51384 The World Bank Asia Sustainable and Alternative Energy Program Pacific Islands CoConuT oIl PoWEr GEnErATIon: A how-to guide for small stationary engines December 2009 Cover Photos © M. Carr except front middle photo © S. Rigby The findings, interpretations, and conclusions expressed in this report are entirely those of the authors and should not be attributed in any manner to the World Bank, or its affiliated organizations, or to members of its board of executive directors or the countries they represent. The World Bank does not guarantee the accuracy of the data included in this publication and accepts no responsibility whatsoever for any consequence of their use. The boundaries, colors, denominations, and other information shown on any map in this volume do not imply on the part of the World Bank Group any judgment on the legal status of any territory or the endorsement or acceptance of such boundaries. Contents Acknowledgments .......................................................................................................................v Introduction .................................................................................................................................vi The Quick Guide ..........................................................................................................................1 The Diesel Engine ........................................................................................................................2 History: It Started with Peanut Oil ...................................................................................................................................2 Fueling the Engine: Diesel Fuel versus Coconut Oil ........................................................................................................2 Diesel Engine Basics .......................................................................................................................................................3 Combustion System .................................................................................................................................................4 Injection Pump .........................................................................................................................................................5 Coconut Oil as Fuel......................................................................................................................7 The Main Issues ..............................................................................................................................................................7 Incomplete Combustion ...........................................................................................................................................7 Higher Viscosity ........................................................................................................................................................8 Other Issues ....................................................................................................................................................................9 Solidification Temperature.........................................................................................................................................9 Filter Blockage ..........................................................................................................................................................9 Carbon Deposits .....................................................................................................................................................10 Deterioration of Lubrication Oil ..............................................................................................................................10 Distribution Pump Issues .......................................................................................................................................10 Options for Using Coconut Oil .................................................................................................11 Unmodified Engine Using 100 Percent Coconut Oil ...................................................................................................... 11 Adapt Engine and Use 100 Percent Coconut Oil ........................................................................................................... 11 Two-Tank System....................................................................................................................................................12 Two-Tank System and Heat Exchanger...................................................................................................................12 Fuel Blends ....................................................................................................................................................................14 Contents iii Adapting an Engine for Coconut Oil ........................................................................................15 Essentials ......................................................................................................................................................................15 Dual-Tank System ..........................................................................................................................................................15 Dual-Tank and Heat Exchanger System .........................................................................................................................16 Looped Fuel Return .......................................................................................................................................................16 Bleeding the Fuel Line ...................................................................................................................................................17 Hoses and Fittings .........................................................................................................................................................18 Engine Operation and Maintenance ........................................................................................19 Adapted Usage Pattern: The Right Load ........................................................................................................................19 Maintenance Program ...................................................................................................................................................20 Oil Production, Processing, and Quality ..................................................................................21 Minimills ........................................................................................................................................................................21 Feedstock Preparation ............................................................................................................................................21 Oil Extraction ..........................................................................................................................................................21 Filtration..................................................................................................................................................................23 Hand Presses ................................................................................................................................................................25 Feedstock Preparation ............................................................................................................................................25 Oil Extraction ..........................................................................................................................................................26 Filtering...................................................................................................................................................................26 Oil Quality ......................................................................................................................................................................26 Total Solid Particles.................................................................................................................................................27 Water Content ........................................................................................................................................................27 Free Fatty Acids ......................................................................................................................................................28 Storage and Handling Options .......................................................................................................................................28 By-Products ...................................................................................................................................................................29 Appendix 1: Analyze Your Free Fatty Acids: The Titration Test .............................................30 Utensils and Ingredients ................................................................................................................................................30 Step-by-Step Titration.....................................................................................................................................................30 Appendix 2: Coconut Oil Statistics ...........................................................................................31 iv Contents Appendix 3: Equipment and Suppliers ....................................................................................32 Oil Processing Equipment .............................................................................................................................................32 Chinese Equipment ................................................................................................................................................32 Indian Equipment ...................................................................................................................................................33 Other Equipment Providers ....................................................................................................................................34 Country Suppliers ..........................................................................................................................................................35 Papua New Guinea (PNG).......................................................................................................................................35 Fiji ...........................................................................................................................................................................36 The Solomon Islands ..............................................................................................................................................37 Vanuatu...................................................................................................................................................................38 References ..................................................................................................................................39 Figures 1 The Quick Guide to Running a Diesel Engine on Coconut Oil ................................................................................1 2 Diesel molecule ......................................................................................................................................................3 4 Diesel four-stroke cycle...........................................................................................................................................3 3 Vegetable oil molecule............................................................................................................................................3 5 Fuel delivery system of a diesel engine..................................................................................................................4 6 Direct injection........................................................................................................................................................5 7 Indirect injection .....................................................................................................................................................5 8 Viscosity of coconut oil and diesel blends over a range of temperatures...............................................................8 9 Two-tank system and heat exchanger ..................................................................................................................12 10 Series of cascading settling tanks ........................................................................................................................24 Tables 1 Characteristics of Diesel Fuel, Coconut Oil, and Rapeseed (Multiple Referees) ....................................................2 2 Quality Standard for Rapeseed Oil .......................................................................................................................27 A.1 Quality Standard for Rapeseed Oil .......................................................................................................................31 Acknowledgments This guide was written by Matt Carr, World Bank Consultant, and was funded by ASTAE as part of the World Bank Sustainable Energy Financing Program. The author would like to acknowledge the support of the PNG Sustainable Development Program and the assistance of Peter Lynch (of Pelena Energy), Jan Cloin (formerly of SOPAC), Matthias Horn, and Daniel Fürstenwerth in researching, preparing, and peer-reviewing this manual. Contents v Introduction This "how-to" guide will assist anyone interested in run- Most standard diesel engines will run on vegetable oil, ning small, stationary diesel-powered engines on coco- but the key issue for the engine here is: for how long will nut oil. It provides you with relevant information on every it run? A good diesel engine that is well maintained can aspect of fueling an engine with coconut oil. provide tens of thousands of hours of operation, but the "pour-it-in-and-go" method has the potential to reduce The guide specifically describes small (less than about that to just tens of hours. Conversely, an overly sophisti- 50 kilovolt-amperes [kVA]) diesel generators in a station- cated system may not be appropriate if there is no way ary position. Although the information and principles to source spare parts or technical assistance. given in this guide can be applied to all diesel engines, it is intended only for stationary applications--ones that In this guide, we will try to strike a balance between typically involve few stop/starts, long running times, and these two approaches ("pour-it-in" and sophisticated), consistent loads. You must consider additional complicat- the goal being to develop a practical solution. We want ing factors when applying the information and principles a system that: to a vehicle, for example. Diesel engines that stop/start regularly and unpredictably (for example, a car engine or · Will work, a backup generator) are outside the scope of this guide. · Will not adversely damage the engine, · Is manageable, The technical considerations for running a diesel engine · Is suitable for the specific situation, and on coconut oil--or any vegetable oil, for that matter-- · Is as simple as possible. are not particularly complex. The concept of powering a diesel engine with vegetable oil is, after all, as old as To fuel an engine with coconut oil, we need to consider the diesel engine itself. To do it successfully, however-- a number of interdependent factors. These mostly relate particularly with today's modern diesel engines--several to the type of engine being used, but also include how key