Dissertaton Benoît Robart - MSc. Environmental Entrepreneurship

Assessing the business opportunities for
microalgae technologies as a means of
reducing carbon emissions.
By Benoît Robart
A dissertation submitted by Benoît Robart to the Department of Civil and Environmental
Engineering, University of Strathclyde, in part completion of the requirements for the MSc in
Environmental Entrepreneurship.
I, Benoît Robart, hereby state that this report is my own work and that all sources used are
made explicit in the text.
Supervisor: Dr. Jennifer Roberts
Number of words (excluding tables, appendices, and references): 16065
August 2014

ii
Benoît Robart – MSc. in Environmental Entrepreneurship 2013-2014
The copyright of this dissertation belongs to the author under the terms of the United
Kingdom Copyright Acts as qualified by University of Strathclyde Regulation 3.49. Due
acknowledgement must always be made of the use of any material contained in, or derived
from, this dissertation.

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Abstract
Purpose of the research
Humankind must act now to address the problem of global warming initiated by
anthropogenic emissions of Green-house gases like CO2. Microalgae could be used to
mitigate CO2 emissions. Microalgae are micro-organisms which transform CO2 and nutrients
into biomass through the process of photosynthesis, like plants. However, microalgae are ten
to fifty times more efficient at capturing CO2 than plants. 1.8kg of CO2 is required to produce
1kg of microalgal biomass. Therefore, they have the potential to capture CO2 from flue gas or
from the atmosphere and to reduce the net carbon emissions into the atmosphere. This
dissertation attempts to assess business opportunities for microalgae-based solutions to
mitigate carbon emissions.
Methodology
A qualitative research was undertaken, based on a literature review and on interviews of
experts in this field (N=9) both from research background and from business background. The
literature review covered the techniques to produce and harvest microalgal biomass, the
potential for microalgae-based carbon capture from flue gas, and the business opportunities
for microalgae-based technologies. Data collected in the literature review and during the
interviews were compared together and analyzed to identify a list of findings and
recommendations for future practice.
Findings and conclusion
It was found that a combination of several business opportunities was often recommended for
a microalgae-based business to be profitable. Save for production of nutraceuticals and
chemical compounds out of microalgae, which are very profitable products already.
Microalgae enable to reduce carbon emissions, as (1) they feed on CO2 to grow, either it is
CO2 from flue gas or from the atmosphere, and (2) microalgae by-products would have emit
more CO2 during their life if they had been produced with fossil-fuel-based solutions. The
drivers and opportunities for this field have been found to be (1) carbon taxes and subsidies
from governments, (2) R&D, especially in genetics and (3) acceptance by people that
microalgae can be used to make products for everyday life.

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Acknowledgements
I want to express my gratitude to my supervisor, Dr Jennifer Roberts, for her patient guidance
and her sense of details in her feedbacks on my work. She helped me learn and improve
myself during the whole process of writing this dissertation.
Also, I want to thank Dr Elsa João, for her valuable comments on my proposal and her choice
of supervisor for my dissertation.
I want to thank all the nine participants to the interviews, for their invaluable insights on my
topic and their availability. I am sincerely grateful to them for sharing their culture and up-to-
date knowledge with me, and for tolerating my strong French accent during our discussions.
Also, I express my gratitude to Andrea, who evocated algae-based biofuel during a
discussion. He gave me the idea to investigate deeper into this topic and to pursue my
dissertation in a related area.
I want to specially thank Aline for her priceless advice on communication and for staying at
my side during this time of stress that is the dissertation writing.
I want to thank my friends who supported me during the writing of this thesis: Samir,
Guislaine, Pierre, Gurkan, Daniele, Timothy, and Boom.
Finally, I want to thank my parents for believing in me and for giving me their support during
this summer spent at writing this dissertation far from them.

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Contents
Abstract .....................................................................................................................................iii
Acknowledgements ...................................................................................................................iv
List of figures ............................................................................................................................. 1
List of tables............................................................................................................................... 3
List of abbreviations................................................................................................................... 4
Glossary...................................................................................................................................... 6
1. Introduction ............................................................................................................................ 7
1.1. Background of the research ............................................................................................. 7
1.1.1. The situation – the needs for technologies reducing carbon emissions .................... 7
1.1.2. The potential of microalgae to sequestrate carbon dioxide....................................... 9
1.2. Goals of the research ....................................................................................................... 9
1.3. Structure of the dissertation........................................................................................... 10
2. Microalgae: an overview...................................................................................................... 11
2.1. What are microalgae and why are they important? ....................................................... 11
2.1.1. What are algae?....................................................................................................... 11
2.1.2. How can microalgae act as carbon sink.................................................................. 12
2.1.3. Some microalgae species and their characteristics ................................................. 13
2.2. Technologies to grow microalgae.................................................................................. 14
2.2.1. Open ponds ............................................................................................................. 14
2.2.2. Closed systems........................................................................................................ 17
2.2.3. Comparison of these two technologies for large-scale commercial production..... 19
2.3. Technologies to harvest microalgae .............................................................................. 20
3. Carbon capture and storage and applicability to algae-based technologies......................... 23
3.1. What does (non-algae-based) ―Carbon Capture and Storage‖ mean and what is
currently being done? ........................................................................................................... 23
3.1.1. Definition of ―Carbon Capture and Storage‖.......................................................... 23

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3.1.2. Step 1 - carbon capture............................................................................................ 23
3.1.3. Step 2 - transport..................................................................................................... 24
3.1.4. Step 3 - storage........................................................................................................ 25
3.1.5. Bio-CCS – Classic CCS combined with biofuels combustion ............................... 25
3.2. Opportunities for Algae-based carbon capture.............................................................. 26
3.2.1. Introduction............................................................................................................. 26
3.2.2. Using microalgae to capture CO2 from power plants flue gas................................ 26
3.2.3. Potential for CO2 capture by microalgae ................................................................ 28
4. Business opportunities in the field of microalgae ................................................................ 33
4.1. Introduction ................................................................................................................... 33
4.2. Microalgae for biofuel production................................................................................. 34
4.2.1. Why microalgae-based biofuel?.............................................................................. 34
4.2.2. Technical and economic aspects of making biofuels with microalgae................... 36
4.3. Microalgae used to treat waste water ............................................................................ 37
4.4. What can be done with algae biomass........................................................................... 40
4.4.1. Fertilizers ................................................................................................................ 40
4.4.2. Human food industry, pharmaceuticals and nutraceuticals .................................... 40
4.4.3. Animal food industry .............................................................................................. 42
4.4.4 Other business opportunities and algae-based technologies being developed......... 43
4.5. Conclusion of the literature review ............................................................................... 44
5. Methodology of the dissertation........................................................................................... 46
5.1. Introduction ................................................................................................................... 46
5.2. Conducting qualitative research .................................................................................... 47
5.2.1. Conducting qualitative research.............................................................................. 47
5.2.2. Semi-structured interviews ..................................................................................... 48
5.3. Questions ....................................................................................................................... 49
5.4. Identification of the potential interviewee..................................................................... 50
5.5. Analysis ......................................................................................................................... 51
6. Findings and analysis of the results...................................................................................... 53

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6.1. Objective 1 – To investigate the technical and financial aspects of growing microalgae
.............................................................................................................................................. 53
6.1.1. Growing microalgae - Open ponds versus photobioreactors.................................. 53
6.1.2. Production costs and profitability ........................................................................... 55
6.1.3. Recommendations................................................................................................... 56
6.2. Objective 2 – To investigate the potential of microalgae to mitigate carbon emissions
from flue gas......................................................................................................................... 56
6.2.1. Findings and analysis.............................................................................................. 56
6.3. Objective 3 – To identify the main opportunities and challenges for the development of
microalgae-based technologies ............................................................................................ 59
6.4. Objective 4 – To investigate the potential of microalgae-based biofuel to mitigate
carbon emissions, and as an alternative to fossil fuel in the Future.................................... 61
6.5. Objective 5 – To explore activity in the field of microalgae today and to identify
profitable business opportunities in the field of microalgae to mitigate carbon emissions. 64
6.5.1. Growing microalgae reduces net CO2 emissions.................................................... 64
6.5.2. Food production...................................................................................................... 65
6.5.3. Other business opportunities................................................................................... 65
6.5.4. Combination of business opportunities................................................................... 67
7. Conclusion............................................................................................................................ 69
7.1. Summary of key findings and recommendations for future practice ............................ 69
7.2. Limitations..................................................................................................................... 71
7.3. What further research could be done............................................................................. 71
7.4. Concluding the dissertation ........................................................................................... 72
Table of references................................................................................................................... 73

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Appendix I – Information sheet for interview.......................................................................... 83
Appendix II – Consent form for interview............................................................................... 86
Appendix III – Questions for interview and format................................................................. 88
Appendix IV – Information sheet for questionnaire ................................................................ 92
Appendix V – Consent form for questionnaire ........................................................................ 95
Appendix VI – Questionnaire .................................................................................................. 97
Appendix VII – Advertisement.............................................................................................. 101
Appendix VIII – Advertising Email/cover letter.................................................................... 102
Appendix IX – Answers to the interviews ............................................................................. 103
Interview 1 - Rhona ............................................................................................................ 103
Interview 2 - Robert............................................................................................................ 105
Interview 3 - Brennan......................................................................................................... 108
Interview 4 - Prakash.......................................................................................................... 110
Interview 5 – Kyle .............................................................................................................. 112
Interview 6 – Raphaël......................................................................................................... 114
Interview 7 - Barrack.......................................................................................................... 116
Interview 8 – Ryan ............................................................................................................. 118
Interview 9 - Paulo ............................................................................................................. 120

