the emergence
of an eco-friendly, alternative fuel biodiesel. According to
United States Environmental Protection Agency, the volume
requirement of the biomass based diesel in  is . million
gallons which accounts for .% of the total renewable fuels.
is, combined with growing demand, signicantly increases
the worldwide prices of petroleum derived products. Most
important concerns are the availability and price of liquid fuel
for transportation [].
In recent years, the use of biofuels has shown manifold
global growth in the transport sector due to the policies
concentration on achieving energy conservation and the
avoidance of excess or extremes of GHG (greenhouse gases)
emissions []. e st generation biofuels which are extracted
from oil crops like rapeseed oil, sugarcane, sugar beet, and
maize [] including vegetable oils and animal fat using
conventional technology have attained protable levels of
production []. But the use of st generation biofuels has
raised questions and controversies due to their impact on
theglobalfoodmarketandfoodsecurity[]. For example,
the demand for biofuels may impose additional pressure on
naturalresourcebase,withpotentiallyharmfulsurrounding
and social concerns [].
Energy shortage refers to the crisis of energy resources
to an economy. ere has been a massive upli in the
global demand for energy in recent years as a result of
industrial development and population growth. Since the
early s, the demand for energy, especially from liquid
fuels, and limits on the rate of fuel production have created
such a stage leading to the current energy crisis. e cause
maybeoverconsumption,agedinfrastructure,chokepoint
disruption or crisis at oil reneries, and port facilities that
conne fuel supply.
Hindawi Publishing Corporation
Biotechnology Research International
Volume 2014, Article ID 272814, 8 pages
http://dx.doi.org/10.1155/2014/272814
Biotechnology Research International
In this paper, we have focused on addressing the global oil
shortage by replacing nonrenewable source of oil reservoir by
evergreen renewable natural source, algae oil.
Microalgae cover unicellular and simple multicellular
microorganisms, including prokaryotic microalgae that are
cyanobacteria (chloroxybacteria) and eukaryotic microalgae
for example, green algae (chlorophyta), and diatoms (bacillar-
iophuta). ese microalgae are benecial as they are capable
of all year production []; they grow in aqueous media and
hence need less water than terrestrial crops []; microalgae
can be cultivated in brackish water on noncultivated land []
andtheyhaverapidgrowthpotentialandhaveoilcontent
up to –% dry weight of biomass [,]. Unlike other
biodeisel corps microalgae does not require herbicides or
pesticides [], microalgae also produce benecial coproducts
such as proteins and residual biomass aer oil extraction,
which can be used as feed or fertilizer or can be fermented to
produce ethanol or methane []; the oil yield, can be signi-
cantly increased by varying growth conditions to modulate
biochemical composition of algal biomass []. ey also
produce benecial coproducts such as proteins and residual
biomass aer oil extraction, which can be used as feed or
fertilizer or can be fermented to produce ethanol or methane
[]; the oil yield can be signicantly increased by varying
growth conditions to modulate biochemical composition of
algal biomass [].
e algal biofuel technology includes selection of specic
species for production and extraction of valuable co-products
[]. e algaes are bioengineered for achieving advanced
photosynthetic eciencies through continued development
of production system []. Challenges include, only single
species cultivation techniques which are developed so far and
are recommended to follow globally, but mixed culture may
yield more algae oil than mono culture []. Algae oil may
be less economically which includes techniques such as water
pumping, CO2transmission, harvesting and extraction [].
Fatal compounds such as NO𝑥and SO𝑥are produced in high
concentrations as fuel gases, which are not environmental
friendly [].
Microalgae are sunlight-driven cell factories that trans-
form carbon dioxide to potential biofuels, foods, feeds,
and high-value bioactive. In addition, these photosynthetic
microorganisms are useful in bioremediation applications
and as nitrogen xing biofertilizers. is review focuses on
microalgae as a potential basis of biodiesel.
e idea of using microalgae as a source of fuel is
not novel, but it is now taken seriously because of the
increasing price of petroleum and, more signicantly, the
emerging issues about global warming and greenhouse eect
that is associated with incinerating fossil fuels. us, several
companies are involved in the production of algal fuel in
order to decrease global warming and greenhouse eect.
Biodiesel is an established fuel. In the United States, biodiesel
is produced mainly from soybeans []. Other origins of
commercial biodiesel include canola oil, animal fat, palm oil,
corn oil [], and waste cooking oil. Microalgae oer several
dierent kinds of renewable biofuels [].
e yields of dierent oil producing feedstock can be
explained, as shown in Tab l e  .
T : Amount of oil produced by various feedstocks [].
