HAWASSA UNIVERSITY INSTITUTE OF
TECHNOLOGY
FACULTY OF MANUFACTURING
DEPARTMENT OF CHEMICAL ENGINEERING
Production of Biodiesel from Micro Algae by Transesterification process
A Thesis Submitted to the Department of Chemical Engineering in Partial
Fulfillment of the Requirements for the Degree of Bachelor of Science (B.Sc.) in
Chemical Engineering
Prepared by
1. Bereket Getnet ……….... (Tech/1102/09)
2. Tewodros Terefe ………..(Tech/1151/09)
3. Hanna Desta.....................(Tech/1077/09)
Date 26/12/2013 E.C
Hawassa, Ethiopia
Production of Biodiesel from Micro Algae by Trans-esterification process
Production of Biodiesel from Micro Algae by Transesterification process
Prepared by
1. Bereket Getnet
2. Tewodros Terefe
3. Hanna Desta
A Thesis Submitted in Partial Fulfillment of the Requirements for the Degree of
Bachelor of Science (B.Sc.) in Chemical Engineering (Process Stream)
Department of Chemical Engineering
Hawassa University Institute of Technology
Hawassa University
///////////
Advisor: Dr. Getnet Abera
ii
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
DECLARATION
We, the undersigned, declare that this thesis presented for the attainment of the degree of
Bachelor of Science in Chemical Engineering is our original work and has not been presented
or submitted, in part or as a whole, for a degree in any other institution or university. And all
sources of information or materials used for the thesis have been duly acknowledged.
______________________Signature: _______________ Date: ___________________
B.Sc. Candidate
______________________Signature: _______________ Date: ___________________
B.Sc. Candidate
______________________Signature: _______________ Date: ___________________
B.Sc. Candidate
This thesis has been submitted for examination with my approval and done under my supervision
as University advisor.
_________________________Signature: ______________ Date: ____________________
Advisor
The undersigned members of the thesis examining board appointed to examine this thesis
confirmed that the thesis fulfills the requirements of the undergraduate program and approved it
to be accepted.
Approved by the Examining Board:
Signature
Date
_________________________________
Chairman, Head of the Department
_____________________ ___________________
____________________
Internal Examiner
_________________
External Examiner
_____________________
__________________
_____________________
__________________
iii
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
ACKNOWLEDGEMENT
Beyond all we thank our almighty God who allows us to do this thesis and helped us to
accomplish our BSc. Degree successfully. Let also our great thankfulness goes to our advisor Dr.
Getnet Abera who helped us to advise our thesis, followed our work attentively and provided us
his professional supports. Lastly we would like to acknowledge all of the staffs of Chemical
Engineering department and laboratory technicians for their helps in every scenario. Let our
heartily thankfulness also goes to all of our friends who helped us by providing resources,
information and a kind cooperation.
iv
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
ABSTRACT
The world's primary energy source is petroleum-derived fuels. Petroleum resources, on the other
hand, are limited and rapidly depleting. As a result, biodiesel, which is a fatty acid ester
generated from triglycerides through a process known as trans-esterification with alcohol, is a
good fuel substitute. Nowadays, the world is paying close attention to the development of
microalgae biofuels. this study investigates production of biodiesel from the extracted
microalgae by the method of Soxhlet extraction with optimum operating conditions of
temperature and time, after the oil extraction the transesterification reaction proceed by 200ml of
oil at 600 c by the solvent of methanol with 600 rpm of mixing speed for 1 hour after the reaction
complete the product had been put in the separating funnel finally 100ml of biodiesel had been
separated and characterized.
v
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
ACRONYMS
LCA………………………………………. life cycle assessment
FFA………………………………………. free fatty acid
WC ………………………………………. water content
PC ………………………………………....phosphorus content
SC………………………………………….Sulfur content
SV ………………………………………....saponification value
FAE ………………………………………..fatty acid esters
FCI…………………………………………fixed capital investment
ROI…………………………………………rate of investment
TCI………………………………………….total capital investment
NPV…………………………………………net present value
TPC………………………………………….total production cost
WC………………………………………….working cost
BEP………………………………………….breakeven point
IRR………………………………………….internal rate of return
vi
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
Table of Contents
DECLARATION ........................................................................................................................... iii
ACKNOWLEDGEMENT ............................................................................................................. iv
ABSTRACT.................................................................................................................................... v
ACRONYMS ................................................................................................................................. vi
List of Figures ................................................................................................................................ ix
List of Tables ................................................................................................................................. ix
1
2
INTRODUCTION ................................................................................................................... 1
1.1
Background ...................................................................................................................... 1
1.2
Statement of the problem ................................................................................................. 2
1.3
Objective of the Study ...................................................................................................... 3
1.3.1
General Objective ..................................................................................................... 3
1.3.2
Specific Objectives ................................................................................................... 3
1.4
Scope of the study ............................................................................................................ 4
1.5
Significance of Study ....................................................................................................... 4
LITERATURE REVIEW ........................................................................................................ 5
2.1
Study on micro algae ........................................................................................................ 5
2.1.1
2.2
Algae growth technology ................................................................................................. 5
2.2.1
Photoautotrophic production ..................................................................................... 6
2.2.2
Heterotrophic Production .......................................................................................... 8
2.2.3
Mixotrophic Production ............................................................................................ 8
2.3
3
Classification of micro algae .................................................................................... 5
Algae harvesting methods ................................................................................................ 9
2.3.1
Centrifugation ........................................................................................................... 9
2.3.2
Flocculation............................................................................................................. 10
2.3.3
Flotation .................................................................................................................. 11
2.3.4
Filtration .................................................................................................................. 11
2.3.5
Screening................................................................................................................. 12
2.4
Extraction and Purification of Micro algal Biomass ...................................................... 13
2.5
Production of biodiesel from Micro Algae Oil .............................................................. 15
2.6
Advantages of Algae for Biodiesel Production .............................................................. 16
2.7
Sources of biodiesel production ..................................................................................... 17
MATERIAL AND METHOD ............................................................................................... 19
3.1 Collection of Sample ........................................................................................................... 19
vii
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
3.1.1
Apparatus ................................................................................................................ 19
3.1.2
Reagents .................................................................................................................. 19
3.1.3
Production Procedures ............................................................................................ 20
3.2
4
Methods of Data Analysis .............................................................................................. 23
RESULT AND DISCUSSION .............................................................................................. 25
4.1Algae Harvesting, Drying and Extraction Process ............................................................... 25
5
MATERIAL AND ENERGY BALANCE ............................................................................ 30
5.1 Material balance .................................................................................................................. 30
5.1.1
Balance on oven/Drier ............................................................................................ 30
5.1.2
Balance on Soxhlet Extractor.................................................................................. 31
5.1.3
Balance on reactor................................................................................................... 33
5.2
6
Energy balance ............................................................................................................... 34
5.2.1
Energy balance on drier .......................................................................................... 34
5.2.2
Energy balance on the Soxhlet extractor ................................................................ 34
5.2.3
Energy balance on reactor ....................................................................................... 35
EQUIPMENT DESIGN AND SELECTION ........................................................................ 36
6.1
7
Reactor Unit Equipment Design and Selection .............................................................. 36
ECONOMIC ANALYSIS AND PLANT LOCATION ........................................................ 38
7.1
Economic Analysis ......................................................................................................... 38
7.1.1
Total Capital Investment ......................................................................................... 38
7.1.2
Fixed Capital Investment ........................................................................................ 39
7.1.3
Total production cost .............................................................................................. 40
7.1.4
Economic evaluation ............................................................................................... 42
7.2
Plant Location Selection................................................................................................. 46
8
ENVIRONMENTAL IMPACT ............................................................................................ 47
9
CONCLUSION ..................................................................................................................... 48
10
RECOMMENDATION ..................................................................................................... 49
REFERENCES ............................................................................................................................. 50
11
Appendix A ........................................................................................................................ 52
12
Appendix B ........................................................................................................................ 53
viii
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
List of Figures
Figure 1: Open pond algae production system .............................................................................. 7
Figure 2: Manually harvesting algae by filtering in Hawassa lake ............................................... 12
Figure 3: Soxhlet extractor............................................................................................................ 15
Figure 4: Different sources of biodiesel production ..................................................................... 18
Figure 5: Titrate of the mixture..................................................................................................... 21
Figure 6: Production of biodiesel from algae ............................................................................... 22
Figure 7: a. Dry and crushed algae
b. Biodiesel product ......................................................... 29
Figure 8: discount cash flow ......................................................................................................... 45
Figure 9: Oil and methanol mixture heating using magnetic stirrer ............................................. 52
Figure 10: Transesterification of triglyceride with alcohol .......................................................... 53
List of Tables
Table 1: The biodiesel production feedstock properties ............................................................... 16
Table 2: European biodiesel standard (EN 14214) ....................................................................... 16
Table 3: Technical properties of biodiesels .................................................................................. 28
Table 4: Purchased equipment ...................................................................................................... 38
Table 5: fixed capital investment .................................................................................................. 39
Table 6: Raw material cost ........................................................................................................... 40
Table 7: Results of biodiesel production costs ............................................................................. 45
ix
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
1
INTRODUCTION
1.1 Background
Biodiesel is a diesel engine alternative fuel made by combining a vegetable oil or animal fat with
an alcohol such as methanol in a chemical reaction. The reaction necessitates the use of a
catalyst, usually a strong base like sodium or potassium hydroxide, and results in the formation
of new chemical compounds known as methyl esters. Biodiesel is the term used to describe these
esters[1].
Biodiesel is often considered renewable because its principal source is vegetable oil or animal
fat. Biodiesel is thought to contribute far less to global warming than fossil fuels because the
carbon in the oil or fat comes primarily from carbon dioxide in the air. When diesel engines run
on biodiesel instead of petroleum-based diesel fuel, they emit less carbon monoxide, unburned
hydrocarbons, particulate matter, and air toxics[1].
Limiting the consumption of fossil fuels (coal, natural gas and oil) had been obligatory demand
of the 21st century .It has not been mandatory just considering its depleting sources but harmful
environmental impact have been the prime concerns behind it .the alternative sources of fossil
fuels should be sustainable, renewable, readily available, environmental friendly and affordable
.Biodiesel is a potential fuel having the ability to replace conventional fossil diesel fuel .the first
and second generation biodiesel production due to food verses fuel warfare .Microalgae biodiesel
has been identified as one such sources which can cater the ever increase demand of
transportation fuel.[2] Their photosynthetic efficiency is very high, they can absorb atmospheric
CO2,thus have added advantages of CO2 fixation .They had
also been explored for their
domestic wastewater by absorbing nutrients from it, thus may facilitate even in wastes water
treatment[3].
