Methodology and application of algae as biofuel
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Transcript of Methodology and application of algae as biofuel
METHADOLOGY AND APPLICATION OF ALGAE AS BIOFUEL 2013-2014
CHAPTER - 1
INTRODUCTION
The global economy is massively dependent on fossil fuels and the every growing nation is
becoming increasingly dependent upon foreign sources of crude oil.. The rising energy demand
in many rapidly developing countries around the world is beginning to create intense competition
for the world’s dwindling petroleum reserves. Furthermore, the combustion of petroleum-based
fuels has created serious concerns about climate change from the greenhouse gas (GHG)
emissions which is responsible for the global warming. In recent times all the growing nation
have new standards for vehicle fuel economy, as well as made provisions that promote the use
of renewable fuels, energy efficiency, and new energy technology research and development.
For these reasons since a couple of years there is a lot of researches in progress for
ALTERNATIVE FUEL like BIOFUEL
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BIOFUEL
The first generation of bio fuels is ethanol made out of crops. This kind of fuels has, like
fossil fuels, also many disadvantages. First of all it needs agricultural space for its cultivation.
This means that it is in competition with the arable land for human nutrition. The consequences
of this competition are the scarcity of food and the increasing of the world food prices. One of
the goals of producing and using crop bio fuels was the reducing of greenhouse gas emissions
due to burning fossil fuels. The idea behind is that the released CO2 due to burning bio fuels is
rebounding by crop growth through the mechanism of photosynthesis. But the hole gaining
process of ethanol from crops consumes a lot of energy (mostly from fossil fuels). First of all the
industrial cultivation and harvesting needs machines operating by fossil fuels. Then the
transformation from plants to ethanol is also energy intensive
The second generation of biofuels was made out of residues from crops, animals, timber and
food. This application reduces the disadvantage competition with human food. But the crop
residues are an essential source of nutrients for plants. Burning these crop residues means
decreasing of organic matter in agricultural soils and using more mineral fertilizer like
ammonium which is made under high energy use.
Now the third generation of biofuels is developing. In a very short abstraction it is biofuel
made directly by algae i.e. microalgae (microorganisms).
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WHAT ARE ALGAE?
Algae range from small, single-celled organisms to multi-cellular organisms, some with fairly
complex and differentiated form. Algae are usually found in damp places or bodies of water and
thus are common in terrestrial as well as aquatic environments. Like plants, algae require
primarily three components to grow: sunlight, carbon-dioxide and water. Photosynthesis is an
important bio-chemical process in which plants, algae, and some bacteria convert the energy of
sunlight to chemical energy.
The existing large-scale natural sources are of algae are bogs, marshes and swamps - salt
marshes and salt lakes. Micro-algae contain lipids and fatty acids as membrane components,
storage products, metabolites and sources of energy. Algae contain anything between 2% and
40% of lipids/oils by weight.
ADVANTAGES OF ALGAL FEED STOCKS
There are several aspects of algal bio fuel production that have combined to capture the interest
of researchers and entrepreneurs around the world:
• Algal productivity can offer high biomass yields per acre of cultivation.
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• Algae cultivation strategies can minimize or avoid competition with arable land and nutrients
used for conventional agriculture.
• Algae can utilize waste water, produced water, and saline water, thereby reducing competition
for limited freshwater supplies.
• Algae can recycle carbon from CO2-rich flue emissions from stationary sources, including
power plants and other industrial emitters.
• Algal biomass is compatible with the integrated biorefinery vision of producing a variety of
fuels and valuable co-products.
CHAPTER - 2
METHADOLOGY OF ALGAE FUEL
The commercial-scale production of algae requires careful consideration of many issues that can
be broadly categorized into four main areas: selecting algae species that produce high oil levels
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and grow well in specified environments, water source and issues algae growth methods, and
nutrient and growth inputs.
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1. SELECTING ALGAE SPECIES
Research into algae for the mass-production of oil focuses mainly on microalgae (organisms
capable of photosynthesis that are less than 0.4 mm in diameter, including the
diatoms and cyanobacteria) as opposed to macroalgae, such as seaweed. The preference for
microalgae has come about due largely to their less complex structure, fast growth rates, and
high oil-content (for some species). However, some research is being done into using seaweeds
for biofuels, probably due to the high availability of this resource.
Genetically modified strains of algae are being developed for algae biofuels, especially high
lipid-content algae. Certain companies have developed algae strains with unique characteristics .
