The Manufacture of Biodiesel from the used vegetable oil

Transcription

1 The Manufacture of Biodiesel from the used vegetable oil By Nada E.M. ElSolh A thesis submitted to the Faculty of Engineering at Kassel and Cairo Universities for the degree of Master of Science Departments of Electrical and Mechanical Engineering Degree Program: Renewable Energy and Energy Efficiency for the Middle East North Africa Region- Cooperation between Kassel and Cairo Universities Under the supervision of Prof. Jürgen Schmid Electrical Engineering Department Faculty of Engineering Kassel University Prof. Fatma Ashour Chemical Engineering Dpartment Faculty of Engineering Cairo University Kassel, 28 Feb i

2 The Manufacture of Biodiesel from the used vegetable oil By Nada E.M. ElSolh A thesis submitted to the Faculty of Engineering at Kassel and Cairo Universities for the Degree of Master of Science Departments of Electrical and Mechanical Engineering Degree Program: Renewable Energy and Energy Efficiency for the Middle East North Africa Region- Cooperation between Kassel and Cairo Universities 1 st examiner: Prof.-Dr. Fatma Ashour 2 nd examiner: Prof.-Dr. Jürgen Schmid 3 rd examiner: Prof. Hendawi Salem Kassel, 28 Feb ii

3 Abstract The increasing awareness of the depletion of fossil fuel resources and the environmental benefits of biodiesel fuel has made it more attractive in recent times. Its primary advantages deal with it being one of the most renewable fuels currently available and it is also non-toxic and biodegradable. It can also be used directly in most diesel engines without requiring extensive engine modifications. However, the cost of biodiesel is the major hurdle to its commercialization in comparison to petroleum-based diesel fuel. The high cost is primarily due to the raw material, mostly neat vegetable oil. Used cooking oil is one of the economical sources for biodiesel production. However, the products formed during frying, can affect the transesterification reaction and the biodiesel properties. The production of biodiesel from waste vegetable oil offers a triple-facet solution: economic, environmental and waste management. The new process technologies developed during the last years made it possible to produce biodiesel from recycled frying oils comparable in quality to that of virgin vegetable oil biodiesel with an added attractive advantage of being lower in price. Thus, biodiesel produced from recycled frying oils has the same possibilities to be utilized. From an economic point of view; the production of biodiesel is very feedstock sensitive. Many previous reports estimated the cost of biodiesel production based on assumptions, made by their authors, regarding production volume, feedstock and chemical technology. From a waste management standpoint, producing biodiesel from used frying oil is environmentally beneficial, since it provides a cleaner way for disposing these products; meanwhile, it can yield valuable cuts in CO2 as well as significant tail-pipe pollution gains. Any fatty acid source may be used to prepare biodiesel. Thus, any animal or plant lipid should be a ready substrate for the production of biodiesel. The use of edible vegetable oils and animal fats for biodiesel production has recently been of great concern because they compete with food materials - the food versus fuel dispute (Pimentel et al., 2009; Srinivasan, 2009). There are concerns that biodiesel feedstock may compete with food supply in the long-term. Hence, the recent focus is the use of non-edible plant oil source and waste products of edible oil industry as the feedstock for biodiesel production meeting the international standards. Quality standards are prerequisites for the commercial use of any fuel product. iii

4 This Master Thesis is about the manufacturing of biodiesel from the used vegetable oil. This study aims to define the requirements for biodiesel production by the esterification process, testing its quality by determining some parameters such as density, kinematics viscosity, high heating value, cetane number, flash point, cloud pint and pour point and comparing it to Diesel fuel, testing the engine performance, testing the emissions of biodiesel and comparing it to diesel emission, and the strategic issues to be considered to assess its feasibility, or likelihood of succeeding. This analysis is useful either when starting a new business, or identifying new opportunities for an existing business. Therefore, it will be extremely helpful for taking rational decisions about the development of a biodiesel production plant. iv

5 Acknowledgements In the first place I want to thank God for giving me the strength to finish this Master Thesis. Three semesters passed and I had some good days and other hard ones, and whenever I was down, God gave me the hope and strength to continue this Master Thesis successfully. Words cannot express my thanks to my wonderful family for their non stopping support during the period of my study and for believing in me and in my work. Special thanks go to Prof. Dahlhaus, the coordinator of the REMENA Master Program, for being understandable and allowing me to do my defense in Kassel, that was very kind and generous of him, it s known about him that he s very supportive to students. I would like to thank my supervisors Prof. Fatma Ashour from Cairo University and Prof. Jürgen Schmid from Kassel University for their supervision, advice and guidance from the very early stage of my Master thesis as well as providing me great experiences through out this work. And of course many thanks to all my professors in Cairo and Kassel Universities for their non stopping support I also want to thank Prof. Schmid for arranging the practical work of my Master thesis in the University of Applied Science (HAW) in Amberg, in Germany and giving me this opportunity to work in the Mechanical Engineering department that will help me out in many ways in my future education. Special thanks to Stefanie Reil, Prof. Schmid s PhD student, for helping from the first day I arrived to Amberg, from putting the basics for my Master Thesis until the day of submitting it, also I will not forget her wonderful team, Sabine Feldmeier for letting me work with her CHNS device and Suzanna Ritz for helping me in arranging my thesis, and of course many thanks to the other people who helped me in my thesis. I just can t remember all the names. Many many thanks to Raphael Lechner, a PhD student, for helping me in performing all the experiments needed for my thesis in the lab, also many thanks to him for giving me much from his time whenever I have questions concerning my thesis and for reviewing all of my thesis. This paper would not have been possible without the support of the DAAD, the German Academic Exchange Service, special thanks to Mr. Heinemann and Mrs. Anke Stahl for bearing with us and answering all of our questions patiently. Also many thanks to everyone who made the REMENA Master Program a successful one. Finally, I would like to thank my colleagues in the REMENA Master Program for their support and I would like to say that it was a nice opportunity for me to meet these nice people. v