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List of figures
Figure 1.1.1.a. The greenhouse effect (CO2CRC, 2014)........................................................... 7
Figure 1.1.1.b. Cumulative total anthropogenic CO2 emissions from 1870 and in the Future, as
forecasted by the IPCC (2013a) ................................................................................................. 8
Figure 2.1.1. A sample of microalgae under the microscope (Qualitas, 2014)........................ 11
Figure 2.1.2. Tubes of culture after the experiment: one was bubbled normal air (on the left –
culture is less dense) and the other one was bubbled air with additional CO2 (culture is denser)
(Packer, 2009) .......................................................................................................................... 12
Figure 2.2.1.a. Example of open-pond systems (Spath and Mann, 2002) ............................... 15
Figure 2.2.1.b. Example of circular algal pond with rotating agitator in Taiwan (Becker, 1994)
.................................................................................................................................................. 15
Figure 2.2.1.c. Example of open-pond for large-scale production, with several raceways,
adapted from Demirbas and Demirbas (2010) ......................................................................... 16
Figure 2.2.1.d. Aerial view of spiral algal pond at Lake Texoco in Mexico (Becker, 1994)... 16
Figure 2.2.2.a. Example of tubular PBR system (algae-energy, 2014).................................... 18
Figure 2.2.2.b. Vertical column photobioreactors at the MIT (Roidroid, 2007)...................... 18
Figure 2.2.2.c. Mechanism of a flat-plate photobioreactor (Newman, 2008).......................... 19
Figure 3.2.3.a. Schematic process of microalgae-based carbon capture from power plants
(Powerplantsccs, 2014) ............................................................................................................ 29
Figure 3.2.3.b. Global distribution of some companies having projects related to microalgae-
based carbon capture from flue gas (Powerplantsccs, 2014) ................................................... 31
Figure 3.2.3.c. Combination of carbon capture with microalgae farm and classic CCS of the
biofuels produced by the microalgae........................................................................................ 32
Figure 4.1. The different products that can be made out of micro-algae, adapted from
Reissman (2013)....................................................................................................................... 33
Figure 4.2.2. Diagram showing expected trends for the evolution of prices for petroleum and
algal oil production and enlightening the fact that if the trends go on, algal oil will become
cheaper than petroleum at some point (on creation) ................................................................ 37
Figure 4.3.a. Schematic diagram showing the concept of utilizing microalgae production for
combined waste water treatment and biogas fabrication to power the water treatment plant,
adapted from Craggs et al. (2012)............................................................................................ 39

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Figure 4.3.b. Photograph of one of the 1.25-ha algal ponds with an algal harvester (Craggs et
al., 2012)................................................................................................................................... 39
Figure 4.4.4. Algae-powered streetlamp of Pierre Calleja (Calleja, 2013).............................. 43
Figure 6.4.1. Sustainable cycle of microalgae-based biofuel production and combustion (on
creation).................................................................................................................................... 63
Figure 6.5.1. Diagram illustrating reduction in net CO2 emissions in the atmosphere by
producing by-products out of algal biomass (on creation)....................................................... 64
Figure 6.5.5. Arranged SADT presenting the whole process of growing microalgae with
business opportunities spoken of in the research (on creation) ………………………………68

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List of tables
Table 2.1.3. Growth characteristics for some algae strains adapted from Li et al. (2006)....... 14
Table 2.2.2. Main types of photobioreactors, adapted from Ugwu et al. (2008)………….18
Table 2.2.3. Comparison between open ponds and closed systems for microalgae culture .... 20
Table 2.3. Summary of biomass recovery options adapted from Li et al. (2006).................... 22
Table 3.1.2. List of the three major options to capture CO2 from the flue gas created by the
combustion of fossil fuel.......................................................................................................... 24
Table 3.1.4. List of available options for carbon storage......................................................... 25
Table 3.2.3. Comparison between microalgae-based carbon sequestration versus classic CCS,
adapted from Powerplantsccs (2014) ....................................................................................... 30
Table 4.2.2. Different types of microalgae-based biofuels and their manufacturing process,
adapted from Chisti (2007), Brennan and Owende (2010), Mata et al. (2010), Amaro et al.
(2012) and Powerplantccs (2014) ............................................................................................ 36
Table 4.3. Advantages and drawbacks of combining waste water treatment with microalgae
production, adapted from Benemann and Pedroni (2007), Park et al. (2011), and Craggs et al.
(2012), ...................................................................................................................................... 38
Table 4.4.2.a. Non-exhaustive list of microalgal species with some of their potential
downstream applications, adapted from Borowitzka (1999), Spolaore et al. (2006), Chisti
(2007), Wang et al. (2010), and Ho et al., (2011) .................................................................... 41
Table 4.4.2.b. Some company names with the substances they extract from microalgae for
their food- or drug-related industry, adapted from Pulz and Gross (2004).............................. 42
Table 4.5. Summary of the advantages of microalgae for business applications to mitigate
CO2 emissions .......................................................................................................................... 45
Table 5.2.1. Comparison between the main types of interviews, adapted from Langley (1987)
and Burns (2000)...................................................................................................................... 48
Table 5.4. List of respondents with details regarding their activity and expertise................... 51
Table 7.1. Summary of key findings and recommendations for each objective …………69

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List of abbreviations
Air Separation Unit ASU
Australian Dollar A$
Carbon Capture and Storage CCS
Carbon dioxide removal CDR
Chlorofluorocarbon CFC
Methane CH4
Carbon dioxide CO2
Enhanced Oil Recovery EOR
European Union EU
Flue-gas Desulphurization FGD
Greenhouse Gases GHG
Gigawatt Hour GWh
Hydrogen H2
Mercury Hg

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Micrometre μm
Megawatt MW
Nitric Oxides NOx
Oxygen O2
Parts per million ppm
Photobioreactor PBR
Research and Development R&D
Representative Concentration Pathway RCP
Structured Analysis and Design Technique SADT
Sulphur Oxides SOx
Species sp.
United States dollar US$
United States of America USA
Ton t

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Glossary
1
Parts per million (ppm): Unit which applies for very dilute concentrations of substance. Just
as one percent is one part out of cent, one ppm is one part out of one million. Thus, the units
mg/ton or mL/m3
are examples of ppm units.
2
Net Present Value (NPV): The NPV of a project is the sum of net cash inflows (incomes and
outcomes) over the years, divided by a discount rates which takes into account the time value
of money, the interest rates, the risks and uncertainty of future cash flows.
3
Acre: Surface unit - 1 acre = 0.405 hectare = 4047 m2
3
Nutraceutical: The term nutraceutical refers to products which supposedly provide health
benefits and which are derived from food sources.
4
Lignocellulosic biomass: refers to naturally occurring terrestrial plants like trees, bushes,
grass, waste biomass and non-food crops
5
Eutrophication: The term eutrophication here refers to the saturation of a water body with
nutrients, which leads to radical changes in the ecological balance: decreased percentage of
dissolved O2, new species invasion, decreased biodiversity, and toxicity are some of the
symptoms of eutrophication.
6
Profit margin:
7
SADT (Structured Analysis and Design Technique): methodology to describe a process with
identification of inputs, process and its function(s), and outputs.

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1. Introduction
1.1. Background of the research
1.1.1. The situation – the needs for technologies reducing carbon emissions
Data show that global mean temperatures of the atmosphere and ocean have been increasing
for 150 years, reaching unprecedented records over the last 2000 years (IPCC, 2013b). This
on-going phenomenon is known as global warming. Anthropogenic emissions of Greenhouse
Gases (GHGs) are probably the major cause of it (Huntley and Redalje, 2007).
GHGs are gases like water vapour, CO2, Methane (CH4), Nitric oxides (NOx), sulphur oxides
(SOx) and chlorofluorocarbons (CFCs). They contribute to the greenhouse effect which causes
the atmosphere to retain heat (Lashof and Ahuja, 1990): when sunrays reach the atmosphere,
part of their energy is absorbed by the atmosphere and released as heat (infrared radiation).
GHGs act like a blanket and the more GHGs there are in the atmosphere, the more energy will
be absorbed from the sun and turned into heat by the atmosphere, warming the earth (EPA,
2014). This phenomenon is illustrated by figure 1.1.1.a.
Figure 1.1.a. The greenhouse effect (CO2CRC, 2014)

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CO2 is considered as the most noxious GHG, as its emissions account for approximately 80%
of the volume of GHGs produced by human activity (Lashof and Ahuja, 1990; EIA, 2011)).
As figure 1.1.1.b. shows, cumulative total emission of CO2 and global mean temperature are
approximately linearly related. Reduction of CO2 emission is therefore a priority in the fight
against global warming.
Figure1.1.b. Cumulative total anthropogenic CO2 emissions from 1870 and in the Future, as forecasted by
the IPCC (2013a)
Technologies using renewable energies to produce electricity are being developed, as the
major sources of CO2 emissions are fossil-fuel-fired power plants. These technologies are
becoming more efficient and less expensive to implement, but still lots of improvements are
required in this field. Meanwhile, emissions of GHGs from the combustion of fossil fuel keep
increasing and are forecasted to exponentially increase in the next decades if nothing is done
to mitigate these emissions (IPCC, 2013b). For now, the IPCC targets stabilization of CO2
concentration in the atmosphere at between 350 and 450 ppm1
. But this can only be done if all
solutions to capture mitigate net carbon emissions in the atmosphere are investigated.

