Abstract

Fuel and energy demand is high in the 21st century, however the non-renewable energy resources are

becoming scarcer. Biofuels are developing as a potential substitute for conventional fuels and waste coffee

grounds is one of the novel resources that offers feedstock for biofuel obtainment. Coffee oil contains lipids,

which contain fatty acid methyl esters (FAME). FAME is – biodiesel. There are two types of coffee beans.

Arabica (Coffea Arabica) and Robusta (Coffea Canephora). Arguably, the more expensive Arabica coffee

beans give more lipid content, hence more biodiesel than blends (Arabica and Robusta). This theory was

tested when spent coffee grounds were acquired from Starbucks, Costa and Nero coffee houses. Starbucks

uses 100% Arabica coffee beans, whereas Costa uses a blend (70% Arabica and 30% Robusta). Nero uses a

blend of the two types of coffee beans, although the exact percentage is not known. Spent coffee grounds

were obtained from six different coffee houses of 3 brands (Starbucks, Costa, and Nero). With a yield of

0.93 g and 1.6 g of biodiesel per 10 g of spent coffee grounds acquired from Starbucks, the evidence was

found to support the statement that Arabica beans give more biodiesel than the blends. In comparison, waste

coffee grounds obtained from Costa gave 0.18 g and 0.37 g of biodiesel. Nero gave 0.33 g and 0.25 g of

biodiesel. It was also decided to determine the feasibility of the obtained biodiesel by analysing samples

using an infra-red spectroscopy analysis. During the analysis it was found that all samples contained fatty

acid methyl esters (FAME). This finding provided evidence that obtained substance was biodiesel and that it

had the same compound as biodiesel previously obtained by other researchers.

Acknowledgements

The author would like to thank Dr Roy Lowry for suggesting this topic as well as helping with the progress

of the research and also mention and thank The University of Plymouth 5th floor Davy Building laboratory

technicians. Especially Andrew Tonkin for his great help with the laboratory research part of this project,

Claire Williams, Rebecca Sharp and Louise Argent for their cooperation.

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Table of Contents

Chapter 1. Introduction_______________________________________________________________4

Chapter 2. Literature Review__________________________________________________________5

Chapter 3. Methodology______________________________________________________________9

Chapter 4. Research Findings, Results, and Discussion______________________________________17

Chapter 5. Conclusions, Research Limitations, and Suggestion for Future Research_______________26

References_________________________________________________________________________29

Appendix A. Biodiesel Sample Photographs and a Scanned Lab. Book Page_____________________37

Appendix B. Sample Infra-Red Graphs Before Transesterification_____________________________41

Appendix C. Excel Data Analysis_______________________________________________________47

Appendix D. Energy Input Calculations__________________________________________________48

Appendix E. Scanned Laboratory Book__________________________________________________50

Appendix F. COSHH and Risk Assessment_______________________________________________64

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List of Figures

Figure 1___________________________________________________________________________18

Figure 2___________________________________________________________________________19

Figure 3___________________________________________________________________________20

Figure 4___________________________________________________________________________21

Figure 5___________________________________________________________________________22

Figure 6___________________________________________________________________________23

Figure 7___________________________________________________________________________24

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Chapter One. Introduction

As early as in 1926, American inventor-Samuel Morey took out a patent for the engine that used alcohol and

turpentine as fuel (Masum et al., 2015). In 1953 it was stated that vegetable oil can potentially be used as

fuel in steam engines and steamships (Demirbas, 2009). Notably, the first operational steam engine was

powered by coal (Spear, 2008). The first four-cycle internal-combustion engine was created by a German

engineer-Nikolaus August Otto and it was powered by ethanol. Interestingly, various modifications of this

engine are still used these days (Churchward, 2009). In the beginning of the 19th century Rudolf Diesel has

built an engine, he fuelled with peanut oil (Dunn and Knothe, 2001). The reason Rudolf Diesel substituted

coal dust with peanut oil was simply because it offered more safety. Biodiesel has a higher flash point than

conventional diesel fuel and is less explosive (Muniyappa, Brammer and Noureddini, 1996). Henry Ford

worked with engines fuelled by alcohol until the 1940s (Kovarik, 1998). In 1908 he used ethanol to fuel his

Model T Ford (Reitze, n.d.). In the beginning of the 40s the Second World War started. Hard-to-reach areas

did not get enough fuel supply and had to use vegetable oils to power diesel engines (Sidibé et al., 2010).

Approximately 40 years ago in 1973 the world experienced dramatic rise in oil prices (Voudouris, 2014). In

the 1986 oil prices collapsed (Gately, Adelman and Griffin, 1986). However, today in the 21st century oil

prices rise again due to the declining amount of oil reserves that can be accessed easily (Burkart and

Mayfield, 2013). Promptly, a need for new renewable energy sources arises (Johansson and Burnham,

1993). Biodiesel is one of such sources. Bio - meaning life from Greek - and Diesel coming from Rudolf

Diesel refers to fuel made of vegetable oil or animal fat (Tan, Abdullah and Nolasco-Hipolito, 2015). These

days, biodiesel is especially widely used in Germany, where annually 3.5 billion litres are produced. In Italy

the number is 1.2 billion litres/year and France – 1 billion litres per year (Воронков, 1999). Biodiesel is

blended with the conventional diesel fuel. This reduces greenhouse gas emissions by 70% (Фелленберг,

1997). Spent coffee grounds – as a potential biodiesel source were chosen to be a topic of this research

project. Other types of biodiesel sources, such as: rapeseed oil, palm oil, sunflower-seed oil, and cottonseed

oil are often mentioned in the wider literature (Германович and Турилин, 2014). However biodiesel

obtained from waste coffee grounds is a relatively new approach. This research project looks into its’