It is a fatty acid ester which can be produced from either vegetable oil or animal fats through
trans-esterification reaction with alcohol (methanol or ethanol) using a suitable catalysis such as
an alkali, acidic or enzyme is called Biodiesel. The name biodiesel was interdicted in American
in 1992 by the National soy Diesel Development Board which has pioneered the
commercialization of biodiesel in the American or untied.2 Biodiesel is a fatty acid ester which
is derived from triglycerides by the process is called Trans esterification with alcohol. In 21st
1
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
century the world has given a great attention for microalgae bio fuel developments .many
counters such as America, Asia and Europe have their own microalgae bio energy research
project to promote this renewable energy industrialization.[4] Therefore, scientists are beginning
to play more attention to develop microalgae for extracting more sustainable energy. A
photosynthetic microorganisms that cover sunlight, water and carbon dioxide to sugars, from
which biological macromolecule, such as lips, can be obtained is called microalgae. They have
been suggested as very good candidates for fuel production because of their advantage of higher
photosynthetic efficiency, higher biomass production and faster growth compacted to other
energy crops.
1.2 Statement of the problem
The main source of greenhouse gases (GHGs) in the environment is fossil fuels, which emitted
29 G tonnes of CO2 (2006). Natural processes are estimated to remove only around 12 G tonnes,
thus suitable CO2 reduction initiatives are required to offset the extra CO2. With the rise in
anthropogenic GHG emissions, owing mostly to the widespread use of fossil fuels for
transportation, electricity, and thermal energy generation, it is becoming increasingly vital to
seek for renewable and environmentally friendly energy sources.
Data suggests that when countries' gross domestic product per capita rises, their usage of fossil
fuels rises, and competition for these finite resources rises, resulting in an unfair price increase
for fossil fuels. In addition, global economic expansion has resulted in a significant increase in
global energy demand. Energy consumption in emerging countries is expected to rise by 84
percent by 2035, and new sources of energy, such as biodiesel, may play a part in satisfying this
need.
The continual availability and supply of affordable energy for consumers and industry is referred
to as energy security. Energy security is threatened by disruptions in the supply of imported
fossil fuels, limited fuel availability, and energy price spikes. Many countries, including
Ethiopia, are interested in producing biodiesel from locally grown sources and using it as an
alternative for petrol products. This can help a country become more energy secure and less
reliant on other countries for fuel.
2
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
Even though Ethiopia has the second-largest population, it consumes the least petroleum fuel per
capita in comparison to other African countries. In 2008, petroleum imports accounted for 97
percent of the country's earnings from agricultural exports. This has had a significant impact on
the country's purchasing power for commodities and machinery that would otherwise be used to
better people's lives and the country's overall economy.
Finally, with the rapid increase in fossil fuel usage and, as a result, the rapid emergence of
negative environmental effects produced by greenhouse gas emissions, there are growing worries
about energy sustainability and carbon dioxide emissions. Soya beans, for example, are the most
common source of diesel in the United States. However, due to competition with food resources,
high material costs, and difficulty of collection, these oils are not an attractive feedstock for
biodiesel synthesis. According to Chisti's research, given current arable land supplies, only
biodiesel from oil palm and microalgae can supply the United States' transportation fuel needs.
As a result, it is vital to seek for alternative fuels that may be made from locally available
materials and do not contaminate the environment. To address this issue, microalgae production
of biodiesel is one of the greatest options for biodiesel production because to its higher oil output
capacity, lack of land constraints, and other benefits. As a result, the manufacture of diesel from
microalgae will be examined in further length here [5].
1.3 Objective of the Study
1.3.1 General Objective
The main objective of this thesis is to produce biodiesel from micro algae and to determine if
biodiesel production from algae is feasible in Ethiopia.
1.3.2 Specific Objectives
•
To dry and crush the algae using small-scale system
•
To extract oil from dry algae
•
To produce biodiesel from extracted oil
•
To study the economical feasibility
3
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
1.4 Scope of the study
This study will attempt to achieve producing biodiesel from microalgae that get from Lake
Hawassa which considers the characteristics of producing the biodiesel, all the way from
choosing an algal strain suited to this thesis, from harvesting of the algae to drying, crushing and
extracting of oil from the algae that would be converted into biodiesel by using transesterification reaction..
1.5 Significance of Study
The study’s ultimate purpose is to improve the energy industry by generating biodiesel locally,
which helps to reduce petroleum fuel imports. This thesis will aid in the development of drive
and creativity in other specialists in order to come up with novel algae cultivating methods. We
can make Ethiopia's energy secure and use the budget for fuel imports to improve people's lives,
infrastructure, and the country's entire economy by manufacturing biodiesel from microalgae.
We can also lower the quantity of CO2 emitted into the atmosphere by using biodiesel instead of
petroleum-based fuel. Biofuels, such as biodiesel, could help enhance economic development by
creating new jobs and income streams for individuals. Ethiopia and other developing countries
would profit from this.
4
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
2
2.1
LITERATURE REVIEW
Study on micro algae
Algae are one of the most ancient forms of life. They're thallophytes, which mean they don't
have roots, stems, or leaves, don't have a sterile layer of cells around reproductive cells, and use
chlorophyll as their principal photosynthetic pigment. Without any expansion beyond cells, algae
structures are primarily for energy conversion, and their simple development allows them to
adapt to changing environmental conditions and thrive in the long run.
Microalgae have a complicated composition that necessitates the use of specialized harvesting
technologies. They are a diverse collection of photosynthetic, heterotrophic organisms that span
several taxonomic divisions and evolutionary families. They are minuscule unicellular creatures
that create biomass using sunlight as a source of energy and CO2 as a carbon source, with higher
yields than photosynthetic plants[6].
2.1.1
Classification of micro algae
Eukaryotic cells with nuclei and organelles are found in the majority of microalgae.
Cyanobacteria are microalgae with prokaryotic cells that lack specific organelles. All microalgae
have chloroplasts, which are photosynthesis pigments that include chlorophyll and other
photosynthetic pigments. An example of eukaryotic and prokaryotic algae cells with their
various diameters is given. Cyanobacteria are prokaryotic microalgae, while green algae, golden
brown algae, and diatoms are eukaryotic microalgae.
2.2 Algae growth technology
The technology chosen for the facility designs had to meet three criteria: scalability, low
parasitic energy demand, and low cost. The culture systems are open, racetrack, paddle wheel
“mixed ponds ("high rate ponds"), a technology that has already been deployed in commercial
microalgae production plants and certain pilot-scale biofuels projects.
Phototrophic algae absorb sunlight and assimilate carbon dioxide from the air as well as nutrients
from aquatic habitats under normal growth conditions. As a result, artificial manufacturing
should try to duplicate and improve natural growing circumstances as much as feasible. CO2
from the atmosphere, CO2 from discharge gases from heavy industries, and CO2 from soluble
carbonates are all sources of CO2 for microalgae. Microalgae absorb CO2 from the air in their
5
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
natural environment (contains 360 ppm CO2). Most microalgae can tolerate and use much greater
CO2 concentrations, generally up to 150,000 ppm. CO2 is fed into the algal growth media in
common production units either from external sources such as power plants or in the form of
soluble carbonates such as Na2CO3 and NaHCO3. Nitrogen, phosphorus, and silicon are among
the other inorganic nutrients required for algae formation. While certain algal species can fix
nitrogen in the form of NOx from the air, the majority of microalgae require it in a soluble form,
with urea being the optimum source. Phosphorus is less important and only required in trace
amounts during the algal growth cycle, but it must be supplied in excess of the basic requirement
since phosphate ions link with metal ions, making not all of the added P bioavailable.
Photoautotrophic, heterotrophic, and mixotrophic production mechanisms, all of which follow
natural growth processes, are the three types of algae production mechanisms. Photoautotrophic
production is autotrophic photosynthesis, heterotrophic production requires organic molecules
(e.g. glucose) to boost growth, and mixotrophic production occurs when algal strains combine
autotrophic photosynthesis and heterotrophic assimilation of organic materials.
2.2.1 Photoautotrophic production
Microalgae are microorganisms that produce biomass by combining water and carbon dioxide
using solar energy1-2. Photoautotrophic algae's growth kinetics are influenced by the availability
of carbon sources (for example, bicarbonate), which are mostly produced by the solubility of
atmospheric carbon dioxide3–6. The splitting of H2O and the subsequent development of O2 is a
frequent photosynthetic mechanism in algae (driven by light absorbed by photosystem II).
Following that, electrons are transmitted from photo system I reaction centers to hydrogenase
(H2ase) via ferredoxin, a natural electron donor (powered by photo system I light absorbed)
while generating biomass or providing energy7–9. Photosynthetic electrons are given to [FeFe]H2ase instead of NADPH via ferredoxin under particular conditions (anaerobic conditions with
light), and [FeFe]-H2ase uses them to convert protons to molecular hydrogen. [FeFe]-H2ase
catalyzes this process, which is particularly sensitive to oxygen and requires no additional energy
in the form of ATP10. Meanwhile, cyanobacteria can create hydrogen as a byproduct of nitrogen
fixation via nitrogenase11 or through a reversible NAD (P) H-dependent NiFe-H2ase12
system[7].
6
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
Photoautotrophic production is currently the only approach for large-scale production of algal
biomass for non-energy purposes that is both technically and commercially feasible. Open pond
and closed photo bioreactor technologies have been used in the deployment of two systems. The
intrinsic qualities of the chosen algal strain, as well as meteorological conditions and land and
water costs, all influence the technical viability of each system.
2.2.1.1 Open Pond Production Systems
The most basic growth system is an open raceway pond, which is used to grow algae as a food
supplement and for pigment synthesis. In raceway ponds, biomass productivities are poor;
however this is offset by high product prices and inexpensive construction and operation costs.