elements of the fuel delivery and combustion sys- it is used and such local conditions as temperature. To tem must be "just right" or made so. If they are not suit- develop a solution for any given situation, it is important able, the engine will be damaged, ultimately leading to to understand the impact of these variables. The follow- premature engine failure. ing sections and chapters will provide some necessary background, including the relevant aspects of the diesel A significant amount of material about running vegetable engine system and the theory of running an engine on oils in diesel engines is available. Recommendations coconut oil. about how to go about this are as varied as the types of oils and engines themselves, ranging from to the "pour-it-in-and-go" method to sophisticated conversion systems. vi Coconut-Oil Power Generation: A How-to Guide for Small Stationary Engines The Quick Guide Whether a diesel engine requires conversion to be successfully operated on coconut oil is typically deter- mined by a few key factors relating to the engine. This Quick Guide aims to give you a quick snapshot of the key factors that influence running a diesel engine on coconut oil. It steps you through the four main consider- ations when assessing the suitability of an engine for coconut oil and what adaptation measures are required to successfully operate an engine on coconut oil. Figure 1: The To running a diesel engine on coconuT oil Use coconut oil only if 75 percent Direct injection Coconut oil not What combustion system? load can be guaranteed at ALL times. recommended in most cases Full conversion necessary. Indirect injection Rotary Rotary Lucas/CAV pumps have a Lucas/CAV Coconut oil not high failure rate with coconut oil. What type of fuel pump? recommended Their use is considered experimental. Full conversion necessary. In-line Rotary Bosch Minimum conversion is a dual tank. Regularly <25ºC Up to 100% coconut oil, Heat exchanger is recommended What ambient temperature? convert engine in all cases, and is necessary for rotary Bosch pumps. Usually >25ºC No Yes Up to 100% coconut oil, Only robust, older-style engines such as Historical-style engine? no conversion needed Listers should be used unmodified. The Quick Guide 1 The Diesel Engine History: It Started with Peanut Oil the past 20 years or so, engines have been optimized to run on a specific grade of diesel fuel. The diesel engine is named after Rudolf Diesel, who presented his prototype engine--running on peanut oil--at the 1900 World Exhibition in Paris. Following this, Fueling the Engine: Diesel proved that his engine could run on a range of Diesel Fuel versus Coconut Oil liquid fuels, including vegetable oils, animal fats, and gasoline. If you physically compare diesel fuel with coconut oil or, say, the vegetable oil you cook with at home, it is easy It was about this time also that new drilling technologies to understand that the two have different properties. The enabled the exploitation of cheap and plentiful petroleum most obvious one of these is that coconut oil is much fuels. Initially, these were being produced predominantly thicker, or viscous, than diesel fuel. This factor of viscos- for the lighter distillates such as gasoline. When the ity accounts for many of the main problems associated petroleum industry realized that the low-value by-prod- with using coconut oil as fuel. The other important dif- uct of this refining process could power Diesel's new ference between the two relates more specifically to engine, they capitalized on it by labeling it diesel fuel. combustion properties, in that coconut oil has a much The abundance of cheap diesel fuel ultimately caused higher ignition temperature than diesel fuel. The key the decline of using biomass-based fuels, which since physical properties are listed in table 1 (data for rapeseed then have been used only during periods of instability in oil, a very popular vegetable-oil fuel used in Europe, is the petroleum market. included for comparison). Over time, diesel engines have evolved to efficiently In its simplest form, the diesel-fuel molecule comprises burn the fossil fuel powering them. In the early days, hydrogen and carbon atoms that are linked together to they were built strong and robust to handle the broad form a single solid chain known as a paraffin, comprising range of crude distillates being produced at that time. As an average of 12 links and with a typical range of 10­16 fuel quality and standards have improved, particularly in links. In reality, the diesel-fuel molecule can come in a Table 1: characTerisTics oF diesel Fuel, coconuT oil, and rapeseed (MulTiple reFerees) specific Kinematic energy density cetane Viscosity solidification Flash iodine Fuel (MJ/kg) (kg/m3) number (cst 40°c) Temp. (°c) point (°c) Value Diesel fuel 42.6 828 40­55 2­4 -9 >62 -- Coconut oil 35.8 915 60­70 27 22­25 200­285 6­12 Rapeseed 35.0 915 38­42 38 -5 to 0 290­330 100­120 Sources: See References section, table 1. Flash Point--the autoignition temperature (at which fuel will Note: Specific Energy--the energy released when burned start to ignite) Density--the weight of fuel per unit volume Iodine Value--the fuel's chemical stability and tendency to Cetane Number--the ability to ignite when compressed polymerize (the lower, the better) (the higher, the better) MJ/kg--millions of Joules per kilogram Kinematic Viscosity--the ability of the fuel to flow and kg/m3--kilograms per cubic meter also atomize (the lower, the better) cSt--centistokes Solidification Temp.--the temperature at which the fuel °C--degrees centigrade will become solid 2 Coconut-Oil Power Generation: A How-to Guide for Small Stationary Engines Figure 2: diesel Molecule Figure 3: VegeTable oil Molecule Schematic (left) and 3D (right) representation of the diesel fuel molecule Schematic (left) and 3D (right) representation of a triglyceride molecule number of molecular orientations, displaying a range of the pressure in the chamber and forcing the piston or chemical bondings, substitutions, and inclusions that will power stroke. In contrast, gasoline engines operate by not be discussed here in more detail. spark ignition, in which fuel and air are mixed before entering the combustion chamber and ignited by a spark. Coconut oil, like all vegetable oils, predominantly com- Diesel engines contain no spark plugs, ignition coil, dis- prises hydrogen and carbon atoms that are linked tributor, or carburetor; their overall simplicity makes them together. They differ from diesel fuel, however, in that more reliable and durable than a gasoline engine. instead of forming a single chain, three chains are all linked together at one end to form something like a tri- Most diesel engines operate on a four-stroke cycle, con- pod, which is referred to as a triglyceride. sisting of two up and two down strokes of the piston and two revolutions of the crank shaft per cycle. Typically only All vegetable oils will burn and therefore have the ability very large engines, such as those in large ships, operate to be used as a diesel-fuel alternative. Different types of on a two-stroke cycle. vegetable oil, however, display very different properties, which makes some vegetable oils more suited to replacing diesel fuel than others. In this sense, coconut oil can be considered Figure 4: diesel Four-sTroKe cycle one of the best vegetable oils for use as a diesel-fuel alternative because is it made up of medium-length, saturated hydrogen and Fuel Exhaust Intake Exhaust Both Intake carbon chains, making it chemically stable injector valve valve valve valves valve and less likely to react or polymerize. It also open open closed closed closed has better combustion properties than any other vegetable oil. Diesel Engine Basics The diesel engine is an internal combustion engine that uses compression ignition to ignite the fuel injected into the combustion chamber. It does this by first compress- ing air in the combustion chamber with a piston, causing the air to become very hot. Intake Compression Power Exhaust Fuel is injected into this hot pressurized air and spontaneously combusts, increasing Most diesel engines operate on the four-stroke cycle. The Diesel Engine 3 can come in all shapes and sizes and with many Figure 5: Fuel deliVery sysTeM oF a diesel engine refinements. Some of these variants are criti- cal when running a diesel engine on coconut oil. Fuel return line The two most critical factors are the type of combustion system and the type of injection Injectors pump. Combustion System Fuel tank Fuel can be injected and combusted in two dif- ferent ways in a diesel engine: one method is to inject the fuel directly into the cylinder chamber Injector Filter Distributor pump while the other injects fuel into a precombus- pump tion chamber that is offset, but attached to the cylinder chamber. These methods are called direct injection and indirect injection. Low pressure High pressure direct injection. The prevailing type of injec- tion system in small, modern diesel engines is Fuel is delivered from the tank to the combustion cham- direct injection. It is preferred to indirect injec- ber via low-pressure and high-pressure systems. The tion because of the greater efficiency (approximately 10 low-pressure system is made up of the fuel tank, the percent), resulting from reduced heat loss. The piston fuel-distribution pump, and one or more filters. On some has a hollow in the top that contains most of the com- small engines where the fuel tank sits above the engine pressed air when the piston is at the top of the cylinder there is no distribution pump and fuel is fed by gravity during the compression cycle. Fuel is injected through and the suction created by the injection pump. The pri- a multiport injector nozzle into the piston hollow, mixes mary purpose of the low-pressure system is to deliver with the compressed air, and combusts. In direct-injec- fuel from the tank to the injection pump. tion engines, the ability of the injector to deliver a finely atomized mist of fuel is responsible for good fuel-air mix- The main components of the high-pressure system ing and complete combustion. include the injection pump and the injectors. The injec- tion pump builds up the necessary pressure to spray a Small direct-injection engines have become common only dosed amount of fuel into the combustion chamber via in the past 10 years or so. If they were run on the diesel the injector nozzles. The pump always delivers an excess fuel common 20 or more years ago, most direct-injection of fuel to the injectors, which is returned to the fuel tank engines would not have lasted very long. The variable via the return line. grade of diesel fuel back then would have impacted (over time) the spray pattern required to achieve complete Although all diesel engines are alike in that they use the combustion and started creating problems with carbon principle of combustion ignition described above, they deposits. In addition, the cooler combustion temperatures Q Which combustion system is best for coconut oil? A multitude of studies on using vegetable oils in unmodified direct-injection engines have indicated that it leads to premature engine failure. This is typically attributed to incomplete combustion of the fuel, which creates carbon deposits throughout the combustion system. However, in several cases in the Pacific, coconut oil has been successfully used in adapted direct-injection engines. Although this has been considered experimental and a risk to engine life, many reports indicate no detrimental effects in practice if certain procedures and conditions are consistently met. These include starting and stopping the engine on diesel fuel, preheating the fuel, and maintaining a consistently high load on the engine at all times. A Indirect injection is best. Direct injection is feasible only if certain adaptations to the engine are made. 4 Coconut-Oil Power Generation: A How-to Guide for Small Stationary Engines The single orifice of the pin-type injector noz- Figure 6: direcT inJecTion zle is larger than that of the multiport nozzle in direct-injection engines, making the former more suitable for crude fuels. The pin-type nozzle also has a self-cleaning effect, unlike the multiport nozzle. Injection Pump Closed Open The injection pump is responsible for deliver- Multiport injection nozzle ing high-pressure fuel to the injector nozzle. In some engines, particularly small ones that have the fuel tank raised up above the engine, the injection pump is the only pump- ing mechanism used to deliver fuel from the tank to the injector. In most engines, a dis- Figure 7: indirecT inJecTion tribution or "lifter" pump first draws the fuel from the tank to the injection pump. Injection pumps in small generator engines typically fall into one of three categories: jerk or single-cylinder pumps, in-line pumps, and rotary pumps. Electronically controlled and high-pressure pumps such as common rail or unit injection pumps are uncommon in small generator engines; however, common rail is Closed Open becoming increasingly common in automo- Pin-type injection nozzle tive and large industrial diesel engines, so this trend may change. Today's common rail injec- tion systems are not suitable for using with coconut oil, but their electronic management systems in direct-injection engines would not always have been could, in the future, allow for the use of variable fuels. high enough to completely burn all fractions of a crude diesel fuel, leading to further problems with deposits. Jerk pumps are the simplest type of injection pump and are found only indirect injection. Most older diesel engines use indirect in single-cylinder engines. They use injection. This combustion system was designed in an a piston-and-barrel-style mecha- era when fuels were crude, and as such, these engines nism to deliver fuel to the injector are generally more durable and reliable compared with via a high-pressure pipe. The piston their direct-injection counterparts. The piston head does inside a jerk pump uses a timing not have a hollow, and the air in the precombustion mechanism running from the engine camshaft. chamber gets compressed and heated. in-line pumps operate on Fuel is sprayed by a single-port, pin-type injection nozzle the same principle as jerk into a precombustion chamber adjoining the top of the pumps, but are for multi- cylinder (hence the name indirect injection). In indirect- cylinder engines. A number of injection engines, the turbulent air flow created in the jerk pumps are combined "in- precombustion chamber is responsible for fuel-air mix- line" to form a single compo- ing, leading to complete combustion. Most of the fuel nent. The pistons operating combustion takes place inside the precombustion cham- each injector use a timing mechanism running from the ber, and then the expanding gases flow into the main cyl- engine camshaft. inder chamber to drive the power stroke. The chamber is also referred to as a prechamber, swirl chamber, or turbulence chamber. The Diesel Engine 5 TIP: In-line pumps and rotary pumps can be distinguished from each other by the location of the pipes exiting the pump. With rotary pumps, the outlets are arranged in a square or circular configuration and come out of the side of the pump. The outlets on an in-line pump come out in a row across the top of the pump. rotary pumps are found on modern multicylinder Q Which injection pump is best for coconut oil? engines and use a single pumping mechanism rotat- Jerk and in-line pumps are more robust than rotary pumps ing at high speed to dis- and are suitable to use with coconut oil. Lucas/CAV tribute fuel to as many as injection pumps are susceptible to malfunctions when six cylinders. They typically running on coconut oil because of their less rug- operate at higher pres- ged construction. Successful use of these pumps is Bosch-style rotary pump sures than in-line pumps; reported, but it should be attempted only if you have to achieve this, they oper- a high degree of mechanical resources available. Great ate at very high speeds. care should be taken to ensure that the coconut oil is thoroughly filtered, heated, and/or blended before use. Rotary injection pumps are Bosch rotary pumps use a more robust mechanism and produced by a large num- can be safely run on heated or blended coconut oil. ber of manufacturers, yet most models are licensed A Jerk and in-line injection pumps are best. copies of either Bosch Bosch rotary pumps can be used with Lucas/CAV-style rotary pump coconut oil, but Lucas/CAV pumps have or Lucas/CAV. Bosch-style rotary pumps are also produced by Denso, Zexel, and high failure rates. Diesel-Kiki. Lucas/CAV-style pumps also appear under the brand names Stanadyne, Roto-Diesel, Condiesel, and Delphi. 