6 Contentsts 1 Motivation Why Biodiesel?! Introduction An Overview Bio Energy Biomass energy The Carbon Cycle Movement of Carbon through the atmosphere The carbon cycle and biofuels Biofuels What are Biofuels Biofuel generation Biodiesel Production What is Biodiesel History of Biodiesel The advantages of using vegetable oils as fuels: Characteristics of oils or fats affecting their suitability for use as biodiesel Review of biodiesel feedstock Vegetable oils as diesel fuels Transesterification of vegetable oil: Biodiesel production from used cooking oil Biodiesel as an engine fuel Overview Technical characteristics of biodiesel as a transportation fuel Engine performance characteristics of biodiesel Engine emissions from biodiesel Environmental Benefits of Biodiesel Fuel Environmental benefits in comparison to petroleum based fuels include Some challenges for using biodiesel fuel Biodiesel Economy Overview.43 vi

7 8.2 Biodiesel production economic balance Feedstock prices Biodiesel production costs Taxation of energy products Experimental Part The production of Biodiesel from rapeseed oil experiment Pressing of Rapeseed oil The determination of free fatty acid Transestrification: Thin layer chromatography Fuel analytics Introduction Technical Details and Standards of diesel and biodiesel Kinematic Viscosity measurement: The Ubbelohde viscometer Density Measurement: Hydrometer and Pycnometer Hydrometer Pycnometer Heating value Measurement: the Bomb Calorimeter Measuring the oxidation stability CHNS Elemental Analyzer (EA) Experimental and Standard results of density, viscosity, heating value and oxidation stability for rapeseed oil, two types of biodiesel and diesel fuel Discussion of results The Emission testing experiment for rapeseed oil, low sulfur diesel fuel and biodiesel (from gas station) Equipment used Procedure of the emission testing experiment Tabulated Results of the emission testing experiment Graphical Results: Comparing the emissions of rapeseed oil, diesel and biodiesel Discussion of Results: Comparing between the results of the emission testing experiment of diesel and biodiesel fuels...92 vii

8 10 Summary Conclusion and Recommendations..97 Bibliography List of Figures List of tables Appendix A Appendix B viii

9 Abbreviations Symbol Meaning ASTM Bxx B2 B5 B20 B100 BD Bsfc Btu/lb CH4 CI CO CO2 D2 Derv DI American Society for Testing and Materials The level of blending biodiesel with petroleum diesel 2% biodiesel and 98% petroleum diesel 5% biodiesel and 95% petroleum diesel 20%biodiesel and 80% petroleum diesel Pure biodiesel Bio Diesel brake-specific fuel consumption British thermal unit per pound Methane Compression Ignition Carbon monoxide Carbon dioxide Diesel fuel Diesel engine road vehicle Direct injection DME Dimethyl ether (CH3OCH3 ) DMF EEA EPA Dimethylfuran ((CH3)2C4H2O) European Environment Agency Environmental Protection Agency EN14214 European standards for biodiesel EU FAE FAME European Union Fatty acid esters Fatty acid methyl ester ix

10 FFAs FID H 2 IEA KW LHV LPG CNG MTBE NDIR NO NOx N 2 O O 2 OECD POME PM Pr REN21 R&D Rpm SME SO 2 THC UV VIS Free fatty acids Flame ionization detector Hydrogen International Energy Agency Kilo watt Lower heating value Liquefied petroleum gas Compressed natural gas Methyl tertiary-butyl ether Non dispersive infrared sensor Nitric oxide Nitrogen Oxide Nitrous oxide Oxygen Organization for Economic Co-operation and Development Palm oil methyl esters Particular matter Rapeseed price Renewable Energy Policy Network for the 21st Century Research & Development Revolutions per minute Soya bean oil methyl ester Sulfur dioxide Total Hydrocarbon Analyzer Ultra Violet Visual light spectrometer x