ADVANTAGES OF MICROALGAE:
(1) Microalgae are capable of all year round production, therefore, oil productivity of microalgae
cultures exceeds the yield of the best oilseed crops, e.g. biodiesel yield of 12,000 l ha_1 for
microalgae (open pond production) compared with 1190 l ha_1 for rapeseed .
(2) They grow in aqueous media, but need less water than terrestrial crops therefore reducing the
load on freshwater sources .
(3)Microalgae can be cultivated in brackish water and therefore may not incur land-use change,
minimizing associated environmental impacts . while not compromising the production of food,
fodder and other products derived from crops.
(4) Microalgae have a rapid growth potential and many species have oil content in the range of
20–50% dry weight of biomass, the exponential growth rates can double their biomass in periods
as short as 3.5 h .
(5) With respect to air quality maintenance and improvement, microalgae biomass production
can effect bio fixation of waste CO2 (1 kg of dry algal biomass utilize about 1.83 kg of CO2) .
(6) Nutrients for microalgae cultivation(especially nitrogen and phosphorus) can be obtained
from wastewater, therefore, apart from providing growth medium, there is dual potential for
treatment of organic effluent from the agri-food industry ;
(7) Algae cultivation does not require herbicides or pesticides application .
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(8) They can also produce valuable co-products such as proteins and residual biomass after oil
extraction, which may be used as feed or fertilize , or fermented to produce ethanol or methane ;
(9) The biochemical composition of the algal biomass can be modulated by varying growth
conditions , therefore, the oil yield may be significantly enhanced , and
(10) Microalgae are capable of photobiological production of ‘biohydrogen’. The outlined
combination of potential biofuel production, CO2 fixation, biohydrogen production,and bio-
treatment of wastewater underscore the potential applications of microalgae.
2. GROWTH INPUTS
LIGHT
Algae generally require light to grow. If the primary light source is natural sunlight, it
may be advisable to secure solar rights, for the project site. Many companies are developing
systems and technologies using artificial light sources. OriginOi l has developed a Helix
BioReactorTM that features a rotating vertical shaft with low-energy lights arranged in a helix
pattern.
HIGH TEMPERATURE AND PRESSURE
An alternative approach employs a continuous process that subjects harvested wet algae to high
temperatures and pressures—350 °C (662 °F) (662 °F) and 3,000 pounds per square inch
(21,000 kPa).
NUTRIENTS
Nutrients like nitrogen (N), phosphorus (P), and potassium (K), are important for plant growth
and are essential parts of fertilizer. Silica and iron, as well as several trace elements, may also be
considered important marine nutrients as the lack of one can limit the growth of, or productivity
in, an area.
CARBON DIOXIDE
Bubbling CO2 through algal cultivation systems can greatly increase productivity and yield (up
to a saturation point). Typically, about 1.8 tonnes of CO2 will be utilized per tones of algal
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biomass (dry) produced, though this varies with algae species.. Each tones of microalgae absorbs
two tonnes of CO2.
NITROGEN
Nitrogen is a valuable substrate that can be utilized in algal growth. Various sources of nitrogen
can be used as a nutrient for algae, with varying capacities. Nitrate was found to be the preferred
source of nitrogen, in regards to amount of biomass grown. Urea is a readily available source that
shows comparable results, making it an economical substitute for nitrogen source in large scale
culturing of algae.Despite the clear increase in growth in comparison to a nitrogen-less medium,
it has been shown that alterations in nitrogen levels affect lipid content within the algal cells.
WASTEWATER
A possible nutrient source is waste water from the treatment of sewage, agricultural, or flood
plain run-off, all currently major pollutants and health risks. However, this waste water cannot
feed algae directly and must first be processed by bacteria, through anaerobic digestion..
The utilization of wastewater and ocean water instead of freshwater is strongly advocated due to
the continuing depletion of freshwater resources. However, heavy metals, trace metals, and other
contaminants in wastewater can decrease the ability of cells to produce lipids biosynthetically
and also impact various other workings in the machinery of cells. The same is true for ocean
water, but the contaminants are found in different concentrations.
3. CULTIVATION
PRINCIPLE
Algae grows naturally in fresh, brackish, or salt water, depending on the algae species. Under
natural growth conditions algae absorb sunlight, and assimilate carbon dioxide from the air and
nutrients from the aquatic habitats. Therefore, as far as possible, artificial production should
attempt to replicate and enhance the optimum natural growth conditions.