6 Coconut-Oil Power Generation: A How-to Guide for Small Stationary Engines Coconut Oil as Fuel Most diesel engines can run on 100 percent coconut oil, at least for a short while. Tempting as it may be to sim- ply pour coconut oil into the fuel tank of your engine, this approach will probably have you shopping for a new generator in a very short space of time. However, if you have a sound understanding of the issues of using coco- nut oil and effectively manage those issues, then your coconut-powered generator can run as long than a gen- erator using diesel fuel--or even outlive it. Some of the key points regarding the type of engine were touched on in the previous section. Here we will discuss the key problems with using coconut oil and provide the neces- sary information about how to avoid them. Partially burned fuel on the cylinder walls has caused the top piston ring to stick and completely malfunction. The Main Issues producing larger fuel droplets that do not burn com- There are two fundamental issues with using coconut oil pletely, leading to more carbon buildup and escalating in a diesel engine: the problem that will eventually lead to engine failure if left unchecked. · Incomplete combustion · Viscosity If partially burned fuel makes contact with the cylinder walls, it will get picked up by the piston rings and can cause them to stick and malfunction. Also, very low com- Incomplete Combustion bustion temperatures will leave unburned fuel on the cyl- For coconut oil to burn completely, a minimum combus- inder walls that can be transferred to the engine sump tion chamber temperature of 500°C is required, com- (oil pan) either by the sweeping nature of the piston or pared with about 250°C for diesel fuel. If this minimum blown through as "blowby" because of malfunctioning is not reached, partially burned fuel will form carbon piston rings and lost compression. deposits (coking) on injector nozzles, cylinder walls, and elsewhere throughout the combustion system. Coked To achieve complete combustion using coconut oil, it injector nozzles have a strong, self-enforcing negative is critical that the engine is regularly and consistently effect. This is particularly the case for multiport injector loaded--a typical rule of thumb being about a 75 per- nozzles found in direct-injection engines, where a finely cent load. This will ensure that complete combustion is atomized fuel-spray pattern is more critical. Deposits achieved. This factor is critical if attempting to use coco- around the injector ports create an uneven spray pattern, nut oil in direct-injection engines: a load of 75 percent or more MUST be placed on the engine at all or nearly all times. In contrast, indirect-injection engines are more tolerant of underloading and have proven that they can TIP: White smoke coming out of your exhaust pipe indicates that the fuel is not combusting completely and is usually caused by the engine being under- loaded. Hold a piece of white paper or cloth over the exhaust airstream while the engine is running, and This multiport injector tip shows significant carbon buildup, which has a self-enforcing effect. check for deposits of unburned coconut oil. Coconut Oil as Fuel 7 successfully run on loads down to 50 percent. There Figure 8: ViscosiTy oF coconuT oil and diesel are three reasons for this: the precombustion chamber blends oVer a range oF TeMperaTures retains heat, assisting combustion; any partially burned fuel lines the precombustion chamber, rather than the 80 walls of the cylinder chamber, and gets blown out with 70 100 Kinematic viscosity (cST) the exhaust gases; and the single larger port of the pintail 60 injector nozzle has a self-cleaning effect and is less sus- Volume % coconut oil to diesel fuel 50 ceptible to coking. (Direct-injection engines are more sus- 80 40 ceptible to problems for the opposite of these reasons.) 30 60 20 40 20 Higher Viscosity 10 0 At 25°C, coconut oil is about 10 times more viscous than 0 0 10 20 30 40 50 60 70 80 90 100 diesel fuel. This can have two detrimental effects on the Temperature (ºC) engine: it produces an altered spray pattern of injected fuel, and it creates additional stresses on both the injec- tion pump and the distribution pump. The more viscous coconut oil will not produce as fine indicates the overall effect on viscosity as different a fuel mist as with diesel fuel, and the larger droplets blends of coconut oil and diesel fuel are heated. The do not burn as effectively. This leads to the problems of graph shows that at temperatures around 80°C, coco- incomplete combustion and deposits of carbon through- nut oil has a viscosity of about 10 centistokes (cSt)--the out the combustion system, introduced above. Multi- measurement for kinematic viscosity--which is only port injector nozzles in direct-injection engines are more twice the viscosity of diesel fuel at normal operational prone to this problem because they have smaller holes temperatures. Most diesel-engine makers specify a max- than pin-type injectors. This problem is even worse in imum fuel viscosity of 10­15 cSt, so coconut oil at 80°C very small (about 5kVA) direct-injection engines. is within the design parameters of most diesel engines at this temperature. Experience has shown that jerk and in-line injection pumps are better able to tolerate the more viscous coco- nut oil than rotary pumps, particularly those of the Lucas/ TIP: You can test the comparative viscosity of coco- CAV variety. nut oil against diesel fuel yourself by timing how long it takes for a marble or ball bearing to fall through a The viscosity of coconut oil can be reduced by two fixed vertical column of each liquid (using a tall glass methods: heating and blending. The adjacent graph tube is best). Coconut oil can be safely blended with diesel fuel in any ratio to thin the fuel. This approach is used by many practitioners during times of cooler weather as a safety measure. Others blend with a small percentage (less than 10­15 percent) of kerosene to achieve the same result, but because the cetane number of kerosene is substantially different from that of diesel fuel, it results in two separate ignitions during the ignition cycle, which is believed to stress the engine. NOTE: Cetane is a 16-carbon-chain paraffin that is used as a reference material to measure the com- bustibility of fuels: the higher the cetane number, The fuel spray pattern of a single-port pin-type fuel injector the better the combustion quality of the fuel during is detrimentally affected on the right by using more viscous fuel. compression ignition. 8 Coconut-Oil Power Generation: A How-to Guide for Small Stationary Engines Other Issues If there is water in the oil or in the fuel tank, it can emulsify with free fatty acids and form a white sticky or gummy A number of other issues can arise from using coco- residue that will block your filter. High free fatty acids nut oil. These can be broken down into the following can also react with some metals and rubber components categories: in the fuel system to produce globular residues, but this only occurs when they are in very high concentrations, · Solidification temperature indicative of very low-grade oil. (More will be discussed · Filter blockage about water and free fatty acids under Oil Quality.) · Carbon deposits · Lubrication oil deterioration Another common cause of filter blockage follows the · Distribution pump problems introduction of coconut oil into an engine that has previ- ously been operated on diesel fuel. Fuel tanks get dirty over time, particularly if the diesel fuel used has been Solidification Temperature handled multiple times and passed through dirty fuel Coconut oil solidifies within the temperature range of drums or containers. Much of this dirt will settle out in 22­25°C. At temperatures within or below this range, the base of the fuel tank. Coconut oil is about 10 percent the semisolidified to solidified oil can have a catastrophic denser by volume than diesel fuel, which means that impact on the injection pump and the distribution pump. some particles that settle out in diesel fuel will, when in coconut oil, float or become neutrally buoyant. This Heating or blending is the solution to this problem. In newly mobilized dirt will block the fuel filter following climates where temperatures commonly drop to 25°C, changeover from diesel fuel to coconut oil. To avoid this you can install a dual-tank system, so the engine can be problem, the fuel tank should be removed and thoroughly started and heated up on diesel fuel, or you can blend washed before switching over to coconut oil. with diesel fuel or kerosene to lower the solidification temperature. TIP: Remove and thoroughly clean the fuel tank before switching to coconut oil. Filter Blockage Using coconut oil as fuel can cause filter blockage for a The final common cause of filter blockage is the result variety of reasons, putting stress on the injection pump of the buildup of solid oil on the filter medium. Although and distribution pump and potentially leading to failure of coconut oil solidifies between 22°C and 25°C, a tiny per- either pump. When using coconut oil, it is important to centage of oil can precipitate out as a solid fat at tem- use a quality filter rated to 5 microns; because these can peratures above this. If you allow well-filtered coconut be expensive, you do not want to have to change them oil to stand in a glass jar for a period of two weeks or regularly. more, you can see this solid fat accumulate on the base of the jar, and if rubbed between two fingers, it readily The first step is to ensure that the oil used is of sufficient melts. The problems caused by this fat can be solved by quality (that is, prefiltered to 5 microns or less, dewa- either heating the fuel or settling the oil for a period of tered, and without an excessively high free-fatty-acid two weeks. content [free fatty acids are discussed in more detail in the section on Oil Quality in the chapter on Oil Produc- tion]). Poorly filtered oil will quickly block your engine filter with coconut particu- late matter. If the oil has been prefiltered, then the engine fuel filter merely acts as a final safety step and should not block for this reason. Carbon deposits on head of exhaust valve and inside exhaust manifold indicate incomplete combustion. Coconut Oil as Fuel 9 Carbon Deposits TIP: Monitor lubrication oil levels regularly, and if you Earlier in this chapter, we discussed how incomplete see them increasing, you know that coconut oil is combustion can lead to the formation of carbon depos- entering the engine sump. its on injector nozzles and piston rings and how this can lead to engine failure. Carbon deposits can also form in other areas of the combustion system, causing problems of the lubrication oil, increasing the wear on bearings with airflow and compression and a reduction in power and other moving engine parts. This problem is usually and further worsening the well-known problems. The symptomatic of an underloaded engine, although issues areas where this can occur include the exhaust valves with compression loss or injection timing can create the and inside the exhaust manifold itself. Deposits can form same outcome. on the valve heads so that they do not seal properly, causing compression loss, and also on the valve stems, which can lead to the valve sticking. A buildup of depos- Distribution Pump Issues its inside the exhaust system affects the required back Most distribution pumps use a diaphragm-pumping pressure and also leads to power loss. mechanism to deliver fuel from the tank to the injection pump at low pressure. These pumps are typically quite robust, but can suffer a reduced design life because of Deterioration of Lubrication Oil the higher viscosity of coconut oil. In most cases, the Deterioration of lubrication oil can occur when unburned failure rate is very low, and you can expect to get many coconut oil gets into the engine sump by being swept years of trouble-free operation before any issues arise. off the cylinder walls by the pistons or blown through Apart from ensuring that the coconut oil is completely as blowby because of malfunctioning piston rings. liquid, little can be done to negate this hazard; just accept Whereas diesel fuel evaporates out of the hot lubrica- it as one of the elevated operational risks of using coco- tion oil, coconut oil accumulates. This in turn reduces the nut oil. overall viscosity and lubricity (the "antiwear" property) 10 Coconut-Oil Power Generation: A How-to Guide for Small Stationary Engines Options for Using Coconut Oil To operate a diesel engine on coconut oil, there are four historical-style engines produced in China are based on options: the design of Changfa engines and are produced by many manufacturers. These engines have often run success- · Use an unmodified engine with 100 percent coco- fully--unmodified--on coconut oil throughout the Pacific nut oil and in Asia. The key point in choosing an engine of this · Adapt the engine and use 100 percent coconut oil style--or any other engine, for that matter--is whether · Blend coconut oil and use in either unmodified or spare parts are easily available. modified engine · Modify coconut oil chemically to produce biodiesel fuel and use in unmodified engine Adapt Engine and Use 100 Percent Coconut Oil This manual will address the first three options men- tioned above, but will not discuss further the modifica- In most situations, some form of engine modification is tion of coconut oil to form biodiesel fuel. The chemical recommended. Many adaptation technologies are avail- process called transesterification used to produce biod- able, and several companies now make conversion kits iesel fuel requires the use of a specially built reactor ves- that can be bought off the shelf or ordered through the sel and chemicals that can be difficult and expensive to Internet. These commercial kits are typically designed source and potentially unsafe to use. In any case, the for the conversion of diesel vehicles. Although these extra effort, expense, and potential for producing poor- kits (or at least parts of them) can be used on a genera- quality biodiesel fuel are not warranted in most cases in tor engine, most components either are unnecessary or relation to small stationary power systems. can be easily sourced locally and more cheaply. Because vehicle engines regularly stop and start and have varying loads, they require a more complicated conversion sys- Unmodified Engine tem than do stationary engines. Using 100 Percent Coconut Oil Adaptation technologies recommended in this manual consist of modifications to the fuel delivery system only Using an unmodified engine on 100 percent coconut oil and include the two-tank system, the two-tank system is viable in the long term only if both the engine and the and heat exchanger, and looping the fuel return. Although climate are suitable. This approach is only recommended it is possible to make changes to the cylinder, injectors, with "historical-style" engines using design principles pistons, and injection pump (for example) and to alter that are a few or more decades old. Modern-day produc- combustion timing, these measures are considered too tion of such engines is all but limited