11 Chapter 1 Motivation Several billions of gallons of waste vegetable oil are produced every year around the world, mainly from industrial deep fat fryers found in potato processing plants, factories manufacturing foods, and restaurants. Some of this wastage is already being re-used by other industries, such as in animal feed and cosmetics, but the amount that is still being wasted and ending up in land-fill sites is alarming. Therefore it makes commercial and environmental sense to re-use this oil for making biodiesel. Making biodiesel from waste vegetable oil (WVO) is much the same as when using straight vegetable oil, except that the oil will need filtering first to remove debris, and because it has been used and most likely reheated several times, more fatty acids will be present so we need to determine how much more sodium hydroxide (or potassium hydroxide) to add to neutralize these acids. This is called a titration test.(1) Vegetable Oil is commonly available everywhere and there at every home and most households dump the waste oil rather than utilizing that. Making biodiesel from waste vegetable oil is one of the most productive ways to utilize waste vegetable oil. Moreover, day by day fuel is getting expensive and inflation is hitting new highs across every country across the world. Everyone has started looking for cheap substitutes for everything in the world. Making Biodiesel from waste vegetable oil is an upcoming way of preserving energy and meeting our own requirements without depending on anyone. Biodiesel is a diesel fuel that is made by reacting vegetable oil (cooking oil) with other common chemicals that are easily available in the market. Biodiesel may be used in any diesel automotive engine in its pure form or blended with petroleum-based diesel, so need not worry about anything. No modifications are required, and the result is a less-expensive, renewable, clean-burning fuel.(2) Biodiesel is a product of great interest for its environmental characteristics. It is biodegradable and it s renewable. It has the advantages of dramatically reduced sulfate and hydrocarbon emissions and reduces particulate matter. It is nontoxic and does not damage water quality. Biodiesel is a fuel that can be made from pure or waste vegetable oils such as soya and rape seed (canola) oil, mixed with methane and a small amount of lye. It runs a diesel engine just as petroleum-based diesel would. (3) 1

12 Additionally to its environmental characteristics, It is evident, that there is a latent demand of this product because of the recent rises in the price of oil, and the realization that fossil fuels will eventually run out, not to mention the damage burning them does to our planet, this resulted in renewed interest in fuel made from plant oils or biodiesel. That is why it is necessary to study the potential of biodiesel, as well as to study its feasibility, if it will be used as a viable alternative fuel in the future. 2

13 Chapter 2 Why Biodiesel?! It's Economical Biodiesel can be produced by individuals on a small scale relatively inexpensively when compared to Petrodiesel. Figures range anywhere from $0.40 a gallon to about $1.25 a gallon depending on the cost of materials required to make it. With prices that low, most people are able to save hundreds of dollars on their fuel bills. In some cases it even goes into the thousands of dollars. With savings like that, most people are able to recoup their initial investment on the equipment needed to make biodiesel within a matter of months. It's Renewable Biodiesel has been touted far and wide for its renewable properties. Instead of making a fuel from a finite resource such as crude oil, Biodiesel can be produced from renewable resources such as organic oils, fats, and tallows. This means that it can be made from things that can be regrown, reproduced, and reused. So, if you need more, you can just grow another crop of seeds for the oil. It's Good For the Environment When Biodiesel is used to power diesel engines, the emissions at the tailpipe are significantly reduced. Studies by the US National Renewable Energy Lab indicate drops in several key areas that help the environment. Carbon Dioxide, Hydrocarbons, and Particulate Matter (the black smoke from diesels) all are significantly reduced when Biodiesel is used. When used in older diesel engines such as indirect combustion diesels, the results are astounding. There was a reduction in the tailpipe emissions of nearly 90%. It also has a positive energy balance. 3

14 It supports farmers When Biodiesel is made from organic oils such as Canola, Soy, Peanut, or other domestically grown seed crops, it helps the farming community out. Because the oil used to make Biodiesel is "domestically grown", it keeps the money flowing to those that "grow" the feedstock. This continues to help out the renewable aspect of Biodiesel because this means more seed crops can be grown by local farmers. It reduces dependency on Crude Oil When Biodiesel is used in place of petrodiesel, it reduces the amount of crude oil used up. This means that it helps to reduce our dependence on a limited resource and increases our use of renewable resources. We think that's a great step toward reducing our dependence on a fuel that may not be around forever. It's enjoyable to make We think that making Biodiesel is one of the funniest things in the world to do. With a little practice and know-how it can easily be made and is extremely simple to do. We've found it to be an incredibly fulfilling experience. There's just something to be said for being able to make your own fuel and drive past a gas station and wave instead of pulling up for a fill-up. Words just don't describe the incredible feeling we get each time we make a batch. It's good for the engine Biodiesel, unlike Petrodiesel, has a much higher "lubricity" to it. This means that it's essentially "slipperier" than normal diesel fuel. With the added "lubricity" of Biodiesel, engines have been shown to experience less wear and tear when used on a regular basis. Also, because Biodiesel is less polluting, it means that it's easier on the engine. US Government Studies have shown that in some cases large fleets using Biodiesel have been able to go longer between oil changes because the oil stay's cleaner when Biodiesel is used. It's the perfect alternative fuel When compared to several other Alternative Fuels available, Biodiesel comes out way ahead. Most alternative fuels require changes to a vehicle to be used. Natural Gas & Propane require special tanks to be installed and changes to the fuel injection system must be made as well. Ethanol also requires specialized changes to the fuel injection system. Electricity requires a completely different engine. In most cases, once a vehicle undergoes 4

15 the conversion necessary to run the alternative fuel, there's no going back. You either run the alternative fuel or you don't run the vehicle. (4) 5