Feedstock Liters/hectare
Castor 
Sunower 
Palm 
Soya bean 
Coconut 
Algae 100000
1.1. Unavailability of Resources. e feedstock is not available
for the biodiesel production as it is unethical to use these cash
cropsforfuelwhiletheworldiswitnessingfoodshortage.
eprimarycauseforglobalfoodshortagemaybedueto
overconsumption, overpopulation, and overexploitation.
1.2. Peak Oil. Peak oil is the point where maximum extraction
of petroleum is reached, aer which the rate of production
enters decline stage []. e invention of new elds, the
development of new production techniques, and the misuse
of eccentric supplies have resulted in productivity levels,
which endure to increase. Peak oil is oen confused with oil
depletion; peak oil is the point of maximum extraction, while
depletion indicates the period of falling in production and
supply.
2. Sources of Biodiesel
Avarietyofoilscanbeusedtoproducebiodiesel.ese
include the following.
2.1. Virgin Oil Feedstock. Rapeseed and soybean oils are most
commonly used, mostly in U.S []. ey also can be obtained
from Pongamia, eld pennycress, Jatropha, and other crops
such as mustard, jojoba, ax, sunower, palm oil, coconut,
and hemp. Several companies in various sectors are piloting
research on Jatropha curcas, a poisonous shrub-like tree that
produces seeds, considered by many to be a feasible source of
biodieselfeedstockoil[].
2.2. Waste Vegetable Oil (WVO). Ve g e ta b l e o il i s a n a lter n a-
tive fuel source for diesel engines and for heating oil burners.
e viscosity of the vegetable oil plays an important role in
the atomization of fuel for engines designed to burn diesel
fuel;otherwise,itcausesimpropercombustionandcauses
engine collapse. e most important vegetable oils used as
fuel are rapeseed oil (also known as canola oil, which is mostly
used in the United States and Canada). In some places of the
United States, the use of sunower oil as fuel tends to increase
[]. Some island nations use coconut oil as fuel to lower their
expenses and their dependence on imported fuels. e annual
vegetable oil recycled in the United States, as of , was
in excess of  billion liters (. billion U.S. gallons), mainly
produced from industrial deep fryers in potato processing
plants, snack factories and fast food restaurants. If all those
 billion liters could be recycled, it could replace the energy
equivalent amount of petroleum []. Other vegetable oils
Biotechnology Research International
which can be used as fuel are cottonseed oil, peanut oil, and
soybean oil [].
2.3. Animal Fats. Animal fats are the by-product of meat
production and cooking. ese include tallow, lard, yellow
grease, chicken fat, and the by-products of the production of
omega- fatty acids from sh oil []. Oil yielding Plants like
Salicornia bigelovii, a halophyte, is harvested using brackish
water in coastal areas where conventional crops are not
feasible to be grown. e oil from Salicornia bigelovii equal to
theyieldsofsoybeansandotheroilseedsgrownbyfreshwater
irrigation [].
Multifeedstock biodiesel facilities produce high standard
animal-fat based biodiesel. Currently, a -million-dollar plant
is being built in the USA, with the objective of producing .
million litres ( million gallons) biodiesel from the evaluated
billion kg (. billion pounds) of chicken fat produced
annually at the local Tyson poultry plant [].
2.4. Sewage Sludge. Sludge refers to the unused, semisolid
material le from industrial wastewater or sewage treatment
processes. It can also refer to the settled suspension obtained
from drinking water treatment and other industrial pro-
cesses. Sludge is generally produced by a poorly designed
or defective ventilation system, low engine operating tem-
peratures or the presence of water in the oil. e sewage-
to-biofuel eld process is developing interest from major
companieslikeWasteManagementandstartupslikeInfoSpi,
which are challenging that renewable sewage biodiesel can
become modest with petroleum diesel on price [].
3. Algal Fuel
Algae fuel or algal biofuel is another form of fossil fuel that
uses microalgae as its source of natural deposits []. Some
of the unique characteristics of algal fuels are as follows: they
can be grown with negligible impact on fresh water resources
[], they can be synthesized using ocean and wastewater,
and they are biodegradable and relatively harmless to the
environment if spilled [,]. Algae cost more per unit mass
duetothehighcapitalandproductioncosts.
e US Department of Energy’s Aquatic Species Program,
–, was engrossed in biodiesel from microalgae. e
nal report recommended that biodiesel could be the only
feasible method to produce enough fuel to change current
world diesel consumption [].Algalfuelishighlyfavorable
andfeasiblerelatedtootherbiofuels,astheydonothaveto
produce structural compounds and they can convert higher
fractions of biomass to oil compared to other cultivated crops
[].
Studies display that some species of algae have the ability
to produce up to % of their dry weight in the form of oil.
Because the cells grow in aqueous suspension, where they
have more eective access to water, CO2and nutrients are
capable of producing large amounts of biomass and usable oil
in either high rate algal ponds or photobioreactors (Table  ).