Microalgae production for biofuels in open pond settings has recently been investigated. These
researches look at algae culture in conjunction with a number of processing procedures to turn
lipids into biofuels. Although open ponds are simple systems, general algal productivities are
used to estimate algae productivity, and there is a wide range of estimates used. For open ponds,
some life cycle assessments (LCAs) anticipate biomass yields of up to 110 ton ha1 year1, and
even greater productivities have been suggested.[8]
Figure 1: Open pond algae production system Source: [9]
2.2.1.2 Closed Pond Production Systems
Microalgae production in closed photo bioreactors is intended to address some of the primary
issues that have been identified with open pond production techniques. For example, open pond
systems are generally not suitable for the processing of high-value goods for use in the
pharmaceutical and cosmetics industries due to pollution and contamination issues. In addition,
7
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
unlike open pond production, photo bioreactors allow single-species microalgae to be cultured
for longer periods of time with less chance of contamination. Tubular, flat plate and column
photo bioreactors are examples of closed systems. These systems are better for delicate strains
since the closed configuration allows for easier contamination control. Harvesting costs can be
significantly lowered as a result of the increased cell mass productivities gained. Closed systems,
on the other hand, are much more expensive than open pond systems.
2.2.1.3 Hybrid Production Systems
Hybrid two-stage culture is a technology that combines distinct growth stages in photo
bioreactors and open ponds. In the first stage, cells divide constantly in a light bioreactor under
regulated conditions that keeps other species out.
In order to promote the synthesis of the desired lipid product, the cells are exposed to dietary
stresses in the second stage of production. With the transfer of the culture from photo bioreactors
to the open pond, the environmental factors that drive production can occur spontaneously,
making this stage suitable for open pond systems.
2.2.2 Heterotrophic Production
Algal biomass and metabolites have both been effectively produced through heterotrophic
production. Microalgae are cultivated in stirred tank bioreactors or fermenters on organic carbon
substrates such as glucose. Algae growth is independent of light energy, making scale-up much
easier because smaller reactor surface-to-volume ratios can be used. Because of the higher cell
densities achieved, these systems enable a high degree of growth control and lower harvesting
costs.
2.2.3 Mixotrophic Production
Many algal organisms have the ability to grow using either autotrophic or heterotrophic
metabolism pathways. That is, they can both photosynthesize and eat prey or organic stuff.
Because mixotrophs can digest organic substrates, cell development isn't entirely reliant on
photosynthesis; as a result, light energy isn't an absolute limiting factor for growth, as either light
or organic carbon substrates can support growth. Spirulina platensis, a cyanobacterium, and
Chlamydomonas reinhardtii, a green alga, are examples of microalgae with mixotrophic
metabolism pathways for growth.
8
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
During the light and dark phases, the media supplement with glucose influences growth,
resulting in decreased biomass loss during the dark phase. Mixotrophic algae growth rates are
superior to photoautotrophic algae cultivation in closed photo bioreactors. The rates are higher
than those for open pond cultivation but far lower than those for heterotrophic production.
During the diurnal cycle, successful production of mixotrophic algae allows for the integration of
both photosynthetic and heterotrophic components. This reduces the amount of organic
substances used during growth and reduces the impact of biomass loss during dark respiration.
These characteristics suggest that mixotrophic production could play a key role in the
microalgae-to-biofuels conversion process.
2.3
Algae harvesting methods
The harvesting process chosen is determined by microalgae properties such as size, density, and
the value of the intended products. Microalgae harvesting is a two-stage process. These are:
❖ Bulk harvesting—aimed at separating biomass from the bulk solution during the
microalgae harvesting stage of the operation. To achieve 2–7% total solid matter, the
concentration factors for this procedure are typically 100–800 times. The starting biomass
content as well as the technologies used, such as flocculation, flotation, or gravity
sedimentation, will determine this.
❖ Thickening—the goal of thickening is to concentrate the slurry using techniques
including centrifugation, filtration, and ultrasonic aggregation. This is a more energyintensive process than bulk harvesting.
2.3.1 Centrifugation
Centrifugation is a type of gravity sedimentation in which centrifugal force is used to separate
microalgae from their growing medium instead of gravity. The cell settling parameters (cell size
and insignificant density difference of micro algal cells to their culture medium), as well as the
cell slurry retention duration in the centrifuge, influence centrifugal separation of microalgae.
[10].
The settling characteristics of suspended particles are determined by the density and radius of
algal cells (Stroke's radius) and sedimentation velocity in gravity and centrifugation
sedimentation processes. Because of the vast volumes of waste water treated and the low value
9
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
of the biomass created, gravity sedimentation is the most popular harvesting technique for algal
biomass in waste water treatment. The approach, however, is only suitable for giant (>70 mm)
microalgae like Spirulina. For aquaculture hatcheries and nurseries, centrifugation recovery (CR)
is preferred for harvesting high value metabolites and prolonged shelf-life concentrates. The
process is quick and energy-intensive, and biomass recovery is determined by cell settling
properties, centrifuge slurry residence time, and settling depth. The technique has a number of
drawbacks, including high energy costs and the potential for increased maintenance due to freely
moving parts.
2.3.2 Flocculation
Flocculation is used in a variety of industries, including brewing, waste and drinking water
treatment, and mining. While liquid is frequently the final product in many applications, the
biomass harvested from microalgae is the end product. Biomass contamination with a chemical
flocculent is a significant issue in microalgae harvesting by flocculation. The final product
(biomass for food or feed) or biomass processing can be harmed by chemical flocculants (lipid
extraction).
Flocculation is typically employed as a pre-harvesting phase in conjunction with other harvesting
(dewatering) processes. Mechanical dewatering costs are reduced when water is removed during
flocculation. To maximize cost savings during mechanical dewatering, obtaining the least
volume of algal slurry in the shortest amount of time is advised. As a result, microalgal flocs
should be big and sediment at a fast rate. Magnetic flocculating agents can also help with this.
Cell surface features, cell concentration, pH of the environment, ionic strength, and the type and
amount of flocculent all play a role in flocculation. Mixing is also important for flocculation
efficiency since it determines the quantity and intensity of collisions, which allows for floc
formation and influences its characteristics. A good flocculent should be cheap, nontoxic, and
effective at low concentrations, and preferably sourced from non-fossil fuel sources, making it
sustainable and renewable. Although flocculation is thought to be the best method for harvesting
microalgae biomass, it has a number of economic and technological limitations, including a high
energy cost, toxicity of the flocculent, and inability to scale up[11].
10
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
2.3.3 Flotation
Small bubbles connect to destabilized particles in flotation separation, causing them to rise to the
surface and concentrate. Flotation has emerged as a prominent microalgae harvesting strategy
when combined with the use of a flocculent to disrupt the cells. Under the same conditions,
flotation has been found to be more successful than sedimentation at removing microalgae from
water. Furthermore, the enhanced concentration factor is caused by the gravity drainage of water
from the foam. Flotation can be thought of as inverted sedimentation, and it is favorable since
microalgae prefer to float rather than settle.
High overflow rates, short detention times, a small footprint, and a thicker concentrate are all
advantages of flotation over sedimentation. Flotation produces sludge that is typically 2–7%
solid. The economic feasibility of flotation has been reported to range from high capital and
operating expenses to cheap initial and operating costs, low energy input, and simple operation.
Despite these variations, flotation has been identified as the most cost-effective approach for
harvesting microalgae in bulk. While widely employed in water treatment, it has long been
demonstrated to be a versatile treatment for microalgae and other microorganisms. When
different species of microalgae are present, however, flotation has been described as challenging.
Despite this, flotation has the advantage of being able to gather a wide variety of species once the
technique is improved. [12]
2.3.4 Filtration
Filtration is accomplished by using a suction pump to force algal suspension through a filter
medium. The algae biomass is then harvested after it has been retained and concentrated on the
medium. The main benefit of filtration is that it can harvest very low-density microalgae or algal
cells. In order to force fluid to flow through, a pressure drop must be maintained across the
medium. Various filtration methods with driving forces derived from gravity, vacuum, pressure,
or magnetic have been devised depending on the required pressure drop.
Surface filtration and deep-bed filtration are two types of filtering. Solids are deposited as a paste
or cake on the filter media in surface filtering. Algal cells are deposited on the precoat, which
serves as a filter medium in and of itself, after an initial thin layer of cake is created on the
medium surfaces as a precoat. The resistance to flow across the medium would increase as algal
11
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
accumulation thickens. For a steady pressure-drop operation, the filtration flow would decrease.
Solids are deposited within the filter-bed matrix in deep-bed filtration.
The primary issues with utilizing filtration to collect algae are that the fluid flow is limited to
tiny volumes and that the deposited cells clog/foul the medium. To avoid filter clogging or
membrane fouling, several additional approaches have been created. One method is to utilize a
reverse-flow vacuum, in which the pressure is applied from above, making the process less
forceful and preventing the deposition of algal cells. A second method employs a direct vacuum
with a paddle above the filter to agitate the particles and prevent them from settling on the
medium. A micro strainer can help prevent clogging and increase algae harvesting by acting as a
pretreatment for filtration. The vast majority of filtration processes would include frequent
backwashing as a routine maintenance to tackle filter clogging or fouling.
Algae harvesting has been attempted using a variety of filtration technologies, with varied
degrees of success. [13]
Figure 2: Manually harvesting algae by filtering in Hawassa lake Source: self camera
2.3.5 Screening
In most wastewater treatment plants, screening and algae harvesting are the first unit operations.
Screening works by placing algal biomass onto a screen with a specific aperture size. The space
between screen apertures and the size of the algae particle determine the efficiency of the
screening action. Micro strainers and vibrating screens are common screening devices for algae
harvesting.
12
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
Microstraining uses a rotary drum with a stainless steel or polyester straining fabric. Smaller
algae can still slip through the screen and go unnoticed. Microstraining costs vary between $5
and $15 every 106 liters. In clearing algae pond effluents, microstrainers with 6 mm and 1 mm
meshes retain Francea Micractinium algae. Chlorella algae passed past the 1 mms screen,
however the 6 mm screen did not catch them. It's possible that this is due to a lack of mesh size
quality control.
Vibrating screens are widely utilized in a variety of industries, including the paper and food
industries. They're also utilized to concentrate sludge in municipal wastewater treatment plants.
It was previously reported that vibrating screens were used to gather Coelastrum algae. [13]
2.4
Extraction and Purification of Micro algal Biomass
The dewatered algal slurry was dried after harvesting for stability, end use, extraction, or other
processing. Drying such a delicate substance was difficult and necessitated a creative solution.
The most practical algae drying procedures should prevent algal quality degradation during the
drying process.[14]
The harvested biomass slurry (typically 5–15% dry solid content) is perishable and must be
treated as soon as possible after harvest; depending on the ultimate product required, dehydration
or drying are commonly used to extend the viability. The following drying methods were can be
used: sun drying, low-pressure shelf drying, spray drying, drum drying, fluidized bed drying,
freeze drying, and Refractance WindowTM technology drying. For this thesis, we used the sun
drying technique. Because it is a simple, cheap and available drying method.