16 Chapter 3 Introduction During the last century, the consumption of energy has increased a lot due to the change in the life style and the significant growth of population. This increase of energy demand has been supplied by the use of fossil resources, which caused the crises of the fossil fuel depletion, the increase in its price and the serious environmental impacts as global warming, acidification, deforestation, ozone depletion, Eutrophication and photochemical smog. As fossil fuels are limited sources of energy, this increasing demand for energy has led to a search for alternative sources of energy that would be economically efficient, socially equitable, and environmentally sound. Two of the main contributors of this increase of energy demand have been the transportation and the basic industry sectors, being the largest energy consumers. The transport sector is a major consumer of petroleum fuels such as diesel, gasoline, liquefied petroleum gas(lpg) and compressed natural gas (CNG) (Demirbas, 2006). Demand for transport fuels has risen significantly during the past few decades. (IEA, 2008). The demand for transport fuel has been increasing and expectations are that this trend will stay unchanged for the coming decades. In fact, with a worldwide increasing number of vehicles and a rising demand of emerging economies, demand will probably rise even harder. Transport fuel demand is traditionally satisfied by fossil fuel demand. However, resources of these fuels are running out, prices of fossil fuels are expected to rise and the combustion of fossil fuels has detrimental effects on the climate. The expected scarcity of petroleum supplies and the negative environmental consequences of fossil fuels have spurred the search for renewable transportation biofuels (Hill, Nelson, Tilman, Polasky& Tiffany, 2006). Biofuels appear to be a solution to substitute fossil fuels because, resources for it will not run out (as fresh supplies can be re grown), they are becoming cost wise competitive with fossil fuels, they appear to be more environmental friendly and they are rather accessible to distribute and use as applicable infrastructure and technologies exists and are readily available. Forecasts are that transport on a global scale will increase demand for conventional fuels with up to a maximum annual growth of 1.3% up to This would result in a daily demand of around 18.4 billion litres (up from around 13.4 billion litres per day in 2005) (The Royal Society, 2008). 6

17 Conventional fuel, however, are predicted to become scarcely (The Royal Society, 2008) as petroleum reserves are limited (Demirbas, 2006), for this reason these fuels are set to become increasingly costly in the coming decades. Renewable fuels, made from biomass, have enormous potential and can meet many times the present world energy demand (IEA, 2008). Biomass can be used for energy in several ways; one of these is the conversion into liquid or gaseous fuels such as ethanol and bio-diesel for use in mobile source combustion (Marshall, 2007). In fact global demand for liquid biofuels more than tripled between 2000 and And future targets and investment plans suggest strong growth will continue in near future (IEA, 2008). The potential of biofuels appear to be enormous from an economical, political and environmental perspective. Speaking in terms of advantages, much heard is that they, as an alternative fuel, could solve several issues as the increasing energy prices worldwide, the increasing need of energy imports, the negative environmental consequences of fossil fuel combustion and the security of national energy supply for many countries. Biofuels appear to be more environment friendly in comparison to fossil fuels considering the emission of greenhouse gasses when consumed. Examples of those gasses are carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). Those gasses pose risks as they tend to warm the earth s surface (Randelli, 2007). The energy content of biofuels differs from conventional fuels. Total energy output per liter of biofuel is determined by the feedstock used, region where the feedstock is grown and production techniques applied. Randelli (2007) provides, for example, energy contents of biodiesel and bio ethanol. According to Randelli, Biodiesel has an energy ratio compared to diesel of about 1.1 to 1, which means that its energy contents are 87% of those of diesel. Bio ethanol has an energy ratio compared to gasoline of 1.42 (67% of gasoline).the amount that is similar to the amount of energy content of one litres gasoline is referred to as gasoline equivalent. Biodiesel production is a very modern and technological area for researchers as an alternative fuel for diesel engines because of the increase in the petroleum price, its renewability and the environmental advantages. Biodiesel can be produced from renewable sources such as vegetable oil, animal fat and used cooking oil. Currently, the cost of biodiesel is high as compared to conventional diesel oil because most of the biodiesel is produced from pure vegetable oil. Extensive use of edible oils may cause other significant problems such as starvation in developing countries. 7

18 However, the cost of biodiesel can be reduced by using low cost feedstock such as animal fat and used cooking oil. It is estimated that the cost of biodiesel is approximately 1.5 times higher than that of diesel fuel due to the use of food grade oil for biodiesel production. The term waste vegetable oil (WVO) refers to vegetable oil which has been used in food production and which is no longer viable for its intended use. Waste vegetable oil arises from many different sources, including domestic, commercial and industrial. Waste vegetable oil is a potentially problematic waste stream which requires to be properly managed. The disposal of waste vegetable oil can be problematic when disposed, incorrectly, down kitchen sinks, where it can quickly cause blockages of sewer pipes when the oil solidifies. Properties of degraded used frying oil after it gets into sewage system are conductive to corrosion of metal and concrete elements. It also affects installations in waste water treatment plants. Thus, it adds to the cost of treating effluent or pollutes waterways. The use of used cooking oil as feedstock reduces biodiesel production cost by about 60 70% because the feedstock cost constitutes approximately 70 95% of the overall biodiesel production cost. It is reported that the prices of biodiesel will be reduced approximately to the half with the use of low cost feedstock [Kemp, 2006; Radich, 2006; Anh et al., 2008]. Moreover used cooking oils can be a workable feedstock for biodiesel production as they are easily available. The use of non-edible plant oils when compared with edible oils is very significant because of the tremendous demand for edible oils as food, and they are far too expensive to be used as fuel at present. The land use for growing oilseeds as feedstocks for the biodiesel production competes with the use of land for food production. (5) 8