to China and India. costly and impractical for small diesel engines. Compared with their modern-day counterparts, these engines are slower, have a long bore stroke, and are fitted with a heavy flywheel. Possibly the best-recognized engines to fall into this category are those of the Lister CS series. True Lister engines have not been made since , 1987 but since then, a range of copies, commonly called Listeroids, have been produced in India under a host of different names. Most Lister (left) and Changfa (right) engines are typical of "historical-style" diesel engines. Options for Using Coconut Oil 11 injected, reducing its viscosity so it behaves more like Figure 9: Two-TanK sysTeM and heaT exchanger diesel fuel. Start/stop Coconut The heat exchanger should be placed on the coconut- tank oil tank oil fuel line before the junction with the diesel line so that diesel fuel from the start/stop tank does not pass Heat through the heat exchanger. With the heat exchanger exchanger located in this position, the coconut oil is heated before passing through the filter, reducing stress placed on the pumping system and stopping the accumulation of any Looped solid oil in the filter. fuel return Filter The most convenient heat source to use is the coolant fluid (that is, radiator water), which typically maintains a temperature above or around 80°C once the engine is up Engine to operating temperature. A suitable heat exchanger should raise the temperature of the coconut oil close to this temperature so that the viscosity of the coconut oil is approaching that of diesel fuel. The idea here is to start the engine on diesel fuel to allow the engine and coolant water heat up and then to Two-Tank System switch across to coconut oil once everything is hot. A diesel engine is particularly susceptible to damage on A number of heat exchanger varieties are appropriate for start-up when the engine is cold. The simplest and mini- this job. Commercially built varieties can be bought or mum adaptation method to counter many of these issues ordered at marine, truck, or general engineering-supply is the inclusion of a second fuel tank. The dual-tank sys- stores and generally fall into two categories: plate heat tem with a manual switching device allows the engine to exchangers and shell-and-tube heat exchangers. Alterna- be started and stopped on diesel fuel, while being domi- tively, you can make one yourself or have one made up nantly powered by coconut oil. This approach means that for you. Homemade exchangers or workshop varieties the engine is sufficiently hot before introducing coconut can be built from stainless-steel pipe (preferred), steel oil and that the fuel lines and filter are flushed with diesel pipe, or copper pipe and threaded pipe fittings (for exam- fuel before the engine is turned off. The amount of time , ple, BSP BSPT, NPT, and others) to suit connection to required for the engine to reach operating temperature is the engine. Copper is less preferred because it can react dependent on the engine, but five minutes is usually suf- with the free fatty acids in the oil. The reaction, however, ficient. To determine the time required to flush the sys- is very slow, and there are many cases where copper has tem, you can measure the time it takes from switchover been used successfully for many years without trouble. for diesel fuel to come out of the fuel return line. Two-Tank System and Heat Exchanger Adding a heat exchanger to the coconut-oil line represents an added safety measure and is recommended in all instances. A heat exchanger uses a heat source from the engine to pre- heat the coconut oil before it is Commercially made heat exchangers include plate (left) and shell-and-tube (right). 12 Coconut-Oil Power Generation: A How-to Guide for Small Stationary Engines should be attempted only on single-tank systems and as such is limited to historic-style engines or engines using indirect injection and a jerk or in-line injection pump. Using the exhaust heat is a considerably more risky option compared with using the coolant fluid. Whereas coolant fluid will maintain a consistent temperature of about 80°C, the exhaust temperature can range between 250°C and 500°C, depending on the type of engine and how much load is on the engine. TIP: When bending copper or other metal pipe, fill the pipe with fine sand before attempting to bend. This will stop the pipe from pinching and breaking. Clear the pipe using compressed air afterwards. If the coconut oil is heated above 100°C, it can cause residual water to boil off, which can damage the engine and potentially rupture the fuel line, causing a fuel hose to blow off. For these reasons, it should be attempted only if there are no other options available. It should not be used in conjunction with a dual-tank system because the coconut oil will overheat when running from the die- sel-fuel start/stop tank. If attempting this method, start Varieties of home- and workshop-made heat exchangers: Top--Homemade copper hose-in-hose with about five coils and check the temperature of the Middle--Coiled hose-in-hose by Motor Traders, Vanuatu pipe as it leaves the exhaust. If it is not hot enough, you Bottom--Shell-and-tube made by Bishop Brothers, PNG can try another winding and so on. The final option for preheating coconut oil is electric The simplest approach for small engines is to run coolant heating. Commercially made fuel heaters typically use a through a length of copper pipe adjacent to another sec- 12 volt (V) input and have a built-in upper limit of about tion of metal pipe for the fuel and insulate the two pipes 70°C. Heated fuel filters are made by a number of filter together. This is referred as the hose-on-hose method. The amount of heat transfer will depend on the length that the two pieces of pipe are in contact, which may not be effective in raising the coconut-oil temperature to the target 75­80°C. A more complicated and more effective option is to run the fuel-line pipe inside a pipe carrying coolant fluid; this is called the hose-in-hose method. There are many varia- tions of the hose-in-hose method, including coiling the pipe inside the coolant hose to increase the surface area. The longer the contact between the fuel line and the coolant fluid, the greater the heat exchange will be. If your engine is not water cooled, the alternative is to loop a section of copper pipe carrying the coconut oil around the engine exhaust pipe. This approach, however, Copper tubing coiled around the exhaust of this Lister heats the fuel to 80­90°C before it is injected. Options for Using Coconut Oil 13 manufacturers and work very well, but in the Pacific they Fuel Blends will usually need to be ordered from overseas. In-line fuel heaters can also be ordered through overseas suppliers. Coconut oil can be blended with diesel fuel in any ratio to reduce the overall viscosity of the fuel. Kerosene can Electric heaters can sometimes draw many amperes of also be used, but no more than a 15 percent blend is rec- current, sometimes close to the maximum output of the ommended because of the different combustion proper- alternator, thereby reducing the usable power available ties. Blending is most suited to situations in which an for other items. Care should also be taken to ensure that unmodified engine is being used to reduce the solidifica- any electric heater does not operate at excessively high tion temperature in times of cool weather. The use of temperatures that will char the coconut oil. Given that alcohols, petrol, surfactants, cetane improvers, solvents, most engines have an unused waste-heat source in the and other fluids should be avoided. form of coolant water that can be used to preheat the fuel, electric heating is not the preferred method of pre- In most Pacific island countries, the hot tropical weather heating fuel. means that blending is usually unnecessary (and besides, the concept of using coconut oil is primarily about not using diesel fuel). Although blending has been popular with those using coconut oil in unmodified vehicles, in stationary engines, with their predictable and consistent usage patterns, heating coconut oil is considered a more practical option to reduce viscosity. 14 Coconut-Oil Power Generation: A How-to Guide for Small Stationary Engines Adapting an Engine for Coconut Oil In the previous section, we looked at the options for If you are heating your coconut oil before it passes using coconut oil in a diesel engine. Of the few available, through the filter, you need to ensure that the filter is adapting your engine is recommended in most cases. rated for heated fuel. This should be indicated either on Three adaptation options are recommended: the filter itself or on the packaging that comes with it. The brands mentioned above typically use the same filter · Dual-tank, so the engine starts and stops on diesel medium for their fuel filters as they do for their oil filters fuel and, as such, do not have problems with heat. Low- · Dual-tank with heat exchanger, so the coconut oil is quality paper filters have been known to disintegrate with preheated before it is injected heated fuel, causing blockage and failure of the injection · Looping the fuel return to reduce stresses on the pump. injection pump The method you choose will depend on the type of TIP: Before using an unknown filter type on coconut engine you have, the ambient temperatures, and the oil, you should fully immerse the filter cartridge in level of precaution you wish to take. heated coconut oil for 24 hours to check that it does not degrade the filter material or the glues used. The most common and practical method of preheating the coconut oil is to use a coolant-heated heat exchanger (the steps required to install this system are discussed Fuel tanks get dirty over time, particularly if the diesel below). Exhaust heating is not discussed further because fuel used has been handled multiple times and passed it applies only to single-tank systems and simply involves through dirty fuel drums or containers. Much of this dirt coiling a section of copper pipe around the exhaust. Elec- will settle out in the base of the fuel tank, except with tric-heated filters and in-line heaters are not discussed some small generators, where the tank sits above the further because these methods involve merely installing engine and the fuel drains from the base of the tank. the system in-line with the fuel-supply line, in accordance with supplier instructions. As we saw in the section on Filter Blockage in the previ- ous chapter, coconut oil is about 10 percent denser by volume than diesel fuel, which means that some par- Essentials ticles that settle out in diesel fuel will float or become neutrally buoyant in coconut oil. This mobilized dirt will Before switching to coconut oil, it is essential that the block the fuel filter following changeover from diesel fuel following two measures are met: to coconut oil. To avoid this problem, the fuel tank should be removed and thoroughly washed before switching to · A quality fuel filter rated to 5 microns is installed. coconut oil. This can be done using soapy water and suc- · The fuel tank is free of dirt and/or water. cessive thorough rinses of water and then diesel fuel or coconut oil before being reinstalled. In most situations, the fuel filter should be upgraded to one rated to 5 microns and of larger capacity (about double) than the factory-supplied filter. Some manufac- Dual-Tank System turers make 12V or coolant-heated fuel filters, which are ideal for using with coconut oil. In tropical Pacific coun- In most cases when installing a dual-tank system, the tries, however, these are invariably difficult to obtain, simplest option is to use the original fuel tank as the and it is usually easier to use a standard filter and a heat coconut-oil tank and then install a small, auxiliary start/ exchanger to achieve the same result. Quality filter man- stop diesel tank. Ideally, the coconut-oil tank should be ufacturers include, but are not limited to, Racor, Baldwin, positioned above the engine, to reduce stress on the fuel Fleetguard, DAVCO, Lucas/CAV, Delphi, and Bosch. pumps, and close to the engine, to receive heat from the Adapting an Engine for Coconut Oil 15 Custom-built Dual-Tank and Heat Exchanger System coconut-oil fuel tank There are usually a number of options for tapping into the coolant-water system of your engine. You will need to decide what option is best or easiest for you, based on the engine you have. If your engine has a factory-designed coolant circuit that you can tap into, this is the simplest and most common option. In vehicles, this circuit supplies hot water to the adjustable cabin-heater unit. Most diesel engines in gen- erators larger than about 10kVA will have such a circuit, The conversion of this six-cylinder Deutz engine included the fabrication but it will be plugged off. In this case, it is simply a matter of a raised-steel coconut-oil fuel tank. of removing the plugs and plumbing into the ports. The location of these ports varies from one engine to engine. In places where temperatures drop below 25°C, another, and you may have to consult the operator's man- the radiant heat of the engine can be sufficient to ensure ual to find them. Typically, they are 3/8 inch (9.525 mm) that the coconut oil is fully liquid before the engine is in size, and one will be located somewhere around the switched across from diesel fuel. If you do not think engine head, near the outlet of the water pump, and that radiant heat is sufficient, a small U-bend of metal close to the junction for the radiator hose or somewhere pipe (preferably stainless-steel) connected to the coolant along the manifold. You can recognize it because the plug fluid can be fitted and used to heat the fuel tank. Taking will usually have a square nib on the end, rather than a these factors into consideration, you might decide that hexagonal one like most nuts. A port in this position will the original tank is not suitable for coconut oil and buy or act as the hot-feed inlet for your heat exchanger. construct a new one. The outlet from your heat exchanger will then need to feed back into the coolant system. In most cases, this TIP: If you decide to make a fuel tank, do not use should connect directly into the radiator, using a purpose- galvanized steel because the coconut oil will react built port (if there is one) or using the drainage port at the with the zinc coating. base of the radiator. Another option is to tap into the water line designed to Any sealed and vented container suitable for diesel fuel cool the lubrication oil. In many engines, an external pipe or chemical storage can be used as the start/stop diesel comes out of the engine block and runs into the junc- tank. The easiest option is to use a small tank designed tion where the oil filter screws on. Your heat exchanger for fuel (such as an old tank from a small diesel genera- can be installed in-line with this pipe. It is usually a fixed tor or lawn mower). Other examples include outboard metal pipe, and you will need to cut away a section so motor-fuel tanks or high-density polyethylene (HDPE) you can attach the heater hoses onto it. plastic containers. If none of the above options are available, another one is The start/stop tank should be bolted or braced to the to install your heat exchanger into the main radiator hose. engine or chassis or located in a suitable and secure posi- If choosing this option, the most important consideration tion. Additional fuel lines will need to be purchased or is that you do not restrict the flow of water because this acquired, along with some valves to allow the switching will put stress on the water pump and cause the engine from one fuel to another. These items should be sized to to overheat. match the original fuel lines. The switching mechanism can be fitted using either two Looped Fuel Return three-way valves or four ball valves and two T-pieces. Three-way valves are more convenient to use, but are Looping the