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benefits and drawbacks, as well as, the differences in the coffee bean type. There are approximately 6

million tons of coffee produced annually (Haile, 2014). According to (Ching et al., 2011), 45% of waste sent

to landfills in Malaysia is made of waste that has spent coffee in it. Waste coffee sludge is also problematic

to dispose of (Rathinavelu and Graziosi, 2005). Its’ moistness as well as the presence of proteins, sugars,

and inorganic matter results in a rapid growth of microorganisms (Fujii and Takeshi, 2007). Hence, if it is

not immediately processed it puts the surrounding environment under the risk of contamination (Vardon et

al., 2013). Waste coffee grounds dumped to landfills contribute to a higher carbon footprint (Noponen et al.,

2012). Carbon footprint (CO2e) stands for the total amount of greenhouse gases emitted (Shrestha et al.,

2012). As stated by (Ching et al., 2011), burning 1000 g of coffee produces 538 g of CO2. However, there is

a chance that waste can prove to be valuable instead of being detrimental to the environment. In 2014 a

company called Bio-bean was established in London. Bio-bean acquires spent coffee grounds from local

coffee houses and turns them into biodiesel to be utilized as fuel and biomass pellets to be used for heating

buildings (bio-bean, 2016). There are two main types of coffee: Arabica (Coffea Arabica) and Robusta

(Coffea Canephora). Arabica is more expensive than Robusta and has a higher commercial value (Dias and

Benassi, 2015). Current research project aimed at determining how much biodiesel it is possible to obtain

from Arabica beans and blends (Arabica and Robusta), as well as looking into the feasibility aspect of the

obtained biodiesel. This study highlighted the importance of researching alternative energy and fuel sources.

Thus, it is significant because in the times of a constant search for new resources (Винокурова and

Трушин, 1998) it is very timely.

Chapter two. Literature Review

Inflationary pressure, resource deterioration, and rising greenhouse gas emissions that amplify CO2

concentrations and entail further climate change, urge the modern society to consider biofuel as a potential

source of clean and renewable energy and fuel (Guo, Song and Buhain, 2015). Resource deterioration issue

is highly relevant to such conventional energy source as oil. According to (Fantazzini, Höök and

Angelantoni, 2011), most oil these days is almost out of reach, whereas extracting oil from existing oil wells

requires tremendous financial and energy inputs due to the necessity of using specific equipment and

technology. In the 21st century, energy demand is as high as ever (Гринин and Новиков, 2002). When

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inputs into fuel obtainment are bigger than the outputs, it does not only make the fuel economically

unviable, but also stimulates greenhouse gas emissions (Han et al., 2015). This is especially relevant to the

oil and gas industry. A large amount of energy is required to produce fuels made of hydro-carbons, such as

crude oil and gas. This threatens energy security and environmental sustainability. Hydro-carbons demand

high energy inputs and fuel based on hydro-carbons contributes to greenhouse gas emissions into the

atmosphere (IPIECA, 2013). Still, the consumption rates hence the dependence on crude oil is very high

nowadays. If current demands for this resource fail to diminish, the society will only have approximately 45

years before its depletion (Guo, Song and Buhain, 2015). This interlinks with other reasons listed above, to

come up with a novel way of producing fuel. One of such novel, renewable resources is biofuel. Most

biofuels used today are first-generation biofuels. First-generation biofuels are generally produced from food

sources such as, grain, vegetable oil etc. (Mohr and Raman, 2013). There are various types of plants that can

be used for oil extraction. One of the most widely used is rapeseed oil. The advantage of it is a high

tolerance to different climate conditions and soil types. In contrast, palm oil, is a very effective resource due

to its high oil yield (Luque, 2010). However, it lacks such good adaption to diverse conditions and has its’

cloud point at 16 ºC and pour point at 15 ºC (Dunn, 2011). Cloud point is the temperature at which the

crystallization of the fuel occurs (IMAHARA, MINAMI and SAKA, 2006). Pour point usually occurs at

lower temperatures than cloud point and is the lowest fuel pouring/flowing temperature (Veríssimo and

Gomes, 2011). For this reason Asian countries, where climate is mild and warm, represent its main market.

The drawback of other types of energy crops such as flaxseed and sunflower, is their high value as a food

source. Continually increasing demand for new renewable energy and fuel sources results in energy crops

competing with food crops. The outcome of such competition is the increase in food price and decrease in

its availability, whereas the demand for it grows with growing numbers of the Earths’ population.

Encouraging energy crops to compete with food crops could be socially inadmissible (Luque, 2010). Thus,

flaxseed and sunflower situation accentuates the fact that efficiency and practicality of potential biofuel

sources are not only identified by their oil and biomass yield, it is also important to consider whether other

uses of the resource are more commercially, politically, environmentally and socially significant (White and

Plaskett, 1981). Despite a number of controversies regarding the sustainability and energy-efficiency of

first-generation biofuels, policies released by the governments continue to involve biofuel use. In addition to

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the food crop competition controversy, mentioned above, another issue is that emissions that come from

crop cultivation account for 80% of total greenhouse gas emissions that originate from biofuel obtained

from plants (Hennecke et al., 2013). These issues have developed a surge of second-generation biofuels

research (Montross, 2010). Second-generation biofuels are mainly obtained from straw, wood chippings,

hay, agricultural forestry residues and other residual waste (Sims et al., 2010). (Grover, Grover and

Hogland, 2002) state that the main goal of waste to energy proposals are “…to maximize combustion and

minimize pollution”. (Gupta and Demirbas, 2010) noted that oil obtained from waste is a crucial resource,

nevertheless it is only marginally utilized due to the lack of the resource supply. However, referring to

waste, the article did not mention spent coffee grounds. Spent coffee grounds are a good example of the

second-generation source for biodiesel production. According to (Caetano et al., 2014) coffee market is a

growing market. The amount of annually consumed coffee on a global level was quantified as 16.34 billion

pounds and the amount of waste per 1g of cofee is 0.91g (Kondamudi, Mohapatra and Misra, 2008).