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1.1.2. The potential of microalgae to sequestrate carbon dioxide
Before so many GHGs were emitted in the atmosphere by human activity, the biosphere was
able to regulate CO2 in the atmosphere by itself. Even today, still approximately one third of
total carbon emissions per year are absorbed by the biosphere, which accounts for about 250
billion tons of CO2 (Socolow et al., 2004). More than half of these carbon emissions are
absorbed by the ocean thanks to organisms like microalgae.
Microalgae are micro-organisms which use photosynthesis chemical reaction to grow.
Photosynthesis turns carbon dioxide (CO2) into Oxygen (O2) and organic matter (Janssen,
2002). Moreover, they are made of about 50% of carbon (Putt, 2007) and are very efficient in
the process of photosynthesis: under good conditions, they can grow exponentially and their
weight can double within a day (Goodall, 2009). In addition, the sources of CO2 that
microalgae can capture carbon from are typically the atmosphere, flue gas from power plants
or industrial processes, and soluble carbonates (Wang et al., 2008). So microalgae have
potential for carbon capture.
In addition, microalgae can be used for several valuable activities at the same time, such as
biofuel production, carbon dioxide fixation from flue gas, production of valuable by-products
like food, feed, or fertilizer, and wastewater treatment at the same time. Therefore they offer a
potentially highly efficient tool for anthropogenic carbon emissions mitigation (Wang et al.,
2008).
1.2. Goals of the research
The dissertation presents an overview of the technologies and innovations in the field of
microalgae as a way to mitigate carbon emissions. The main goal is to assess the business
opportunities for microalgae-based technologies to mitigate carbon emissions. This is
done using two sources of data: literature review (secondary data), and interviews (primary
data).
To do answer the research question, five objectives were identified and answered during this
research:
 Objective 1 – To investigate the technical and financial aspects of growing
microalgae

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 Objective 2 – To investigate the potential of microalgae to mitigate carbon emissions
from flue gas
 Objective 3 – To identify the main opportunities and challenges for the development of
microalgae-based technologies
 Objective 4 – To investigate the potential of microalgae-based biofuel to mitigate
carbon emissions, and as an alternative to fossil fuel in the Future
 Objective 5 – To explore activity in the field of microalgae today and to identify
profitable business opportunities in the field of microalgae to mitigate carbon
emissions
Answers to these objectives will enrich current database on microalgae-based technologies
and business opportunities to mitigate carbon emissions, and provide this database with up-to-
date information. The researcher used his background in Mechanical Engineering and his
knowledge acquired through his academic year at Strathclyde University in the MSc. of
Environmental Entrepreneurship to lead this research.
1.3. Structure of the dissertation
This thesis is divided into several chapters. The first three chapters are the summary of the
literature review made by the researcher:
 Chapter 2 explains what microalgae are and how they are grown and harvested
 Chapter 3 presents how microalgae can be used to capture CO2 from industry flue
gases and compares carbon capture with microalgae to classic Carbon Capture and
Storage (CCS)
 Chapter 4 draws an overview of business opportunities for entrepreneurs in the field of
microalgae
Following the literature review, chapter 5 explains the methodology of research for this
dissertation and in particular how primary data collection and analysis are handed out. Finally,
Chapter 6 presents the findings and analyses data gathered during this research, before a
conclusion is made in chapter 7, with a summary of key findings and recommendations for
future practice.

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2. Microalgae: an overview
This chapter explains what microalgae are, and explores technics used to grow and
harvest microalgal biomass.
2.1. What are microalgae and why are they important?
2.1.1. What are algae?
Algae are a very large family of organisms, whose size vary between a few micrometres and
more than 50 metres for some species of giant alga like the giant kelp (Algae Biomass
Organization, 2014a). They belong to the kingdom of Protista, which regroups all organisms
that do not belong in any other five kingdoms (Becker, 1994).
Two categories of algae can be distinguished: microalgae and macroalgae. Macroalgae (more
commonly called ―seaweed‖) are complex multicellular organisms, while microalgae are a
family of unicellular or simple multi-cellular fast-growing micro-organisms (Graham and
Wilcox, 2008). Microalgae started to arouse the interest in the beginning of the 20st
century
and though more than 50,000 strains of microalgae have been identified yet, only a few
thousands of them have been studied so far (Deng et al., 2009; Brennen and Owende, 2011).
Microalgae are very interesting organisms for carbon capture. Through the process of
photosynthesis (see 1.1.2), they are capable of capturing CO2 at efficiency 10 to 50 times
faster than that of terrestrial plants (Li et al., 2008). A sample of microalgae under the
microscope can be seen on figure 2.1.1 below.
Figure 2.1.1. A sample of microalgae under the microscope (Qualitas, 2014)

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Most microalgae grow with CO2, sunlight and nutrients through the process of
photosynthesis. These microalgae are called autotrophic microalgae. Some microalgae can
grow in the dark, using starch or sugar, through a process of fermentation. These microalgae
are called heterotrophic microalgae. This research focuses on autotrophic microalgae, which
require gaseous or aqueous CO2 to grow (Xu et al., 2006; Shamzi et al., 2011).
2.1.2. How can microalgae act as carbon sink
Microalgae are champions for capturing carbon dioxide from the atmosphere. They contain a
high percentage of carbon: 50% of their mass is made of carbon (Putt, 2007). Approximately
1.8 kg of CO2 is required to provide enough carbon to grow 1 kg of microalgae (Becker,
1994; Sudhakar et al., 2011). This characteristic is combined with a very fast growth: under
good conditions, microalgae can grow exponentially and their weight can double within a day
(Goodall, 2009). These characteristics led several scientists and entrepreneurs to consider
using microalgae to act as carbon sink, to mitigate carbon emissions, as will be explained in
the next chapters.
A solution will be investigated in particular in chapter 3, which consists in injecting directly
flue gases from power plants or other CO2 emitting industries into microalgae farms. One of
the numerous characteristics of microalgae is that they bloom in an environment with a high
concentration of CO2. A laboratory experiment shows that under the same condition of
growth, an environment with more dissolved CO2 leads to a better development of microalgae
than an environment with no additional CO2 (figure 2.1.2).
Figure 2.1.2. Tubes of culture after the experiment: one was bubbled normal air (on the left – culture is
less dense) and the other one was bubbled air with additional CO2 (culture is denser) (Packer, 2009)

13
Not only are microalgae very efficient at converting CO2 into biomass, but they are very
tolerant to high concentrations of CO2 and pollutants in their environment too (Graham and
Wilcox, 2008; Lee, 2009). Chapter 3 will investigate further on the viability of using
microalgae to capture carbon from industrial flue gas.
Apart from carbon capture from flue gases, microalgae can be used as an alternative solution
to produce services or goods like recycling of waste water, biofuel, plastics, food and
fertilizers, whose production would have emitted more CO2 into the atmosphere otherwise
(Benemann and Pedroni, 2007). These applications will be investigated in more details in
chapters 3 and 4.
2.1.3. Some microalgae species and their characteristics
Strains are chosen based on several criteria, among which yielding, percentage of oil,
harvestability, and tolerance to temperature extremes and to pollutants (Benemann, 2008).
For example, if one wants to put emphasis on the ability of microalgae to capture carbon
dioxide from flue gas, the strains should fill the following criteria (Ono and Cuello, 2003;
Brennan and Owende, 2010):
 Tolerance to high CO2 concentrations
 Tolerance to pollutants and trace elements in flue gas
 Tolerance to high temperatures
 Ability to capture CO2
 Efficiency at capturing light
Below is a table summarising the growth characteristics of some strains of microalgae (Table
2.1.3). Each strain has its own advantages and drawbacks and therefore the optimal strain can
be selected from the large range of criteria and microalgae species available, depending on the
purpose of the production.

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Table 2.1.3. Growth characteristics for some algae strains adapted from Li et al. (2006)
Among the species of microalgae already studied by researchers, Chlorella, Spirulina and
Dunaliella fill the criteria for carbon capture from flue gas, and they have commercial values
too (Ono and Cuello, 2003; Li et al., 2006). They can therefore be used for two kinds of
money incomes: carbon capture from flue gas and use of biomass through the manufacturing
of by-products.
Microalgae farming therefore have interesting prospects and potential. But the question is:
how do you commercially grow and harvest microalgae?
2.2. Technologies to grow microalgae
2.2.1. Open ponds
Microalgae are almost exclusively cultivated on land. Two families of options are being used
to cultivate autotrophic microalgae: open ponds and closed systems (photobioreactors).
The most common systems to grow micro-algae are open ponds (figures 2.2.1.a and 2.2.1.b).
There are two types of artificial open ponds: raceways, which look like a race track; and
circular ponds. The depth of an open pond is between 15 cm and 40 cm and water is
circulated thanks to a mechanical system (e.g. a paddle wheel), which enables the microalgae
and the nutrients to be mixed and uniformly exposed to sunlight, and which forces microalgae
to stay in suspension and not to sink to the bottom of the pond (Becker, 1994; Li et al., 2006).