Three distinct algae production mechanisms including photoautotrophic, heterotrophic and
mixotrophic production, all of which follow the natural growth processes.
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PHOTOAUTOTROPHIC PRODUCTION
Currently, photoautotrophic production is the only method which is technically and economically
feasible for large-scale production of algae biomass for non-energy production .
Two systems that have been deployed are based on open pond and closed photobioreactor
technologies . The technical viability of each system is influenced by intrinsic properties of the
selected algae strain used, as well as climatic conditions and the costs of land and water .
OPEN POND PRODUCTION SYSTEMS
These systems can be categorised into natural Algae cultivation in open pond production systems
has been used waters (lakes, lagoons, and ponds) and artificial ponds or containers.
Raceway ponds are the most commonly used artificial system .They are typically made of a
closed loop, oval shaped recirculation channels (Fig. 1), generally between 0.2 and 0.5mdeep,
with mixing and circulation required to stabilize algae growth and productivity.
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Raceway ponds are usually built in concrete, but compacted earth lined ponds with white plastic
have also been used. In a continuous production cycle, algae broth and nutrients are introduced
in front of the paddlewheel and circulated through the loop to the harvest extraction point. The
paddlewheel is in continuous operation top revent sedimentation. The microalgae’s CO2
requirement is usually satisfied from the surface air, but submerged aerators may be installed to
enhance CO2 absorption.
Compared to closed photo bioreactors , open pond is the cheaper method of large-scale algal
biomass production. Open pond production does not necessarily compete for land with existing
agricultural crops, since they can be implemented in areas with marginal crop production
potential. They also have lower energy input requirement and regular maintenance and cleaning
are easier and therefore may have the potential to return large net energy production
Fig. . Plan view of a raceway pond. Algae broth is introduced after the paddlewheel, and completes a cycle while
being mechanically aerated with CO2. It is harvested before the paddlewheel to start the cycle again (adapted from
Chisti ).
CLOSED PHOTOBIOREACTOR SYSTEMS
Microalgae production based on closed photobioreactor technologies designed to overcome
some of the major problems associated with the described open pond production systems. For
example,pollution and contamination risks with open pond systems, for the most part, preclude
their use for the preparation of high-value products for use in the pharmaceutical and cosmetics
industry. Closed systems include the tubular, flat plate, and column photobioreactor. These
systems are more appropriate for sensitive strains as the closed configuration makes the control
of potential contamination easier. Owing to the higher cell mass productivities attained
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harvesting costs can also be significantly reduced. However, the costs of closed systems are
substantially higher than open pond systems.
Photobioreactor consist of an array of straight glass or plastic tubes as shown in Fig. The tubular
array captures sunlight and can be aligned horizontally, vertically, inclined or as a helix and the
tubes are generally 0.1 m or less indiameter
Fig.. Basic design of a horizontal tubular photobioreactor (adapted from Becker Two main sections: airlift system
and solar receiver; the airlift systems allow for the transfer of O2 out of the systems and transfer of CO2 into the
system as well as providing a means to harvest the biomass. The solar receiver provides a platform for the algae to
grow by giving a high surface area to volume ratio.
Algae cultures are re-circulated either with a mechanical pump or airlift system, the latter
allowing CO2 and O2to be exchanged between the liquid medium and aeration gas as well as
providing a mechanism for mixing. Agitation and mixing are very important to encourage gas
exchange in the tubes. The reactors are made of transparent materials for maximum solar energy
capture, and a thin layer of dense culture flows across the flat plate which allows radiation
absorbance in the first few millimeters thickness. Closed photobioreactor have received major
research attention in recent years.
HYBRID PRODUCTION SYSTEMS
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The hybrid two-stage cultivation is a method that combines distinct growth stages in photo
bioreactors and in open ponds.
HETEROTROPHIC PRODUCTION
In this process microalgae are grown on organic carbon substrates such as glucose in stirred tank
bioreactors or fermenters and independent of photosynthesis
MIXOTROPHIC PRODUCTION
Many algal organisms are capable of using either metabolism process (autotrophic or
heterotrophic) for growth, meaning that they are able to photosynthesise as well as ingest prey or
organic materials .
4. HARVESTING ALGAE AND DEWATERING
Generally, microalgae harvesting is a two stage process, involving:
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(1) BULK HARVESTING—aimed at separation of biomass from the bulk suspension.