19 Chapter 4 An Overview of Bioenergy, Biomass and the Carbon Cycle 4.1 Bio Energy Bioenergy is one of the so-called renewable energies. It s is the energy that is contained in living or recently living biological organisms. (6) Bio-energy is obtained from organic matter, either directly from plants or indirectly from industrial, commercial, domestic or agricultural products and waste. The use of bioenergy is generally classed as a carbon-neutral process because the carbon dioxide released during the generation of energy is balanced by that absorbed by plants during their growth. (7) The term bio-energy really covers two areas: bio-fuel which is the transformation of plant materials into liquid fuel, and bio-mass, where solid plant materials are burnt in a power plant and this process creates energy, which can then be for immediate use or stored. (8) Advanced and efficient conversion technologies now allow the extraction of biofuels besides the traditional use of bioenergy; Modern bioenergy comprises biofuels for transport, and processed biomass for heat and electricity production. 9

20 4.2 Biomass Energy Biomass is the name given to all the earth s living matter. It is a general term for material derived from growing plants or from animal manure (which is effectively a processed form of plant material). It is a rather simple term for all organic material that stems from plants (including algae), trees and crops. Biomass energy is derived from plant and animal material, such as wood from natural forests, waste from agricultural and forestry processes and industrial, human or animal wastes. Plants absorb solar energy, using it to drive the process of photosynthesis, which enables them to live. The energy in biomass from plant matter originally comes from solar energy through the process known as photosynthesis. The energy, which is stored in plants and animals (that eat plants or other animals), or in the wastes that they produce, is called biomass energy. This energy can be recovered by burning biomass as a fuel. During combustion, biomass releases heat and carbon dioxide that was absorbed while the plant was growing. Essentially, the use of biomass is the reversal of photosynthesis. Therefore, the energy obtained from biomass is a form of renewable energy and, in principle, utilizing this energy does not add carbon dioxide to the environment, in contrast to fossil fuels. Biomass can be used directly (e.g. burning wood for heating and cooking) or indirectly by converting it into a liquid or gaseous fuel (e.g. alcohol from sugar crops or biogas from animal waste). Biomass is used in a similar way to fossil fuels, by burning it at a constant rate in a boiler furnace to heat water and produce steam. Liquid biofuels, such as wheat, sugar, root, rapeseed and sunflower oil, are currently being used in some member states of the European Union. Biomass provides a clean, renewable energy source that could dramatically improve our environment, economy and energy security. Biomass energy generates far less air emissions than fossil fuels, reduces the amount of waste sent to landfills and decreases our reliance on foreign oil. Biomass energy also creates thousands of jobs and helps revitalize rural communities. (9) 10

21 4.3 The Carbon Cycle Carbon is an element that is part of oceans, air, rocks, soil and all living things, Carbon doesn t stay in one place but it is always on the move. Carbon moves naturally to and from various parts of the Earth. This is called the carbon cycle. Today, however, scientists have found that more carbon is moving into the atmosphere from other parts of the Earth when fossil fuels, like coal and oil, are burned. Carbon dioxide is a greenhouse gas and traps heat in the atmosphere. Without it and other greenhouse gases, Earth would be a frozen world. But humans have burned so much fuel that there is about 30% more carbon dioxide in the air today than there was about 150 years ago. The atmosphere has not held this much carbon for at least 420,000 years according to data from ice cores. More greenhouse gases such as carbon dioxide in our atmosphere are causing our planet to become warmer. (10) Figure 4.3.1: The Carbon Cycle; the movement of Carbon dioxide through the atmosphere. (

22 4.3.1 Movement of Carbon through the atmosphere - Carbon moves from the atmosphere to plants. In the atmosphere, carbon is attached to oxygen in a gas called carbon dioxide (CO2). With the help of the Sun, through the process of photosynthesis, carbon dioxide is pulled from the air to make plant food from carbon. - Carbon moves from plants to animals. Through food chains, the carbon that is in plants moves to the animals that eat them. Animals that eat other animals get the carbon from their food too. -Carbon moves from plants and animals to the ground. When plants and animals die, their bodies, wood and leaves decay bringing the carbon into the ground. Some becomes buried miles underground and will become fossil fuels in millions and millions of years. -Carbon moves from living things to the atmosphere. Each time you exhale, you are releasing carbon dioxide gas (CO2) into the atmosphere. Animals and plants get rid of carbon dioxide gas through a process called respiration. -Carbon moves from fossil fuels to the atmosphere when fuels are burned. When humans burn fossil fuels to power factories, power plants, cars and trucks, most of the carbon quickly enters the atmosphere as carbon dioxide gas. Each year, five and a half billion tons of carbon is released by burning fossil fuels. That s the weight of 100 million adult African elephants! Of the huge amount of carbon that is released from fuels, 3.3 billion tons enters the atmosphere and most of the rest becomes dissolved in seawater. - Carbon moves from the atmosphere to the oceans. 12

23 The oceans, and other bodies of water, soak up some carbon from the atmosphere The carbon cycle and biofuels CO2 is part of the Earth s natural carbon cycle, which circulates carbon through the atmosphere, plants, animals, oceans, soil, and rocks. This cycle maintains a life-sustaining and delicate natural balance between storing, releasing, and recycling carbon. By using biofuels such as bioethanol and biodiesel for transportation, we can help restore the natural balance of CO2 in the atmosphere. Besides displacing fossil fuels, the feedstocks used to make biofuels require CO2 to grow, and they absorb what they need from the atmosphere. Thus, much or all of the CO2 released when biomass is converted into a biofuel and burned in automobile engines is recaptured when new biomass is grown to produce more biofuels. (13) Figure 4.3.2: Biofuels and the carbon cycle (