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Figure 2.2.1.b. Example of circular algal pond with rotating agitator in Taiwan (Becker, 1994)
Some open ponds with several tracks are designed for large scale production, as can be seen
on figures 2.2.1.c and 2.2.1.d.
Figure 2.2.1.a. Example of open-pond systems (Spath and Mann, 2002)

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Figure 2.2.1.d. Aerial view of spiral algal pond at Lake Texoco in Mexico (Becker, 1994)
Open ponds are the cheapest solution to build and operate. This technology is mature and
widely used, and therefore is the most economical solution for large-scale production of
microalgae, provided some conditions are filled (Borowitzka, 1999; Li et al., 2006):
 An abundant supply of water or waste water must be available.
 Weather is important: Relative humidity is key factor (too low humidity rate results in
evaporation and too high humidity rate can result in overheating of the water).
Precipitation rate is very important too (high precipitation rates may cause dilution and
loss of biomass).
Indeed, the biggest disadvantage of open ponds is that they are exposed to open air. Not only
are they subject to rainfalls and evaporation and their productivity is dependent on the
Figure 2.2.1.c. Example of open-pond for large-scale production, with several raceways,
adapted from Demirbas and Demirbas (2010)

17
weather and the season, but they are prey of invading algae species, grazers, fungi and
amoeba (Demirbas and Demirbas, 2010).
A hybrid solution of open ponds consists in protecting the pond with a transparent covering.
This solution limits the drawbacks due to exposition of the culture to open air, but covering
the pond implies big capital costs and reduction of sunlight which reaches the culture (Li et
al., 2006).
2.2.2. Closed systems
Photobioreactors (PBRs) are systems where microalgae grow within a closed container. This
means that algae are not exposed to the atmosphere, which poses a problem for open systems.
These work as follows (Demirbas and Demirbas, 2010; algae-energy, 2014):
 CO2 and nutrients are brought to the containers with a pump, and bubbled into the
culture.
 Microalgae are periodically transferred to a degassing zone, where they are bubbled
and ―purified‖ of the O2 produced through photosynthesis.
 Heat exchangers allow the temperature within the containers to be regulated day and
night.
 All parameters of growth are controlled in a PBR (like temperature, flow rate,
Concentration of CO2, and pH) and thus productivity of PBRs is optimized compared
with open ponds.
Microalgae production can be 5 times more important in PBRs than in open ponds, which
results in a denser culture which facilitates harvesting (Demirbas and Demirbas, 2010; algae-
energy, 2014).
Photobioreactors can take many different shapes and sizes: they can be tubular, panels or bag-
type, inclined vertically or horizontally, and using artificial light or not. These specifications
are dependent on the targets of the activity (research, production of biomass) and on the
resources available.
Table 2.2.2 below draws an overview of the different types of PBRs with their advantages and
drawbacks.

18
Table 2.2.2. Main types of photobioreactors, adapted from Ugwu et al. (2008)
Figures 2.2.2.a, 2.2.2.b and 2.2.2.c illustrate the different kinds of photobioreactors.
Figure 2.2.2.b1. Vertical column photobioreactors at the MIT (Roidroid, 2007)
Figure 2.2.2.a. Example of tubular PBR system (algae-energy, 2014)

19
Figure 2.2.2.c. Mechanism of a flat-plate photobioreactor (Newman, 2008)
Closed systems are globally more expensive than open ponds and require more maintenance
(algae-energy, 2014). They are being developed for high scale production but in the moment,
but today they are mostly used for research, to incubate open ponds, and to grow particular
types of microalgae under ideal conditions (i.e. optimal exposure and invasion from other
organisms avoided) (Ugwu et al., 2008; Benemann, 2008).
2.2.3. Comparison of these two technologies for large-scale commercial
production
Open and closed systems can be compared in terms of costs, productivity, energy-efficiency,
resilience, and possibility to control the growth parameters. Comparison between open-ponds
systems and closed systems tend to show that for large-scale production, open ponds are more
economically viable and more energy efficient, provided conditions are favourable for their
implementation (i.e. good weather conditions, limited probability of invasive species and
contamination, abundant water resources available) (Borowitzka, 1999; Benemann, 2008;
Resurreccion et al., 2012).
Scale-up of PBRs is feasible by increasing the length, the height, the diameter, or the number
of compartments. But as PBRs get bigger, problematics of light exposure, temperature, mass
transfer and mixing are more difficult to overcome (Ugwu et al., 2008).
However, a combination of photobioreactors and open ponds systems seems to be a very
powerful combination presently, as PBRs present a very high productivity and can be used to
produce ―inoculum‖ culture, to seed open ponds to start culture (Benemann, 2008; Schenk et
al., 2008; Demirbas and Demirbas, 2010).

20
A summary of the advantages and drawbacks of each solution has been made in table 2.2.3
below.
Table 2.2.3. Comparison between open ponds and closed systems for microalgae culture
Today, open ponds produce up to 98% the total commercial algae biomass, even for high
value products (Benemann, 2008).
2.3. Technologies to harvest microalgae
Once microalgae are grown, biomass needs to be separated from water, so that it can be
transformed into a valuable product.
The technique used to harvest microalgae depends on its characteristics e.g. density, size and
target product (Olaizola, 2003). This part represents 20-30% of the total production costs of
microalgae biomass (Molina et al., 2003). Harvesting is generally a three stage process:
1. Bulk harvesting, which consists in separating biomass from bulk suspension. For this
step, three main techniques are employed:
a. Flocculation – polymers are added to the solution, to make microalgae
aggregate and form bigger systems to facilitate their extraction (Molina Grima
et al., 2003)
b. Flotation – air is bubbled from the bottom of the system, capturing microalgae
on their way to the surface and thus grouping microalgae in a layer near the
surface. Compared with the previous process, this technique does not require
chemicals to work (Wang et al., 2007)
c. Gravity sedimentation – This process consists in letting gravity operate to
form a layer of microalgae at the bottom (or at the top, depending on their

21
relative density) of the slurry. Though it is a time-consuming process, it is very
efficient and low-cost (Brennan and Owende, 2010)
2. Thickening – this step aims to thicken the bulk. After bulk harvesting step,
concentration of biomass is about 2-7% in the slurry (Brennan and Owende, 2010).
Several methods are used:
a. Centrifugation - Because of Stoke‘s law, settling characteristics of suspended
solids depend on density, radius of microalgae-cells, and on sedimentation
velocity. Centrifugation process is rapid but consumes energy. It can be
combined with flocculation to be more time-efficient (Schenk et al., 2008)
b. Biomass filtration (filter under pressure or suction) can be used for
microalgae larger than 70 μm (Brennan and Owende, 2010)
c. Ultrasonic aggregation can be used to concentrate microalgae. This process
does not induce shear stress on microalgae, which could be damageable for the
potentially high-nutritional value metabolites (Brennan and Owende, 2010)
d. Thermal drying can be used to evaporate water and thicken biomass. It is an
energy-expensive process though (Molina Grima et al., 2003)
3. After these two steps, the concentration of microalgae in the slurry is typically 5-15%
dry solid content and dehydration or drying is needed to concentrate even more the
biomass (depending on what the target product is). Methods that are used include
(Brennan and Owende, 2010):
a. low-pressure shelf drying
b. sun drying (the cheapest method, but requires large drying surface area, good
weather conditions and time)
c. spray drying (commonly used for extraction of high-value products, but more
expensive)
d. fluidised bed drying
e. drum drying
f. and freeze drying (expensive but adapted for e.g. extraction of oil)
Table 2.3 below summarizes advantages and drawbacks of these different harvesting
techniques.

22
Table 2.3. Summary of biomass recovery options adapted from Li et al. (2006)

23
3. Carbon capture and storage and applicability to algae-
based technologies
This chapter starts with an introduction to the classic processes used today for Carbon
Capture and Storage (CCS), before analysing the potential for microalgae to grow in
the adversity of waters bubbled with flue gases and their ability to capture CO2 from
flue gases in this environment. The chapter concludes on the potential of large-scale
carbon capture from flue gas with microalgae.
3.1. What does (non-algae-based) “Carbon Capture and Storage” mean and
what is currently being done?
3.1.1. Definition of “Carbon Capture and Storage”
Carbon Capture and Storage (CCS) is a term which refers to all processes of trapping CO2
emitted during the combustion of fossil fuels or any other chemical, and storing this carbon
dioxide for long time periods so that it is not released to the atmosphere where it would
contribute to anthropogenic climate change (Rackley, 2010). CCS aims to reduce carbon
emissions from large industrial point sources, thus mitigating the impact on the atmosphere
and on global warming induced by carbon dioxide. CCS can reduce up to 90% of CO2
emissions from a site.
CCS is a three-step process: capturing, transporting, and storing CO2; and each of these steps
have their own technological and financial challenges.
3.1.2. Step 1 - carbon capture
To separate and capture carbon dioxide from flue gas, three methods distinguish themselves.
Each of them has their advantages and disadvantages. The table 3.1.2 below draws an
overview of these methods.

24
Table 3.1.2. List of the three major options to capture CO2 from the flue gas created by the combustion of
fossil fuel.
3.1.3. Step 2 - transport
Once captured, CO2 is commonly transported via pipelines, boats, trucks or railway after
compression of the gas (Singh, 2013). But the most common technic is pipelines, as the
development of the oil and gas industry has made gas transportation through pipelines a very
mature technology (Azar et al., 2006; Johnson, 2011).
Other options are being developed to transport CO2, like the storage and transport of CO2 as
an aqueous bicarbonate solution (Chi, 2011). This last solution is interesting as no
compression of CO2 is required to transport CO2 and microalgae have the ability to process
carbon from bicarbonates (Sayre, 2010; Chi, 2011).
Name of the
solution
Description Details
Pre-
Combustion
Carbon dioxide is withdrawn from flue
gas before combustion of the
combustible (Rackley, 2010)
Transformation of the fossil fuel into CO2 and
hydrogen (H2). CO2 is captured and H2 is used as a
clean fuel. The main disadvantage of this
technology is the high capital cost (Pires et al.,
2011).
Post-
combustion
Carbon dioxide is withdrawn from flue
gas after combustion of the fossil fuel
(Chou, 2013)
Chemical absorption of CO2 in the fumes by an
amine-solvent is the process the most used in this
category of capture systems. The main costs of this
process come from the recovery of the solvent.
Adsorption, cryogenic distillation and gas-
separation membranes are other solutions for post-
combustion capture systems, but they are
considered even less cost-efficient than the first
one (Stewart and Hessami, 2005; Pires et al.,
2011). The main advantage of post-combustion
capture systems is that they can be used to retrofit
existing power plant or to capture CO2 from
industrial processes (cement and steel factories for
examples) (Chou, 2013)
Oxy-fuel
Like for the post-combustion process,
carbon dioxide is withdrawn from flue
gas after combustion of the fossil fuel,
but combustion is made with a pure
stream of O2, which results in emissions
of almost pure CO2 and water vapour in
the flue gas (Pires et al., 2011).
Because the flue gas contain mainly CO2 and water
vapour, it is easy to condense water to separate it
from CO2. The challenge in this process is to
generate enough O2 for a large scale power plant at
low cost (Rackley, 2010; Pires et al., 2011; Chou,
2013).