This will depend on the initial biomass concentration and technologies employed, including
flocculation, flotation or gravity sedimentation.
(2)THICKENING - the aim is to concentrate the slurry through techniques such as
centrifugation, filtration and ultrasonic aggregation, hence, is generally a more energy intensive
step than bulk harvesting.
Method Description Materials Advantages Disadvantages References
Centrifugation
Mechanical method that removes water by centrifugal force
Centrifuge
High recovery rate, high rate of solids, no contamination by chemicals
High energy requirement, damage to cells by shearing
Filtration
Algae passes through membrane that retains the solids while the media passes through
Filter, suction pump
High recovery rate, lower energy requirement, no contamination by chemicals
Redilution (dewatering) may be required, fouling of filter membrane may occur
Flocculation
Aggregation of cells is caused by removing the electrostatic barrier that separates them
Flocculant, such as NaOH, chitosan, aluminum chloride
Less damaging than centrifugation, low energy requirements, efficient
Contamination of harvested algae with chemicals, hard to flocculate saltwater algae
Flotation
Algae is floated to the surface using bubbling, and skimmed off the surface, often in combination with flocculation
Flocculant, gas impeller, collection bowl
No damage to cells, simple, low energy
May not work well for dense cultures
Ultrasonic separation
Sound waves cause the cells to agglomerate
Ultrasonic wave generator,
Removal of most water, no damage to cells,
High energy input, high cost, cells not as
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resonator chamber, pump
no fouling of system
concentrated as other harvesting methods
Electrolytic methods
Electrodes cause coagulation of cells so that they fall out of suspension
Electrodes
Low energy input, no contamination, media can be recycled
Electrodes may foul
Flocculation
Since microalgae cells carry a negative charge that prevents natural aggregation of cells in
suspension, addition of flocculants such as multivalent cations and cationic polymers neutralizes
or reduces the negative charge. It may also physically link one or more particles through a
process called bridging, to facilitate the Multivalent metal salts like ferricchloride (FeCl3),
aluminium sulphate (Al2(SO4)3) and ferric sulphate (Fe2(SO4)3) are suitable flocculants.
Ultrasound
Gentle, acoustically induced aggregation followed by enhanced sedimentation can also be used
to harvest microalgae biomass..The main advantages of ultrasonic harvesting are that it can be
operated continuously without inducing shear stress on the biomass, which could destroy
potentially valuable metabolites, and it is a non-fouling technique.
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Figure Schematic of an ultra filtration unit
Harvesting by flotation
Flotation methods are based on the trapping of algae cells usingdispersed micro-air bubbles and
therefore, unlike flocculation, does not require any addition of chemicals
Gravity and centrifugal sedimentation
Gravity and centrifugation sedimentation methods are basedon Stoke’s Law i.e. settling
characteristics of suspended solids is determined by density and radius of algae cells
(Stoke’sradius) and sedimentation velocity
Biomass filtration
A conventional filtration process is most appropriate for harvesting of relatively large (>70 mm)
microalgae .It cannot be used to harvest algae species approaching bacterial dimensions (<30
mm) .
Dehydration processes
The harvested biomass slurry (typical 5–15% dry solid content)is perishable and must be
processed rapidly after harvest; dehydration or drying is commonly used to extend the viability
depending on the final product required. Methods that have been used include sun drying low-
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pressure, shelf drying, spray drying, drum drying, fluidized bed drying, freeze drying], and
Refractance Window TM technology drying .
5. EXTRACTION
After the cells are harvested, lipids must be extracted from the cells. In order to accomplish this,
cell walls must be disrupted without extracting other components. Like harvesting, there are
mechanical, chemical, and physical methods. Methods of extraction are listed in Table .
Method Description Comments
HomogenizationAlgae is expelled through small valves which disrupt the cell walls
Often used as a pretreatment for further extraction, no chemical contamination
Bead MillingAlgae is placed in a chamber with small beads that are agitated and disrupt cells
No chemical contamination
Bligh and Dyer
After determining the water content, sample is homogenized with 2:1 methanol:chloroform, and washed with chloroform and water. Two phases are formed, and the lipid phase is collected.
Not accurate with samples of greater than 2% lipid, originally designed for extraction of phospholipids of fish.
FolchAlgae is mixed with 2:1 chloroform:methanol, allowed to settle into phases. The lipid phase is washed and collected, and then allowed to dry.
