ABSTRACT
Biodiesel was produced from Avocado (Persea Americana) pulp oil by trans esterification with methanol and ethanol (6:1 methanol/ethanol-to-oil ratio) using 0.09% sodium hydroxide as catalyst in 60 minutes reaction time. The percentage yield of the methyl ester was 78% while that of the ethyl ester yield was 66%. Avocado pulp oil (APO) biodiesel obtained in each case showed good qualities on characterization with the fuel properties showing good qualities and promising diverse applications for various purposes. The brown coloured APO methyl ester was of similar acid value (0.8) with the standard ASTM D6751, with relative density (0.86) similar with that of the standard ASTM D975 petrodiesel but with slightly higher kinematic viscosity (8.1cst) than those of petrodiesel, while the ethyl ester has a higher acid value (1.26) and the relative density was 0.01 above that of petrodiesel. The pour point of the methyl ester (-40C) and that of the ethyl ester (-20C) were within the standards specified by ASTM D975 for petrodiesel and ASTM D6751 for biodiesel.
CHAPTER ONE
INTRODUCTION
There is a need for alternative energy sources to petroleum-based fuels due to the depletion of the worlds’ petroleum reserves,global warming and environmental concerns. American standard testing and materials defined biodiesel as a fuel composed of monoalkyl esters of long-chain fatty acids derived from renewable vegetable oils or animal fats and meets the requirements of ASTM 6751(ASTM, 2008). Ozone depletion,global warming,greenhouse gases concerns have promoted biodiesel as an alternative renewable and eco-friendly fuel.The concept of biofuel is notnew. Rudolph Diesel was the first to use a vegetable oil(peanut oil) in a diesel engine in 1911(Akoh et al ., 2007 ; Antczak et al., 2009). The use of biofuels in place of conventional fuels would slow the progression of global warming by reducing sulphur,carbon oxides and hydrocarbon emissions (Fjerbaek et al., 2009). Because of its high viscosity and low volatility, the direct use of vegetable oil in diesel engines can cause problems including;high carbon deposits,scuffing of engine liner,injection nozzle failure,gum formation,lubricating oil thickening,high cloud and pour point (Fukuda et al., 2001; Murugesan et al.,2009). In order to avoid these problems, the feedstock is chemically modified to its derivatives which have properties more similar to conventional diesel (Fukuda et al., 2001).Transesterification is the process by which biodiesel is produced,in this process vegetable oil reacts with an alcohol(methanol) to form methyl ester (biodiesel) and another alcohol (glycerol) with NaOH as catalyst (Pinto et al., 2005). Biodiesel can be used as a fuel for vehicles in its pure form, but it is usually used as a diesel additive to reduce levels of particulates, carbon monoxide, and hydrocarbons from diesel-powered vehicles. Biodiesel is produced from oils or fats using transesterification and is the most common biofuel in Europe.
In 2010, worldwide biofuel production reached 105 billion liters (28 billion gallons US), up
17% from 2009, and biofuels provided 2.7% of the world’s fuels for road transport, a contribution largely made up of ethanol and biodiesel. Global ethanol fuel production reached
86 billion liters (23 billion gallons US) in 2010, with the United States and Brazil as the world’s top producers, accounting together for 90% of global production. The world’s largest biodiesel producer is the European Union, accounting for 53% of all biodiesel production in
2010. As of 2011, mandates for blending biofuels exist in 31 countries at the national level and in 29 states or provinces. The International Energy Agency has a goal for biofuels to meet more than a quarter of world demand for transportation fuels by 2050 to reduce dependence on petroleum and coal.There are various social, economic, environmental and technical issues relating to biofuels production and use, which have been debated in the popular media and scientific journals. These include: the effect of moderating oil prices the “food vs fuel debate, poverty reduction potential, carbon emissions levels, sustainable biofuel production, deforestation and soil erosion loss of biodiversity and impact on water resources (Mc Carthy et al., 2011).
Biodiesel refers to a vegetable oil- or animal fat-based diesel fuelconsisting of long-chain alkyl (methyl, ethyl, or propyl) esters. Biodiesel is typically made by chemically reacting lipids(e.g., vegetable oil, animal fat (tallow) with an alcohol producing fatty acid esters (Fletcher et al., 2011). Biodiesel is meant to be used in standard diesel engines and is thus distinct from the vegetable and waste oils used to fuel converted diesel engines. Biodiesel can be used alone, or blended with petrodiesel in any proportions. Biodiesel can also be used as a low carbon alternative to heating oil (Monyem and Van Gerpen, 2001).