25
3.1.4. Step 3 - storage
CCS requires usually that the carbon captured be stored into sinks. The most common
solutions involve injecting CO2 into suitable geological formations deep underground,
although deep ocean storage also shows potential (Rackley, 2010). A listing of different
carbon storage options is shown in Table 3.1.4. However these options could have impacts on
the environment like the modification of the pH of the water for ocean storage, which could
be very damageable to the fragile ocean ecological balance, or other unpredicted impacts
(Stewart and Hessami, 2005).
Table 3.1.4. List of available options for carbon storage
CCS could help reach the stabilization targets of the IPCC (2005), which aim for a
concentration of CO2 within the atmosphere between 350 and 450 ppm. Azar et al. (2006)
identified in an economic appraisal that CCS would allow reaching the IPCC‘s stabilisation
targets of CO2 concentration in the atmosphere over the period 2000-2999 for half the costs of
the solution in which CCS is not used, in terms of Net Present Value2
. And this study did not
take into account the potential of bio-CCS and carbon capture with microalgae to mitigate
carbon emissions, which will now be discussed.
3.1.5. Bio-CCS – Classic CCS combined with biofuels combustion
As mentioned earlier (see 1.1.2), microalgae convert nutrients, CO2 and sunlight into oil and
sugar, which can be processed into biofuel (Weber, 2009). The potential for microalgae-
Name of the
solution
Description Details
Geological
storage
Sequestration of CO2 into basalt
formations, depleted oil and gas
reserves, deep saline aquifers or
unmineable coal seams (Singh,
2013)
Oil and gas industry provide technological advantages
for this solution as site characterization, injection and
monitoring technologies are very mature. CO2 can be
used to make EOR (Enhanced Oil Recovery) i.e.
injection of CO2 into wells to mix it with oil and
maximize well‘s oil yielding (Rackley, 2010).
Ocean storage
Injection of CO2 into the ocean at
different depths (Stewart and
Hessami, 2005)
CO2 is injected into the ocean and is dissolved or
forms plumes that sink at the bottom of the ocean
(Pires et al., 2011)
Mineral
storage
CO2 is reacted with metal oxides to
form carbonates (Pires et al., 2011)
The process of mineral carbonation occurs naturally
and is slow at ambient temperature (weathering) but
fast at high temperature. However, once stored by
mineral carbonation, CO2 is very stable and there is no
problematic of re-release of CO2 into the atmosphere
with this process (Pires et al., 2011).

26
biofuel will be investigated in the next chapter, but it is interesting to see in this section if
CCS processes which usually are used for fossil fuel combustion can be used to capture CO2
emitted by the combustion of microalgae-based biofuels too. The process in which
microalgae-based biofuel is burnt and then CO2 in flue gas is captured by one of the methods
cited above is called bio-CCS (ZEP, 2012).
In contract to carbon capture from conventional fossil fuel combustion, bio-CCS has potential
to achieve a NET carbon removal from the atmosphere, as CO2 reduction is achieved by
photosynthesis during the formation of biofuel, and CO2 capture and storage of the combusted
biofuel. In Europe, bio-CCS has already entered the EU debates: in the Energy Roadmap
2050 (European Commission, 2011), it is said that not only CCS will have to be applied to all
fossil fuel-fired power plants by 2030 to reach the targets of 80-95% overall decarbonisation
by 2050, but it is recognized that CCS ―combined with biomass could deliver „carbon
negative‟ values‖ (p.12). Bio-CCS has the potential of removing up to 800.106
tons of CO2
from the atmosphere each year in Europe by 2050. This is 50% of the EU power sector
emissions of CO2 and this is without taking into account the reduction of CO2 emissions
induced by the replacement of fossil fuels by biofuels (ZEP, 2012).
According to the Zero Emissions Pole (2012), three key drivers for this process would be the
acceleration of R&D for sustainable microalgae-biofuels, the reward of negative emissions
with European credits, and the awareness-raising of people.
3.2. Opportunities for Algae-based carbon capture
3.2.1. Introduction
Wang et al. (2008) defends the opinion by which using microalgae to capture carbon would
be an economically viable and sustainable solution. Carbon captured using microalgae would
not be sequestrated into the geosphere, but would rather be used to make sustainable by-
products or biofuel, which would then be used as an alternative to fossil fuel (Packer, 2010;
Singh and Olsen, 2011).
3.2.2. Using microalgae to capture CO2 from power plants flue gas
What is interesting with microalgae is that they can directly use flue gas to grow, with no
need for separation of CO2 from the stream and no need for compression (Sahoo et al., 2012).

27
As pure CO2 streams are not needed, no expensive technology in terms of capital costs or
energy consumption is required to separate carbon dioxide from flue gas. It results in a huge
saving of money compared with a classic carbon capture system as described in part 3.1.2.
Fossil fuel-fired power plants emit different gases in their flue gas, like CO2, SOx, NOx, and
traces of heavy metals like Mercury (Hg) (IEA, 2007). Coal-fired power plants emit the most
GHGs compared with gas fired power plants. For example, a typical coal-fired power plant
would emit between 912 and 1280 t/GWh CO2, up to 54 t/GWh SO2 and 4.9 t/GWh NOx, and
up to 70 kg/MWh Mercury (EPA, 2014). But these GHGs in these concentrations which are
produced in abundance by fossil fuel-fired power plants and other industrial plants (like
cement factories) are compatible with the development of algae: as explained in part 2.1.2,
microalgae develop more rapidly in an environment which contains more CO2. Nitric oxides
at their level of concentration in flue gas do not influence the development of microalgae, as it
has been shown in different studies (Maeda et al., 1995; Zeiler et al., 1995; Vunjak-
Novakovic et al., 2005). However, if concentrations of SOx are above 400 ppm in flue gas, it
can lead to a modification of the pH of the culture which can inhibit the normal growth of
microalgae (Maeda et al., 1995; Matsumoto et al., 1997, as cited in Packer, 2009). But such
SOx concentrations are rarely reached in industries‘ gaseous emissions in the EU or in the
USA, as regulations like the Industrial Emissions Directive in the EU (Directive 2010/75/EU)
and the Cross-State Air Pollution Rule in the USA (EPA, 2011) are limiting concentrations of
sulphates in flue gas to less than 400 ppm, which forced industries to install SOx scrubbers
(FGD systems) to control Sulphates emissions in their flue gas already.
Microalgae are very tolerant to chemical modifications of their environment by injection of
flue gas into their cultures. Even, some species like Chlorella grow even better with flue gas
than with pure CO2 at the same percentage (Douskova et al., 2009). Thus, there is an
opportunity for the development of microalgae to capture carbon dioxide (and other pollutants
like nitric oxides) from fossil-fuel fired power plants flue gases, via the direct injection of
these flue gases into the microalgae farms (Doucha et al., 2005; Packer, 2009; Sahoo et al.,
2012; Powerplantccs, 2014).This can apply to other industries as well, as shows the research
from Talec et al. (2013), which concludes that injection of gaseous effluent from cement
industry had no influence over the development of the four species of microalgae tested
during the experiment.

28
Moreover, microalgae have been proved to be very resistant to changes in temperatures and
are tolerant towards high temperatures. For example the microalga Chlorella sp. starts to see
its growth rate slowing down at a temperature of 45°C (Maeda et al., 1995), which is far
above average temperatures of microalgae cultures. And if the species of microalgae is
sensible to high temperatures of flue gases, solutions like heat exchangers can be used to cool
the stream of flue gases while using the heat energy to e.g. dry the biomass (Roidroid, 2007).
From all this, we can say that microalgae are biologically suited to grow in an environment
containing high concentrations of flue gases. But a question remains to be answered: up to
which percentage of CO2 contained in these flue gases can be captured by microalgae farms?
This highly depends on the growth conditions and the environment, but Doucha et al. (2005)
calculated after an experiment that microalgae could capture up to 39% of carbon dioxide
contained in the flue gas of a biogas-fired power plant over one year emission with
microalgae grown in photobioreactors, taking into account the amount of daylight received by
the farms throughout the year. De Morais and Costa (2007) obtained a mean fixation rate of
38% CO2 with Spirulina sp., while the MIT successfully captures 80% carbon in the flue
gases of their boiler room (Roidroid, 2007) and Sayre (2010) reports a carbon fixation rate for
microalgae up to 90% in open ponds.
3.2.3. Potential for CO2 capture by microalgae
As it has just been shown, microalgae are efficient in the process of capturing CO2 from flue
gas. Now the question is: how does it work?
 First of all, flue gases are transformed and processed to be partially cleaned of SOx in
a flue-gas desulfurization (FGD) unit.
 After that, flue gases go through a drying process, to decrease their concentration in
water vapour,
 before being cooled in a heat exchanger, depending on the tolerance of the microalgae
strains to high temperatures.
 Gases are then propelled into the microalgae farm thanks to the propeller, assisted by
the aerator and the flow monitor, which is used to adapt the flow rate.
 Meanwhile, the waste heat can be used to support the biomass drying process after the
harvesting.