Therefore more than 90% of coffee waste is being sent to a landfill. Considering all mentioned above, spent

coffee grounds could prove to be a reasonable second-generation alternative to first-generation biofuels.

This statement presents the importance of this potential fuel source to be studied. The literature review of

this study is based on the two questions identified as the most important ones to this research project. The

first question asked whether the bean type, Arabica (coffea arabica) or Robusta (coffea canephora) impact

the amount of biodiesel obtained. Approximately 90% of the coffee produced worldwide is made of the

expensive Arabica coffee beans. Less tasty and cheaper Robusta coffee beans account for only 9% of the

worldwide coffee production (El-Abassy, Donfack and Materny, 2011). The second question this research

project investigated is whether it is feasible to use biodiesel obtained from spent coffee grounds. The

literature review focused on the search for answers to these questions in the literature. The concept of the

hypothesis of this research project was that spent coffee grounds from Starbucks gives more biodiesel, than

Costa or Nero. This hypothesis was based on a theory that Arabica beans, which are used in Starbucks

coffee, have a higher lipid content than Robusta beans. Notably, both Costa and Nero use a blend of Arabica

and Robusta. This theory about differences in the lipid content was derived from the statement made by

(Jenkins et al., 2014). Although it is important to note that the article also mentioned that the difference

between the lipid content was not significant between pure Arabica and a blend (Arabica and Robusta).

7

Lipid content is important, because it contains glycerides which, when transesterified, produce biodiesel

(Jenkins et al., 2014). Transesterification is a reaction used to produce esters and in this study is used to

produce biodiesel from the glyceride portion of the coffee oil content (Otera, 1993). Interestingly, after

performing a spectroscopy analysis, (Rubayiza and Meurens, 2005) have also stated that dry roasted Arabica

beans have 16.8% and Robusta 11.5% of lipid content. In the research, studying coffee oils, done by (Ferrari

et al., 2010) it was also clearly stated that green Arabica coffee beans have 15% of the lipid content

compared to Robusta having only 10%. It was apparent after the review of the literature, that although pure

Arabica beans are said to have a higher lipid content, hence give more biodiesel than pure Robusta, it was

either stated that the blends of the two are not significantly different from Arabica, for example by (Jenkins

et al., 2014), or the blends were not mentioned at all. The second question of this research project asked if

it’s feasible to use biodiesel obtained from the waste coffee grounds. A few of the previously done studies

focused on the feasibility of biodiesel made from coffee grounds. (Kondamudi, Mohapatra and Misra, 2008)

for example claimed biodiesel obtained from spent coffee grounds to be a high quality substitute to diesel.

(Murthy and Madhava Naidu, 2012) have also agreed on the feasibility of the biodiesel made of coffee,

stating that the solid content of spent coffee grounds, left after oil extraction, is perfect for fertilization and

can also be used as biomass pellets and ethanol feedstock. In relation to this it is noteworthy to mention that

the company called “Bio-Bean” is already obtaining biodiesel from spent coffee grounds and utilizing solid

waste left after oil extraction as biomass pellets to use in boilers (Smedley, 2014). There were a few studies

conducted in relation to the biodiesel obtainment from spent coffee grounds. However, in the literature

about biofuels in general, an apparent tendency of excluding spent coffee grounds as a potential biofuel

source has been observed. It could have been suggested that such trend exists due to the chosen literature

being outdated, with the oldest source reviewing coffee as a biodiesel resource being published in 1996.

However, there were newer books referenced in the current report, which were published in 2010 and 2011.

Therefore, it can be assumed that spent coffee grounds have not yet been widely considered as a potential

biofuel resource. Hence, it can also be proposed that this particular resource has not been well researched to

this point in time and in order to reduce the possibility of exhaustion of alternative sources, it is vital to

invest in, promote, and persist with the further research of surrogate biofuel sources (Fisheries and Food,

1996). Hence, this research project aims at demonstrating an importance of coffee as a potential second-

8

generation biodiesel source. Through centuries, coffee has been disliked by the rulers of countries it has

been introduced to. It has been banned by the Koran in Arabic countries. The government in London in the

17th century suspected that it was consumed in areas where mutineers gathered. At the same time in France

the government tried to impose high taxes on the beverage due to its inconvenient concurrence with wine

industry. Nevertheless, coffee has always been popular among all nations and social categories, no taxes or

prohibitions could intervene with its highly valued repute (Flament and Bessiere-Thomas, 2002). Coffee is

still one of the global favourite beverages (Li, Strezov and Kan, 2014). These facts suggest that it might be a

long time before the popularity of the drink decreases, therefore there will always be valuable coffee waste.

This enhances the chances of this resource utilization to achieve success.