Originally designed for extracting lipids from brain tissue. Considered the standard for lipid extraction
Soxhlet A weighed sample is placed in a soxhlet Can be a long process
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apparatus, and solvent is added. The lipids are slowly extracted and then dried.
Supercritical
A supercritical fluid is created by adding high pressure and temperature until it has properties of both. It has the density of a liquid and the compressibility of a gas. Algae is placed in an extraction vessel, and the supercritical fluid passes through the vessel and then vents to the atmosphere.
Carbon dioxide is of special interest. Temperature may be used to select for specific lipids because of its effect on solubility.
SonicationBubbles are created by ultrasound, and when they burst, they disrupt cell walls.
No chemical contamination
Subcritical waterWater is heated to boiling, and pressure is applied, creating a solvent.
Mostly used with higher plants
MicrowavesMicrowaves are used to generate energy in polar solvents and remove water in order to disrupt cell walls.
Rapid method
Table. Methods used to extract lipids from microalgae
The soxhlet method uses solvents, as diagrammed in Figure. Unfortunately, most solvent
methods of extraction may contaminate the finished product with unwanted chemicals. The
benefit of mechanical methods is that they leave no unwanted residue.
Figure. A diagram of a soxhlet apparatus.
6. CONVERSION OF ALGAE OIL INTO BIOFUEL
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Algae can be converted into various types of fuel, depending on the technique and the part of the
cells used. The lipid, or oily part of the algae biomass can be extracted and converted into
biodiesel through a process similar to that used for any other vegetable oil, or converted in a
refinery into "drop-in" replacements for petroleum-based fuels. Alternatively or following lipid
extraction, the carbohydrate content of algae can be fermented into bioethanol or biobutanol New
technologies like the Mcgyan® Process offer flexible feedstock options that could work well if
an algae biofuels facility was not able to produce enough oil to fully supply a plant.
THERMOCHEMICAL CONVERSION.
Thermochemical conversion covers the thermal decomposition of organic components in
biomass to yield fuel products, and is achievable by different processes such as direct
combustion, gasification, thermochemical liquefaction, and pyrolysis.
GASIFICATION
Gasification involves the partial oxidation of biomass into a combustible gas mixture at high
temperatures (800–1000 8C) .The key advantage of gasification as abiomass-to-energy pathway
is that it can produce a syngas from awide variety of potential feedstocks
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Thermochemical liquefaction is a process that can be employedto convert wet algal
biomass material into liquid fuel .
Pyrolysis is the conversion of biomass to bio-oil, syngas andcharcoal at medium to high
temperatures (350–700 8C) in theabsence of air
In a direct combustion process, biomass is burnt in the presenceof air to convert the stored
chemical energy in biomass into hot
gases
The biological process of energy conversion of biomass intoother fuels includes anaerobic
digestion, alcoholic fermentationand photobiological hydrogen production.
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Anaerobic digestion (AD) is the conversion of organic wastesinto a biogas, which consists
of primarily methane (CH4) andcarbon dioxide, with traces of other gases such as
hydrogensulphide.
Alcoholic fermentation is the conversion of biomass materialswhich contain sugars, starch
or cellulose into ethanol.
Hydrogen (H2) is a naturally occurring molecule, which is aclean and efficient energy carrier
[163]. Microalgae possess thenecessary genetic, metabolic and enzymatic characteristics
tophotoproduce H2 gas .
Biodiesel is a derivative of oil crops and biomass which can beused directly in conventional
diesel engines .It is a mixture of
monoalkyl esters of long chain fatty acids (FAME) derived from arenewable lipid feedstock such
as algal oil
The last step in the process to creating a viable fuel is to convert the TAG to fatty acid methyl
esters (FAME), the lipids that constitute fuel. The process of converting TAG to FAME is
known as transesterification. In this reaction, a simple alcohol such as methanol is added to
lipids. A catalyst, such as NaOH, can be used. The reaction takes place in a vessel while being
stirred, creating FAME and a glycerol byproduct. If supercritical alcohol is used in the reaction a
catalyst may not be necessary, and also may be used to bypass the extraction method. The
supercritical alcohol method is accomplished by adding methanol to dried algae and heating for
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40 minutes at 90º C to cause a supercritical reaction. Mixing helps the separation process.
Finally in producing viable Fuel is to remove the glycerol byproduct, along with any other
contaminant that may be present via gravitational settling or centrifugation.
Algae biofuels plants will generally produce a new type of fuel that has not yet been
commercialized, and the plant backers will need to clear significant hurdles to achieve success.