29
 After that, flue gases are propelled into the microalgae farms where they are bubbled.
Figure 3.2.3.a provides a schematic view of the process of carbon capture from flue gases
with microalgae.
Figure 3.2.3.a. Schematic process of microalgae-based carbon capture from power plants (Powerplantsccs,
2014)
The main challenges which remain to be addressed for the development of carbon capture
from flue gas with microalgae are the large surface required, and the biomass production costs
which are still a bit high (Benemann, 2008; Sayre, 2010).
In order to be able to capture 80% carbon dioxide emitted in the flue gases of a 200 MWh
gas-fired power plant, 3600 acres3
of microalgae farms would be needed. And the area
required for microalgae farms to capture carbon dioxide from a 200 MWh coal-fired power
plant would be 7000 acres (Sayre, 2010). Such an area is rarely available for construction near
powerful power plants. Smaller areas for smaller processes emitting carbon dioxide in their
flue gases may be easier to find; otherwise, there is the possibility of transporting flue gases
through pipes to the microalgae farms.

30
In 1993, Benemann estimated that US$ 100 was required to capture one ton of CO2 with
microalgae. To reduce the costs, Benemann proposed in 1997 to combine carbon capture from
flue gas with waste water treatment to be even more cost-effective. Other authors propose
estimations of costs for producing microalgae with carbon dioxide from flue gas:
 Kadam (1997) who estimates that it would cost US$30/tCO2
 Stepan et al. (2002) who estimate that production costs in raceways would be
US$110/ton of dry microalgae biomass (i.e. US$55/tCO2)
 Chisti (2007) who estimates that production costs in photobioreactors would be
US$500/ton of dry microalgae biomass (i.e. US$250/tCO2).
Advantages and drawbacks of using microalgae to capture carbon dioxide from flue gas have
been compared with using classic CCS technics in table 3.2.3 below.
Table 3.2.3. Comparison between microalgae-based carbon sequestration versus classic CCS, adapted
from Powerplantsccs (2014)
Carbon capture from flue gas with microalgae presents lots of advantages. The potential for
by-products made out of microalgae will be studied in the next part. Several authors in the
literature say that though the process of capturing carbon from flus gas with microalgae still
needs improvement and development and will need to be more funded by governments, it
looks like a viable process for small-scale flues gases, due to all its advantages economically
speaking in terms of use of biomass, its low environmental impact and the high productivity
of microalgae compared with terrestrial crops (Doucha et al., 2005; Schenk et al., 2008; Vaela
et al., 2009; Sayre, 2010; Sudhakar et al., 2011).

31
Governments and private companies are already investing and having projects in the field of
capturing CO2 in flue gas with microalgae. Especially in the United States. Figure 3.2.3.b
below shows some companies names with their implantation in the world.
Figure 3.2.3.b. Global distribution of some companies having projects related to microalgae-based carbon
capture from flue gas (Powerplantsccs, 2014)
Other opportunities for carbon capture with microalgae are being developed with for example
the idea of Chi (2011) to transform CO2 from flue gas into bicarbonates which can then be
used as a source of carbon for the production of microalgae. This could be an alternative
solution to the problematic of area availability around the fossil fuel-fired power plants to
implement microalgae farms. Nevertheless, processes like this are still in the R&D phase and
do not represent business opportunities for the moment.
A process could be thought of, in which microalgae farms are used to capture carbon from
flue gas and in which the resulting biomass is transformed into biofuels. Resulting biofuel
would then be burnt and released flue gas would be captured and permanently stored with
classic CCS. Figure 3.2.3.c schematizes this process. But such a process would require further
investigation, as no relevant publications have been found in the literature for such a process.

32
The conclusion of this part is that microalgae farms implemented near fossil-fuel fired power
plants or other industries can be used to capture carbon dioxide from flue gases. Because CO2
emissions in the atmosphere are reduced, carbon credits are being generated from the
production of microalgae with flue gases, and in addition, microalgae farms benefit from a
free source of CO2. Therefore, by using flue gas from industry to provide CO2 to microalgae
farms, production costs of microalgal biomass can be reduced by up to 15% (Doucha et al.,
2005). However, carbon capture from flue gas with microalgae is hardly achievable for large-
scale industry, as surface area required for the implementation of microalgae farms near the
source of flue gases would be too big. And using microalgae for the sole purpose of capturing
CO2 from flue gases does not look like a viable option economically speaking. However, after
the production process, biomass can be used to make lots of different value-added by-
products that have the potential to make a microalgae-based carbon capture from flue gas
system a good business opportunity, as we are going to see in the next chapter.
Figure 3.2.3.c. Combination of carbon capture with microalgae farm and classic CCS of the biofuels produced by the
microalgae

33
Figure 4.1. The different products that can be made out of micro-algae, adapted from Reissman (2013)
4. Business opportunities in the field of microalgae
This chapter draws an overview of the business opportunities in the field of
microalgae, among which biofuel production, use of microalgae to recycle waste
water, and use of microalgal biomass to make valuable by-products.
4.1. Introduction
As explained in the previous chapters, microalgae can grow at a very fast rate and in very
adverse conditions. Microalgae have the potential of being used to mitigate carbon emissions
in flue gas from power plants and industry manufactories (like cement factories or steel
manufactories). Using flue gases to provide CO2 to microalgae, which are essential to their
growth, is the first business opportunity that has been evocated in this research. If several
authors support the idea of using microalgae to capture carbon dioxide from flue gas, this is
not only because microalgae can capture carbon dioxide from flue gases, but this is because
valuable by-products can be made out of microalgae too, thus making microalgae-based
businesses potentially profitable.
Several by-products can be made with microalgal biomass, like biofuel, animal food,
pharmaceuticals and nutraceuticals4
, human food, chemicals like colourings, or fertilizer
(Spolaore et al., 2006; Priyadarshani and Rath, 2012). Figure 4.1 below illustrates this idea.

34
The process of growing microalgae can be associated with the recycling of waste water too
(Mata et al., 2010). This chapter will investigate the opportunities of business in the field of
microalgae. First of all, let‘s have a look at the potential for microalgae-based biofuel.
4.2. Microalgae for biofuel production
4.2.1. Why microalgae-based biofuel?
Several forms of fuel made out of vegetable oil – or biofuel – have been being developed until
now:
 First generation biofuels are made with food crop like rapeseed oil, sugarcane, wheat,
soybean, sunflower oil, palm oil and maize (Sahoo, 2010). Unluckily, it is considered
that first generation biofuels cannot satisfy even a small portion of the actual demand
for oil (Chisti, 2007) and that they compete with food production and can precipitate
water shortages and deforestation (Brennan and Owende, 2010).
 Second generation biofuels are made with lignocellulosic biomass4
, and do not impact
directly the food market, but they still compete for land with food production
(Brennan and Owende, 2010).
 Microalgae-based third generation biofuels, however, do not have all the major
drawbacks of first and second generation biofuels, and are considered to be a
technically viable alternative energy resource (Brennan and Owende, 2010).
Indeed, because they are very rich in oil and because of the rising prices of petroleum,
biofuels from microalgae have been arousing interest since the middle of the 20th
century.
Meier is one of the pioneers in this field, and had already suggested the idea of using
microalgae to produce biofuels in 1955 (Meier, 1955, as cited in Packer, 2009).
When compared with terrestrial oil crops, microalgae have a yielding for biomass and oil
production between 30 and 100 times higher (Chisti, 2007; Demirbas and Demirbas, 2011).
Based on the yielding of microalgae, only 1-3% of the total cropping area of the USA would
be required to produce 50% of USA‘s demand for oil (Chisti, 2007). Goodall (2009)
calculated that to completely replace the 80 million barrels of oil a day that the world is
currently using to power engines with microalgae-biofuel, only 30 million hectares of farming
surface would need to be used, which is slightly more than the size of the United Kingdom.

35
And the lands used to produce these algae do not need to be arable lands that could otherwise
have been used to grow food crops, as algae can be grown on any land, as long as they have
salty water or even wastewater.
This high yielding is coupled with other advantages which make microalgae a very high
potential for biofuel production:
 Though they need an aqueous environment to develop correctly, microalgae require
less water than other oil crop to grow and do not require fresh water (brackish water
can be used) (Amaro et al., 2012)
 They do not need arable land to grow (Amaro et al., 2012)
 Microalgae-farms can be used for several goals: biofuel production can be combined
with waste water treatment (which moreover offers the advantage of providing free
nutrients for microalgae) (Singh and Gu, 2010) and CO2 capture from industrial flue
gas (Doucha et al., 2005)
 They do not need pesticides to grow (Amaro et al., 2012)
 Algae biofuel is non-toxic, contains no sulfur, and is highly biodegradable
(Powerplantccs, 2014).
Moreover, using biofuels as an alternative to fossil fuel is sustainable: only one unit of energy
is required to produce eight units of microalgae-based biofuel energy (Chisti, 2008) and
burning biofuel instead of fossil fuel contributes to reducing net carbon emissions into the
atmosphere. Indeed biofuels are made thanks to photosynthesis, which is the process that
takes CO2 out of the atmosphere (or flue gas) to convert it into biomass, which is then
transformed and burnt, and consequently releases back carbon into the atmosphere, thus
maintaining a sustainable cycle (Chisti, 2008; Taylor et al., 2013). Microalgae-based biofuels
could even be considered as carbon negative: the process of transforming microalgae into
biofuel leaves waste biomass behind, which contains a high percentage of carbon and which
can be either used for production of valuable by-products or be buried for long-term carbon
storage (Taylor et al., 2013).
Because of all these qualities, microalgae present a high potential for biofuel production.
R&D for microalgae-based biofuel is today a strategic issue for governments and global
companies, which are investing billions of dollars in research for microalgae-based biofuels
(Oilgae, 2014). Among these companies, there are the NASA, Boeing, the US army, BP, the

