Will/fillMill/WIWIN/llll/lfllI/llellllll/M 0600 3563 This is to certify that the thesis entitled CONVENTIONAL AND ALCOHOL FUEL CONSUMPTION MODEL FOR CROP PRODUCTION MACHINERY SYSTEMS presented by Carlos Fontana has been accepted towards fulfillment of the requirements for M.S. fiegreein Agric. Engr. Tech. 6,14%, Major profes/ Date May 21, 1981 0-7639 OVERDUE FINE§: 25¢ per day per m- RETQRNLNG LIBRARY MATERIALS: Place in book return to renove charge from circulation records CONVENTIONAL AND ALCOHOL FUEL CONSUMPTION MODEL FOR CROP PRODUCTION MACHINERY SYSTEMS BY CARLOS FONTANA A THESIS submitted to Michigan State University In partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Agricultural Engineering 1981 ABSTRACT CONVENTIONAL AND ALCOHOL FUEL CONSUMPTION MODEL FOR CROP PRODUCTION MACHINERY SYSTEMS BY CARLOS FONTANA A computer program was develOped which models machine performance to calculate the energy requirements for 50 field Operations from soil pre- paration to tranSportation. The model was develOped with standard rela- tionships of the American Society of Agricultural Engineers. Validation of the program was made by comparing the results with field data collected on Michigan farms. Further validation was made by comparing results of modeled farms to data of a Michigan Energy Audit Study which collected fuel consumption averages from 52 Michigan farms. Modeled data was within 6 percent of actual data of farms studied. Results from the computer program for fuel consumption by machine, by operation group, and by enterprise are presented for three farm sizes. Farms are actual Michigan farms which produce corn, oats, wheat, hay, soybeans, navy beans, and sugar beets. Carlos Fontana The use of alcohol (ethanol) as an alternative fuel was investigated. Alcohol is better utilized in gasoline engines where engine conversions to run on straight alcohol are possible. With today's energy scenario only tractors with high annual use can be economically Operated on a dual- fuel system. For the three farms studied, 34, 29, and 35 percent of the total fuel use could be replaced by alcohol. This would require 1.4, 1.4, and 1.7 percent of the total farming area to be planted in corn for alcohol production to supply the supplementary fuel needs for 79, 200, and 550 hectare farms, respectively. Four conversion methods were modeled including two methods for spark- ignition engines and two methods of dual-fueling diesel engines. For diesel and gasoline prices of $0.40 per liter, break-even prices for alcohol of $0.30, $0.31, $0.16, and $0.20 per liter were obtained for the first, second, third, and fourth conversion methods, respectively. fl Approved L. / Major ro essor ./'\ 4/] ”>0 *5] .. AppT‘OVEd ! Y fill/£11252 - 5' {4" (’5 2:1ng Department Chairman To Elena, for her help and encouraging words ii ACKNONLEDGEMENTS I wish to thank Dr. C. Alan Rotz who served as major professor on this thesis. It was only through his help, advice and councel that this project was possible. Dr. Roy Black and Dr. John Waller made valuable contributions and were the other members of the thesis committee. I would like to thank Mr. Robert Chaffin and Mr. Duane Watson for being extremely helpful during the data collection phase of this project. I also would like to thank Dr. Valdecir Dalpasquale, Dr. Juarez de Souza e Silva and fellow graduate students, Jose Marcio Cruz and Juan Carlos Rodriguez, for being my true friends during the completion of this study. And finally, my appreciation to everyone in the Agricultural Engineering Department who have been an inspiration to me and a pleasure to work with. iii TABLE OF CONTENTS LIST OF TABLES . ............ . . . . . . ...... LIST OF FIGURES . . . . . . . . . . . . . . . . . . . . . . . . LIST OF SYMBOLS, ABBREVIATIONS AND NOMENCLATURE ........ Chapter 1 INTRODUCTION ...... . . . . . ....... . . . 2 OBJECTIVES ........... . ........... 3 LITERATURE REVIEW ................... 3.1 Energy consumption for field Operations 3.2 Machinery models . . . . . . . . . . . . . . . 3.2.1 Machinery selection models ...... 3.2.2 Economic models . . . ......... 3.2.3 Energy models . . . . . . . . . . . . . 3.3 Alcohol utilization . . . . . . . . ..... 3.3.1 Alcohol use in spark-ignition engines . 3.3.1.1 Alcohol use in blends with gasoline . . . . . . . . . . . 3.3.1.2 Straight alcohol use in gasoline engines . . . . . . . 3.3.2 Alcohol use in diesel engines . . . . . 3.3.2.1 Alcohol use through dual- fueling ........ . . . 3.3.2.2 Straight alcohol use in diesel engines . . . . . . . . . . . iv NVO‘ 21 21 22 25 26 26 27 28 31 31 33 Chapter Page 4 MODEL FORMULATION ........... . ........ 34 4.1 Feasibility study ............... 34 4.1.1 Needs analysis . . . . ......... 34 4.1.2 System identification ..... . . . . 35 4.1.2.1 Model inputs . . . . ..... 36 4.1.2.2 Model outputs ......... 37 4.1.3 Problem formulation .......... 37 4.2 Model description . . . . . . . ........ 38 4.2.1 Energy subroutine . . . . ....... 38 4.2.1.1 Draft requirements for tillage ' Operations ...... . . . . 38 4.2.1.2 Draft requirements for seeding Operations . . . . . . . . . . 43 4.2.1.3 Draft requirements for cultivation Operations . . . . 44 4.2.1.4 Draft requirements for fertilizer and chemical application . . . . . ..... 44 4.2.1.5 Power requirements for harvesting Operations . . . . . 