1.1.Blends
Blends of biodiesel and conventional hydrocarbon-based diesel are products most commonly distributed for use in the retail diesel fuel marketplace (Demirbas, 2007). Much of the world uses a system known as the “B” factor to state the amount of biodiesel in any fuel mix:
100% biodiesel is referred to as B100
20% biodiesel, 80% petrodiesel is labeled B20
5% biodiesel, 95% petrodiesel is labeled B5
2% biodiesel, 98% petrodiesel is labeled B2
Blends of 20% biodiesel and lower can be used in diesel equipment with no, or only minor modifications, although certain manufacturers do not extend warranty coverage if equipment is damaged by these blends (Friedrick, 2004). The B6 to B20 blends are covered by the ASTM D7467 specification.Biodiesel can also be used in its pure form (B100), but may require certain engine modifications to avoid maintenance and performance problems. Blending B100 with petroleum diesel may be accomplished by:
Mixing in tanks at manufacturing point prior to delivery to tanker truck
Splash mixing in the tanker truck (adding specific percentages of biodiesel and petroleum diesel)
In-line mixing, two components arrive at tanker truck simultaneously.
Metered pump mixing, petroleum diesel and biodiesel meters are set to X total volume, transfer pump pulls from two points and mix is complete on leaving pump.
1.1.1 Applications of Biodiesel
Biodiesel can be used in pure form (B100) or may be blended with petroleum diesel at any concentration in most injection pump diesel engines. New extreme high-pressure (29,000 psi) common rail engines have strict factory limits of B5 or B20, depending on manufacturer. Biodiesel has different solvent properties than petrodiesel, and will degrade natural rubber gasketsand hoses in vehicles (mostly vehicles manufactured before 1992), although these tend to wear out naturally and most likely will have already been replaced with FKM, which is nonreactive to biodiesel. Biodiesel has been known to break down deposits of residue in the fuel lines where petrodiesel has been used. As a result, fuel filters may become clogged with particulates if a quick transition to pure biodiesel is made. Therefore, it is recommended to change the fuel filters on engines and heaters shortly after first switching to a biodiesel blend (Fargione et al., 2008).
1.1.2 Distribution of Biodiesel
Since the passage of the Energy Policy Act of 2005, biodiesel use has been increasing in the United States. In the UK, the Renewable Transport Fuel Obligation obliges suppliers to include 5% renewable fuel in all transport fuel sold in the UK by 2010. For road diesel, this effectively means 5% biodiesel (B5). (Sheehan, 1998).
1.1.3 Vehicular use and manufacturer acceptance of Biodiesel
In 2005, Chrysler (then part of DaimlerChrysler) released the Jeep Liberty CRD diesels from the factory into the American market with 5% biodiesel blends, indicating at least partial acceptance of biodiesel as an acceptable diesel fuel additive. In 2007, DaimlerChrysler
indicated its intention to increase warranty coverage to 20% biodiesel blends if biofuel quality in the United States can be standardized (Muralidharan and Vasudevan, 2011). The Volkswagen Group has released a statement indicating that several of its vehicles are compatible with B5 and B100 made from rape seed oil and compatible with the EN 14214 standard. The use of the specified biodiesel type in its cars will not void any warranty.Mercedes Benz does not allow diesel fuels containing greater than 5% biodiesel (B5) due to concerns about “production shortcomings”. Any damages caused by the use of such non-approved fuels will not be covered by the Mercedes-Benz Limited Warranty.Starting in 2004, the city of Halifax, Nova Scotia decided to update its bus system to allow the fleet of city buses to run entirely on a fish-oil based biodiesel. This caused the city some initial mechanical issues, but after several years of refining, the entire fleet had successfully been converted.In 2007, McDonalds of UK announced it would start producing biodiesel from the waste oil byproduct of its restaurants. This fuel would be used to run its fleet.The 2014 Chevy Cruze Clean Turbo Diesel, direct from the factory, will be rated for up to B20 (blend of 20% biodiesel / 80% regular diesel) biodiesel compatibility (Thevenot,
2006).