It is followed by the cell disruption of microalgae after drying. Depending on the microalgae
wall and the product to be obtained, a variety of procedures can be applied. Lipids and fatty acids
must be removed from microalgae biomass for biodiesel manufacturing. Algal oil can be
extracted using chemical methods or mechanical methods:
2.4.1.1 Mechanical Methods
These methods are classified in mechanical expeller press and ultrasonic assisted extraction.
➢ Expeller press: The oil content of algae can be extracted using an oil press after it has
been dried. In order to extract oil, commercial manufacturers utilize a combination of
mechanical presses and chemical solvents.
13
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
➢ Ultrasonic extraction: Sonochemistry is the name given to this procedure. Ultrasonic
waves are utilized to create bubbles in a solvent material, and when these bubbles
collapse near the cell walls, shock waves and liquid jets are produced, causing the cell
walls to rupture and the contents to spill into the solvent. This process can be used with
either dry or wet microalgae; when using wet microalgae, it is required to remove some
of the water from the mash before extracting the oils with a solvent.
2.4.1.2 Chemical Methods
Non-polar solvents such as diethyl ether or chloroform are used to extract neutral or storage
lipids, whereas membrane-associated lipids are more polar and require polar solvents such as
ethanol or methanol to break hydrogen bonding or electrostatic forces.
Hexane, benzene, and petroleum ether are the chemical extraction solvents. The first is the most
common and least expensive, although it is only suitable for low-polarity lipids. Benzene is no
longer utilized because it is now known to be a powerful carcinogen. Toluene could be used
instead. When working with chemicals, it's important to prevent inhaling fumes and coming into
contact with the skin.
➢ Hexane solvent method: Hexane solvent can be used together with a mechanical
extraction method, first pressing the oil. After the oil has been extracted using an
expeller, the remaining product can be mixed with hexane to extract all the oil content.
Then, Oil and hexane are separated by distillation. Different solvents can be also used
such as ethanol (96%) and hexane-ethanol (96%) mixture. With these solvents it is
possible to obtain up to 98% quantitative extraction of purified fatty acids.
➢ Soxhlet extraction: Oils from algae are extracted through repeated washing, with an
organic solvent such as hexane or petroleum ether, under reflux in special glassware or
Soxhlet extractor.
14
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
Figure 3: Soxhlet extractor
•
Folch method: the tissue is homogenized with chloroform/methanol (2:1 v/v) for 1,5h.
The liquid phase is recovered by filtration or centrifugation, and the solvent is washed
with 0.9% NaCl solution. The lower chloroform phase containing lipids is evaporated
under vacuum in a rotary evaporator.
➢ Supercritical fluid extraction: in supercritical fluid/CO2 extraction, CO2 is liquefied
under pressure and heated to the point that it has the properties of both liquid and gas.
This liquefied fluid then acts as a solvent for extracting the oil. CO2 is the most used
supercritical solvent because the compounds can be obtained without contamination by
toxic organic solvents and without thermal degradation.
2.5
Production of biodiesel from Micro Algae Oil
Biodiesel is one of the most important renewable energy sources for long-term development,
with the potential to replace fossil fuels. It is also free of sulphur and aromatic chemicals, as well
as being biodegradable and carbon neutral.
It's critical that the feedstock has a high lipid content, high productivity, and a reasonable price.
Physical and chemical qualities of the feedstock oil, on the other hand, are critical in biodiesel
manufacturing since they influence biodiesel quality and yield. Fatty acid composition, free fatty
acid content (FFA), water content (WC), phosphorus content (PC), sulfur content (SC), and
saponification value (SV) are among the features.[15]
15
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
Table 1: The biodiesel production feedstock properties Source: [15]
Feedstock
Saturation FFA (%)
WC (%)
PC (ppm)
SC (ppm)
SV (mg KOH/g)
level (%)
Soybean oil
15.34
0.07
0.029
3.7
0.8
195.3
Sunflower oil
9.34
0.04
0.02
< 0.1
0.1
193.14
Palm oil
47.3
0.54
0.049
7.3
1.0
208.62
Canola oil
4.34
0.34
0.085
17.9
5.7
189.80
Corn oil
14
12.22
0.153
< 0.1
10.5
183.06
Peanut oil
16
<2
< 0.5
NA
10
191.50
Cottonseed oil
30.6–29
9.8
0.05
0.5
10
194
Coconut oil
68.7
0.07
0.027
2.0
2.7
267.56
Jatropha curcas oil
27.1
1.17
0.073
322.9
3.5
200.80
Poultry fat
29.69
1.7
0.065
209.3
27.2
188.08
Microalgae oil
12–21
0.45–1.75
0.014–0.021
286.2–339.7
15.4–28.1
160.6–185.82
Table 2: European biodiesel standard (EN 14214) Sources: ( Biodiesel_ Quality, Emissions and
By-Products - Google Books, n.d.)
2.6 Advantages of Algae for Biodiesel Production
Many study publications have discussed the various advantages of employing microalgae for
biodiesel synthesis over other accessible feed stocks, and we may summarize them as follows:
1. Algae are simple to cultivate since they may grow with little care in waste or marine
water that is unfit for human consumption.
2. When compared to other feed stocks, they have substantially better growth rates and
productivity while using much less land.
16
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
3. Microalgae species can be adapted to survive in extreme environments. Thus, species
best adapted to local settings or unique growth circumstances may be identified,
which is not achievable with other biodiesel feed stocks such as rapeseed, sunflower,
or palm oil.
4. Other sustainable fuels that microalgae can make include methane, hydrogen, and
ethanol.
5. In the process of photosynthesis, microalgae transform solar energy into chemical
energy, completing a whole growth cycle every few days. Furthermore, they may
grow practically anywhere, albeit the addition or removal of specific nutrients can
accelerate growth rates and lipid content.[17]
2.7 Sources of biodiesel production
Edible oil seed crops such as sunflower, palm, rapeseed, soybean, coconut, and other first
generation biodiesel feed stocks can be used to make biodiesel. However, using such feedstocks
for biodiesel production has caused issues because they disrupt the global food supply and
security balance. In recent years, non-edible seed crops such as jatropha, karanja, jojoba, and
mahua, as well as waste cooking oil, grease, and animal fats, have gained prominence as secondgeneration feed stocks for biodiesel synthesis. However, these second-generation feedstocks are
insufficient to completely replace current transportation requirements.
A micro alga has received a lot of attention recently as a third-generation feedstock. Microalgae
have various advantages, including increased photosynthetic efficiency and biomass generation.
Microalgae do not compete for land and can grow in a variety of environments, including
brackish saline water. The current research efforts are focused on improving the lipid content of
microalgae and algal culturing. More concerted efforts for precise evaluation of algal biomass,
algae oil, and algae biodiesel are needed to establish the potential of microalgae biomass as a
biodiesel alternative, as there is very little information in the literature on the subject.[18]
17
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
Edible
Sources
biodiesel
production
Corn,
soybean,
sunflower
rapeseed,
Vegetable oil (Jatropha, karanja,
macaw oil, palm oil)
for
Non-edible
Waste animal oil (pork lard and
tallow)
Waste cooking oil
Other sources (algae, organic waste,
lignocellulosic, sludge)
Figure 4: Different sources of biodiesel production. Source [19].
18
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
3
MATERIAL AND METHOD
3.1 Collection of Sample
The microalgae were collected from Lake Hawassa, at Hawassa city sidama region, Ethiopia.
After the collection process the drying stage takes place by direct sunlight method and oven
drying method next the algae were crushed and become ready for the oil extraction process
which is the benchmark for the final trans-esterification reaction.
3.1.1 Apparatus
The instruments which were used are:
✓ Magnetic Stirrers
✓ Erlenmeyer Flasks
✓ Soxhlet extractor
✓ Distillation unit
✓ Aluminum foil
✓ Decanters
✓ Measuring Cylinders
✓ Watch-Glass
✓ Mixer
✓ Beaker
✓ Thermometers
✓ Oven
✓ Pipettes
3.1.2 Reagents
The chemical that those used for the extraction of microalgae oil and for the transesterification
processes are:
➢ Microalgae oil
➢ Methanol 99.5% w/w
➢ Catalysts: NaOH or KOH
➢ Phosphoric acid 85% w/w
➢ Petrol ether
19
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
➢ Acetone
➢ Phenolphthalein
3.1.3 Production Procedures
Production of biodiesel experimental procedure
•
Step 1: algae collection and extraction Stage
Stages of collection of algae from Lake Hawassa and drying process were takes place
simultaneously within two weeks this drying process was performed by Solar Heat Drying
system.
•
Step 2 : algae oil extraction
Lipid extraction was done for ± 2 weeks in Hawassa University Chemical Engineering
Processing Unit Laboratory. The research was conducted on the laboratory scale. The algae
collected were dried (100%) and powdered; 50 g of dried algae was placed in the thimble of the
Soxhlet extractor packed in filter paper. A round bottom flask was filled with solvent by the ratio
of 15ml micro algae with 200ml of petrol ether. The Soxhlet is equipped with condenser setup.
The solvent was heated to many refluxes for three hours at 620C. After such reflux cycles, a
portion of oil was dissolved in petrol ether. This solution was separated and concentrated in a
distillation setup. The insoluble portion of the algae remained in the thimble. [20]
•
Step 3 : Mixture of catalyst and alcohol
Prior to the biodiesel process, titration tests were performed on the algae oil to determine amount
of catalyst and alcohol. A syringe, small beakers for titration, a 250 ml jar and conical flask with
a stopper were used during the titration. Titration solution was prepared using 1 g of KOH pellets
into 1 L of DI water. The titration solution was stirred until KOH pellets were completely
dissolved in DI water. 1 ml of the algae oil was placed in the beaker, and 10 ml of methanol was
added into the same beaker. While stirring, 2-3 drops of phenolphthalein was added in this
solution, which was then mixed for a few minutes. The titration solution was added drop wise to
the previous mixture by means of a syringe. The titration process was continued until the
solution color was changed from light yellow to complete pink. After repeating this process 3-4
times, average titration solution was found to be 3.0 ml. Based on the calculations, we found that
0.4 g of KOH catalyst and 8 ml of methanol would be necessary to convert 40 ml of filtered
20
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
algae oil into biodiesel and glycerin. After the titration process, biodiesel was produced from the
algae oil using the procedures described earlier
The amount of methanol that will be needed will be measured in a test tube and poured into the
Erlenmeyer flask. Then KOH will be weighed out by the electronic balance and added to the
flask. After mixing the catalyst with the methanol it will be continuously stirred and heated to
make the dissolution process faster. Sodium methoxide is formed by dissolving
potassium/sodium hydroxide into ethanol.