24 Chapter 5 Biofuels 5.1 What are Biofuels Biofuels are energy carriers that store the energy derived from biomass, commonly produced from plants, animals and micro-organisms and organic wastes. Biofuels may be solid, liquid or gaseous and include all kinds of biomass and derived products used for energetic purposes. Biofuels are renewable energy sources, meaning that fresh supplies can be regrown. They are a possible substitute product for fossil fuels. Compared with the latter product there are some advantages to subscribe to biofuels. Advantages and benefits of biofuels, however, depend on the categorization of the specific biofuel, type of feedstock used and technology applied to produce it. Table 5.1: Major benefits of Biofuels ( 14 Political, economic and environmental impacts of biofuels: A review Ayhan Demirbas * Sila Science, Trabzon, Turkey) 14

25 There are two global liquid transportation biofuels that might replace gasoline and diesel fuel; these are ethanol and biodiesel, respectively. Transport is one of the main energy consuming sectors. It is assumed that biodiesel is used as a petroleum diesel replacement and that ethanol is used as a gasoline replacement. Figure shows the sources of the main liquid biofuels for automobiles. Figure 1.1.1: Sources of main liquid biofuels for automobiles ( 15 Biodiesel, a realistic fuel alternative for diesel engines- springer-2008.pdf) Bioethanol, followed by biodiesel are the most produced types of biofuel. Figure shows the world s top ethanol and biodiesel producers in The United States (US) and Brazil are currently the leading ethanol producers and the expectations are that this will at least until 2018 remain so. The European Union (EU) is the world s leading producer of biodiesel. 15

26 Figure 5.1.2: The world s top ethanol and biodiesel producers in 2008 (REN21, 2009) Biofuels for transportation primarily driven by government policies, world ethanol production for transport fuel tripled between 2000 and 2007 from 17 billion to more than 52billion litres, while biodiesel expanded eleven-fold from less than 1 billion to almost 11 billion litres (Fig.3). These fuels together provided 1.8% of the world s transport fuel by energy value (36 Mtoe out of a total of 2007 Mtoe) (OECD 2008). In Europe there has been a continuing increase in the use of biofuels in road transport over the past decade from 0.1% in 1997 to 2.6% in 2007 (EEA 2008 a,b). Figure 5.1.2: Global ethanol and biodiesel production with projection to

27 There are a variety of biofuels potentially available, but the main biofuels being considered globally are biodiesel and bioethanol. Bio-ethanol can be produced from a number of crops including sugarcane, corn (maze), wheat and sugar beet. Biodiesel is the fuel that can be produced from straight vegetable oils, edible and non-edible, recycled waste vegetable oils, and animal fat. The main producing countries for transport biofuels are the USA, Brazil, and the EU. Production in the United States was mostly ethanol from corn, in Brazil was ethanol from sugar cane, and in the European Union was mostly biodiesel from rapeseed. Figure 5.1.3: Biodiesel Production Cycle ( 16 Figure shows the Biodiesel production Cycle, solar energy and carbon dioxide along with other inputs are used to grow crops that are in turn harvested and processed. As an example, soybeans are crushed to produce oil that is the basic material to be turned into biodiesel. The production process forces the vegetable oil to react with a catalyst to produce fatty acid esters, the chemical name for biodiesel. The fuel is then used in existing vehicles which also produce carbon dioxide. 17

28 Figure 4.1.5: Ethanol Production Cycle ( 17 Figure shows Ethanol Production Cycle, Ethanol supporters say that its production and consumption are carbon-neutral. Crops like corn are finely ground and separated into their component sugars. The sugars are distilled to make ethanol, which can be used as an alternative fuel, which releases carbon dioxide that is reabsorbed by the original crops. 18

29 5.2 Biofuel generation Biofuels for transport are commonly addressed according to their current or future availability as first, second or third generation biofuels (OECD/ IEA 2008). Second and third generation biofuels are also called advanced biofuels. First-generation biofuels are commercially produced using conventional technology. The basic feedstocks are seeds, grains, or whole plants from crops such as corn, sugar cane, rapeseed, wheat, sunflower seeds or oil palm. These plants were originally selected as food or fodder and most are still mainly used to feed people. The most common first-generation biofuels are bioethanol (currently over 80% of liquid biofuels production by energy content), followed by biodiesel, vegetable oil, and biogas. Second-generation biofuels can be produced from a variety of non-food sources. These include waste biomass, the stalks of wheat, corn stover, wood, and special energy or biomass crops (e.g. Miscanthus). Second-generation biofuels use biomass to liquid (BtL) technology, by thermo chemical conversion (mainly to produce biodiesel) or fermentation (e.g. to produce cellulosic ethanol).many second-generation biofuels are under development such as biohydrogen, biomethanol, DMF, Bio-DME, Fischer-Tropsch diesel, biohydrogen diesel, and mixed alcohols. Third-generation biofuel: Algae fuel, also called oilgae, is a biofuel from algae and addressed as a third-generation biofuel (OECD/IEA 2008). Algae are feedstocks from aquatic cultivation for production of triglycerides (from algal oil) to produce biodiesel. The processing technology is basically the same as for biodiesel from second-generation feedstocks. Other third -generation biofuels include alcohols like bio-propanol or bio-butanol, which due to lack of production experience are usually not considered to be relevant as fuels on the market before 2050 (OECD/IEA 2008), though increased investment could accelerate their development. The same feedstocks as for first-generation ethanol can be used, but using more sophisticated technology. Propanol can be derived from chemical processing such as dehydration followed by hydrogenation. As a transport fuel, butanol has properties closer to gasoline than bioethanol. 19