1.1.4 Railway Usage of Biodiesel
Biodiesel locomotive and its external fuel tank at Mount Washington Cog RailwayBritish train operating company Virgin Trains claimed to have run the UK’s first “biodiesel train”, which was converted to run on 80% petrodiesel and 20% biodiesel.The Royal Train on 15
September 2007 completed its first ever journey run on 100% biodiesel fuel supplied by Green Fuels Ltd. His Royal Highness, The Prince of Wales, and Green Fuels managing director, James Hygate, were the first passengers on a train fueled entirely by biodiesel fuel. Since 2007, the Royal Train has operated successfully on B100 (100% biodiesel).Similarly, a
state-owned short-line railroad in eastern Washington ran a test of a 25% biodiesel / 75% petrodiesel blend during the summer of 2008, purchasing fuel from a biodiesel producer sited along the railroad tracks. The train will be powered by biodiesel made in part from canola grown in agricultural regions through which the short line runs.Also in 2007, Disneyland began running the park trains on B98 (98% biodiesel). The program was discontinued in
2008 due to storage issues, but in January 2009, it was announced that the park would then be running all trains on biodiesel manufactured from its own used cooking oils. This is a change from running the trains on soy-based biodiesel.In 2007, the historic Cog Railways added the first biodiesel locomotive to its all-steam locomotive fleet. The fleet has climbed up the Mount Washington in NewHampshire since 1868 with a peak vertical climb of 37.4 degrees.On 8th July 2014, Indian Railway Minister announced in Railway Budget that 5% bio-diesel will be used in Indian Railways’ Diesel Engines (Chen et al., 2013).
1.1.5 Aircraft usage of Biodiesel
A test flight has been performed by a Czech jet aircraft completely powered on biodiesel. Other recent jet flights using biofuel, however, have been using other types of renewable fuels.On November 7, 2011 United Airlines flew the world’s first commercial aviation flight on a microbially derived biofuel using Solajet™, Solazyme’s algae-derived renewable jet fuel. The Eco-skies Boeing 737-800 plane was fueled with 40 percent Solajet and 60 percent petroleum-derived jet fuel. The commercial Eco-skies flight 1403 departed from Houston’s IAH airport at 10:30 and landed at Chicago’s ORD airport. December 2008, Air New Zealand, Boeing 747 Jatropha completed a two hour test flight using a 50-50 mixture, the engine was then removed to be scrutinized and studied to identify any differences between jatropha blend and regular Jatropha, no effect to performance were found (Bailis and Baka,
2010).
1.1.6 Cleaning of Oil Spills
With 80-90% of oil spill costs invested in shoreline clean-up, there is a search for more efficient and cost-effective methods to extract oil spills from the shorelines.Biodiesel has displayed its capacity to significantly dissolve crude oil, depending on the source of the fatty acids (Zhang et al., 1998). In a laboratory setting, oiled sediments that simulated polluted shorelines were sprayed with a single coat of biodiesel and exposed to simulated tides. Biodiesel is an effective solvent to oil due to its methyl ester component, which considerably lowers the viscosity of the crude oil. Additionally, it has a higher buoyancy than crude oil, which later aids in its removal. As a result, 80% of oil was removed from cobble and fine sand, 50% in coarse sand, and 30% in gravel. Once the oil is liberated from the shoreline, the oil-biodiesel mixture is manually removed from the water surface with skimmers. Any remaining mixture is easily broken down due to the high biodegradability of biodiesel, and the increased surface area exposure of the mixture (DeMello et al., 2007).
1.2 Biodiesel in Generators
Biodiesel is also used in rental generators, In 2001 University of California Riverside installed a 6-megawatt backup power system that is entirely fueled by biodiesel. Backup diesel-fueled generators allow companies to avoid damaging blackouts of critical operations at the expense of high pollution and emission rates. By using B100, these generators were able to essentially eliminate the byproducts that result in smog, ozone, and sulfur emissions. The use of these generators in residential areas around schools, hospitals, and the general
public result in substantial reductions in poisonous carbon monoxide and particulate matter (Tippayawong et al., 2002).
1.2.1 Fuel efficiency of Biodiesel
Biodiesel will have a varying amount of power output depending on its blend, quality, and load conditions under which the fuel is burnt. The thermal efficiencyfor example of B100 as compared to B20 will vary due to the BTUcontent of the various blends. Thermal efficiency of a fuel is based in part on fuel characteristics such as: viscosity, specific density, and flash point; these characteristics will change as the blends as well as the quality of biodiesel varies. The American Society for Testing and Materials has set standards in order to judge the quality of a given fuel sample (Wang et al., 2007).A study on the brake thermal efficiency of varied biodiesel blends were tested under a series of load conditions as well as compression ratios. A part of the trial was comparing the thermal efficiency of B40 to traditional petrodiesel, as well as varying blends of biodiesel; as a result it was found that B40 performed at greater levels of efficiency over its traditional counterpart at higher compression ratios (this higher brake thermal efficiency was recorded at compression ratios of 21:1). It was noted that as the compression ratios increased the efficiency of all fuel types as well as blends being tested increased; though it was found that a blend of B40 was the most economical at a compression ratio of 21:1 over all other blends. The study implied that this increase in efficiency was due to fuel density, viscosity, and heating values of the fuels (Jessica, 2012).