Chapter three. Methodology

Introduction

Upon the theoretical perspective of the current issue, it is now fundamental to provide convincing arguments

that would justify the use of the chosen methodology. It is also necessary to demonstrate how the selected

research approach aligns with the issue under consideration. The main purpose of this methodology chapter

is to give a detailed description of how the research was conducted and data obtained in order to present the

evidence base and support for the arguments. The structure of the methodology chapter in the current piece

of work begins with the description of the research design chosen for this dissertation, as well as the

research questions. The next section will talk about the validity and reliability of the data obtained, looking

into the laboratory methods, equipment and analytical approaches. A brief description of the two locations,

first, where the samples were collected and second where the samples were analysed will follow.

Subsequently, a very detailed section with a precise description of samples, materials and methods will be

written to be thereafter followed by the conclusion summarising the key arguments of this methodology.

Research Design and Research Questions (Aims and Objectives)

Already at the planning stage, it was evident that this study will follow the quantitative approach.

Representing a vital constituent of the science studies, the skill of quantitative analysis plays an important

role in the science degree (Ling and Bridgeman, 2011). As mentioned by (Hoe and Hoare, 2012), in regards

9

to nursing, quantitative analysis might potentially present a new possibility of choosing an appropriate

treatment approach. Additionally, due to a wide variety of data available via online sources these days, the

ability of correctly interpreting the clinical data by the medical personnel is vital to provide valuable advice

to the patient. In relation to this study, the abundance of modern-day environmental issues results in a large

number of people being deeply concerned about the environment. However the richness of often inaccurate

data available via online sources gives rise to multiple misconceptions that the concerned but incompetent

general public acquires (Walz and Kerr, 2007). Logically, this enhances the need of environmental scientists

to train in quantitative research in order to develop the ability to recognize both strengths and limitations of

data (Vaccaro, Smith and Aswani, 2010). This argument presents a strong support for the quantitative

research method chosen for the current research project. Being a relatively new approach, biodiesel

obtainment from waste coffee grounds is subject to many questions, therefore it is critical not only to state

the theoretical reasons to support it but also to underpin it with evidence derived from both primary and

secondary data. This dissertation has adopted an inductive approach. It is aimed at testing the theory that

Arabica coffee beans give a significantly higher lipid content than Robusta coffee beans (Ferrari et al.,

2010). As stated by (Jenkins et al., 2014) the glyceride portion of oil that produces biodiesel via

transesterification is present in lipids in 80-95%. Therefore, it was hypothesized that Starbucks coffee beans

which, according to the official Starbucks website (Starbucks Coffee Company, 2016) consist of 100% pure

Arabica beans would give a higher biodiesel yield than Costa that uses a blend of Arabica and Robusta

(Costa.co.uk, 2016) and Nero that also blends Arabica beans with Robusta (Caffenero.co.uk, 2016). In order

to test the hypothesis, a series of laboratory experiments on Starbucks, Costa, and Nero waste coffee

grounds were conducted. Thus, the amount of biodiesel obtained from each coffee house was determined.

The feasibility of the obtained biodiesel from each coffee house was also examined, using infrared

spectroscopy. Thus, this research project had two objectives. The primary objective of the study was to

demonstrate that a higher biodiesel yield can be obtained from Starbucks waste coffee grounds, which use

100% Arabica than from Costa and Nero, which use a blend of Arabica and Robusta. The rationale behind

this objective was to obtain spent coffee grounds from all three houses and perform a series of experiments

to obtain biodiesel. The secondary objective was to understand whether it is feasible to use the biodiesel

obtained from the three coffee houses. In turn, the rationale behind this objective was to examine the

10

chemical composition of the compounds of biodiesel from the three coffee houses, using the Brucker

infrared atomic absorption spectrometer. By performing infrared spectroscopy analysis it became possible to

compare the obtained biodiesel to findings retrieved from the literature in order to see if it would be feasible

to utilize it.

Data and Sample Collection and Analysis

In regard to the chosen settings, the crucial part was the choice of the same three coffee houses-Costa,

Starbucks and Nero, but located in 6 different stores. This approach was chosen in order to test the

homogeneity of coffee beans used by the same brand but in different shops. Hence, two different Starbucks

coffee houses were chosen, one at the Drake Circus shopping centre, another located on Armada Way

Street. This was also done to Nero coffee with one sample obtained from Cornwall Street and one from

Debenhams on Royal Parade. Costa coffee samples were acquired from Drake Circus shopping centre and

University of Plymouth campus. The conditions, coffee grounds were brewed under were uncontrolled, due

to the grounds being acquired from the shop after brewing. Coffee grounds from all three coffee houses

were of mixed content (caffeinated with decaffeinated), the amounts represented by each type are unknown.

Spent coffee grounds (SCGs) were warm and humid. On the grounds that this research project deals with

organic chemistry, to analyse the collected samples, organic chemistry laboratory number 501 in Davy

Building at the University of Plymouth was used for the most procedures of the current experiment. Such

equipment as the rotary evaporator Buchi Rotavapor R-300 and reflux apparatus electromantle EM0500/CE

were used during the process of biodiesel obtainment. There are several laboratory techniques that can be

used to obtain biodiesel from spent coffee grounds. Pyrolysis is one of them. Pyrolysis is a process of

keeping the organic mass heated in the absence of oxygen. Since oxygen is a neccessary requirement in

order for combustion to occure, the organic material does not burn (Ars.usda.gov, 2010). Instead, the

process of decomposition follows and results in two products bio-oil and char. The advanced product of bio-

oil is biodiesel (Montross, 2010). (Li, Strezov and Kan., 2014) who have used pyrolysis to obtain bio-oil and

other pyrolysis products, have found that pyrolysis improves the elemental composition of bio-oil. (Bok et

al., 2012), however noted that the obtainment of biodiesel from waste coffee grounds via pyrolysis has not

yet been widely studied. In spite of pyrolysis being extensively applied in current worldwide research, it