Figure 5: Titrate of the mixture
•
Step 4 : Preheat oil to 100 ºC
The extracted microalgae oil will be preheated into the flask on the shaker plate to remove water
traces. Oil temperature must reach 100 ºC, the water boiling point.
•
Step 5: Preparation of the water bath
While initial steps were carrying out, the water bath will be filled with tap water and
programmed to the required temperature usually between 40-50 ºC.
•
Step 6: Transesterification reaction
Transesterification is the process of separating the fatty acids from their glycerol backbone of oil
to form fatty acid esters (FAE) and free glycerol. Biodiesel, also known as fatty acid esters, can
be produced in a continuous and batch scale by trans-esterifying triglycerides in vegetable oil
and animal fats and other organic waste which has lower molecular weight in the presence of a
21
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
base or acid as a catalyst.[21] In our case the algae oil would be mixed with the methanol
catalyst solution by a magnetic stirrer.
•
Step 7: Separation of products
When the reaction is finished, the resulting mixture will be removed from the vessel and poured
into a decanter. The products are separated by density differences. Glycerin phase is much denser
than biodiesel phase and it can be gravity separated into the bottom of the settling vessel. The
separation will take about 24 hours to carry out correctly.
•
Step 8: Cleaning biodiesel with phosphoric acid 5% w/w
When biodiesel and glycerin are clearly separated, glycerin has to be removed leaving only
biodiesel in the decanter. To clean the biodiesel, a phosphoric acid solution at 5% w/w will be
used. An amount of acid solution (similar to the amount of biodiesel) will be added into the
settling vessel and mixed gently to remove residual glycerin and impurities. Few minutes later
the cleaned biodiesel will be deposited in a new vessel.
Macro and Micro algae
Grinding
Oil extraction
Transesterification
Separation of biodiesel and glycerin
Water washing soap and glycerine
Biodiesel
Figure 6: Production of biodiesel from algae Source:[3]
22
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
3.2 Methods of Data Analysis
The following physiochemical properties were determined and compared with the same of
standard algae oil. Some of it was discussed in literature review session.
Saponification value
Petroleum products can contain additives that react with alkali to form metal soaps. Fats are
examples of such additives. Used engine oils, especially from turbine or internal combustion
engines, can contain chemicals that will similarly react with alkali. Saponification value
represents the number of milligrams of potassium hydroxide required to saponify one gram of fat
under the conditions specified. It is a measure of the average molecular weight (or chain length)
of all the fatty acids present. Oils which possess high saponification values are good for making
soap. If the saponification value is more than the limit prescribed above, the oil would precipitate
and form soap. The saponification value of the extracted oil is 173.56 which falls in the
permissible range, thus the oil extracted may be used for biodiesel production.[20]
Iodine value
Iodine value is the mass of iodine in grams that is consumed by 100 g of a chemical substance.
Iodine numbers are often used to determine the amount of unsaturation in fatty acids. This
unsaturation is in the form of double bonds, which react with iodine compounds. The higher the
iodine number, the more CDC bonds are present in the fat. The iodine value of a good lubricant
is generally low. The iodine value determined for the algae oil under investigation is 65 which
lies in the permissible range.[20]
Calorific value
The calorific value is the energy released in the form of heat when a hydrocarbon (fuel)
undergoes complete combustion with oxygen under standard conditions. The above chemical
reaction is typically a hydrocarbon reacting with oxygen to form carbon dioxide, water and heat.
The obtained calorific value is close to the algae oil standards. Studies have shown that calorific
values for fuels where higher due to high energy releasing from fuels during combustion. The
standard range of calorific values for algae is 3000--3700 kcal/ kg. The calorific value of the
extracted oil is 3257 kcal/ kg.[20]
23
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
Flash point
Flash point is the minimum temperature at which the fuel gives a flash. It is desirable to have low
flash point temperature so that it can be burned at lower temperature. In the present study the
flash point of the algae oil reported is 78C which falls within the standard flash point value of
algae oil (the standard range of flash point of algae is 650 – 1150C)[20].
Acid value
The acid value is a measure of the amount of carboxylic acid groups present in a chemical
compound, such as a fatty acid or a mixture of compounds. If the acid value of a substance is
high, it will affect the material in which it can be stored or transported hence a low acid value is
suggested for a fuel oil. the oil acid value as measure while the experiment becomes 2.3[20].
Density
It is important to know the mass and volume of the extracted oil in order to calculate its density.
The volume of generated oil will be measured with a measuring cylinder. After that, using beam
balance, the mass will be computed. The density, which is defined as mass divided by volume, is
calculated using these two numbers. The density obtained must be between 860 and 894m3/kg.
Dynamic Viscosity
Viscosity is a measure of the internal friction or resistance of an oil to flow.
Viscosity coefficients can be defined by:
➢ Dynamic viscosity, also called absolute viscosity, the more usual one;
➢ Kinematic viscosity is the dynamic viscosity divided by the density.
This dynamic viscosity is calculated using a viscometer. A hollow tube with an item is part of the
apparatus. The dynamic viscosity of the biodiesel is measured in this tube, which is filled with
the medium being examined. Finally, the kinematic viscosity will be calculated by dividing
dynamic viscosity by density, with the resulting value falling between 3.3 and 5.2 mm2/s.
24
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
4
RESULT AND DISCUSSION
4.1Algae Harvesting, Drying and Extraction Process
The algae were harvested from the lake of Hawassa manually then dried by both in the oven
between 60-80℃ for one hour and by direct sun light. The raw algae were grounded by using
crusher. Before this, the amount of sample was weighted using a balance for each experiment.
Again, the weight of the sample after dying was measured. Three experiments were conducted
and the moisture content was determined for each of them.
Moisture Content =
w1−w2
w2
x 100
Where W1 = Original weight of the sample before drying;
W2= Weight of the sample after drying
Moisture content =
290gm−160gm
290gm
x 100 = 81%
Oil extraction
After the dried algae are grinded in to fine particles size in order to make it suitable for Soxhlet
extraction unit. The extraction process was performed by solvent called petroleum ether with a
boiling point of between 60 – 80℃.
The mass of extracted oil was; m = 𝜌 x 𝑣
= 864 kg/m3 x 1.5 x 10-4m3
= 130 gm
We have done this extraction process again and again finally found 200 ml of oil.
Yield of oil (Oil Content) within the grinded dry algae was calculated as follows;
Yield of oil =
mass of crude oil extracted
total mass of dry algae
130gm
x 100 = 160gm x 100 = 81 %
Determination of the acidity of the oils
The acidity of all the oils was determined through titration analysis with KOH 0.05 M or 0.1 M
in ethanol. The neutralization reaction of the FFA is a saponification reaction, schematized as
follows:
25
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
Since oil and methanol are not miscible, a mixture was used as co-solvent for the titration.
Phenolphthalein 2% in methanol was used as indicator. The percentage of FFA content per
weight was calculated as follows:[22]
FFA =
V× MW×C
𝑊
X 100
Where; V is the volume of KOH solution employed for the titration in ml
MW is the molecular weight of the oil used.
C is the concentration of KOH (mmol mL-1)
W is the weight of the analysed sample (mg).
Determination of saponification number
Saponification value (or "saponification number", also referred to as "sap" in short) represents
the number of milligrams of potassium hydroxide or sodium hydroxide required to saponify 1g
of fat under the conditions specified. It is a measure of the average molecular weight (or chain
length) of all the fatty acids present.
The long chain fatty acids found in fats have low
saponification value because they have a relatively fewer number of carboxylic functional groups
per unit mass of the fat as compared to short chain fatty acids. The calculated molar mass is not
applicable to fats and oils containing high amounts of unsaponifiable material, free fatty acids
(>0.1%), or mono- and diacylglycerols (>0.1%). Saponification number measurement is based
on a back-titration: the sample is treated with a known amount of solution of potassium
hydroxide in ethanol in excess and heated to reflux for at least 1 hour. At the end of the hour,
after cooling, the excess of potassium hydroxide, which has not reacted, is quantified by titration
with a solution of hydrochloric acid in the presence of phenolphthalein as indicator. In this work
25 ml of KOH solution 0.5 M were added to 2 g of the sample. Concurrently, a blank test, i.e., a
test containing only the KOH solution was carried out. Both the mixtures were kept in reflux for
1 hour and titrated with HCl aqueous solution 0.5 M. The saponification value was then
determined as follows:[22]
SV (mg KOH / 100g oil) =
56.1 × C × (V1 − V2)
W
where 56.1 is the molecular weight of KOH (mg mmol-1),
26
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
C is the concentration of the KOH solution in methanol used for the titration,
V1 and V2 are volume of the KOH solution required for the titration of the blank and
the oil sample,
W is the weight of the oil sample. and W is the weight of the oil sample.v
=
Sv =56.1 * 1M * 6ml – 1ML/ 0.9g
Sv = 311mg/g
Physico-Chemical Properties of Biodiesel
Specific Gravity (Density)
To determine specific gravity
Specific gravity =
W3 – W2
W1
Where,
W3 = weight of container and biodiesel = 51g
W2 = weight of empty container = 14.8g
W1 = weight of equal volume of water = 41g
So, Specific Gravity =
W3 – W2
W1
=
51 − 14.8
41
= 0.88
The density of the biodiesel produced was performed and observed to be in the range 860 960kg/m3 at different transesterification process parameters. When we compare the average of
the results for biodiesel 860–900 kg/m3 is acceptable.
Viscosity
The viscosity is a very important property related to the biodiesel utilization in direct injection
diesel engines. High values of viscosity give rise to a poor fuel atomization, incomplete and
27
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
carbon deposition on the injectors. We observe that the biodiesel is very viscous at lower
temperature and non-catalysts.
Acid Value and FFA Composition
The Acid value of the biodiesel produced was found to be 0.413-0.744 mgKOH/g. The result of
which indicates that acid value of the diesel decreased significantly after transesterification
reaction. Algae oil biodiesel has acid values within the standard specification limit (max 0.8).