fuel-return line back into the supply line adds more expensive and sometimes difficult to source. The another level of complication to the conversion, but helps junction where two fuel lines meet should be located reduce the stress on the injection pump. In most cases, above the fuel filter. it is considered unnecessary, but if you are attempting to 16 Coconut-Oil Power Generation: A How-to Guide for Small Stationary Engines heat exchanger engine-heater hose port (partially obscured) original fuel tank used as coconut-oil tank Two 3-way (diesel start/stop fuel-changeover valves tank not visible) This three-cylinder direct-injection Perkins engine in a 13.5kVA generator was converted with dual tank and heat exchanger. convert an engine with a Lucas/CAV injection pump, it is power from your engine and other possible causes such highly recommended. These pumps are less rugged than as a blocked filter or fuel line are not at fault, then it is others, and a looped return is one method of reducing likely that you have air in your line, and you will need to the stresses on the pump. bleed the system again. All diesel engines draw more fuel to the injector than what is actually required by the engine. The surplus fuel Bleeding the Fuel Line exits a port in the injector housing and returns back to the fuel tank via the return line. Looping the return line When you adapt your engine to run on coconut oil, you refers to splicing the return fuel back into the supply line, will invariably introduce air into the fuel-distribution sys- using a "tee" piece. The junction should be located just tem that must be bled out. The easiest way to remove before the filter. air is to manually pump fuel from the tank toward the engine and vent air at all available points along the fuel This system has two beneficial effects: it reduces the system. Most diesel engines will have a built-in primer stress on the injection pump because less fuel is drawn pump for this purpose, but if not, a squeeze-bulb pump from the tank, and it helps boost the temperature of the for an outboard motor can be fitted to the supply line coconut oil. The downside of looping the return is that coming out of the fuel tank. any air that gets into the system is not given the opportu- nity to escape. It is critical when installing a looped return Bleeding begins downstream from where air leaked that you thoroughly bleed the fuel system and ensure in and must be done in order, starting at the filter (or that all connections are airtight. If you notice reduced filters), and moving toward the injectors. In the case of Adapting an Engine for Coconut Oil 17 a two-tank modification, bleeding begins at the primary located at the top of each injector where the high-pres- filter (if there is one) and moves on to the secondary sure line connects, can be loosened with a spanner or filter. In most cases, the primary or coalescing filter will shifter, and need to be only slightly opened with a quarter not accumulate air, and you can move directly to the sec- to a half turn. Fuel will dribble out of the fitting, removing ondary filter. Either way, air can be removed from the any air with it. Once the fuel is exiting consistently and filters using the bleed screw located somewhere on the free of air bubbles, you can tighten the fitting and move top of the filter body. To do this, loosen the bleed screw on to the next injector until all have been done in the and pump fuel through, using the primer until a steady same manner. flow of fuel, without bubbles or air, exits from under the screw. While fuel is still pumping out, close and tighten Now that you have finished bleeding the fuel system, the screw. you should make a final and thorough check of all hoses and fittings along the delivery system. The most common When bleeding the fuel filters, you need to be aware that place where air enters the system is between the distri- air can get trapped in high spots along the fuel line. By bution pump and the tank, because this is where suction bending the fuel hose and progressively moving the high is taking place. Downstream from the distribution pump, spot toward the filter while you are pumping, you can the fuel is under pressure; therefore, any leaks will cause move these air pockets into the filter where they can be fuel to leak out rather than air to leak in. vented. Once the engine has been operating for an hour or so, With a two-tank system, air will need to be bled out on you should check that there is no air accumulating in the both the diesel-fuel start/stop line and the coconut-oil secondary fuel filter by slightly opening the bleed screw line. If you first bleed air out of the coconut-oil line, you on top and checking for bubbles. will then need to switch to the diesel-fuel line and repeat the above steps. Hoses and Fittings If air did not enter the system downstream of the sec- ondary filter--it usually does not with a two-tank mod- When converting an engine using any of the above meth- ification--then your work is done. Start the engine on ods, purchase extra hoses and fittings. Normal fuel hoses diesel fuel, check for leaks, run it for 10 minutes, load work fine, and brass, stainless-steel, or high-pressure the engine, switch to coconut oil, and run it for another PVC fittings can be sourced from auto- or engineering- 10 minutes or so, checking for leaks. supply stores. Try to avoid copper fittings because the free fatty acids in coconut oil can cause them to corrode. If you changed over the secondary filter or suspect that This will also happen to a lesser extent with brass, but air has entered the lines downstream of the secondary will occur only if using low-grade oil (and even then, the filter, you will also need to purge the injector pump and corrosion will take a very long time before it becomes a the injectors. Your operator's manual should indicate problem). where the injection pump's bleed screws are located and in which order you should bleed them. After bleeding the A commonly encountered problem following conversion injection pump by using the same technique as you used is air getting into the fuel line. Rubber hoses expand for the filters, move on to the injectors. and contract with changes in temperature, and install- ing a heat exchanger increases this occurrence. It is very To bleed the injectors, you need to start the engine and important to make sure that all hoses and fittings are loosen the high-pressure fuel-line fittings (not the return- fixed off properly, using hose clamps; it may be neces- line fittings) attached to each injector. These fittings are sary to coat joins with silicone to ensure airtight seals. 18 Coconut-Oil Power Generation: A How-to Guide for Small Stationary Engines Engine Operation and Maintenance Experience has shown that, on the whole, using coco- If, for example, the maximum power requirement is nut oil in engines leads to a higher incidence of adverse 10kW of a mixed inductive and resistive load, then a technical effects than occur with diesel fuel. These can generator with a capacity of 13kW would be the most be reduced to an acceptable level (that is, comparable to suitable size. Using an average power factor of 0.8, the that of diesel fuel) only if certain conditions are fulfilled. ideal capacity of the alternator would be about 16kVA These refer not only to the fuel and the engine used, but (16 × 0.8 × 0.75 = 10). also to the usage and maintenance of the engine. There will usually be occasions when an appliance or machine drawing power from the generator is turned Adapted Usage Pattern: off, reducing the total load and causing incomplete com- The Right Load bustion that may damage the engine. Continuing with our example, if an appliance drawing 4kW is turned off, Using coconut oil successfully requires extra work and a the load on the engine will drop to 6kW, which repre- strong commitment to adapt how the engine is used and sents less than 50 percent load. There are three options monitored. In an adapted usage pattern, you will be aware in this type of scenario: first, the 4kW appliance is simply of the specific requirements and issues that can arise left on even if it is not required; second, the engine is from using coconut oil, and you will be on the lookout for switched back to run on diesel fuel during times of low the telltale signs of any problems arising. If a problem is load, or third, a dummy load is used to substitute for the identified, it should be addressed immediately. This will appliance. primarily involve ensuring that the engine is sufficiently loaded at all times, but will also include other factors to A dummy load refers to any electrical load used to bring do with the operation and maintenance of the engine, the total power use up to the target load. In most cases, such as always having spare filter cartridges and fresh the dummy load has no functional purpose except to raise lubrication oil available. the load. The most suitable type of dummy load is one that offers a resistive load. This includes any appliance The most important factor in keeping a suitably high that has a heating element using electrical resistance, load on your engine is to first ensure that the genera- such as a heater, a kettle, or an incandescent lamp. tor is appropriately sized for the application. To do this, you need to add up the watt or kilowatt ratings of all If we consider our example from above again, a suitable the appliances and machines that you wish to run at the dummy load might comprise two 2kW bar heaters or four same time from the generator. This total should repre- 1kW electric-stove elements. Alternatively, a 4kW water- sent about 75 percent of the kilowatt (kW) rating of your heating unit might represent a more beneficial option generator, which is on average about 60 percent of the because it could also provide hot water for washing or kilovolt-ampere (kVA) rating of the alternator. other purposes. Other beneficial options might include a pump to irrigate or fill a header tank or a freezer unit to The difference between the kW and kVA ratings is the make ice. The main point here is that if part of the load is result of the power factor of certain appliances and removed from the generator, then an equal and alterna- machines. The power factor is the ratio of real power tive load must be used to replace it. (in watts) to apparent power (in volt-amperes). Purely resistive loads, such as heating elements and incandes- With most stationary power applications, there is usu- cent lights, have a power factor closer to 1.0, whereas ally a repeated pattern in power usage over the course inductive loads, such as electric motors and fluorescent of a day or in general operation. When you are using lights, might have a power factor of 0.6. The power fac- coconut oil as fuel, you need to become aware of these tor typically averages out at 0.8 (or 80 percent) across a patterns and develop necessary systems and habits as mixed load. part of your adapted usage pattern, whether it be switch- ing on dummy loads or switching back to diesel fuel as necessary. Engine Operation and Maintenance 19 Maintenance Program periods should be halved compared with those for diesel fuel, implying an oil and oil-filter change every The operator's service manual that comes with your 150 hours or fewer. engine should be the primary source of information · injector nozzles. Injectors should be removed, regarding the engine maintenance program. It is impor- inspected for carbon deposits, and cleaned (if nec- tant, however, to understand the added complications essary). This should be done during the 150-hour that can arise from using coconut oil as fuel and to adopt service. a more stringent maintenance program. Engine service · Valves and exhaust. Intake and exhaust valves and periods should be halved compared with those recom- the exhaust manifold should be inspected for carbon mended in the service manual, so that the engine is deposits during the engine service. serviced every 150 or fewer hours of operation. Partic- · piston rings. If engine-oil levels rise or any notice- ular care should be taken and inspection made during able carbon deposits are noted on the injectors, the period following conversion. The maintenance and valves, or exhaust, the pistons should be removed inspection program should include the following: so the piston rings can be examined and cleaned (if necessary). · Fuel filter. The fuel filter needs to be monitored more · coolant fluid. Radiator levels should be checked closely for clogging, and filter cartridges will usually regularly to check for leaks in the heat-exchanger need to be replaced more regularly than if using die- system. sel fuel. Replacement cartridges should always be available so if clogging is identified, the filter can be In addition to the above measures, one long-term user changed immediately. of coconut oil recommends running the engine for sev- · lubrication oil. Oil levels should be checked before eral hours on diesel fuel and a diesel additive between running the engine each time. If oil levels rise, then service periods. A number of commercially available die- coconut oil is entering the sump because of incom- sel additives clean the fuel-delivery system and injector plete combustion or faulty piston rings. Oil-change nozzles. 20 Coconut-Oil Power Generation: A How-to Guide for Small Stationary Engines Oil Production, Processing, and Quality Coconut oil has been produced around the Pacific for efficiency, is boiled off as steam from the heat gener- more than a century, using copra (dried coconut meat) ated during pressing, and produces water-free oil. Too and large centralized mills located in urban centers. How- much moisture in the copra can create issues with water ever, for coconut oil to be used cost-effectively as a fuel in the oil. It can also cause the copra to grow mold during in rural areas, it must be produced locally. There are two storage, reducing oil quality. practical and economical options for small- and medium- scale decentralized oil production: mechanized minimills Before the copra can be pressed in the mill, it must (using oil expellers) and hand presses. be chipped into small pieces within the range of about 1­10 millimeter (mm) cubes. This increases the surface area and makes it easier to extract a higher percentage Minimills of the oil from the flesh. A range of machines are avail- able for this purpose and are commonly called flaking Minimills operate on the same working principle common mills, disk mills, hammer mills, or specifically built copra to large commercial mills. This consists of a three-step cutters. process: feedstock preparation, oil extraction, and filtra- tion. They use copra as the feedstock and are powered Oil Extraction by electric motors or diesel engines, which themselves can be run on coconut oil. A continuous-screw press uses a reduction screw turn- ing inside a press cage to mechanically expel oil from the copra. The press cage can consist of either a barrel with Feedstock Preparation small holes, a series of bars separated by shims (washer- Copra is produced by cutting fresh nuts in half and drying like rings or wedges), or a number of adjoining disks that the coconut kernel. Drying can be carried out by various fit together with small teeth to allow the oil through. A means. The most common methods include direct-heat hopper feeds copra into the open end of the screw, and smoke drying, direct-heat smokeless drying (hot-air dry- the pressed copra meal exits the other end. An adjust- ing), and solar drying. Ideally, the copra produced should able cone or plug creates a restriction along the screw, have a moisture content within the range of 4­6 percent. causing high pressures to build up and forcing the oil out This small amount of water assists with oil-expelling through the press cage. Small disk mill of the FFC range is powered by a 3kW motor. 