11

has its drawbacks. There is a lack of cost competitive capacity of the pyrolysis process when it is applied to

biomass and waste (Bridgwater, 2003). Another way to obtain biofuel is through transesterification. During

transesterification the oil is separated from glycerine, resulting in biodiesel and saponifiable substances

(Biodiesel.org, 2015). The benefit of transesterification process is its ability to lower the viscosity of

biodiesel. The high viscosity of the oil content of biodiesel presents the major issue of biodiesel obtained

from biomass oils. The reduction of viscosity by transesterification improves the functioning of biodiesel

(Gupta and Demirbas, 2010). Thus, the transesterification process was chosen as a technique to obtain

biodiesel in the current research project. The entire sequence of the laboratory processes used to obtain

biodiesel through transesterification is:

1. Stirring dried coffee grounds and an added solvent

2. Mixing methanol with sulfuric acid

3. Transesterification

4. Separation of methyl esters(biodiesel) and saponifiable substances (Biodiesel.org, 2015)

5. Washing biodiesel to remove methanol, glycerol and acid catalyst (Jenkins et al., 2014)

Before and after transesterification, Bruker alpha-p FI-IR Spectrometer was used to analyse the samples.

Infrared spectroscopy is a technique used to show types of mixtures and their amount in a compound

(McKelvy et al., 1998). These characteristics can be obtained from observing a phenomenon called

stretching vibrations of bonds. When a range of infrared frequencies are shone through the compound a

number of frequencies get absorbed by the compound. Energy from these absorptions results in the

appearance of the bond stretches, which in their turn indicate what mixture and in what amount is present in

the compound (McKelvy et al., 1998). The appliance of infrared spectroscopy technique to analyse samples

correlates well with the chosen research type. In his book from 1963, Rao states that infrared spectroscopy

appears to be supreme in relation to other techniques for both qualitative and quantitative analyses. In the

end of the analysis, graphs with peaks were produced by a computer. Interpretation of these graphs allows

scientists to analyse samples and determine what compounds and in what amounts are inside the

samples (Stuart, 2004).

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Data Validity and Reliability

Data validity and reliability is an important tool to make the research a subject of consideration and

convince the public to place confidence in the obtained results (Ekstedt et al., 2014). Unlike qualitative

research, quantitative research focuses on the internal validity of the chosen research methods rather than

general trustworthiness of the study (Appleton, 2006). Therefore in order to determine validity and

reliability of the obtained data, laboratory research techniques and equipment should be examined as well as

the chosen software for the data analysis. Due to a range of different equipment used and a high number of

other experiments conducted using the same equipment, the risk of sample contamination was present.

According to (EnviroMatrix Analytical, Inc., n.d.) laboratories often work with small-scale samples and at

this level contamination can easily occur. Whereas (Smith, 2000) states that all laboratories encounter this

issue and even though it is regarded as unavoidable, it can however be minimized by keeping laboratories

clean. Other simple methods, such as wearing gloves and using wipes will help prevent sample

contamination (EnviroMatrix Analytical, Inc., n.d.). In the current experiment all mentioned above was

abided by. In order to avoid contamination fresh heptane was also used after the rotary evaporation. Same

equipment such as syringes, spatulas etc. was never used with different substances. Also, not only validity

and reliability of equipment and laboratory conditions should be examined. Microsoft Excel 2013 was

chosen as a software for data analysis. As stated by (Odeh, Featherstone and Bergtold, 2010), Excel 2007

shown greater reliability than the previous versions of the software, however minor problems were still

encountered in their research of the software credibility. It was also mentioned that full trust into the

software reliability might result in the potential generation of false and biased deductions (Odeh,

Featherstone and Bergtold, 2010). However, in regard to the current study it can be assumed that Excel

software has improved throughout years and the newer version used for this research provided more

credibility during data analysis. Although, no legitimate proof was found to support this statement. Infrared

spectroscopy is widely used in science and is a reliable technique to identify organic mixture compounds

(Shipman et al., 2013). In comparison to some previously conducted studies, this research has used the same

laboratory equipment as both (Jenkins et al., 2014) and (Zannikos et al., 2011). Interestingly, the same

13

laboratory methods, such as transesterification and equipment, as well as infrared spectroscopy, were not

only used for extracting biodiesel from coffee, but also for the biodiesel obtainment from frying oil,

described by (Leung and Guo, 2006). This might suggest the relative credibility of data obtained and

analysed using these methods.

Materials and Methods

The current research project used a mixed method research. Both primary and secondary data were used in

order to support the arguments and objectives stated in methodology. Secondary data was obtained from a

variety of sources available as scientific papers and books. Primary data was collected from three local

coffee houses located in Plymouth-Costa, Starbucks and Nero. The first sample of spent coffee grounds was

obtained from Starbucks café at Drake Circus shopping mall, Plymouth, UK. Spent coffee grounds (SGSs)

were put into ceramic plates and put into the 67 degree Celsius oven for 24 hours to dry. After exactly 24 h

of drying, the ceramic plates with dried spent coffee ground from were removed from the oven and put into

2 1L plastic containers. 10 g of SCGs were put into a pre-weighed conical glass flask. In a fume cupboard

100 ml of fresh heptane (solvent), accurately measured with a beaker were added to the flask along with a

stirrer bar. Subsequently the flask was put on an electro-magnetic stirrer, a stirring power of 7 was chosen

and the solution was left to stir in a room temperature in a fume cupboard for exactly 180 minutes. After the

stirring process was stopped the stirred content of the flask was filtered into a pre-weighed round bottom

glass flask, using a 110 mm Whatman filter paper and a 7cm glass funnel. To the solid content left after

filtering another 100 ml of fresh heptane was added and left to stir for another 180 minutes in a room

temperature in a fume cupboard. The liquid from the first filtration was put into a rotary evaporator at 40 °C.