1.2.2 Combustion of Biodiesel
Fuel systems in modern diesel engine were not designed to accommodate biodiesel. Traditional direct injection fuel systems operate at roughly 3,000 psi at the injector tip while the modern common railfuel system operates upwards of 30,000 psi at the injector tip (Monyem and Van Gerpen, 2001). Components are designed to operate at a great temperature range, from below freezing to over 378 0C. Diesel fuel is expected to burn efficiently and produce as few emissions as possible. As emission standards are being introduced to diesel engines the need to control harmful emissions is being designed into the parameters of diesel engine fuel systems. The traditional inline injection system is more forgiving to poorer quality fuels as opposed to the common rail fuel system. The higher pressures and tighter tolerances of the common rail system allows for greater control over atomization and injection timing. This control of atomization as well as combustion allows for greater efficiency of modern diesel engines as well as greater control over emissions. Components within a diesel fuel system interact with the fuel in a way to ensure efficient operation of the fuel system and so the engine. If a fuel is introduced to a system that has specific parameters of operation and you vary those parameters by an out of specification fuel you may compromise the integrity of the overall fuel system. Some of these parameters such as spray pattern and atomization are directly related to injection timing (Ryan et al., 1984). One study looked at these characteristics of biodiesel in a fuel system. It was found that during atomization biodiesel and its blends produced droplets that were greater in diameter than the droplets produced by traditional petrodiesel. The smaller droplets were attributed to the lower viscosity and surface tension of traditional petrol. It was found that droplets at the periphery of the spray pattern were larger in diameter than the droplets at the center which was attributed to the faster pressure drop at the edge of the spray pattern; there was a proportional relationship between the droplet size and the distance from the injector tip. It was found that B100 had the greatest spray penetration, this was attributed to the greater density of B100. Having a greater droplet size can lead to; inefficiencies in the combustion, increased emissions, and decreased horse power. In another study it was found that there is a short
injection delay when injecting biodiesel. This injection delay was attributed to the greater viscosity of biodiesel. It was noted that the higher viscosity and the greater cetane rating of biodiesel over traditional petrodiesel lead to poor atomization, as well as mixture penetration with air during the ignition delay period. Another study noted that this ignition delay may aid in a decrease of Noxemission (Wang et al., 2006).
1.2.3 Emissions
There are a number of emissions that are inherent to the combustion of diesel fuels that are regulated by the Environmental Protection Agency, E.P.A. As these emissions are a byproduct of the combustion process in order to ensure E.P.A. compliance a fuel system must be capable of controlling the combustion of fuels as well as the mitigation of emissions. There are a number of new technologies that are becoming phased in order to control the production of diesel emissions. The exhaust gas recirculation system, E.G.R., and the diesel particulate filter, D.P.F., are both designed to mitigate the production of harmful emissions. While studying the effect of biodiesel on a D.P.F. it was found that though the presence of sodium and potassium carbonates aided in the catalytic conversion of ash, as the diesel particulates are catalyzed, they may congregate inside the D.P.F. and so interfere with the clearances of the filter. This may cause the filter to clog and interfere with the regeneration process. In a study on the impact of E.G.R. rates with blends of jathropa biodiesel it was shown that there was a decrease in fuel efficiency and torque output due to the use of biodiesel on a diesel engine designed with an E.G.R. system. It was found that CO and CO2emissions increased with an increase in exhaust gas recirculation but NOx levels
decreased. The opacity level of the jathropa blends was in an acceptable range, where
traditional diesel was out of acceptable standards. It was shown that a decrease in NOx emissions could be obtained with an E.G.R. system. This study showed an advantage over traditional diesel within a certain operating range of the E.G.R. system (EPA, 2002).
1.2.4 Material Compatibility of Biodiesel
Plastics: High density polyethylene (HDPE) is compatible but polyvinyl chloride
(PVC) is slowly degraded. Polystyrene is dissolved on contact with biodiesel.
Metals: Biodiesel (like methanol) has an effect on copper-based materials (e.g. brass), and it also affects zinc, tin, lead, and cast iron. Stainless steels (316 and 304) and aluminum are unaffected.
Rubber: Biodiesel also affects types of natural rubbers found in some older engine components. Studies have also found that fluorinated elastomers (FKM) cured with peroxide and base-metal oxides can be degraded when biodiesel loses its stability caused by oxidation. Commonly used synthetic rubbers FKM- GBL-S and FKM- GFS found in modern vehicles were found to handle biodiesel in all conditions (Singh et al., 2012).
This material content is developed to serve as a GUIDE for students to conduct academic research
COMPARATIVE PROPERTIES OF THE METHYL AND ETHYL ESTERS PRODUCED FROM AVOCADO (PERSEA AMERICANA) PULP OIL
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