Regional cultivation of microalgae and producing bio-
fuels will ensure economic benets to rural communities
Microalgae
Algae for
biofuel
Macroalgae
Sea
lettuces
Dunaliella
Chlorella
Botryococcus
braunii
Sargassum
pleurochrysis
carterae
Gracilaria
F : Classied Algae used for biodiesel production.
Easy growth
rate
Renewable
source of
energy
Emit less
particulate
pollution
Algal
fuel
Sustainability
Ve r y
inexpensive
to produce
Cheaper than
fossil fuel
Food impact
Wast e
minimization
F : Advantages of algal fuel.
[]. Figure  dierentiates algae based on the species and
their size range (few micrometers (𝜇m) to a few hundreds of
micrometers), as macroalgae and microalgae are used in the
production of biodiesel.
4. Advantages of Algal Fuel over
Other Sources
4.1. Easy Growth Rate. One of the most important advantages
of using algae as the source is that it can be grown very
easily. Wastewater which normally hinders plant growth is
very eective in growing algae. e growth rate of algae is
– times faster than other conventional crops like Jatropha
[]. A diagram of the advantages of algal fuel is presented in
Figure .
4.2. Food Impact. Many outmoded feedstocks for biodiesel,
suchascornandpalm,canalsobeusedasfeedforlivestock
on farms, as well as reliable source of food for humans.
Because of this, using them as biofuel decreases the amount of
food available for both, and this causes an increased expense
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T : Algae species for alga oil and their typical oil content [].
Strain Oil content (% dw) Images
(-N-A-: Not Available)
Ankistrodesmus TR-87 –% dw -N-A-
Botryococcus braunii –% dw
Chlorella sp. % dw
Chlorella protothecoides –% dw -N-A-
Cyclotella DI-35 % dw -N-A-
Dunaliella tertiolecta –% dw
Hantzschia DI-160 % dw -N-A-
Nannochloris % dw
Nannochloropsis sp. ()%dw
Marine microalga
Nannochloropsis  (–) % dw
Phaeodactylum tricornutum % dw -N-A-
Scenedesmus TR-84 % dw -N-A-
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T : C o nt i n u e d .
Strain Oil content (% dw) Images
(-N-A-: Not Available)
Porphyra Red alga  (–) % dw
Tetra selmis suec i c a –% dw -N-A-
Diatoms Nualgi (–) % dw
Microalga Rich alga % dw
Neochloris oleoabundans –% dw -N-A-
Schizochytrium –% dw -N-A-
Sargassum
for both the food and the fuel produced. By using algae as a
source of biodiesel can make this issue in a number of ways.
First, algae are not used as a primary food source for humans,
meaningthatitcanbeuseddistinctlyforfuelandtherewould
be less impact on the food industry []. Second, many of
the waste-product sources produced during the processing
of algae for biofuel can be used as an ecient animal feed.
is is an ecient way to minimize waste and a much cheaper
remedy to the more traditional corn or grain based feeds [].
4.3. Waste Minimization. Growing algae have been shown
to have various environmental benets, proved to be the
environmental friendly biofuel [,]. Because of this, it
ensures that contaminated water does not mix with the
lakes and rivers that presently supply our drinking water.
In addition to this, the ammonia, nitrates, and phosphates
that would generally render the water unsafe actually serve
as excellent nutrients for the algae [].
5. Production
5.1. Algae Cultivation. Algae are typically found growing
in ponds, waterways, or other wetlands which receive sun-
light and CO2. Growth varies on many factors and can be
enhanced for temperature, sunlight utilization, pH control,
uid mechanics, and more [,]. Man-made production of
algae tends to replicate the natural environments to achieve
ideal growth conditions. Algae production systems can be
organized into two distinct categories: open ponds and closed
photo bioreactors. Open ponds are simple expanses of water
sunkenintothegroundwithsomemechanismtodeliverCO
2
and nutrients with paddle wheels to mix with the algal broth.
Closed photo bioreactors are a broad category referring to
systems that are bounded and which allow more precise
control over growth conditions and resource management.
5.2. Algae Biolm. Biolm formed by algae can be harvested
easily using unit operations like ltering, scraping, size
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Algae cultivation
Biodiesel
Transesterication
Lipid
extraction
Algae
harvesting and
drying
F : Algae growth and harvesting process [].
Microalgae
biomass
Oil Biophotolysis Dark
fermentation
Residual
biomass
Hydrothermal
liquefaction
Bio-oil
Anaerobic
digestion
Biogas
Hydrolysis:
acid, alkali,
enzymatic
Fermentation
Transesterication:
acid, alkali,
enzymatic
Biodiesel
Biohydrogen
Bioethanol
F : Principal Microalga biomass transformation processes for biofuel production [].
reduction, and drying. Photoreactors are used to produce
high quality algae in either sessile from or mainly biolm
(attached form). Attached algae have produced more oil than
planktonic form. e reason for high lipid content is due to
alteration in the lipid metabolic pathway of attached algae
resulting in change in the membrane uidity of algae to make
them attached to a substratum. For small-scale as well as
large-scale production, the photoreactors are used wherein
natural or synthetic light can be used to grow algae.