Heptane evaporated and oil was left in the flask. Oil obtained from the first extraction was weighed.

Meanwhile, the content in the conical flask left after the second stirring was filtered into a pre-weighed

round bottom glass flask, using a 110mm Whatman filter paper and 7cm glass funnel. Subsequently, the

filtered substance was put into a rotary evaporator at 40 °C for heptane to evaporate. Oil obtained from the

second extraction was weighed. Oil from both extractions was combined together in one round bottom glass

flask. Oil from both extractions was analysed using a Bruker alpha-p FI-IR Spectrometer. A droplet of oil

was put on the diamond surface of the machine in order to analyse the sample. Transesterification reaction

14

followed: 9.5 g of methanol is added to the round bottom glass flask with the oil from both extractions.

Thereafter 0.17 g of sulphuric acid was added to the flask (roughly 10th of the weight ratio of the oil). Then

the flask with its’ content was put in a fume cupboard to reflux for 24h. Substance was filtered into a pre-

weighed 100 ml round bottom glass flask (r.b.f.), using a 110 mm Whatman filter paper and a 7cm glass

funnel. Whatman paper is weighed in order to determine the amount of unsaponifiable material later in the

process. Methanol was added to the flask to help remove the unsaponifiable material sticking to it and

transfer it into the filter. The flask with unsaponifiable material sticking to it was weighed. The pre-weighed

filter paper was left inside the 40 °C oven for a few days. Filtered substance was transferred into the rotary

evaporator. Methanol evaporated. Hence, only the needed material (biodiesel) and sulphuric acid were left

in the r.b.f. In order to get rid of the sulphuric acid, the flask was washed with 25 ml of diethyl ether

anhydrous into a separating funnel. Subsequently, the flask was washed with water three times and all that

put into the separating funnel as well. In the separating funnel, liquid to liquid extraction technique was

performed to get rid of all the waste material (water and sulphuric acid). The oily substance was then

transferred into a pre-weighed r.b.f. During the transfer, bits of the oily content was left in the separating

funnel. Then, 6 spoons of sodium sulphate anhydrous were added to the flask with biodiesel and ether in

order to dry the flask content. Substance was left to stay and dry for 10 minutes. The substance was then

filtered into another round bottom glass flask. The flask was put into a rotary evaporator and ether

evaporated, leaving only biodiesel in the flask. The biodiesel was weighed. After the biodiesel obtainment

another infrared spectroscopy analysis was performed, using a Bruker alpha-p FI-IR Spectrometer.

Meanwhile, the filter paper with unsaponifiable material was removed from the oven and weighed.

Previously measured weight of unsaponifiable material from the flask was combined with the weight of

unsaponifiable material from the dried filter paper and counted. Next, a sample of waste coffee grounds

acquired from Costa coffee house located on the University of Plymouth campus, another Starbucks sample

taken from the same container as the first sample and waste coffee ground sample obtained from Nero on

Cornwall Street underwent the same procedure as the first Starbucks (Drake) sample. Spectroscopy analysis

was done before and after the transesterification. Then new samples, obtained from Nero (Debenhams),

Starbucks (Armada Way) and Costa (Drake Circus) and a sample from an old container of Nero (Cornwall

Street) followed the same procedure as the previous waste coffee ground samples. As usual all samples were

15

analysed before and after the transesterification using the spectroscopy analysis. The Starbucks (Armada

Way) sample experiment was done on a bigger scale. 100 grams of waste coffee grounds from Starbucks

(Armada Way) were taken and 1 litre of heptane. After first extraction another litre of fresh heptane was

added. 16 ml of concentrated sulphuric acid and 50 g of methanol were added before reflux. Then 250 ml of

Diethyl Ether Anhydrous were used to wash the substance into the separating funnel.

Conclusion

Both practical and literary techniques chosen for this work proved to be concise and easy to follow. Good

research facilities and an easy access to sources explaining the laboratory procedures used contributed to a

well-structured and planned research project. The experience obtained from the use of the chosen laboratory

methods was compared to the methods used in the literature and validity of results was determined via these

comparisons.

16

Chapter four. Research Findings, Results and Discussion

Research Finding and Results

This research project has adopted a quantitative, rather than a qualitative research technique. Hence, order to

comply with the hypothesis and the objectives, this section of the study demonstrates the results produced in

the forms of statistical analysis. In order to analyse the obtained data, Microsoft Excel 2013 was used. The

hypothesis of this research project stated that spent coffee grounds obtained from Starbucks give more

biodiesel than spent coffee grounds obtained from Costa and Nero. Even though more research is required

in order to prove the hypothesis, this study gave evidence that the hypothesis was supported. Figure 1 shows

the amount of biodiesel obtained from 10 grams of each sample of spent coffee grounds acquired from six

coffee shops of three different brands. Starbucks gave the most biodiesel content, yielding in 0.93 g and 1.6

g of biodiesel. Costa gave 0.18 g and 0.37 g of biodiesel. Nero gave 0.33 g and 0.25 g of

biodiesel .Photographs of the biodiesel samples obtained and a scanned copy of the laboratory book page,

describing the laboratory procedure and the results can be found in the Appendix A.