It is in recognition of these challenges that the federal government policy supports advanced
biofuels that conform to existing specifications and serve as a substitution for petroleum-based
fuels. Typically the ASTM International, a private organization, is the primary deliberative body
defining fuel specifications
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CHAPTER - 3
APPLICATION OF ALGAE AS BIOFUEL
BIODIESEL
Biodiesel is a diesel fuel derived from animal or plant lipids (oils and fats). Studies have shown
that some species of algae can produce 60% or more of their dry weight in the form of oilbecause
the cells grow in aqueous suspension, where they have more efficient access to water, CO2 and
dissolved nutrients, microalgae are capable of producing large amounts of biomass and usable oil
in either high rate algal ponds or photobioreactors. This oil can then be turned
into biodiesel which could be sold for use in automobiles.
The U.S. Department of Energy's Aquatic Species Program, 1978–1996, focused on biodiesel
from microalgae. The final report suggested that biodiesel could be the only viable method by
which to produce enough fuel to replace current world diesel usage.
BIOBUTANOL
\Butanol can be made from algae or diatoms using only a solar powered biorefinery. This fuel
has an energy density 10% less than gasoline, and greater than that of eitherethanol or methanol
BIOGASOLIN
Biogasoline is gasoline produced from biomass. Like traditionally produced gasoline, it contains
between 6 (hexane) and 12 (dodecane) carbon atoms per molecule and can be used in internal-
combustion engines.\
METHANE
Methane the main constituent of natural gas can be produced from algae in various methods,
namely Gasification, Pyrolysis and Anaerobic Digestion microalgae cultivation operations, it has
been proposed to recover the energy contained in waste biomass via anaerobic digestion to
methane for generating electricity
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ETHANOL
The Algenol system which is being commercialized by BioFields in Puerto Libertad, Sonora,
Mexico utilizes seawater and industrial exhaust to produce ethanol. Porphyridium cruentum also
have shown to be potentially suitable for ethanol production due to its capacity for accumulating
large amount of carbohydrates
HYDROCRACKING TO TRADITIONAL TRANSPORT FUELS
Algae can be used to produce 'green diesel' (also known as renewable diesel, hydro-treated
vegetable oil or hydrogen-derived renewable diesel) through a hydrocracking refinery process
that breaks molecules down into shorter hydrocarbon chains used in diesel engines. It has the
same chemical properties as petroleum-based dieselmeaning that it does not require new engines,
pipelines or infrastructure to distribute and use. It has yet to be produced at a cost that is
competitive with petroleum.
JET FUEL
Rising jet fuel prices are putting severe pressure on airline companies creating an incentive for
algal jet fuel research. The International Air Transport Association, for example, supports
research, development and deployment of algal fuels. IATA's goal is for its members to be using
10% alternative fuels by 2017Trials have been carried with aviation biofuel by Air New
Zealand, Lufthansa, and Virgin Airlines
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CHAPTER - 4
CONCLUSION
This seminar underlines the existing technical viability for the development of biofuels from
microalgae as a renewable energy resource and for mitigation of GHG related impacts of
petroleum derived fuels. The achievable high yields for both lipids and biomass, combined with
some useful co-products if purposefully exploited, could enhance algae’s economic viability as a
source for biofuels. Phototrophic production is the most effective in terms of net energy balance.
However, productivity values vary immensely and are significantly lower when compared with
heterotrophic production.
The use of waste CO2 from power plants to enhance production has been shown to be
technically feasible, and hence, may be deployed to reduce production costs and for GHG
emission control. Harvesting of algal biomass accounts for the highest proportion of energy input
during production. Lipids are the most readily extractible biofuel feedstock from algae, but
potential storage is hindered by the presence of polyunsaturated fatty acids(PUFAs) causing
oxidation reactions and high moisture content of algal feedstock. This seminar also suggests that
both thermochemical liquefaction and pyrolysis appear to be the most technically feasible
methods for conversion of algal biomass-to-biofuels, after the extraction of oils from algae..
Overall, with the current demand for renewable fuels, especially for use in the transportation
sector, there is a need to develop a range of sustainable biofuels resources as the combined mix
will be a significant step towards the replacement of fossil fuels. Continued development of
technologies to optimise the microalgae production, oil extraction and biomass processing has
the capacity to make significant contributions towards this goal.
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CHAPTER-5
REFERENCES
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