36
Carbon Trust UK (multi-million pound R&D project), CSIRO (Australia), Neste Oil
($850,000 project, New Zealand).
So which biofuels can be synthetized with algal biomass today, and in which extent are
microalgae-based biofuels economically viable?
4.2.2. Technical and economic aspects of making biofuels with microalgae
Research for microalgae-based biofuels has been ongoing and so far, several forms of biofuel
have successfully been synthetized. Some of these biofuels have been computed in table 4.2.2
below, as well as their production processes.
Table 4.2.2. Different types of microalgae-based biofuels and their manufacturing process, adapted from
Chisti (2007), Brennan and Owende (2010), Mata et al. (2010), Amaro et al. (2012) and Powerplantccs
(2014)
Among all these biofuels, biodiesel presents a high potential (Chisti, 2008). The formula of
biodiesel is the same as petroleum diesel and the process of transeterification, which
transforms algal into biomass, has a very high yielding of theoretically 1 kg of biodiesel out of
1 kg of biomass, with glycerine as a valuable by-product, which can be used e.g. for the
manufacturing of soaps (Mata et al., 2006).
Economically speaking, production costs for microalgal biodiesel are estimated to range
between US$2.95/L and US$3.8/L, depending on whether raceways or photobioreactors are
used to grow microalgae (Demirbas, 2010). Chisti (2007) proposes a formula to relate the
price of crude oil (US$/barrel) to the sourcing price of microalgae oil (US$/L) in order for
microalgae oil to be competitive:
With the approximate price of a barrel of oil in August 2014 (Bloomberg, 2014) which is
about US$100, microalgae oil would have to cost US$0.69/L in order to be competitive with

37
petroleum, according to this formula. In 2007, costs at which microalgal oil start to compete
with petroleum were US$0.48/L for cultivation in open ponds, and US$0.72/L for cultivation
in photobioreactors (percentage of oil by weight for microalgae grown in photobioreactors
can reach 70%) (Chisti, 2007).
As prices for oil keep raising and R&D in microalgae production and biofuel keep decreasing,
we may reach a point in the future where microalgae-based biofuels will be economically
more interesting than fossil fuel. Figure 4.2.2 below illustrates this idea.
Production of biofuel with microalgae at small scale is already a well-established process. But
adaptation of microalgae-based biofuel production for large scale will require the intervention
of genetic engineering and optimization of the methods for harvesting microalgae and
extracting oil out of them, in order for microalgae-based biofuel costs to decrease and be
competitive with fossil fuel (Chisti and Yan, 2011).
4.3. Microalgae used to treat waste water
Microalgae can find a high density of nutrients in waste water (mainly Nitrogen and
Phosphorous), which are favourable for their growth (Park et al., 2011). For Benemann
(2008), the most economically viable business opportunity for microalgae-based technologies
to mitigate carbon emissions today lies in the development of solutions which combine
microalgae harvesting for biofuel production and waste water treatment with microalgae.
Figure 4.2.2. Diagram showing expected trends for the evolution of prices for petroleum and algal oil
production and enlightening the fact that if the trends go on, algal oil will become cheaper than petroleum
at some point (on creation)

38
Three kinds of waste water can be used for growing microalgae:
 Urban waste water
 Agricultural waste water
 Industrial waste water
In conventional urban waste water treatment, air is injected to provide O2 to bacteria which
break down the organic waste. This process requires energy (Benemann and Pedroni, 2007).
However, microalgae feed with nutrients contained in waste water and 1kg of microalgae
produces 1kg of O2 with photosynthesis (Benemann and Pedroni, 2007; Park et al., 2011).
Using microalgae to provide O2 to bacteria in waste water treatment ponds would be very
advantageous: the energy-consuming process of injecting air in the pond would not be
necessary anymore, and microalgae could be used to make valuable by-products like biofuel
(Benemann and Pedroni, 2007). The main drawback of urban waste water is that their content
is not predictable, therefore requiring adaptable facilities for their treatment (Benemann and
Pedroni, 2007).
On the contrary, agricultural and industrial waste water content are more easily predictable
and the same process can be used to recycle it. Agricultural and industrial waste water are full
of ions like NH4
+
, NO3
-
, and PO4
3-
, which often contaminate water bodies and unbalance the
local biological equilibrium (with eutrophication5
) (Mata et al., 2010; Singh and Gu, 2010).
These ions are nutrients for microalgae and this waste water could actually be used as a free
source of nutrients for microalgae (Singh and Gu, 2010).
Table 4.3 below draws an overview of the advantages versus the drawbacks of combining
waste water treatment with microalgae production.
Table 4.3. Advantages and drawbacks of combining waste water treatment with microalgae production,
adapted from Benemann and Pedroni (2007), Park et al. (2011), and Craggs et al. (2012),
Advantages Drawbacks
Fresh water consumption reduction – smaller
water footprint
Requires control of parameters like pH, CO2
concentration and nutrients concentration
Nutrients cost reduction Biomass grown with waste water cannot be used for
any application because of sanitary regulations.
Biomass is suitable for products like biofuel or
fertilizer
Win-win situation: makes the process of treating
waste water cheaper, and makes the process of
growing microalgae cheaper
Land use optimization
Requires control of algal species used, presence of
grazers and/or pathogens
Easy retrofitting of existing waste water
treatment plants and reproducibility
Treatment requires daylight – productivity depends
on the season and on the time of the day

39
Craggs et al. (2012) discuss the construction and operation of a 5-ha waste water treatment
plant using microalgae. Figure 4.3.a shows a schematic diagram of the concept discussed and
figure 4.3.b shows a photograph of one of the four 1.25-ha algal ponds discussed. The study
concludes with the high viability (in terms feasibility and costs) of this technology and the
reproducibility of the results gained for all four ponds.
Figure 4.3.b. Photograph of one of the 1.25-ha algal ponds with an algal harvester (Craggs et al., 2012)
Clean water
Waste water
Figure 4.3.a. Schematic diagram showing the concept of utilizing microalgae production for combined
waste water treatment and biogas fabrication to power the water treatment plant, adapted from Craggs et
al. (2012)

40
Recycling waste water with microalgae is a mature technology. Moreover, 10-30% of the
production costs for microalgae come from the nutrients, the CO2, and fresh water (Park et al.
2011). Using waste water for microalgae production would save nutrients and fresh water
costs; and combining it with flue gas injection (as a source of CO2) could break down
radically the production costs for microalgae (Benemann, 2008).
4.4. What can be done with algae biomass
4.4.1. Fertilizers
Another source of GHG mitigation using microalgae is their use as a fertilizer. It is estimated
that 3kg of CO2 are emitted for the production of 1kg of fertilizer with gas as energy
(Benemann and Pedroni, 2007). Whereas industrial fertilizers require Nitrogen and
Phosphorous as ingredients, microalgae can recycle these compounds out of waste water to
grow (Benemann and Pedroni, 2007). Microalgae-based fertilizer is a valuable by-product of
algal biomass and a cheap fertilizer (Mata et al., 2010). Microalgae-based biofertilizer can be
made with ―waste biomass‖, which is what is left after the transformation of microalgae into
another by-product like biofuel, and therefore making microalgae production a zero waste
outcomes system (Brennan and Owende, 2010).
4.4.2. Human food industry, pharmaceuticals and nutraceuticals
Microalgae produce numerous substances which exhibit positive effects on health. (Pulz and
Gross, 2004). Among these substances, the most common are:
 Antioxidants
 Colors and food-coloring products like β-carotene (for vitamin A), astaxanthin
(coloring used for fish flesh), or lutein (coloring used to color chicken skin)
 Polyunsaturated fatty acids (like Omega 3)
 Polysaccharides
 Toxins for drugs with effects like amnesic, cytotoxic (anticancer drug), antiviral,
antimicrobial, and antifungal
(Pulz and Gross, 2004; Priyadarshani and Rath, 2012).

41
Microalgae for human nutrition usually take the form of tablets, capsules of powder, or
liquids, which can be added in beverages, snack food, noodles, candy, or simply be taken as
pills (Spolaore et al., 2006).
Commonly used species of microalgae in nutraceutical/pharmaceutical production include
Chlorella sp., Dunaliella sp., Spirulina sp. (Priyadarshani and Rath, 2012). It is estimated that
about 10,000 tons of dry algal biomass is produced from these species per year already
(Benemann, 2008). Substances extracted from microalgae is highly dependent on the species,
as shows table 4.4.2.a below, which computes possible downstream applications associated
with a species.
Table 4.4.2.a. Non-exhaustive list of microalgal species with some of their potential downstream
applications, adapted from Borowitzka (1999), Spolaore et al. (2006), Chisti (2007), Wang et al. (2010),
and Ho et al., (2011)
Several authors have identified cultivation of microalgae to make food supplements, drugs or
chemicals as one of the most profitable pathway for microalgae biomass‘ by-products

42
(Olaizola, 2003; Pulz and Gross, 2004; Spolaore et al., 2006; Benemann, 2008). Table 4.4.2.b
shows examples of companies which have been using microalgae for their health products.
Table 4.4.2.b. Some company names with the substances they extract from microalgae for their food- or
drug-related industry, adapted from Pulz and Gross (2004)
4.4.3. Animal food industry
Microalgae biomass can be used for animal food production. Microalgae are used as valuable
protein supplement or substitute to more conventional proteins sources like soy bean or fish
meal. It is particularly used for poultry farming and aquaculture: it is estimated that about
30% of the world algal production goes to feed these animals (Spolaore et al., 2006; Becker,
2007). Small amounts of algal biomass have been demonstrated to positively affect the
physiology of animals, by boosting their immune system and improving their external aspect
(hair more shiny, feathers more beautiful) (Pulz and Gross, 2004).
The use of algae biomass as feedstock for animals can be combined with other GHG
mitigating applications. For example, fishes in aquaculture need Omega-3 fatty acids to grow,
which are provided to them through their food. These nutrients in aquaculture are usually
pressed out of low-value fish and krill caught in the ocean and combined in pellets with
additives (Pauly and Watson, 2009). But massive fishing of krill is not sustainable in the long