17

Fig. 1

Starbucks (Drake Circus)

Starbucks (Armada Way)

Costa (University Campus)

Costa (Drake Circus) Nero (Debenhams) Nero (Cornwall Street)

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

Biodiesel per 10g of SCGs (g)

Figure 1. Comparison of biodiesel obtained from 10 g of spent coffee grounds from 6 coffee shops

The Pearson’s correlation test was performed on the data obtained at the laboratory. It was found that r= .9.

In order to support the second objective and find out whether the biodiesel obtained would be feasible to

use, infrared spectroscopy analysis was performed on all samples before and after transesterification.

Spectroscopy graphs showing biodiesel samples analysed after transesterification reaction can be seen

below. Figure 2 shows Starbucks (Drake Circus), figure 3-Costa (University Campus), figure 4-Nero

(Cornwall Street), figure 5-Costa (Drake Circus), figure 6-Nero (Debenhams), and figure 7 demonstrates

Starbucks (Armada Way) biodiesel samples.

18

Fig. 2

Figure 2 showing the Starbucks (Drake Circus) biodiesel sample on the infra-red spectroscopy graph

19

Fig. 3

Figure 3 showing the Nero (Debenhams) biodiesel sample on the infra-red spectroscopy graph

20

Fig. 4

Figure 4 showing the Costa (Drake Circus) biodiesel sample on the infra-red spectroscopy graph

21

Fig. 5

Figure 5 showing the Nero (Cornwall Street) biodiesel sample on the infra-red spectroscopy graph

22

Fig. 6

Figure 6 showing the Costa (University Campus) biodiesel sample on the infra-red spectroscopy graph

23

Fig. 7

Figure 7 showing the Starbucks (Armada Way) biodiesel sample on the infra-red spectroscopy graph

Spectroscopy graphs that show the samples before transesterification processes can be found in the

Appendix B. Two Excel tables showing the Medium amount of the obtained biodiesel and the Pearson’s

correlation value between the amount of biodiesel obtained and the percentage of Arabica beans used, can

be seen in the Appendix C. The mean amount of biodiesel produced among all samples was found to be

24

0.61 g. In this research project calculations have been made to determine the amount energy invested in

order to extract biodiesel from 10 grams of spent coffee grounds. To see a scanned copy of the complete

energy input calculations refer to the Appendix D. It was found that in order to obtain the mean amount of

diesel, 0.61 g, 22200 kJ of energy input is required. In order to see the full copy of the laboratory book see

the Appendix E.

Discussion

The main objective of this research project was to give evidence that more lipid content can be obtained

from Arabica than Robusta coffee beans. This would support the hypothesis that Starbucks waste coffee

grounds, which are 100% Arabica beans (Starbucks Coffee Company, 2016) can be used to extract more

biodiesel than Costa (Costa.co.uk, 2016) and Nero (Caffenero.co.uk, 2016), who use a blend of Arabica and

Robusta. Lipid content contains glycerides. When alcohol is added to glycerides, transesterification reaction

occurs and fatty acid methyl esters (FAME) are created. FAME- is biodiesel (Sawangkeaw, Bunyakiat and

Ngamprasertsith, 2010). In contrast to the (Jenkins et al., 2014) method, it was decided to conduct

experiments for this research project on a small scale. The statistical analysis of all biodiesel samples

obtained during the current research project shows that there is a strong positive correlation between using

Arabica beans in order to obtain biodiesel and the amount of biodiesel obtained. Pearson’s correlation test

gave a value of .9. Therefore, it can be stated that there is evidence that Arabica beans give more biodiesel

than a blend of Arabica and Robusta. The amount of biodiesel is closely related to the amount of the lipid

content in the beans. (Jenkins et al., 2014) stated that the lipid content contains glycerides, of which

biodiesel is made, when transesterified. Therefore, there is support for the theory that more lipid content can

be obtained from Arabica, rather than Robusta coffee beans. The second objective was to show that it is

feasible to use biodiesel obtained from waste coffee grounds. The rationale behind this objective was to

analyse biodiesel samples using infrared spectroscopy and compare it to the infrared analysis of biodiesel in

the literature. The spectroscopy graphs of samples on figure 2-6 are relatively similar, showing low

transmittance carboxylic acid peaks (Practical Infra-Red Spectroscopy, 2002) at 2922 and 2853 on figure 2,

2923 and 2853 on figure 3, 2922 and 2853 on figure 4, 2923 and 2853 on figure 5, as well as, 22923 and

2853 on figure 6. Biodiesel sample on figure 7, however, is different. Its’ peak is of a similar transmittance

25

(around 60%) as samples 2-6, but the frequency is 3389. Due to its’ difference from 5 other samples, it was

considered anomalous and omitted from the discussion. According to (Lewis and Evans, 2006) fatty acids

are carboxylic acids with long hydrocarbon chains. Therefore it can be said that fatty acids are present in

biodiesel samples from all 5 coffee shops. Starbucks (Armada Way) is omitted in the current statement due

to its’ peak being abnormal. (Zannikos, Anastopoulos and Deligiannis, 2011) in their research found that

coffee oil has such fatty acids as: Palmitic, Stearic, Oleic, Linoleic and Arachidic. According to (Jenkins et

al., 2014) fatty acids methyl esters (FAME) is what is called biodiesel. Therefore, due to carboxylic acid

peaks being found in the samples, it can be said that infrared spectroscopy proved that biodiesel was

obtained during this research work. As stated by (Jenkins et al., 2014) if it is blended following the right

recommendations, biodiesel can be used in both U.S.A. and Europe. This statement gives evidence to the

second objective of this report-feasibility of the obtained biodiesel. Finally, after calculating the energy

input, needed to conduct the laboratory procedures and obtain biodiesel, it must be stated that even though

the mean amount of biodiesel produced is 0.61 g, Starbucks spent coffee grounds gave a significantly bigger

amount of biodiesel than Costa and Nero, even though the energy input at the laboratory was the same.