Furthermore, higher acid value resulted in low yield of biodiesel. The acid value is decreases
wish increase reaction temperature at constant reaction temperature, catalyst and methanol to oil
ratio. The other absorptions are acid value increase with non-catalyst rather than catalyst at
constant reaction temperature, reaction time and methanol to oil ratio.
Saponification-value
According to the experiment conducted the saponification number (SN), were determined and
the results are 138mg/g and this result is agree with standard diesel. The detailed calculation is
given in the algae oil saponification value determination.
Table 3: Technical properties of biodiesels Source: [23]
Common name
Bio-diesel or biodiesel
Common chemical name
Fatty acid (m)ethyl ester
Chemical formula range
C14–C24 methyl esters or C15–25 H28–48 O2
Kinematic viscosity range (mm2/s at 313K)
3.3–5.2
Density range (kg/m3 at 288K)
860–894
Boiling point range (K)
>475
Flash point range (K)
428–453
Distillation range (K)
470–600
28
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
Vapor pressure (mmHg, at 295K)
<5
Solubility in water
Insoluble in water
Physical appearance
Light to dark yellow, clear liquid
Odor
Light musty/soapy odor
Biodegradability
More biodegradable than petroleum diesel
Reactivity
Stable, but avoid strong oxidizing agents
Figure 7: a. Dry and crushed algae
b. Biodiesel product
29
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
5
MATERIAL AND ENERGY BALANCE
5.1 Material balance
Material balance for any process system, the material balance is summarized as follows:
Input – Output + Generation – Consumption = Accumulation
The first step is to look at the three basic categories: materials in, materials out and materials
stored. Then the materials in each category have to be considered whether they are to be treated
as a whole, a gross mass balance, or whether various constituents should be treated separately
and if so what constituents.
Assume the capacity of our plant is 250L/day = 91,250L/yr.
From 500000 kg/day powder, 250 L/day of oil is produced.
Assume our plant working day is 310 day/ year
Density of the oil is 864kg/m3
Density of petroleum ether is 640kg/m3
5.1.1 Balance on oven/Drier
Water removed
FEED
Drier
75 % moisture content
Dried leaves
The average moisture content (MC) is 75 %.
By using the moisture content equation;
𝐷𝑟𝑖𝑒𝑑 Leaves = I𝑛𝑖𝑡𝑖𝑎𝑙 leaves (1−𝑀𝐶)
Initial leaves =
Dried Leaves
(1−MC)
236520
= 1 −0.75 = 9460804kg/yr
𝑀𝑜𝑖𝑠𝑡𝑢𝑟𝑒 𝑖𝑛 𝑓𝑒𝑒𝑑 =9460804kg/yr x 0.75
= 7095603 kg/yr
30
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
𝑀𝑜𝑖𝑠𝑡𝑢𝑟𝑒 𝑖𝑛 𝑝𝑟𝑜𝑑𝑢𝑐𝑡 = 7095603 kg/yr*0.25
= 1773900.75 kg/yr
𝐴𝑚𝑜𝑢𝑛𝑡 𝑜𝑓 𝑚𝑜𝑖𝑠𝑡𝑢𝑟𝑒 𝑟𝑒𝑚𝑜𝑣𝑒𝑑 = 7095603 kg/yr - 1773900.75 kg/yr
= 5321702.25 kg/yr
5.1.2 Balance on Soxhlet Extractor
Pure solvent (S)
Soxhlet
extractor
crushed leaves (F)
extract (mixture of oil and solvent)(M)
Xf,o = 0.3
Xo, m =
Xf ,r = 0.7
X s,m =
Residue(R)
Total mass balance
F + 𝑆= 𝑀̇ + R ……………………………………………………….…….5.1
Balance on oil
𝐹 ∗ 𝑋𝑂𝐹 + 𝑆 ∗ 𝑋𝑂𝑆 = R∗ 𝑋𝑂R + 𝑀̇ ∗ 𝑋𝑂𝑀 ……………………….……...5.2
Balance on Residue F ∗ 𝑋𝐶𝐹 + 𝑆∗ 𝑋𝐶𝑆 = R∗ 𝑋R + 𝑀̇ ∗ 𝑋𝐶𝑀……………..5.3
Balance on solvent F ∗ 𝑋𝑆, + 𝑆∗ 𝑋𝑆, = R ∗ 𝑋𝑆, R + 𝑀 ∗ 𝑋𝑆, 𝑀……….….5.4
𝑀̇ ∗𝑋𝑂𝑀
𝑂𝑖𝑙 𝑅𝑒𝑐𝑜𝑣𝑒𝑟𝑦 = F x 𝑋of ……………………………..………………….…5.5
𝑆̇ = 6F………………………………………………………………………..5.6
DOF analysis 𝑁𝑉 is the number of variables
31
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
𝑁𝐸 is the number of independent equations
𝑁𝑉 (𝐹̇, 𝑆̇, 𝑀̇, 𝑋𝑂𝑀, 𝑋𝑆,) = 5 and 𝑁𝐸 = 5
DO𝐹 = 5 − 5 = 0, since DOF is zero, it is possible to solve the above equations.
0.9 =
From oil recovery
M ∗ XOM
F ∗ XOF
=
𝐶
F∗XFc
𝐹̇∗𝑋𝑂𝐹 = 91250 𝐿/ x 0.9 = 82125 L/yr (Amount of oil in algae leaves)
Mass = density * volume Amount of oil in algae leaves
= 0.864kg/L x 82125 L/yr
= 70956 kg/yr
From this 𝐹̇ can be calculated as
𝐹=
mass of oil in the leave
0.3
=
70956
0.3
= 236520 kg/yr (Total crushed leaves)
R = 0.7 x 0.9 x F = 149007.6 kg/yr
From the above equation, the amount of solvent is
S = 6 x 236520 kg/yr =1419120 kg/yr
S = 1419120 L/yr
From total mass balance,
𝐹̇+𝑆̇ = 𝑀̇ + R
M=F+S–R
= 236520 + 1419120 - 149007.6
M = 1506632.4 kg/yr
From oil balance
F x 𝑋𝑂𝐹 = 𝑀̇ x 𝑋𝑂𝑀
Xom =
F x Xof
M
=
236520 X 0.3
1506632.4
= 0.047
Therefore mass of produced oil becomes = 1506632.4 x 0.047 = 70811.72 kg/yr = 194 kg/day
32
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
Xsm = 1 - 0.047 = 0.953
5.1.3 Balance on reactor
The optimum methyl ester yields the methanol to oil ratio is 6:1 and the catalyst amount is 1%
w/w of oil. Therefore Stiochiometric chemical reaction of oil to methanol is 6mole of methanol
and 1mole of oil is used to require 6mole of methyl ester and 1mole of glycerol.
194 kg/day
Number of mole of algae oil = 862.32
kg/kmol
= 0.225 kmol/day
Mass of potassium hydroxide required = 0.01 x 194 kg/day = 1.94 kg/day
Amount of glycerol produced = 0.225kmol/day x 0.98 x 92.1 kg/ kmol= 20.3 kg/day
Fatty acid methyl ester produced = 0.225kmol/day x 0.98 x 864 kg/kmol= 190.5 kg/day
Unreacted oil = 194 kg/day x (1-0.98) = 3.88 kg/day
Mass of methanol can be calculated as follow:
Purified oil + 6methanol
glycerol + 6methyl ester
Number of mole of methanol becomes = 6 * 0.225 kmol/ day =1.35 kmol/ day
Then, the mass of methanol is
M methanol = 1.35 kmol/ day * 32 kg/ kmol
= 43.2 kg/ day
Methanol consumed=3 x 32g/mol x
(194 kg/day) /
(862.32 g/mol)
x 0.98
= 21.16 kg/day
33
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
5.2 Energy balance
5.2.1 Energy balance on drier
Drying is highly energy intensive process and latent heat of evaporation is needed to remove the
water or other solvent. Latent heat is heat energy per mass unit required for a phase change to
happen. Balance on oven/Drier
Latent heat varies with temperature. For the most common solvent, water, the latent heat of
evaporation is 2501 kJ/kg at 0℃ and 2256 kJ/ kg at 100℃. At ambient temperatures, around
200℃, a figure of 2400 kJ/kg is a good working approximation. So, for a drying process which
requires the evaporation of 1kg/s of water from the solid, an absolute minimum of 2256kJ/s
(2256kW) must be supplied to the process in some way.
q
Latent heat(L) = m
Q is amount of heat necessary for phase change.
𝑚 is mass of substance.
Latent heat of evaporation = 2256𝑘𝐽/𝑘𝑔
𝐴𝑚𝑜𝑢𝑛𝑡 𝑜𝑓 𝑚𝑜𝑖𝑠𝑡𝑢𝑟𝑒 𝑟𝑒𝑚𝑜𝑣𝑒𝑑 = 5321702.25 kg/yr (From material balance)
𝐻𝑒𝑎𝑡 𝑛𝑒𝑐𝑒𝑠𝑠𝑎𝑟𝑦 𝑡𝑜 𝑠𝑢𝑝𝑝𝑙𝑦 (𝑄̇) = 𝐿 x 𝑚
𝑄 = 2256𝑘𝐽/𝑘𝑔 x 5321702.25 kg/yr
Q = 12005760276 KJ/yr
5.2.2 Energy balance on the Soxhlet extractor
S = 1419120 L/yr
F= 236520 𝑘𝑔/𝑦𝑟
M = 1506632.4 kg/yr
R=1
49007.6 kg/yr
34
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
Extraction of oil from the algae has been at 70℃ since the boiling point of petroleum ether
solvent is between 60 and 80℃ taking 2200kJ/kg latent heat of evaporation.
Energy balance at 70℃.
Q =𝐿∗m, amount of heat necessary to Soxhlet
Q = 236520 𝑘𝑔/𝑦𝑟 *2200KJ/kg = 520344000 kJ/kg
5.2.3 Energy balance on reactor
Cp of algae oil is 1.58 kj/kg℃
M KoH = 1.94 kg/day
Q= ?
Mmethanol = 43.2 kg/ day
@ 250c
MCrude
methyl
ester
= 237
kg/day
@ 60 0c
M OIL = 194 kg/day
@ 25 0c
Input = output Q methanol + Q cleaned oil + Q hot water + Q CaO
= Q FAME + Q glycerol + Q methanol + Q hot water
Q supplied by heater = (MFAME + M GLYCEROL + MMETHANOL) x 1.58 x (60-25)
Q = 374kg/day x 1.58kj/kg c x 35
Q = 20682.2 KJ/day= 861 kJ/hr
35
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
6
EQUIPMENT DESIGN AND SELECTION
Equipment design is the vital process for any chemical industries this process evaluation
involves determining the size of the equipment in terms of the volume, flow per unit time, or
surface area. Some of the calculations associated with the reactor unit are presented in the
following to indicate the extent of the calculations which are sometimes adequate for a
preliminary design.