11kW flaking mill can process up to 1T/hour. Oil Production, Processing, and Quality 21 Crushing capacities vary according to the physical size of the press and can vary from a few kilograms per hour to several hundred kilograms per hour. Capacity is also determined by how a press is operated. Tightening the adjust- able cone and slowing the revolution speed will increase pressure and pro- duce more oil, but it will also compro- mise the throughput speed. In the end, it is up to the operator to choose how to balance the processing speed and how much residual oil remains in the meal. These are the four key considerations when choosing an oil press: · Volume of oil required, which will determine press size · Power consumption and availabil- ity of power supply (for example, three-phase, single-phase) · Serviceability, spare parts, and cus- tomer service and support · Price, both the purchase cost and running costs The quality of oil produced in this pro- cess mainly depends on the quality of the copra used. The faster the entire process from splitting the nut to extract- ing the oil, the better the oil quality will be. Oil produced from sun-dried or hot- air-dried copra is usually of higher quality than oil from smoke-dried copra, which Continuous-screw oil expellers come in a range of shapes and sizes, but all generally operate contains higher contaminant concen- on the same mechanical principle. trations in the form of particulates that can damage the engine if not filtered sufficiently. Although substandard oils will burn in die- sel engines, practical experience has shown that better- and sunflower. Hard seeds require smaller tolerances quality coconut oil will provide longer-term, trouble-free between the thickest part of the screw shaft (referred to operation of your engine. here as the knuckle) and the press cage, compared with those for coconut. When these presses are used with Oil expellers are made in many countries throughout coconut, there is not enough space between the knuckle the world. The most affordable models are made in and the cage for the coconut meal to pass through, cre- China, with Indian varieties following. (Presses made ating a bottleneck and causing the shaft to seize. (This in countries such as Germany, England, and the United problem does not occur with all Chinese presses, and States will not be discussed because of their significant with those that it does, it can be remedied relatively eas- expense.) ily. If you have or purchase a Chinese press, it is advis- able to first try using it with coconut before you attempt chinese presses to fix it using the method described below.) Many of the Chinese presses are well engineered and properly constructed, but are commonly designed to To fix a Chinese press that is seizing regularly, reduce process hard seeds such as canola, jatropha, cotton, the thickness of the knuckle by grinding off a thin layer. 22 Coconut-Oil Power Generation: A How-to Guide for Small Stationary Engines Larger presses that process more than about 100 kilo- These are the four filtration methods: grams per hour (kg/hr) of copra will usually have a double-tapered screw with two knuckles, and as such, · Settling tanks there will be two locations where grinding needs to take · Plate-pressure filters place. If your press is seizing only occasionally, you will · Filter cartridges, bags (disposable and washable) need to grind about 1­2mm from the diameter of the · Coarse filters (homemade) knuckle. In presses seizing regularly, 3­4mm should be ground from the knuckle. If you are unsure how much Because centrifuges are not considered practical for to remove, grind off less rather than more, try the press rural applications because of their significant expense, again, and then grind away more if necessary. we shall not discuss them further. Although it is possi- ble to use just one of the above methods, it is common Although this process may sound daunting, it is a rela- practice to use a combination of two, three, or all four tively simple matter and can be done using nothing more of these methods. The goal here is to develop a system than an electric grinder and a vernier caliper, which are that is practical and cost-effective; therefore, the meth- used to check the diameter. Using the caliper, check the ods chosen will depend on your personal circumstances, thickness of the knuckle, deduct the required amount location, and access to materials. (say, 2mm), and set the caliper to that diameter. Using the caliper, mark out the area on the shaft that requires settling Tanks grinding. Remove the press cage and press-cage hous- If coconut oil is allowed to stand for a period of time, ing so that the screw shaft is exposed, but still fitted the suspended particles will settle out at the base of the into the drive shaft. Start the motor so that the exposed containing vessel, leaving clean oil that can be decanted shaft rotates in place, in much the same way as if on a from the top. Large particles will drop out first, while lathe. With a steady hand, grind away the marked area, smaller particles take longer. Temperature also affects regularly checking progress with the caliper. settling rates because cooler oil is thicker and will require longer to settle. As a rule of thumb, however, it takes indian presses about two weeks for coconut oil to settle to a rating of Indian presses typically cost up to twice as much (or more) 5 microns, and a one-week settling period is the recom- as Chinese presses and are in general built no stronger mended minimum. or better. They are, however, specifically designed for pressing coconut oil, meaning that there is no need to make modifications and that general operation is easier. TIP: Two weeks of settling is usually enough to In addition, they tend to use different gear ratios, which remove all suspended particles down to 5 microns. allow them to run a smaller motor compared with that in similarly sized Chinese presses. The other benefit of settling is that it removes other non- With regard to operational performance, Indian presses solid contaminants also: Small droplets of suspended slightly outperform Chinese presses on power efficiency free water are able to coalesce and drop out, as are and general ease of use; however, Indian presses are minor concentrations of vegetable gums. The tiny frac- more expensive than Chinese presses. One important tion of fat that has a higher melting point will also drop factor in choosing a press is the ease of obtaining replace- out over two weeks of settling. ment parts. If there is a local dealer or agent selling a par- ticular type of press, it is probably best to purchase what Settling can be achieved by storing oil in single contain- he or she is selling or convince that person to import the ers for two weeks or by using a series of containers variety that you want. linked together in a "cascade" arrangement. This latter option is more suited to semicontinuous-to-continuous operations and is more effective if each successive con- Filtration tainer is larger (specifically, broader) than the tank before The most critical step in oil production relates to remov- it. If settling tanks are located outside, it is a good idea to ing all of the suspended solids from the pressed oil. paint them black so they absorb more of the heat of the These particles will act as abrasives in your engine and sun, which increases settling rates. can create blockages in the fuel-delivery system, particu- larly the injectors. There are a number of methods for Whatever method you choose, the amount of storage filtering coconut oil, but regardless of the method used, for settling needs to be sized accordingly for your opera- a final safety filtration to 5 microns should be completed. tion. For instance, if you are producing 100 liters (L) per Oil Production, Processing, ad Quality 23 Figure 10: series oF cascading seTTling TanKs Feedstock oil in Overflow Clean oil overflow Settling tank Valve Bulk clean oil out Sediment catchment tray If there is sufficient holding time, a series of cascading settling tanks is a low-cost and low-tech method of producing oil with a low-particle load. day, five days per week, you will need 1,000L (100 × outlet ports. There is usually a pressure gauge to indicate 5 × 2 weeks) of storage. For an operation of this size, when it is time to change the filter cloths. They can be 200L drums would be appropriate. For larger opera- cleaned by first scraping the bulk of the debris off the tions, water tanks (not galvanized steel, but polyethyl- cloths before washing them in hot water. ene), intermediate bulk containers (IBCs), or any other tanks suitable for chemical storage can be used. Old fuel Plate-pressure filters do not typically produce oil rated to tanks (in the range of 2,000­5,000L) can often be bought 5 microns. (The standard filter cloths are usually rated at cheaply. They make good settling or storage containers, or near 60 microns.) As sediment builds up on the cloths, but should be used only for fuel-grade oil, not for food or however, they filter to increasingly lower ratings because cosmetic oils. the sediment itself acts as a filter. All settling tanks require a drainage valve at the base to Manufacturers of screw presses usually make plate- periodically remove the sediment buildup. Ideally, tanks pressure filters to match their presses, with the two should have a sloping base so that all settled material will machines often coming in a package. Filter capacity collect immediately above the valve, allowing easy and should be slightly higher than that of the presses to allow effective drainage. for the downtime required to remove the filter cloths for cleaning. Typically, the cost of a plate-pressure Although settled oil may visibly appear clear, it should always be passed through a 5-micron safety filter before being used in an engine. Settling is not a fast method of filtering, but it is an effective, low-cost, low-energy option; it reduces filter-cartridge replacement and is suit- able to remote areas. plate-pressure Filters A plate-pressure filter allows the rapid, continuous filtra- tion of freshly pressed vegetable oil. As the name implies, these filters consist of a number of plates clamped together in a horizontal stack, with sheets of filter cloth sandwiched between them. Oil is pumped under pres- sure into the plate chambers, allowing solids to build up on the filter cloths and filtered oil to escape through the This Chinese-made plate-pressure filter can process up to 150L/hr. 24 Coconut-Oil Power Generation: A How-to Guide for Small Stationary Engines filter is about 40­60 percent compared with that of a screw press. Plate-pressure filters are generally more expensive than settling tanks, but take up less area. If the oil entering the press has a significant proportion of solids, filter-cloth changes will be regular and can become a burden. In most cases, it is advisable to coarse-filter or briefly settle the oil first to remove the larger particles before pumping it through the plate-pressure filter. As with settling tanks, filtered oil should be passed through a 5-micron safety filter before using in an engine. safety Filters Safety filters can come in a Hand presses available in the Pacific: PSS press (left), wide variety of filter mediums, Kokonut Pacific press (right) shapes, and sizes. Their pur- pose is to act as a backup to the primary filtering system to engines, such as a family-owned generator that might be ensure that the oil is filtered run for a few hours every night or so. As with minimills, to 5 microns or less before it it involves a three-step process from nut to oil. is used. Diesel-fuel filters with replaceable cartridges make Other manual methods of oil production, such as (a) suitable safety filters. It is grating and boiling or (b) grating, hand squeezing, and advisable to use in-line safety settling, are considered too inefficient to produce suffi- filters whenever filtered oil is cient quantities of coconut oil for fuel (and will not be transferred from one tank or discussed further). drum to another. Diesel-fuel filters make suitable safety filters. Feedstock Preparation homemade Filters There are many options when Fresh nuts are split in half, and the coconut flesh is making homemade filters, using a wide range of avail- grated, using either a traditional scraper blade, a hand- able filter mediums. For initial coarse filtering, for exam- operated rotary scraper, or an electric-powered scraper. ple, shade cloth or layers of shade cloth can provide a The grated coconut flesh is then dried by either laying it simple, low-cost, reusable method of removing larger out in the sun for a few hours, using a purpose-built solar particles. Other suitable materials can include old towels, dryer or a wood-fired, indirect-heat plate dryer, in which sheets, women's stockings, and flywire mesh. In loca- the shredded flesh is constantly turned and mixed on a tions where access to abundant clean sand is available, heated plate (refer to picture). The dried coconut is ready a simple sand filter can be used for anything from coarse for pressing when it feels slightly crispy to the touch and to fine filtering. The grade of filtration simply depends all but a tiny percentage of moisture is left. on the size of the sand particles, which can be graded by sieving. Hand Presses Hand presses use dried, grated coconut flesh as the feedstock. The oil produced is of a high quality and is clear, has little odor, and is generally suitable for food and cosmetic purposes. Hand pressing is a significantly cheaper option to start producing coconut oil than mini- mills; however, it is labor intensive and produces only up courtesy of SOPAC to 4L/hr. For the purpose of producing fuel, it is consid- ered practical to use only with small, intermittently run Indirect-heat plate dryer Oil Production, Processing, ad Quality 25 Traditional stool scraper Rotary hand scraper Electric scraper Oil Extraction In the Pacific region, two types of coconut hand press are available, both of which produce up to 4L/hr of coco- nut oil. One is manufactured in Papua New Guinea (PNG) by Project Support Services (PSS) and is available in Papua New Guinea and the Solomon Islands via a part- ner organization (supplier details appear at the end of this guide). It is a continuous-operation press that uses a slid- ing piston, a press cage, and an adjustable cone valve. Hundreds of such presses have been sold throughout PNG for village-based production of cooking oil, body oil, and soap. The second press is manufactured by an Australian com- pany, Kokonut Pacific, and the extraction process is called direct microexpelling (DME). DME systems have been installed throughout several Pacific island countries and Indonesia. The system is sold as a complete process- ing package (including training) and is geared toward the production of high-value food-grade oil that is purchased back and marketed by Kokonut Pacific. Because of their high-quality components, these systems are significantly more expensive than the PSS units made in PNG. Filtering Filtering options for low-volume hand-pressed oil should be kept as simple as possible. The most appropriate options include settling, homemade filters (such as sand filters), and a final safety filter using a standard 5-micron fuel filter. Oil Quality In The Diesel Engine, we looked at the inherent "charac- teristic" properties of coconut oil, such as viscosity and A simple gravity-filter system is a suitable option for filtering the low volumes of coconut oil produced by hand pressing. cetane number, alongside those of diesel and rapeseed 26 Coconut-Oil Power Generation: A How-to Guide for Small Stationary Engines oil. The "variable" properties of coconut oil, however, relate to the quality of the oil, which is in turn influenced Table 2: QualiTy sTandard For rapeseed oil by the production process, storage, and handling. Min/Max Variable property unit Value In Europe, a quality standard (DIN V 51 605) has been established for fuel-grade rapeseed oil that outlines Total contamination mg/kg max 24 upper and lower limits for