30 Table 5.2: An Overview of the product biofuel, per generation type ( 18 Own elaboration, primarily based on Current use of biofuels for transport on the global scale is dominated by bioethanol and biodiesel, whereas the use of other biofuels for transport like biogas and pure plant oil seem to be restricted to local and regional pilot cases, and second-generation biofuels are still in the development stage. Commercial investment in advanced (second-generation) biofuel plants is beginning in Canada, Germany, Finland, Japan, the Netherlands, Sweden, and the United States (REN ; EEA 2008a,b). 20

31 Figure 5.2: The World s and EU s biofuel consumption 21

32 Chapter 6 Biodiesel production 6.1 What is Biodiesel In the most general sense, biodiesel refers to any diesel fuel substitute derived from renewable biomass. More specifically, biodiesel is defined as an oxygenated, sulfur-free, biodegradable, non-toxic, and eco-friendly alternative diesel oil. Chemically, it can be defined as a fuel composed of mono-alkyl esters of long chain fatty acids derived from renewable sources, such as vegetable oil, animal fat, and used cooking oil designated as B100, and also it must meet the special requirements such as the ASTM and the European standards. For these to be considered as viable transportation fuels, they must meet stringent quality standards. One popular process for producing biodiesel is transesterification. Biodiesel is made from a variety of natural oils such as soybeans, rapeseeds, coconuts, and even recycled cooking oil. Rapeseed oil dominates the growing biodiesel industry in Europe. In the United States, biodiesel is made from soybean oil because more soybean oil is produced in the United States than all other sources of fats and oil combined. (19) The injection and atomization characteristics of the vegetable oils are significantly different than those of petroleum derived diesel fuels, mainly as the result of their high viscosities. Modern diesel engines have fuel-injection system that is sensitive to viscosity change. One way to avoid these problems is to reduce fuel viscosity of vegetable oil in order to improve its performance. The conversion of vegetable oils into biodiesel is an effective way to overcome all the problems associated with the vegetable oils. Dilution, micro emulsification, pyrolysis, and transesterification are the four techniques applied to solve the problems encountered with the high fuel viscosity. Transesterification is the most common method and leads to mono alkyl esters of vegetable oils and fats, now called biodiesel when used for fuel purposes. The methyl ester produced by transesterification of vegetable oil has a high cetane number, low viscosity and improved heating value compared to those of pure vegetable oil which results in shorter ignition delay and longer combustion duration and hence low particulate emissions. 22

33 6.2 History of Biodiesel Dr. Rudolf Diesel invented the diesel engine to run on a host of fuels including coal dust suspended in water, heavy mineral oil, and, vegetable oils. Dr. Diesel s first engine experiments were catastrophic failures, but by the time he showed his engine at the World Exhibition in Paris in 1900, his engine was running on 100% peanut oil. Dr. Diesel (Fig. 14) was visionary. In 1911 he stated the diesel engine can be fed with vegetable oils and would help considerably in the development of agriculture of the countries, which use it. In 1912, Diesel said, the use of vegetable oils for engine fuels may seem insignificant today. But such oils may become in course of time as important as petroleum and the coal tar products of the present time. Since Dr. Diesel s untimely death in 1913, his engine has been modified to run on the polluting petroleum fuel, now known as diesel. Nevertheless, his ideas on agriculture and his invention provided the foundation for a society fueled with clean, renewable, locally grown fuel. In the 1930s and 1940s, vegetable oils were used as diesel substitutes from time to time, but usually only in emergency situations. Recently, because of increase in crude oil prices, limited resources of fossil oil and environmental concerns, there has been a renewed focus on vegetable oils and animal fats to make biodiesel. Continued and increasing use of petroleum will intensify local air pollution and magnify the global warming problems caused by carbon dioxide. In a particular case, such as the emission of pollutants in the closed environment of underground mines, biodiesel has the potential to reduce the level of pollutants and the level of potential for probable carcinogens. Figure 6.2: Dr. Rudolf Diesel 23

34 6.2 The advantages of using vegetable oils as fuels Vegetable oils are liquid fuels from renewable sources; they do not over-burden the environment with emissions. Vegetable oils have potential for making marginal land productive by their property of nitrogen fixation in the soil. Their production requires lesser energy input in production. They have higher energy content than other energy crops like alcohol. They have 90% of the heat content of diesel and they have a favorable output/input ratio of about 2 4:1 for un-irrigated crop production. The current prices of vegetable oils in world are nearly competitive with petroleum fuel price. Vegetable oil combustion has cleaner emission spectra and simpler processing technology. But these are not economically feasible yet and need further R&D work for development of on farm processing technology. Due to the rapid decline in crude oil reserves, the use of vegetable oils as diesel fuels is again promoted in many countries. Depending up on climate and soil conditions, different nations are looking into different vegetable oils for diesel fuels. For example, soybean oil in the USA, rapeseed and sunflower oils in Europe, palm oil in Southeast Asia(mainly Malaysia and Indonesia), and coconut oil in Philippines are being considered as substitutes for mineral diesel. An acceptable alternative fuel for engine has to fulfill the environmental and energy security needs without sacrificing operating performance. Vegetable oils can be successfully used in CI engine through engine modifications and fuel modifications because Vegetable oil in its raw form cannot be used in engines. It has to be converted to a more engine-friendly fuel called biodiesel. Biodiesel has comparable energy density, cetane number, heat of vaporization, and stoichiometric air/fuel ratio with mineral diesel. The large molecular size of the component triglycerides result in the oil having higher viscosity compared with that of mineral diesel. Viscosity affects the handling of the fuels by pump and injector system, and the shape of fuel spray. 24