6.1 Reactor Unit Equipment Design and Selection
Reactor Design Considerations
• Reactors are vessels designed to carry out different chemical reactions
• It is the site of conversion of raw materials into product and it is also called heart of the plant.
➢ Aim of reactor designing - to produce a specified product at a given rate from known
reactant.
• Chemical reaction, chemical energies, thermodynamic laws and equations-plays important
role in selection and design reactor.
• Reactor is designed based on feature like:i. Mode of operation-Batch or continuous or hybrid of two
ii. Phases present-Homogeneous or heterogeneous
iii. Processing conditions -pressure, temperature and compositions of the reactants
In our case the biodiesel reaction occur by the batch reactor, this type of reactor has the
following characters.
❖ BATCH REACTOR
•
The reagents are added together and allowed to react for a given amount of time.
•
The compositions change with time, but there is no flow through the process.
•
Additional reagents may be added as the reaction proceeds.
•
Products are removed from the reactor after the reaction has proceeded to completion
The transesterification process will be done in a jacketed reactor which will be stirred with
600rpm of mixer speed and kept at a temperature of 60°C. By assuming 3-h cycle and 25%
36
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
safety factors. The volume of this unit should carry the mass consisting of extracted oil,
methanol and KOH:
Vr =
194 kg/day
864kg/m3
+
43.2 kg/ day
792kg/ m3
+
1.94 kg/day
0.00211kg /m3
= 919.7 𝑚3/𝑑𝑎𝑦
By assuming 4 shifts per day;
𝑉𝑟 =
919.7 m3
day
X
day
4 cycle
=
If the reactor is 75 percent full on each cycle, the volume of reactor needed is
𝑉 𝑟 = 230 𝑚3 /𝑐𝑦𝑐𝑙𝑒 ⁄ 0.75
= 306.5 𝑚3
So, we use 306.5 m3, glass-lined and stirred reactor.
37
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
7
ECONOMIC ANALYSIS AND PLANT LOCATION
7.1 Economic Analysis
7.1.1 Total Capital Investment
Total capital investment = fixed capital investment + working capital investment.
For this case capital investment calculated based on the purchased equipment cost of the plant.
Fixed capital cost = f (purchased equipment cost)
Table 4: Purchased equipment Source: http://www.mhhe.com/engcs/chemical/peters/data/
Number
Equipment type
Total Price ($)
m3
Unit
price ($)
12953
1
Plate and filter 1
press
Drum drier
1
800
4
m2
107868
107868
Water recycling
pump
Horizontal tank
48
6
m3/s
8716
418368
48
640
m3
390.4
18739.2
Harvesting water
pump
Flocculation unit
48
15
m3/s
6519
312912
1
500
m3
49332
49332
Carbon steel
storage tank
Reactor
1
1200
m3
376409
376409
1
1
m3/day 11984
11984
Extracted oil
storage tank
Conveyor
1
0.37
m3/day 26142
26142
1
m, m
4800
1
Kg/day 26239
26239
12
Raw algae
storage tank
Settling tank
15 width, 7
length
1177
1
70
m3/day
859
859
13
Evaporator
1
70
m3/day
1
24247
2
3
4
5
6
7
8
9
10
11
quantity Capacity
Unit
4800
12953
Total Purchased equipment ($) 1,390,852.2
38
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
7.1.2 Fixed Capital Investment
Table 5: fixed capital investment
Direct Cost
Percentage (%)
Price ($ )
Purchased equipment
100%E
1,390,852.2
Purchased equipment
25%E
347,713.05
Instrumentation and control
10%E
139,085.22
Piping (installed)
15%E
208,627.83
Electrical( installed)
10%E
139,085.22
Building (including service)
11%E
152,993.742
yard improvement
5%E
69,542.61
Service facilities
35%E
486,798.27
installation
A. Total direct cost (TDC) 2,934,698.14
Indirect cost (IC)
Percentage (%)
Price ($ )
Engineering and Supervision
14%E
194,719.308
Construction
expenses
and 15%E
208,627.83
Contractor’s fee
Contingency
8%E
111,268.176
B. Total indirect cost 514,615.31
Fixed-capital investment (A+B) 3,449,313.45
TCI=FCI+WC, since working capital cost is (10-20) % of total capital investment
39
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
TCI =FCI+0.15TCI
TCI = FCI/0.85= $4,058,015.824
Working cost (WC) = $(4,058,015.824-3,449,313.45) = $ 608,702.37
7.1.3 Total production cost
Determination of the necessary capital investment is only one part of a complete cost estimate.
Another equally important part is the estimation of costs for operating the plant and selling the
Products. These costs can be grouped under the general heading of total product cost. The latter,
in turn, is generally divided into the categories of manufacturing costs and general expenses.
Manufacturing costs are also known as operating or production costs. Further subdivision of the
Manufacturing costs is somewhat dependent upon the interpretation of direct and indirect costs.
Total production cost = manufacturing + general expense
Manufacturing cost = direct production cost +fixed charge +plant overhead cost
General expense = administrative +distribution and selling costs+ interest
Raw material cost
In the industry, one of the major costs in a production operation is for the raw materials involved
in the process. The amount of the raw materials which must be supplied per unit of time or per
unit of product can be determined from process material balances. In many cases, certain
materials act only as an agent of production and may be recoverable to some extent. Therefore,
the cost should be based on the amount of raw materials actually consumed as determined from
the overall material balances.
Total raw material cost = 10 – 50% 0f total product cost
Table 6: Raw material cost
Raw materials
Quantity (kg/yr)
Unit price ($)/kg
Total cost ($) per year
Methanol
2500
353.28
883,200
KOH
800
54.786
43,828.8
Petrol Ether
3200
86.112
275,558.4
Phenolphthalein
1200
14.49
Total raw material cost
40
Hawassa university institute of technology chemical engineering department
17,388
1,219,975
Production of Biodiesel from Micro Algae by Trans-esterification process
I. Manufacturing cost
Manufacturing cost = Direct production costs (DPC) + Fixed charges (FC) + Plant overhead
costs (POC)
A. Direct production cost (60% TPC)
1. Raw material and inputs = $1,219,975
2. Operating labor (10% of TPC) = 0.10 TPC
3. Direct supervisor and clerical labor (12% of operating labor) = 0.10 * 0.12 * TPC = 0.012TPC
4. Utilities (15% of TPC) = 0.15 TPC
5. Maintenance and repair (6% of FCI) = $3,449,313.45* 0.06 = $206,958.807
6. Operating supplies = 0.5% FCI = 0.005* $3,449,313.45 = $17,246.57
Total direct production cost =1,444,180.377 + 0.262 TPC
B. Fixed Charges
1. Depreciation (10% FCI) = $344,931.345
2. Insurance (1% FCI) = $34,493.1345
3. Local taxes (2%FCI) = $68,986.269
Total fixed charges = $448,410.75
C. Plant Overhead costs
1. 5% of total product cost = 0.05 TPC
Total Manufacturing cost = A + B + C
= 1,892,591.127+0.312 TPC
II. General expenses
1. Administrative cost (2% of total product cost) = 0.02 TPC
2. Distribution and selling cost (2% of total product cost) = 0.02 TPC
Total general expenses = 0.04 TPC
41
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
III. Total product cost = Total manufacturing cost +Total general expenses
TPC=$1,892,591.127+0.312 TPC +0.04 TPC
TPC (1-0.352) = $1,892,591.127
TPC= $2,920,665.319
7.1.4 Economic evaluation
7.1.4.1 Gross earn cost
Current price of diesel is $1.57/kg based on the current price of global petrol price and assume
around 7,000,000 kg is produces per year
Annual revenue =$1.57/kg X 7,000,000 kg
=$10,990,000
Gross annual profit = Annual revenue –Total production cost
= $(10,990,000-1,470,574)
= $9,519,426
7.1.4.2 Net income
Net income = gross profit* (1 – income tax)
Tax in Ethiopia is 35% of income.
Net income = $4,899,426/year*(1- 0.35)
Net income = $3,184,626.9/year
7.1.4.3 Breakeven point
The break-even analysis establishes a relationship between operation costs and revenues. It indicates
the level at which costs and revenue are in equilibrium.
Breakeven point (BEP) = Fixed capital investment/ (total annual sale-total product cost) *100
= 3,449,313.45/ (10,990,000-2,920,665.319) *100
= 42.7% = 0.42
42
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
7.1.4.4 Payback Period
Taking the minimum acceptable rate =12%, and taking the percentage of fixed capital investment
to total capital investment.
FCI/ TCI = 3,449,313.45/4,058,015.824 = 0.85
Payback period reference = 0.85/0.12+0.8510 = 4.15year
𝐹𝐶𝐼
Payback period after tax = 𝑁𝐼+𝑑
=
$3,449,313.45
$3,184,626.9/year +$344,931.345
= 0.977~1year
Since payback period is less than payback period reference, the project is feasible.
7.1.4.5 Annual cash flow
Annual cash flow = NI + d
=$3,184,626.9/year + $344,931.345
=$3,529,558.245/year
7.1.4.6 Rate on investment
In financial analysis financial ratios and efficiency ratios are used as an index or yardstick for
evaluating the financial position of a firm. It is also an indicator for the strength and weakness of
the firm or a project.
ROI =
𝐴𝐶𝐹
𝑇𝐶𝐼
*100
$3,529,558.245
=$4,058,015.824*100
= 86.98%
7.1.4.7 Net present value (NPV)
The service life is, n = 10yr
Interest rate(r) = 12%
Depreciation cost = $344,931.345
Annual cash flow (CF) =$3,529,558.245/year
43
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
Now convert to present value
PV =
=
ACF((1+r)^n−1)
r(1+r)
$3,529,558.245(1+0.12)^10−1
0.12(1+0.12)
=$55,302,930.85
NPV = PV – TCI
= $55,302,930.85/year - $4,058,015.824
= $51,244,915.03
7.1.4.8 Discount cash flow rate of return (DCSRR or IRR)
The internal rate of return (IRR) is the annualized effective compounded return rate that can be
earned on the invested capital, i.e., the yield on the investment. Put another way, the internal rate
of return for an investment is the discount rate that makes the net present value of the
investment's income stream total to zero.