various properties. The variable mg Acid value max 2 properties within this standard (listed in table 2) can be KOH/g used as a quality guide for any vegetable oil. Oxidation stability (110°C) h min 6 Phosphorus content mg/kg max 12 In the context of using coconut oil in diesel engines located in rural areas of Pacific island countries, it is unre- Magnesium and calcium content mg/kg max 20 alistic to expect that coconut oil will ever be subject to Ash content mass-% max 0.01 the necessary analyses to determine all of the above variables. For this reason, it is more appropriate to have Water content mass-% max 0.075 some "rules of thumb" that can be carried out with rela- Source: http://bloomingfutures.com/fuel_standards_for_PPO_ tive ease in a rural setting. The key variables that need to vegetable_oil.html be addressed are total solid particles, water content, and Note: Total contamination--amount of suspended particles present free-fatty-acid concentration. Acid value--free-fatty-acid content (a value of 2 is approximately equivalent to 1 percent) Oxidation stability--measure of oil's propensity to oxidize or degrade Phosphorus content--amount of phospholipids NOTE: The three key factors with regard to oil Magnesium and calcium content--measure of alkali content quality are total solid particles, water content, and Ash content--proportion of inorganic solids free fatty acids. Water content--proportion of water in the oil mg--milligram(s) kg--kilogram KOH--potassium hydroxide g--gram Total Solid Particles h--hour mass-%--percentage of entire amount Solid particles in the oil can be small particles of coconut flesh, dust, carbon from smoked copra, rust from an old drum, and so forth. Any of these can cause obstructions will have settled out. Heat encourages water to settle, as in the fuel-supply system, lead to abrasions in the injec- it does for solid particles, and it is beneficial for settling tion system, and contribute to the formation of deposits or storage tanks to be exposed to the sun and painted in the combustion chamber. Oil should be filtered to a black. grade of 5 microns or less to avoid these issues, which is the purpose of the safety filter. The engine should also Fuel-grade coconut oil should be clear and transparent, be fitted with a 5-micron fuel filter as a final backup. with a slight amber color. If the oil has been filtered and looks cloudy, this usually indicates that there is water in the oil. A simple test to determine this is the hot-pan test. Water Content Heat a saucepan or frying pan to about 150°C and pour The water content in coconut oil results from the mois- about 5­10mm of oil into the pan. If any small bubbles ture contained in the pressed coconut, poor storage start forming at the base of the pan, the oil has too much conditions, or both. It can be present in oil as "free water. If the oil starts to snap or pop, it has significantly water, which will eventually drop out of the oil if left to " too much water. " settle, and as "suspended oil, which is bound up in the oil through weak chemical bonds. Pure coconut oil and water are immiscible (incapable of mixing), and any sus- TIP: If the coconut oil bubbles, snaps, or pops during pended water is generally an indication of some form of a hot-pan test, the oil contains too much water, and it oil degradation or contamination. Water in the oil encour- will need to be dewatered before use. ages growth of microorganisms and thereby accelerates degradation. Dewatering oil involves heating it to above 100°C for a If you let coconut oil settle for a period of two weeks, period of time to boil off any residual water. This can be you can practically guarantee that all of the free water done by any method suitable and with whatever materials Oil Production, Processing, ad Quality 27 are available. If you plan to do it in 200L drums using more thoroughly the oil will need to be dewatered and fire, do not expose the drum directly to the fire. Take spe- the shorter the storage time should be to avoid further cial care, particularly if using coconut shells--they burn degradation. very hot, and the fire can burn through the metal drum. Instead, place the drum on a hot plate, and build the fire If chemical analysis is not feasible or available, the gen- underneath the plate. eral rule is to avoid low-grade copra, particularly if it has been smoked and is burned or rancid or has mold. In Free Fatty Acids addition, copra that has been stored for long periods of time (that is, more than a month) should be avoided. Free fatty acids are indicative of oil degradation and are formed by oxidation of the triglyceride molecule. In short, one of the bound fatty-acid chains of the triglyc- TIP: The shorter the time between cracking the eride is separated from the molecule and becomes a nut and pressing the oil, the less free fatty acids "free" fatty acid. are formed. Low-grade copra should be avoided. Free fatty acids are weak organic acids and readily com- bust in diesel engines. In the low concentrations typically Storage and Handling Options found in coconut oil, these acids have very few corro- sive effects on the metallic components of the engines. Good-quality coconut oil is one of the most stable veg- In higher concentrations and in the presence of water, etable oils and is highly resistant to rancidity because they can attack some metals (especially zinc and cop- it has a very high degree of saturation--higher, in fact, per) to release metallic ions. They can also cause some than any other vegetable oil--which means that it can types of rubber and plastic to prematurely degrade and be stored for a long time before it begins to deteriorate. can lead to oxidation and bacterial contamination within Producers of high-grade food and cosmetic coconut oil storage tanks. claim that their oils show very little deterioration within 2­5 years. This length of time, however, is very depen- The formation of a free fatty acid also implies the forma- dent on the initial quality of the oil. Particular factors that tion of a diglyceride molecule. Diglycerides readily com- reduce storage times include free-fatty-acid concentra- bust in diesel engines too, but also act as emulsifying tion, water content, and organic-solids content. It is prob- agents. This means that they bind and hold tiny water ably safe to assume that fuel-grade coconut oil will have droplets in suspension within the oil, making it impos- a storage life of between six months and a year before it sible to dewater the oil through settling alone. Because begins to significantly deteriorate. Your nose is possibly acids operate in the presence of water, oil with high the best judge to indicate whether the oil has become free-fatty-acid and diglyceride concentrations need to be rancid or not; if you suspect that it has, do not use it in dewatered more thoroughly, usually by the application of your engine. heat. However, small concentrations of free fatty acids, diglycerides, and water do not pose an issue for fuel- Coconut oil can be stored in a variety of containers and grade coconut oil. tanks. Common options include 200L fuel drums, steel fuel tanks, polyethylene tanks or drums, intermediate Most free fatty acids in coconut oil are formed during bulk containers (IBCs), or any other vessels suitable for the drying process, between the time that the nut is fuel or chemical storage. In most cases, what you can cracked and the time it pressed. The quicker the drying source most cheaply will determine what you use. Met- time and the shorter the period that copra is stored, the als such as copper and zinc (galvanized steel) should be less free fatty acids will form. Hot-air-dried copra typically avoided because they can react with free fatty acids. The produces less free fatty acids than smoke-dried copra. inherent solvency characteristic of coconut oil has also Hand-pressed oil does not usually have any issues with been known to strip off paints and liners of tanks (such free-fatty-acid formation. as 200L drums). A relatively simple chemical test is available to deter- Unlike those for diesel fuel, there are no special require- mine the free-fatty-acid value and is listed at the rear ments with regard to safety and exposure to coconut of this guide. An acid value below 2 indicates high-qual- oil, and it can be handled with relative ease because of ity oil, below 4 moderate-quality oil, and below 8 low- its benign nature. It is nontoxic and inflammable, has a quality oil. Oil with values above 8 should probably not flash point around 200°C, and even has a low incidence be used in your engine. The greater the acid value, the of allergic reactivity. 28 Coconut-Oil Power Generation: A How-to Guide for Small Stationary Engines By-Products feedstock for cows, pigs, or chickens and can be sold to commercial producers or used locally. Because of The final topic in this section with regard to processing the high fiber content of the meal, it should constitute coconut oil relates to its by-products. Producing coco- only up to 30 percent of the diet for monogastric ani- nut oil also yields a significant amount of coconut meal mals such as pigs and chickens. Ruminant animals such (that is, the coconut meat left over after oil extraction), as cows, sheep, and goats that have four stomachs can for which there are a number of productive uses. It can tolerate significantly more in their diets. Finally, the meal be used in cooking to bake biscuits, cakes, and breads makes a very good organic fertilizer that can be added to or even added to curries or stews. It makes a high-value gardens. Oil Production, Processing, ad Quality 29 Appendix 1: Analyze Your Free Fatty Acids: The Titration Test The following test can be used to determine the free- · Using syringe, add 1ml of coconut oil to the phenol- fatty-acid value of your coconut oil. Although the proce- phthalein/IPA solution. Vigorously swirl jar to ensure dure might look daunting at first, it is in fact relatively complete mixture of the oil and solution. simple. Sourcing the chemicals will be the hard part, but · Draw 1ml of KOH reference water into syringe. most should be available at any chemical-supply store. Carefully drip KOH water into the phenolphthalein/ IPA/coconut-oil solution while swirling the beaker with the other hand. Utensils and Ingredients · The solution will be a milky color at the start of the test and will turn a uniform bright pink when the titra- · 1 medicine glass, glass beaker, or small glass jar tion is complete. The solution will turn pink when · 2 liters (L) of demineralized water (tank water or the KOH water is initially added, but will return to bottled water will do) milky color as you continue to swirl the jar. The solu- · 2 grams (g) of 100 percent pure potassium hydrox- tion must be uniformly pink for at least 30 seconds ide (KOH) (use care to keep the KOH dry, even pre- before the titration is complete. venting exposure to humid air, because it will absorb · Record the amount of KOH reference water in mil- atmospheric water) liliters used to complete the titration. This number · 10 milliliters (ml) of 99 percent pure isopropyl represents the number of grams of KOH required alcohol (IPA) to neutralize the free fatty acids in 1L of coconut oil · 2 small (1ml) diabetic syringes (available from chem- (that is, g/L). ists), with needles removed and holes enlarged · To convert to acid value--grams per kilogram (g/kg)-- (using a small drill bit) multiply this number by 1.081 (1 divided by 0.915, · Phenolphthalein pH indicator solution which is the density of coconut oil). · Coconut oil · Electric scales accurate to 0.1 gram Free-fatty-acid concentration is a good indicator of gen- · Rubber or latex gloves and safety glasses eral oil quality. It is advisable to perform regular titrations of your oil, particularly when you are starting out, so you begin to understand the correlation between copra qual- Step-by-Step Titration ity and oil quality. · Add 2g KOH to the demineralized water container to An acid value below 2 indicates high-quality oil, below make KOH reference water. (This can be used again 4 moderate-quality oil, and below 8 low-quality oil. Oil for up to one year.) with values above 8 should probably not be used in your · Using syringe, measure 10ml of IPA into glass jar. engine. Oil with high acid values requires more thorough · Add two drops (about 0.2ml) of phenolphthalein indi- dewatering. cator to IPA, and swirl to mix. 30 Coconut-Oil Power Generation: A How-to Guide for Small Stationary Engines Appendix 2: Coconut Oil Statistics Table a.1: QualiTy sTandard For rapeseed oil Energy content of coconut oil 35.0 MJ per L Energy content of diesel fuel 41.0 MJ per L Density of coconut oil 0.915 kg per L Density of diesel fuel 0.84 kg per L Oil content of copra 620­680 ml per kg Extraction rate of copra oil, large mill 600­650 ml per kg Extraction rate of copra oil, minimill 500­600 ml per kg 1,000 coconuts are (on average) equivalent to: Coconuts 1.20 metric tons Husks 0.39 metric tons Shells 0.17 metric tons Cocowater 0.24 metric tons Green copra 0.37 metric tons Dry copra 0.20 metric tons Copra meal 0.08 metric tons Copra oil 0.12 metric tons Dry copra 5 (3­7) nuts per kg Copra oil 12 (10­15) nuts per L 1m copra 3 0.53 metric tons 1m3 copra meal 0.47 metric tons Typical yield 2,470 L oil per ha per year Small-generator coconut-oil consumption 0.4­0.5 L per kWh Note: MJ--millions of Joules L--liter ml--thousandth of a liter kg--kilogram m3--cubic meter ha--hectare kWh--kilowatt hour Appendix 2: Coconut Oil Statistics 31 Appendix 3: Equipment and Suppliers This section contains information about where to source Anyang Gemco Energy Machinery Co., Ltd. (www.agitc. the appropriate equipment and expertise for process- cn) and Anyang General International Co. Ltd. (www. ing coconut oil and running an engine on coconut oil. agico.com.cn) also manufactures some of the presses Because this guide has been specifically written for par- listed below. Other press varieties are available, but ticipating countries of the Sustainable Energy Financing because of a lack of relevant experience in the Pacific, Project, which include Papua New Guinea, Fiji, the Solo- they have not been included. The following three trade mon Islands, and Vanuatu, information about equipment Web sites will link you to other manufacturers and and suppliers is tailored for these Pacific countries. agents: www.alibaba.com, www.diytrade.com, www. made-in-china.com. Because of the limited number of companies in the Pacific selling oil-processing equipment, the first half of Project Support Services (PSS) of Papua New Guinea is this section provides information relating to international currently the only known supplier of Chinese presses in manufacturers and agents for oil-processing equipment. the Pacific region. PSS stocks most of the presses listed The second half of this section provides supplier informa- below; makes any necessary modifications for coconut; tion for each country. Every attempt has been made to can order other varieties; and provides parts, servicing, provide complete and relevant information. and training for all equipment. The firm has an agent in the Solomon Islands and is willing to work with other companies working in the Pacific. (Company contact Oil Processing Equipment details are listed under country suppliers.) The following list details some oil presses available on the market, mostly those from Chinese and Indian 6yl-68 manufacturers. It is in no way a complete list, but rather Output: 20L/hr (quoted) covers the presses that are currently operating in Pacific countries and where reliable usage data are available. Weight: 170kg Details regarding copra-cutting equipment and plate- Power: 5.5kW pressure filters are omitted because the manufacturers and agents that sell oil presses also provide a range of Dimensions: 930×490×820 complementary copra cutters and filters. Prices have not Currently untried, but appears to be a smaller version of been included, but Chinese equipment prices are gener- -78 the 6YL and would similarly have a single tapered- ally about half those of Indian equipment. screw shaft and alternative press-cage bar configura- tions to suit different feedstocks. Chinese Equipment A large range of oil presses are made in China, and 6yl-78 many of the same models are manufactured by differ- Output: 30L/hr ent companies and sold through a number of agents. Most presses are designed for hard seeds, and some Weight: 210kg will require minor modification (discussed previously) to Power: 5.5kW operate trouble-free with coconut. The most recognized manufacturer is Henan Double Elephants Machinery I/E Dimensions: 1000×550×580 Co., Ltd., which manufactures all of the presses listed Press comes with either 16 or 20 press-cage bars, below and some larger varieties that are yet untried in depending on feedstock. 