5.3. Algae Harvesting and Oil Extraction. Production of oil
from algae is a straightforward process that consisted of
growing the algae by providing necessary inputs for photo-
synthesis, harvesting, dewatering, and oil extraction. Energy
in the form of photons is absorbed by the algae cells, which
convert the inorganic compounds of CO2and water into
sugars and oxygen. e sugars are eventually converted into
complex carbohydrates, starches, proteins, and lipids within
the algae cells. In order to extract the valuable lipids, a series
of steps must be undertaken to isolate the algae cells and oil.
A diagram of the overall growth and harvesting process
is presented in Figure . e traditional process begins by
separating the algae biomass from the water broth in the
dewateringstage using centrifuges, ltration, or occulation
techniques. Centrifuges collect biomass by spinning the
algae-water broth so that water is ung away from the algae
cells. Flocculation involves precipitating algae cells out of
solution so that they can be concentrated and removed
easily. Once the algae cells have been collected the oil must
be removed from the cells. e oil can then be processed
into biodiesel, jet fuel, ethanol, synthetic fuels, or other
chemicals. Figure  explains the overall microalga biomass
transformation processes for biofuel production.
Liquefaction (Dewatering). High content of water oen
exists in microalgae aer harvesting which requires a great
deal of energy to remove moisture in the algal cells in the
period of pretreatment. Liquefaction has been developed
to produce biofuel directly without the need of drying
microalgae. Moreover, wet microalgae can provide hydrogen
for hydrogenolysis [].
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5.4. Transesterication. Biodiesel is commonly produced by
thetransestericationofthevegetableoil,animalfat,or
algal feedstock. ere are several methods for carrying out
this transesterication reaction including the collective batch
process, supercritical processes, ultrasonic methods, and
even microwave methods.
Chemically, transesteried biodiesel comprises a mix of
mono-alkyl esters of long chain fatty acids. e most conjoint
form uses methanol (converted to sodium methoxide) to
produce methyl esters (commonly referred to as fatty acid
methyl ester (FAME)) as it is the cheapest alcohol available;
though ethanol can be used to form an ethyl ester (commonly
referred to as fatty acid ethyl ester (FAEE)), biodiesel and
higher alcohols such as isopropanol and butanol have also
been used. Using alcohols of higher molecular weights
improves the cold ow properties of the resulting ester, at
the cost of a less ecient transesterication reaction. A lipid
transesterication production process converts the base oil to
the desired esters. Any free fatty acids (FFAs) in the base oil
are either converted to soap or removed from the process, or
they are esteried (yielding more biodiesel) using an acidic
catalyst. Aer this processing, biodiesel has combustion
properties very similar to those of petroleum diesel and can
replace it in most present uses.
e methanol used in most biodiesel production pro-
cesses is made by fossil fuel inputs. However, there are sources
of renewable methanol synthesized using carbon dioxide or
biomass as feedstock, making their production processes free
of fossil fuels [].
6. Conclusion
As justied here, microalgal biodiesel is technically feasible.
It is the only renewable biodiesel that can potentially and
methodically displace liquid fuels obtained from petroleum.
Economics of producing microalgal biodiesel need to impro-
vise substantially to make it competitive with petro diesel, but
the level of improvement necessary appears to be possible.
Producing low-cost microalgal biodiesel requires primarily
improvements to algal biology through genetic and metabolic
engineering. Use of the biorenery concept and advances
in photobioreactor engineering will further reduce the cost
of production. In view of their much greater productivity
than raceways, tubular photobioreactors are likely to be used
in producing most of the microalgal biomass required for
making biodiesel. Algae biolm grown in photobioreactors
provide a controlled environment that can be tailored to the
specic demands of highly productive microalgae to attain a
consistently good annual yield of oil.
Conflict of Interests
e authors declare that there is no conict of interests
regarding the publication of this paper.
Acknowledgments
is study is supported nancially by the Science &
Engineering Research Board (SERB), Department of Science
and Technology, New Delhi, India, by funding the
Project “Dierential membrane lipid prole and uidity
of Acidithiobacillus ferrooxidans during the process of
adhesion to minerals” (D.O no. SR/S/ME//). is
funded project has enabled the corresponding author to
study the bacterial Biolm formation, which enabled him
to understand the structural integrity of cell membrane of
prokaryotes and eukaryotes that is algal biolm with respect
to lipid content.
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