Annual cash flow =$3,529,558.245/year
TCI = $4,058,015.824
Project service life = 10year
NPV=
ACF((1+r)^n−1)
r(1+r)^n
+ Recovery (1+r)-n –TCI
Recovery = 0 and at IRR the net present value is zero (NPV= 0)
ACF((1+r)^n−1)
0=
TCI =
r(1+r)^n
– TCI
ACF((1+r)^n−1)
r(1+r)^n
$8,783,720=
$3,529,558.245 ((1+r)^10− 1)/r(1+r)
2.488617382=
r(1+r)^10
(1+r)^10− 1
r(1+r)^10
By using trial and error method IRR is around 40 %
44
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
Therefore the discount cash flow rate of return (DSRR) is 40%; DSRR is greater than minimum
acceptable rate (mar) so, the thesis is acceptable.
Figure 8: Discount cash flow Source: lecture note
Table 7: Results of biodiesel production costs
Basis of production of 7,000,000kg 𝐨𝐟 𝐛𝐢𝐨𝐝𝐢𝐞𝐬𝐞𝐥/𝐲𝐞𝐚𝐫
Type
Price ($)
Equipment cost
1,390,852.2
Maintenance and repairs
206,958.807
Raw material cost
1,219,975
Labor
292,066.5319
Total fixed charge
448,410.75
Total direct cost
2,209,394.691
Total manufacturing cost
2,803,838.707
Depreciation
344,931.345
Local taxes
68,986.269
Contractors fee
208,627.83
Fixed cost
448,410.75
Insurance
34,493.1345
45
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
Contingence fee
111,268.176
Total production cost
2,920,665.319
Working capital
608,702.37
Total investment capital
4,058,015.824
Gross income
9,519,426
Net Income
3,184,626.9
ROI
86.98%
Payback period
1 year
IRR
40%
NPV
51,244,915.03
7.2 Plant Location Selection
The best option for optimum algal biomass development is to use free CO2 from external
combustion sources. About 210 000 t/yr of CO2 can be processed by a 1000 ha algae growing
system. A 50 MW plant emits about 414 000 t/yr of CO2, implying that the 1000 ha system can
utilize half of the CO2 emitted. Given that no compression mechanism is envisaged in the current
scheme and no night storage is possible, the results for recycling 25% and 50% of the emitted
CO2 are reported, making recycling 50% of the emitted CO2 the high limit for this strategy. As a
result, the 1000 ha algae growing system is a good match for the 50 MW plant in terms of
capacity.[24] A source of CO2 flue gases from a 9.6MW power plant would adequate for this
project, which would evaluate a production facility of roughly 48 independent open ponds of
area 40000m2 each (192ha). Although Ethiopia does not have a single coal-fired power station,
there are some areas in the country where a confirmed quantity of mineral coal can be found.
Yayu (lluababora), Chilga (Gondar), and Wuchale are among the specific places with verified
coal resources (Dessie). Because of current Ethiopian government project activity in Yayu
(Iluababora) for fertilizer production and power generation, which could offer us with exhaust
CO2, the Iluababora area has been chosen for our plant location.
46
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
8
ENVIRONMENTAL IMPACT
Most traditional biofuels, such as ethanol from corn, wheat, or sugar beets, and biodiesel from
oil seeds, are produced from classic agricultural food crops that require high-quality agricultural
land for growth. An important parameter for biomass energy is the impact of land use. This
impact category describes the environmental impact resulting from land use for human activities.
In particular, the land use category considers natural land as a resource and assumes that land
occupation and management causes consumption of the resource. Natural land can be defined as
land not damaged at the moment by human activities and the remaining natural land fraction
under use. Land use is an impact indicator.[3]
Land use impacts have been related to the area of land used, or physical land use.
Specifically, they include impacts on biodiversity, biotic production potential (including soil
fertility and use value of biodiversity), and ecological soil quality (including life support
functions of soil other than biomass production potential). The use of land to produce biofuels in
a well-established infrastructure has an impact on the environment.[3]
Microalgae can grow in waste or seawater, have vastly superior biomass yields per hectare and
,most importantly ,the co2 removed from the atmosphere during photosynthesis growth of the
plant offsets co2 released during fuel combustion. Algae –based fuel products are more promising
than first –generation biofuels, as they exclude land use and food security issues, but require a
mass production breakthrough to be viable. Through a life cycle approach, We evaluate whether
algal biodiesel production can be a viable fuel source once the energy and carbon intensity of the
process are managed accordingly.
47
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
9
CONCLUSION
Biodiesel is a diesel engine alternative fuel created by reacting vegetable or animal fat with an
alcohol like methanol. Algae are one of the oldest forms of life, and its main photosynthetic
pigment is chlorophyll. They're called thallophytes since they have no roots, stems, or leaves.
Algae can be produced through photoautotrophic, heterotrophic and mixotrophic mechanisms
then harvested by using centrifugation, flocculation, flotation, filtration, or screening for this
study we prefer manual filtration method then the drying process were takes place at 500c and
the dry microalgae crushed up to coarse size which is preferable for soxhlet extraction process by
the solvent of petrol ether then after the oil preheat and prepared in the water bath
transesterification process is occur at 600c finally the biodiesel and glycerin were formed and
biodiesel is separate from glycerin by using the separating funnel within 24 hours. The diesel
were also characterized using the parameters like flash point, PH, density and moisture content.
On this study 200ml yield of oil were collected from 4 consecutive extraction processes and after
reacting it with the alcohol catalyst (methanol-KOH) solution by using heat source with
magnetic stirrer, around 100ml biodiesel was separated from glycerin.
48
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
10 RECOMMENDATION
➢ For algae biodiesel production to be a success it must be cultivated on a large scale at first
glance this may seem like a simple process after all algae can be found throughout the
environment so it must be easy to farm however many environmental conditions must be
meet for cultivation to be successful to start with the appropriate level of light must be used
in the cultivation process this is called the light saturation point and it differs for each type of
algae.
➢ As there are different types of algae harvesting mechanism but in this study filtration method
was used of algae from Lake Hawassa with simple manual method but, it is better to use
basic filtration equipments to get maximum amount of algae source.
➢ The other one is type of production of algae; it is better to produce algae in Photoautotrophic
in open pond system because it is simple, inexpensive and have high productivity than other
production methods.
➢ From the result of this paper work, we strongly recommend all concerned body to have
inclination toward algae biodiesel which can supplement the fuel scarcity in the country.
49
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
REFERENCES
[1]
J. Van Gerpen, Fuel Process. Technol. 86 (2005) 1097–1107.
[2]
Y. Chisti, Biotechnol. Adv. 25 (2007) 294–306.
[3]
A. Demirbas, M. Fatih Demirbas, Energy Convers. Manag. 52 (2011) 163–170.
[4]
B. Kiran, K. Pathak, R. Kumar, D. Deshmukh, Ecol. Eng. 73 (2014) 326–330.
[5]
Y. Chisti, Trends Biotechnol. 26 (2008) 126–131.
[6]
V.C. Akubude, K.N. Nwaigwe, E. Dintwa, Mater. Sci. Energy Technol. 2 (2019) 216–
225.
[7]
J.H. Hwang, H.C. Kim, J.A. Choi, R.A.I. Abou-Shanab, B.A. Dempsey, J.M. Regan, J.R.
Kim, H. Song, I.H. Nam, S.N. Kim, W. Lee, D. Park, Y. Kim, J. Choi, M.K. Ji, W. Jung,
B.H. Jeon, Nat. Commun. 5 (2014) 1–6.
[8]
P.M. Slegers, M.B. Lösing, R.H. Wijffels, G. van Straten, A.J.B. van Boxtel, Algal Res. 2
(2013) 358–368.
[9]
J.R. Benemann, (2014).
[10]
G. Singh, S.K. Patidar, J. Environ. Manage. 217 (2018) 499–508.
[11]
I. Branyikova, G. Prochazkova, T. Potocar, Z. Jezkova, T. Branyik, Fermentation 4 (2018)
1–12.
[12]
C.A. Laamanen, G.M. Ross, J.A. Scott, Renew. Sustain. Energy Rev. 58 (2016) 75–86.
[13]
K.Y. Show, D.J. Lee, Algal Biomass Harvesting, Elsevier B.V., 2013.
[14]
K.Y. Show, D.J. Lee, J.S. Chang, Bioresour. Technol. 135 (2013) 720–729.
[15]
J. Chen, J. Li, W. Dong, X. Zhang, R.D. Tyagi, P. Drogui, R.Y. Surampalli, Renew.
Sustain. Energy Rev. 90 (2018) 336–346.
[16]
(n.d.).
[17]
M. El-sheekh, A.E. Abomohra, (2016).
[18]
P. Nautiyal, K.A. Subramanian, M.G. Dastidar, Fuel Process. Technol. 120 (2014) 79–88.
[19]
S. Rezania, B. Oryani, J. Park, B. Hashemi, K.K. Yadav, E.E. Kwon, J. Hur, J. Cho,
Energy Convers. Manag. 201 (2019) 112155.
[20]
A.K. Konga, A.S. Muchandi, G.P. Ponnaiah, Biofuels 8 (2017) 29–35.
[21]
G. Chinni, I. Belachew, R. Asmatulu, ASEE Zo. III Conf. (Gulf Southwest – Midwest –
North Midwest Sect. 2015 (2015).
[22]
D.C. Boffito, (2012).
[23]
K. Worden, Improved Bolted Joint Reliability: Innovative Gasket, Unsurpassed Recovery,
50
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
2014.
[24]
K.L. Kadam, Proc. Int. Jt. Power Gener. Conf. 1 (2001) 339–346.
[25]
H. Fukuda, A. Kondo, H. Noda, J. Biosci. Bioeng. 92 (2001) 405–416.
51
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
11 Appendix A
Magnetic Stirrer
Figure 9: Oil and methanol mixture heating using magnetic stirrer Source: self camera
52
Hawassa university institute of technology chemical engineering department
Production of Biodiesel from Micro Algae by Trans-esterification process
12 Appendix B
Transesterification
R1-COO-R’
CH2-OOC-R1
CH-OOC-R2
+
3R’OH
CH2-OOC-R3
Triglyceride
alcohol
CATALYST
R2-COO-R’
CH2-OH
+
CH-OH
R3-COO-R’
CH2-OH
fatty acid ester
glycerol
REACTION :Transesterification of triglyceride with alcohol Source: [25]
53
Hawassa university institute of technology chemical engineering department