20-bar configuration is more the Pacific. Product and contact details are listed on its suited to coconut. Single tapered-screw shaft needs the Web site at www.holyphant.com. knuckle reduced in diameter by 2mm. 32 Coconut-Oil Power Generation: A How-to Guide for Small Stationary Engines Indian Equipment 6yl-80 and 6yl-100 Indian machinery is tailored specifically for processing Output: 60 and 100L/hr coconut oil by the manufacturer, and there is no require- Weight: 330 and 480kg ment to modify shafts (as with some of the Chinese presses). Indian presses tend to use lower gear ratios Power: 5.5 and 7.5kW and, as such, can be powered by smaller motors com- Dimensions: 1000×550×580 pared with those for Chinese presses. What Indian & 700×670×1320 presses offer in greater efficiency and trouble-free opera- tion, however, is offset by their increased cost. The 6YL-80 is an identical (but smaller) version of the 6YL-100. Both employ a double tapered-screw shaft. Many companies in India manufacture oil presses and Operational experience with the 6YL -100 indicates that related equipment. Tinytech is probably the best-recog- it performs well and seizes rarely. Shaft knuckles could nized manufacturer of minimills in the world and offers be reduced by 1mm to eliminate any problem with an integrated package of presses, copra cutters, and fil- seizing. ters. (Contact and product details can be found at www. tinytechindia.com.) Agents for Tinytech currently oper- 6yl-95a ating in the Pacific include Celtrock Holdings in Fiji and Solomon Tropical Products in the Solomon Islands (both Output: 110L/hr listed under country suppliers). Weight: 530kg Apart from Tinytech, there are only a few other examples .5 Power: 7 to 11kW of small-Indian-press sources operating in the Pacific. Dimensions: 1600×700×1350 Coconut Bioenergy in the Solomon Islands has some experience with Indian presses and is the agent for The 6YL-95A has a double tapered-screw shaft that Goyum Screw Press, which makes presses ranging from unmodified is prone to seizing. Grinding 2mm off the 50 to 6,000L/hr. Solomon Tropical Products, the agent diameter of both knuckles makes this unit a reliable and for Tinytech in the Solomon Islands, also offers an Indian solid performer. press made by Kumar Metal Industries and a Malaysian press by Muar Ban Lee Engineering. Zx-105 Output: 150L/hr (quoted) Tinytech oil Mill Weight: 560kg Output: 60L/hr (quoted) Power: 11 to 15kW Weight: 500kg Dimensions: 1825×700×1350 Power: 7.5kW The ZX-105 is a 20cm-longer version of the 6YL -95A. Size: 1.6 m3 Trials with this machine have yet to prove whether this extra length offers any operational improvement. Contact: Tinytech Double-tapered shaft needs the knuckles reduced by at www.tinytechindia.com least 2mm. Tinytech presses are successfully operating throughout the Pacific. Tinytech makes only one size of press. For larger capacities, two or more presses can be linked together. The firm also manufactures copra cutters and plate-pressure filters to suit press size. Appendix 3: Equipment and Suppliers 33 Other Equipment Providers goyum 10 China and India are obviously not the only countries Output: 50L/hr (quoted) manufacturing coconut-oil­processing machinery. They Dimensions: 1300×475×1075 are, however, the main suppliers of equipment currently being operated throughout the Pacific that is both afford- Power: 4kW able and effective. Other countries within the general Contact: Goyum Screw Press region that make a range of oil-processing machinery www.goyumindia.com include Malaysia, the Philippines, Pakistan, Sri Lanka, and Indonesia. With no known installations in the Pacific, Goyum Screw Press manufactures a range of presses there is a lack of available information about the perfor- with capacities ranging from 50 to 6,000L/hr. The firm mance of machines from these countries. The exception also manufactures a range of copra cutters and filters to to this includes a company from Australia and a company suit press size. from Malaysia, which are listed below. Techso--Tech 14 Kumar simplex no. 1 Output: 10­15L/hr Output: 70L/hr (quoted) Power: 2.2kW Power: 7.5kW Location: Brisbane, Australia Contact: Contact: Kumar Metal Industries Techso www.techso.net www.kumarmetal.com Techso manufactures and sells oil-processing equip- Kumar Metal Industries manufactures presses with ment and tailors complete packages to accommodate capacities ranging from 70 to 2,000L/hr. The firm also any operational capacity. It has significant experience manufactures a range of copra cutters and filters to suit working in the Pacific region. press size. Muar ban lee engineering-- eK-12-cT Additional Indian manufacturers of oil presses and pro- Output: 330L/hr cessing equipment include the following: Weight: 3800kg · Allied Expeller Industries-- Power: 40kW http://allied.indusindustrial.com Dimensions: 4425×1099×1308 · Gobind Expeller Company-- Location: Malaysia www.gobindexpeller.com Contact: MBL www.mbl.com · Guru Teg Engg. Co.-- www.gurtegexpeller.com The EK-12-CT is the smallest press produced by MBL, which primarily services the commercial palm oil · Mitsun Engineering-- industry with very large presses. The firm provides http://mitsunengineering.com cutting and filtering equipment also. · United Oil Mill Machinery & Spares Private Ltd.-- www.umas-india.com · Vijay Expeller Company-- www.vijayexpellers.com 34 Coconut-Oil Power Generation: A How-to Guide for Small Stationary Engines Country Suppliers lohberger engineering Papua New Guinea (PNG) Ph: +675 325 2122 Fax: +675 325 2704 loheng@online.net.pg project support services (pss) www.lohberger.com.pg Ph: +675 472 0088 Lawes Road, Konedobu, Port Moresby, PNG Fax: +675 472 0044 Lohberger offers engineering services and stocks a pssltd@daltron.com.pg range of industrial supplies, including generators, filters, www.psspng.com and all of the necessary parts to adapt engines. The Malahang Industrial Estate, Lae, Morobe Province, firm's engineering workshop has the facilities to fabri- PNG cate heat exchangers and to preadapt engines for use PSS is the only stockist in PNG of complete oil- with coconut oil. processing equipment (in the form of minimills), including copra cutters, screw presses, and filtration brian bell equipment. All machinery is sourced from China, and presses are modified to suit coconut as required. Ph: +675 325 5411 PSS also fabricates coconut-oil hand presses and Fax: +675 325 0167 filtration systems for very small-scale production. www.brianbell.com.pg PSS also sells a range of historical-style Changfa PO Box 1228, Boroko, Port Moresby, PNG engines that can be operated unmodified on straight Brian Bell's industrial division sells a large range of coconut oil and can be coupled with alternators or diesel generators and necessary supplies for adapting power pedestrian tractors. The firm offers training, engines to run on coconut oil. The firm has five store service, and maintenance of all equipment and locations across PNG. machinery. Farmset bishop brothers Ph: +675 732 1955 Ph: +675 325 2900 Fax: +675 732 2423 Fax: +675 325 4104 gorokasales@farmset.com.pg www.bishopbros.com.pg Airport Rd, Goroka, PNG Wards Rd., Hohola, Port Moresby, PNG Farmset mainly services the agricultural sector, can Bishop Brothers stocks a range of industrial products, order oil-processing machinery, and sells some small including generators, filters, and all the necessary parts diesel generators. to adapt engines. The firm has a large engineering workshop and has designed and fabricated an effective and affordable stainless-steel heat exchanger for engine agmark conversion. Bishop Brothers has branches throughout Ph: +675 982 9055 PNG and one in the Solomon Islands. Fax: +675 982 9056 itamur@agmark.com.pg www.agmark.com.pg NGI Haus, Williams Road, Rabaul, PNG Agmark has five store locations across PNG and gener- ally services the agricultural sector. The firm does sell a range of diesel generators and can order oil-processing machinery. Appendix 3: Equipment and Suppliers 35 Fiji Moresby Truck and Tractor Ph: +675 325 8255 sopac energy division Fax: +675 325 8803 mtt@global.net.pg Ph: +679 338 1377 Kenmore Trade Centre, Waigani, Port Moresby, PNG Fax: +679 338 0040 www.sopac.org Moresby Truck and Tractor stocks a large range of Suva, Fiji industrial parts, including filters, valves, hoses, and other necessary parts for converting engines. SOPAC is the Pacific Islands Applied Geoscience Commission. It is an intergovernmental, regional organization dedicated to providing services to hastings deering png promote sustainable development. The energy Ph: +675 300 8300 division of SOPAC has a wealth of experience in Mb: +675 687 2014 using coconut oil as fuel. www.hastingsdeering.com.au Spring Garden Rd, Hohola, Port Moresby, PNG celtrock holdings Hastings Deering is the licensed supplier of Ian Chute ianchute@connect.com.fj CAT engines and generators. Celtrock Holdings Ltd. is the agent for Tinytech mini- mills and is the only provider of oil-processing equip- eltech engineering ment in Fiji. The firm can design and install equipment Ph: +675 323 1988 for a range of capacities and offers training and backup Fax: +675 323 2810 services for all equipment that it sells. Ian Chute can ees@eltechpg.com order alternative oil-processing machinery from China PO Box 228, Gordons, Port Moresby, PNG or India on request and can assist with engine selection and conversion. Eltech is the licensed supplier of Deutz engines and generators. seamech engineering and hydraulic shop uMw niugini Ph: +679 330 1882 Fax: +679 330 0866 Ph: +675 472 2444 drossbrodie@mac.com Fax: +675 472 3342 21 Matua St, Walu Bay, Suva, Fiji msims@umw.com.pg Aircorps Rd, Lae, PNG Seamech has experience in converting diesel engines to run on coconut oil. The firm has a large workshop UMW is the licensed dealer and distributor for with the capabilities to fabricate heat exchangers and to FG Wilson generators and Atlas Copco equipment. refit engines to run on coconut oil. It is the official agent for Deutz in Fiji, but orders engines out of Australia as required. 36 Coconut-Oil Power Generation: A How-to Guide for Small Stationary Engines The Solomon Islands clyde engineering Ph: +679 338 6000 solomon Tropical products Fax: +679 337 0431 www.clydepac.com Ph: +677 38553 31 Viria Rd, Vatuwaqa, Suva, Fiji Fax: +677 38552 stp@solomon.com.sb PO Box 1870, Honiara, Solomon Islands Clyde Engineering stocks a large range of small, medium, and large diesel generators. It sells filters, Solomon Tropical Products is the agent for Tinytech valves, and all of the other necessary equipment minimills. The firm itself operates two Indian presses for engine conversion. The firm has the capability to and one Malaysian press and sells coconut oil and make heat exchangers and can fit out any generator coconut-oil products locally and internationally. It can to run on coconut oil. design and install equipment for a range of capacities and offers training, backup services, and advice on engine-related issues. powerlite generators ltd. Ph: +679 338 4088 coconut bio-energy Fax: +679 338 4096 powerlite@connect.com.fj Ph: +677 39933 19 Shalimar St, Raiwasa, Suva, Fiji smithv@solomon.com.sb PO Box R148, Ranadi, Honiara, Solomon Islands Powerlite is the agent for Hatz diesel generators and can order any other brand of generator out of Australia. Coconut Bio-Energy is the agent for Goyum Screw Press machinery and can install, train, and provide service for any minimill facility across a large range of industrial and Marine engineering ltd (iMel) capacities. The firm commercially produces coconut Ph: +679 331 2133 oil for international export and has experience in Fax: +679 3301364 working with Indian presses and U.S.-built Anderson i.seru.imel@carpenters.com.fj presses. Coconut Bio-Energy is in the process of Eliza St, Walu Bay, Suva, Fiji making an agreement with the Solomon Islands Energy Authority to sell power produced from coconut IMEL has a very large engineering workshop and oil back into the grid. mostly works on large industrial and marine jobs. Its workshop has the capability to fabricate heat exchangers or refit engines. seT Marketing Ph/Fax: +677 25221 carptrac sethori@solomon.com.sb PO Box 1952, Honiara, Solomon Islands Ph: +679 330 8622 Fax: +679 330 8329 SET Marketing is the Solomon Islands agent for Project i.temo.motors@carpenters.com.fj Support Services (PSS) in PNG. (Refer to PSS in PNG 88 Foster Rd, Walu Bay, Suva, Fiji section above for product and service listing.) Carptrac is the licensed agent for CAT engines and generators. Appendix 3: Equipment and Suppliers 37 Vanuatu prosolutions Ph: +677 28027 bodiam pacific engineering colindyer@solomon.com.sb PO Box 1675, Honiara, Solomon Islands Ph: +678 47590 Fax: +678 26138 alex@bodiam.vu ProSolutions is in partnership with Kokonut Pacific PO Box 1548, Port Vila, Vanuatu (www.kokonutpacific.com) and sells the DME hand press and filtration units that produce high-grade Alex Bodiam has a wealth of experience in using coco- virgin coconut oil. Colin Dyer has worked throughout a nut oil as a diesel-fuel replacement and commercially number of Pacific island countries on coconut-oil biofuel sells refined coconut-oil fuel at service stations. projects. He stocks no generators, but can order any variety as required. His large workshop has the facilities to fabricate heat exchangers and to refit engines to run island enterprises on coconut oil. Ph: +677 30152 Fax: +677 30188 Motor Traders phil@ielsi.com.sb PO Box 364, Honiara, Solomon Islands Ph: +678 23430 Fax: +678 23513 Island Enterprises sells a range of modern- and histori- motor-traders@vanuatu.com.vu cal-style diesel-powered generators. Phil Bradford (MD) Port Vila, Vanuatu has some experience with Lister copies out of India and has visited a number of Listeroid factories. The firm Tony Deamer of Motor Traders is one of the pioneers sells all of the necessary equipment to convert engines, of coconut-oil biofuel in the Pacific. His family business has an extensive workshop, can fabricate heat exchang- sells coconut-oil fuel, which is locally called Island ers, and can refit engines to run on coconut oil. Fuel. He does not sell generators, but makes heat exchangers for conversion. bishop brothers south pacific electrics Vanuatu Ph: +677 30046 Fax: +677 30047 Ph: +678 22034 honsales@bishopbros.com.pg Fax: +678 22877 www.bishopbros.com.pg masuino@vanuatu.com.vu PO Box R276, Ranadi, Honiara, Solomon Islands PO Box 1548, Port Vila, Vanuatu Bishop Brothers stocks a range of industrial products, South Pacific Electrics does not have generators in including generators, filters, and all of the necessary stock, but can order in a range of brands from Australia parts to adapt engines. The firm currently lacks a work- on request. The firm stocks the Fleetguard range of shop, but can have tried and tested heat exchangers filters. made in Port Moresby and sent across. 38 Coconut-Oil Power Generation: A How-to Guide for Small Stationary Engines References . Chevron Corporation. 2007 Diesel Fuels Technical Review. Machacon, H., Y. Matsumoto, C. Ohkawara, S. 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