35 6.3 Characteristics of oils or fats affecting their suitability for use as biodiesel Calorific Value, Heat of Combustion Heating Value or Heat of Combustion, is the amount of heating energy released by the combustion of a unit value of fuels. One of the most important determinants of heating value is moisture content. Air-dried biomass typically has about 15-20% moisture, whereas the moisture content for oven-dried biomass is negligible. Moisture content in coals varies in the range 2-30%. However, the bulk density of most biomass feedstocks is generally low, even after densification between about 10 and 40% of the bulk density of most fossil fuels. Liquid biofuels however have bulk densities comparable to those for fossil fuels. Melt Point or Pour Point - Melt or pour point refers to the temperature at which the oil in solid form starts to melt or pour. In cases where the temperatures fall below the melt point, the entire fuel system including all fuel lines and fuel tank will need to be heated. Cloud Point - The temperature at which an oil starts to solidify is known as the cloud point. While operating an engine at temperatures below oil s cloud point, heating will be necessary in order to avoid waxing of the fuel. Flash Point - The flash point temperature of a fuel is the minimum temperature at which the fuel will ignite (flash) on application of an ignition source. Flash point varies inversely with the fuel s volatility. Minimum flash point temperatures are required for proper safety and handling of diesel fuel. Iodine Value - Iodine Value (IV) is a value of the amount of iodine, measured in grams, absorbed by 100 grams of a given oil. Iodine value (or Iodine number) is commonly used as a measure of the chemical stability properties of different biodiesel fuels against such oxidation as described above. The Iodine value is determined by measuring the number of double bonds in the mixture of fatty acid chains in the fuel by introducing iodine into 100 grams of the sample under test and 25

36 measuring how many grams of that iodine are absorbed. Iodine absorption occurs at double bond positions - thus a higher IV number indicates a higher quantity of double bonds in the sample, greater potential to polymerize and hence lesser stability. Viscosity Viscosity refers to the thickness of the oil, and is determined by measuring the amount of time taken for a given measure of oil to pass through an orifice of a specified size. Viscosity affects injector lubrication and fuel atomization. Fuels with low viscosity may not provide sufficient lubrication for the precision fit of fuel injection pumps, resulting in leakage or increased wear. Fuel atomization is also affected by fuel viscosity. Diesel fuels with high viscosity tend to form larger droplets on injection which can cause poor combustion, increased exhaust smoke and emissions. Cetane Number - Is a relative measure of the interval between the beginning of injection and auto ignition of the fuel. The higher the cetane number, the shorter the delay interval and the greater its combustibility. Fuels with low Cetane Numbers will result in difficult starting, noise and exhaust smoke. In general, diesel engines will operate better on fuels with Cetane Numbers above 50. Cetane tests provide information on the ignition quality of a diesel fuel. Research using cetane tests will provide information on potential tailoring of vegetable oil-derived compounds and additives to enhance their fuel properties. Density Is the weight per unit volume. Oils that are denser contain more energy. For example, petrol and diesel fuels give comparable energy by weight, but diesel is denser and hence gives more energy per liter. The aspects listed above are the key aspects that determine the efficiency of a fuel for diesel engines. There are other aspects/characteristics which do not have a direct bearing on the performance, but are important for reasons such as environmental impact etc. These are: Ash Percentage - Ash is a measure of the amount of metals contained in the fuel. High concentrations of these materials can cause injector tip plugging, combustion 26

37 deposits and injection system wear. The ash content is important for the heating value, as heating value decreases with increasing ash content. Ash content for bio-fuels is typically lower than for most coals, and sulphur content is much lower than for many fossil fuels. Unlike coal ash, which may contain toxic metals and other trace contaminants, biomass ash may be used as a soil amendment to help replenish nutrients removed by harvest. Sulfur Percentage - The percentage by weight, of sulfur in the fuel Sulfur content is limited by law to very small percentages for diesel fuel used in on-road applications. (20) 6.5 Review of biodiesel feedstocks In general, biodiesel feedstock can be categorized into three groups: vegetable oils (edible or non-edible oils), animal fats, and used waste cooking oil including triglycerides. But also a variety of oils can be used to produce biodiesel, algae, which can be grown using waste materials such as sewage and without displacing land currently used for food production and oil from halophytes such as salicornia bigelovii, which can be grown using saltwater in coastal areas where conventional crops cannot be grown, with yields equal to the yields of soybeans and other oilseeds grown using freshwater irrigation. Many advocates suggest that waste vegetable oil is the best source of oil to produce biodiesel, but since the available supply is drastically less than the amount of petroleumbased fuel that is burned for transportation and home heating in the world; this local solution does not scale well. (21) 27