Overall it can be said the chosen methodology aligned well with the expected results.

Chapter five. Conclusions, Research Limitations and Suggestions for Future Research

Conclusions

Waste coffee grounds contain oil that is mainly comprised from such fatty acid methyl esters (FAME) as

linoleic acid, palmitic acid (35-40%), (44-50%), oleic acid (7-8%) and stearic acid (7-8%) (Bendall et al.,

2015). FAME are produced via the transesterification reaction, which occurs when triglycerides contained

in the coffee oil react with alcohol (Ault and Pomeroy, 2012). FAME are biodiesel (Jenkins et al., 2014).

However, it was stated by (Ferrari et al., 2010) that Arabica beans give more lipid content than Robusta

coffee beans. This research project aimed at finding whether it is the case with Arabica beans compared to

blend of Arabica and Robusta. It was found that Arabica coffee beans in fact do give more lipid content that

blends. The support for this statement was found via the hypothesis that Starbucks waste coffee grounds

would give more biodiesel, hence contain more lipids than a Costa and Nero waste coffee grounds, The

reason for such comparison was the fact that Starbucks uses 100% Arabica, whereas Costa and Nero both

26

use blends of Arabica and Robusta. Costa is known to use 70% Arabica beans and 30% Robusta, whereas

the blend percentages in Nero are not known. From 10 g of waste coffee grounds acquired from two

Starbucks stores, 0.93 g and 1.6 g of biodiesel were obtained. 10 g of waste coffee grounds from Costa gave

0.18 g and 0.37 g. 10 g of Nero resulted in 0.33 g and 0.25 g. The Pearson’s correlation test showed a strong

positive correlation between Arabica beans and the amount of biodiesel obtained. Thus, the evidence for the

hypothesis that Arabica beans give more biodiesel than blends was found. Hence, the hypothesis supported

the theory that Arabica beans contain more lipids that Robusta coffee beans. Also, the evidence to support

the statement that the obtained biodiesel would be feasible to use was found via infrared spectroscopy

analysis, which determined the presence of fatty acid methyl esters (FAME) in the analysed samples of the

obtained biodiesel. With references to the literature findings of FAME reported before, it was determined

that there was evidence for the biodiesel obtained during this research project to prove to be feasible. In

addition, energy input required to obtain biodiesel from the coffee samples was calculated. Energy

throughput of the laboratory procedures required to produce biodiesel was the same for all samples.

However, Arabica beans used by Starbucks gave more biodiesel, while using the same amount of energy.

Therefore strong positive correlation between using Arabica coffee grounds and obtaining a bigger amount

of biodiesel is an evidence that it is more efficient to use spent coffee grounds from Starbucks.

Research Limitations and Suggestions for Future Research

The current research was limited by the amount of time devoted to it being less than a year. Therefore, for

the future research done on this topic, it can be suggested to explore such properties of biodiesel as: density

and kinematic viscosity. During this study, energy input required to produce biodiesel was found. However,

it can be suggested to also find the energy output of the obtained biodiesel. It can also be suggested to find

the energy input required to produce conventional diesel fuel and compare the inputs.

27

28

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Appendices

Appendix A. Biodiesel Sample Photographs And a Scanned Lab Book Page

Fig. A1

Figure A1 show the Starbucks (Drake Circus) biodiesel sample

37

Fig. A2

Figure A compares Starbucks (Drake Circus) and Costa (University Campus) biodiesel

38

Fig. A3

Figure A3 show Costa (Drake Circus), Nero (Cornwall Street) and Nero (Debenhams) biodiesel

39

Fig. A4

Figure A4 shows the amount of biodiesel (g) obtained from all 6 coffee houses. Figure was obtained from the scanned

copy of the lab book

40

Appendix B. Sample Infra-Red Graphs Before Transesterification

Fig. B1

Figure B1 shows Starbucks (Drake Circus) sample before and after transesterification on the infra-red spectroscopy

graph

41

Fig. B2

Figure B2 shows Costa (Drake Circus) sample before transesterification on the infra-red spectroscopy graph

42

Fig. B3

Figure B3 shows Nero (Debenhams) sample before transesterification on the infra-red spectroscopy graph

43

Fig. B4

Figure B4 shows Nero (Cornwall Street) sample before transesterification on the infra-red spectroscopy graph

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Fig. B5

Figure B5 shows Costa (University Campus) sample before transesterification on the infra-red spectroscopy graph

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Fig. B6

Figure B6 shows Starbucks (Armada Way) sample before transesterification on the infra-red spectroscopy graph

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Appendix C. Excel Data Analysis

Table C1

Table C1 shows the amount of biodiesel (g) obtained from each coffee shop, as well as the found medium

Table C2

Table C2 shows the Pearson’s correlation value between the amount of the obtained biodiesel and the percentage of

Arabica beans in the spent coffee grounds

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Appendix D. Energy Input Calculations

Fig. D1

Figure D1 shows the energy input calculations, using the formula obtained from (Breithaupt, J., 2010). 

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Fig. D2

Figure D2 shows the energy input calculations, using the formula obtained from (Breithaupt, J., 2010). 

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Appendix E. Scanned Laboratory Book

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Appendix F. COSHH and Risk Assessment

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