43
Figure 4.4.4. Algae-powered streetlamp of Pierre Calleja (Calleja, 2013)
term and therefore, alternative solutions need to be found to feed fish farms with Omega-3
fatty acids. One solution which is being developed in Norway consists in capturing CO2 to
supply an algae-farm with nutrients and use these algae to process an oil rich in Omega-3
required for the development of fishes. It is believed that between 300 and 400 kilogrammes
of oil can be processed out of 1 ton of algae. And this oil rich in Omega-3 fatty acids will not
only be used to feed fishes, as there is an important demand in health and pharmaceutical
industry as well (McGrath, 2014).
4.4.4 Other business opportunities and algae-based technologies being
developed
Microalgae have a very high potential for by-products, yet not exploited at its full potential.
Some entrepreneurs and companies are developing microalgae-based innovations which have
the potential to capture carbon from the atmosphere and/or to be an alternative to other
solutions which emit more carbon dioxide. Some of them are:
 Bioplastics – Plastics can be made out of microalgae, thus mitigating carbon
emissions from the production of petroleum-based plastic. Cellulose-based plastics,
poly-lactic acid to produce polymers, PolyHydroxiAlcanoate polymers and bio-
polyethylene are some examples of plastics which can be derived from microalgae
(Benemann and Pedroni, 2007; Oilgae, 2014).
 A streetlamp powered by microalgae – Fermentalg has developed an algae-powered
lamp that should be able to produce light thanks to the storage of the electrons
produced by photosynthesis in batteries and the restitution of this energy as light
through leds (Calleja, 2013), (figure 4.4.4).

44
 Microalgae used as a construction material – Ploechinger (2011) patented a
construction material made out of microalgae, with very good insulating
characteristics.
 Microalgae for cosmetics – Microalgae can be used to make anti-aging creams, hair
and sun care products, or moisturizers. Luxury brands are investigating this market
already and luxury brands like LVMH and Daniel Jouvence in France have even
invested in their own microalgae production systems (Spolaore et al., 2006).
4.5. Conclusion of the literature review
Microalgae have the potential to reduce the net emissions of CO2 into the atmosphere:
 either directly, with e.g. direct injection of flue gases into the microalgae farms and
direct capture of CO2,
 or indirectly, through e.g. recycling of waste water, or the production of goods (like
biofuel, bioplastics, food, biomass by-products) that would have otherwise emitted
more CO2 (Benemann and Pedroni, 2007).
However, exact quantification of net CO2 emissions reduction cannot be achieved. Collet et
al. (2013) investigated fifteen different Life-Cycle Assessments for microalgae-based
biofuels, and concluded that guidelines and rules need to be set for analyses to be comparable
together and for the numbers they display to mean anything.
No general figure can be provided to illustrate the way in which microalgae are reducing net
carbon emissions. It depends on parameters like:
 The source of CO2 used to feed the microalgae (atmosphere, flue gas,
bicarbonates)
 The species of algae (strains do not capture CO2 with the same efficiency)
 The technology used to grow microalgae
 The conditions of growth (environment, weather)
It has been shown that microalgae have a huge potential for fast carbon capture with
photosynthesis. In addition to have the potential to mitigate carbon emissions, microalgae can
be used for a lot of different applications. When several applications are combined together,
microalgae-businesses have the potential to be highly profitable (Benemann, 2008).

45
Moreover, as Pulz and Gross (2004, p.646) say, ―microalgal biotechnology—today still in its
infancy—can be seen as a gateway to a multibillion dollar industry‖. Interest for microalgae is
recent, and R&D keeps decreasing the production costs and making microalgae-by-products
more cost-effective.
Table 4.5 below summarises the advantages of microalgae for business applications to
mitigate carbon emissions.
Table 4.5. Summary of the advantages of microalgae for business applications to mitigate CO2 emissions
Advantages Description Reference
Microalgae grow fast
Microalgae can double their volume within a day, can be
harvested daily, and have the potential to compete with the most
productive biofuel crops in terms of productivity
- Chisti, 2007
- Goodall, 2009
- Demirbas and
Demirbas, 2011
Microalgae can have
high biofuel yields
Through the process of photosynthesis, microalgae convert
sunlight, CO2 and nutrients into oil and sugar, which can be
turned into biofuel. Production of biofuel can range between
2,000 and 5,000 gallons per acre per year
- Weber, 2009
Microalgae consume
CO2
1.8 kg of Co2 is required to produce 1 kg of microalgal biomass.
Activities linked to microalgae production have the potential to
have negative net CO2 emissions (which means that they use
more CO2 than they produce). Microalgae can be used to
capture carbon dioxide in flue gases and therefore diminish the
impact of fossil combustion on the atmosphere.
- Becker, 1994
- Doucha et al.,
2005
- Sayre, 2010
- Sudhakar et al.,
2011
Microalgae farming do
not compete with
agriculture…
Microalgae farms can use lands that are not suitable for proper
traditional agriculture, as well as water that are not useable for
other crops (see next line).
- Amaro et al.,
2012
…and can be used to
recycle waste water
Microalgae can be used to recycle urban, agricultural, or
industrial waste water as they are feeding on the Nitrogen and
Phosphorous compounds present in these water. This is a win-
win situation for the recycling of waste water and the
production of biomass which can afterxards be turned into
useful products like biofuel
- Park et al., 2011
- Craggs et al.,
2012
Microalgal biomass can
be used to make valuable
by-products
Algae biomass can be used to make many by-products, such as
biofuel, human food, animal feed, drugs, plastics, fertilizers, or
cosmetics.
- Benemann and
Pedroni, 2007
Microalgae industry
creates employment
As industry develops, a wide variety of jobs related to
microalgae businesses is defined. It is estimated by the Algae
Biomass Organization that creation of 220,000 jobs in this
sector by 2020 is achievable.
- Obama, 2012
- Algae Biomass
Organization,
2014b

46
5. Methodology of the dissertation
This chapter explains the methodology of the research to gather data, analyse the
findings and compare them together.
5.1. Introduction
In order to answer the questions raised by this dissertation, this chapter discusses the
methodology used to collect and analyse data.
Two types of data were used: secondary data and primary data.
1. Secondary data are described by Webb (2002) as data that have already been gathered
for similar or related studies to the research undertaken. They can be found in
published or electronic sources (Wilson, 2012). Therefore, secondary data are ―faster
and less expensive to acquire than primary data‖ (Wilson, 2012, p.51). Gathering
secondary data is the first step of data collection in a research (Creswell, 2009).
However, their relevancy for the research undertaken may not be optimal, as they were
not gathered for the purpose of answering this research specifically, and as they may
be out of date. Secondary data is collected in chapters two to four, to provide the
researcher with a basic understanding of the current state-of-the-art of microalgae-
based technologies and their potential to mitigate carbon emissions.
2. To supplement secondary data, primary data was collected through interviews of
experts in their field, who provided updated content to the research and also
perspectives on the wider technical, socio-economic and political constraints of
working in this field and scaling up to a business case (which are not necessarily
published).
The next sub-chapters explain how the primary data collection process was designed and how
data was analysed.

47
5.2. Conducting qualitative research
5.2.1. Conducting qualitative research
Qualitative research is being used when data collected is not quantifiable (Saunders et al.,
2007; Wilson, 2012). Examples of tools utilised to collect data for qualitative research
comprehend individual interviews, focus groups, observations, ethnographies and
netnographies (Punch, 2005). To answer the research question, an exploratory research was
undertaken, which is ―a valuable means to ask open questions to discover what is happening
and gain insights about a topic of interest‖ (Saunders et al., 2007, p.137). Experts in the field
of microalgae, both from research and from business backgrounds, were interviewed to get
opinions and insights of the potential of microalgae to make economically viable businesses
while mitigating carbon dioxide.
Interviews can be split between two broad categories: structured interviews, and less-
structured in-depth interviews (Langley, 1987).
 Structured interviews have pre-set questions and sub-questions depending on answers.
Though they facilitate comparison of data, they do not allow flexibility. And sticking
too close to a model may keep the interviewee from elaborating on relevant subjects.
 In less-structured interviews, interviewers can ask questions that were not initially
computed in the set of questions. They can therefore go deeper in the data collection,
focusing on the background of the interviewee. Less-structured in-depth interviews
can be either semi-structured (a mix between pre-established questions and open
questions) or unstructured (takes the form of a conversation between the interviewer
and the interviewee) (Burns, 2000). Table 5.2.1 sums up the advantages and
drawbacks of each kind of interview.

48
Table 5.2.1. Comparison between the main types of interviews, adapted from Langley (1987) and Burns
(2000)
Saunders et al. (2007) recommend doing semi-structured in-depth interviews for exploratory
research, because it is a flexible type of interviewing which allows interactive discussion
while still having a frame. In opposite to structured interviews, which gain ―a ‗superficial
excavation‘ of the respondent‘s knowledge about a specific subject, [semi-structured
interview] tries to go more deeply into the subject as the interview proceeds‖ (Belk et al,
2013, p.31).
5.2.2. Semi-structured interviews
For the purpose of this research, semi-structured interviews were conducted by the researcher
to collect data. Interviews can take several forms like face-to-face, phone interview or email
interview (Punch, 2005; Creswell, 2009). For this research, phone interviews were carried out,
using the software Skype, which allows making cheap international phone calls with video.
Using Skype as a tool for the interview is an efficient way to reaching interviewees who
cannot allocate time for a face-to-face meeting or who are far away (Janghorban et al., 2014).
All Skype interviews were recorded using a plug-in, after making sure that the respondent
agreed with that (Wilson, 2012). It was asked to respondents in the consent form (Appendix
II), and at the beginning of the discussion, whether they agreed to being recorded. And it was

Dissertaton Benoît Robart - MSc. Environmental Entrepreneurship

Dissertaton Benoît Robart - MSc. Environmental Entrepreneurship

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