45 4.2.1.6 Energy requirements for transportation . . . ..... 48 4.2.1.7 Load determination ...... 49 4.2.2 Fuel consumption subroutine ...... A 50 4.2.3 Alcohol subroutine ...... . . . . . 57 4.2.4 Cost subroutine ............ 58 Chapter 5 DATA COLLECTION AND VALIDATION . . . . . . . . . . . . 5.1 Validation by Operation . . . . . . . . . . . 5.1.1 Data collection . . . . . . . . . . . 5.1.2 va‘idation O O O O O O O O O O O O O O 5.2 Whole farm validation . . . . . . . . . . . . 5.2.1 Energy Audit Study data . . . . . . . 5.2.2 va‘ 1dati on O O O O C O O O O O O O O 0 5.2.2.1 Small-size farm . . . . . . . . 5.2.2.2 Medium-size farm . . . . . . 5.2.2.3 Large-size farm . . . . . . . . 6 ETHANOL AS TRACTOR FUEL . . . . . . . . . . . . . . . . 6.1 Conversion methods . . . . . . . ...... 6.2 Ethanol use on typical farms . . . . . . . . 6.3 6.2.1 Small-size farm . . . . . . . . . . . 6.2.2 Medium-size farm . . . . . . . . . . . . 60203 Large-SIZE far“. 0 o o o o o o o o o o Tractor use and ethanol feasibility . . . . . 6.3.1 6.3.2 6.3.3 6.3.4 7 SUMMARY . . . . 8 CONCLUSION LIST OF REFERENCES GENERAL REFERENCES S . . Gasoline tractor with minor modifications . . . . . . . . . . . . . Gasoline tractor with increased compression . . . . . . . . . . . . . . Dual-fueling with spray-injection . . . Dual-fueling with carburated ethanol . . O O O O O O O O O O O O O O O O O O O Page 60 60 60 71 74 74 79 79 81 83 87 87 90 93 95 96 96 97 98 103 105 106 113 Table 10 11 12 13 14 LIST OF TABLES Fuel consumption for tillage Operations for 8 states in liters Of diesel fuel per hectare . . . . . . . . . . . . . Fuel consumption for seeding Operations for 10 states in liters Of diesel fuel per hectare . . . . . . . . . . . Fuel consumption for cultivating Operations for 7 states in liters of diesel fuel per hectare . . . . . . . . . . . Fuel consumption for spraying and fertilizing Operations for 8 states in liters Of diesel fuel per hectare . . . . . Fuel consumption for harvesting Operations for 6 states in liters of diesel fuel per hectare . . . . . . . . . . . Fuel consumption for transportation Operations for 4 states in liters Of diesel fuel per hectare (4.8km from the fan“) 0 O O O O O O O O O O O O O O O I O I O O O O I Approximate energy requirements for corn production per hectare (Madex and Bakker-Arkema, 1978) . . . . . . . . . . Energy requirements for New York state agriculture (sunke1 et a] O , 1974) O O O I O O O O O O O O O O O O O 0 Fuel consumption for field Operations for 4 cropping systems in the state of Michigan (Christenson, 1977) . . . Fuel requirements for corn production systems in liters of diesel fuel per hectare (Collins et al., 1978) . . . . . Specific fuel consumption for 13 diesel tractors (Nebraska Tractor Test data) . . . . . . . . . . . . . . . Specific fuel consumption for 13 gasoline tractors (Nebraska Tractor Test data) . . . . . . . . . . . . . . . Values for the parameters used in the fuel consumption made] 0 0 O O O O O O O I O O O O O O O O O O O O O O O 0 Machinery size and performance for farm number one in the fall season of 1980 . . . . . . . . . . . . . . . . . . . . vii Page 10 11 12 14 18 18 19 20 52 54 55 61 Table 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 Machinery performance and fuel consumption for farm number one in the fall season of 1980 . . Machinery size and performance for farm number two in the fall season Of 1980 ....... Machinery performance and fuel consumption for farm number two in the fall season of 1980 . Fuel consumption for field Operations on farm number one Fuel consumption for field Operations on farm number two Crops grown Power units used on Crops grown Power units used on Crops grown Power units used on Tractor usage level size farm . . . . Fuel consumption by Fuel consumption by Machine usage level size farm . . . . . Fuel consumption by farm Fuel consumption by Machine usage level farm . . . Fuel consumption by farm . Fuel consumption by Parameters used for on the medium-size farm in 1979 . on the large-size farm in 1979 on the small-size farm in 1979 . . . . . . . . the small-size farm in 1979 . the medium-size farm in 1979 the large-size farm in 1979 . . . . . . and fuel consumption for the small- Operation group for a small-size farm . enterprise for the small-size farm and fuel consumption for the medium- Operation group for the medium-size enterprise for the medium-size farm . . and fuel consumption for the large-size Operation group for the large-size enterprise for the large-size farm 4 conversion methods viii Page 62 68 69 72 73 75 76 76 77 77 78 79 80 81 82 82 83 84 85 86 88 Table 36 37 38 39 40 41 42 43 44 45 46 47 48 Fuel consumption for tractor number 1 using 2 different conversion methods on a small-size farm . . . . . . . . . . Break-even prices for alcohol fuel for 2 conversion methods onasm311-51ZEfamooooooooooooooooooo Fuel consumption for tractor number 2 using 2 conversion methods on a mediumusize farm . . . . . . . . . . . . . . . Break-even prices for alcohol fuel for tractor number 2 on a “Edi um-S‘ze fan“ 0 O O O O O O O O O O O O O O O O O O 0 Diesel and alcohol fuel use when spray injection was used for 5 different tractors . . . . . . . . . . . . . . . . . Diesel and alcohol fuel use when the carburated dual-fuel system was used for 5 different tractors . . . . . . . . . Break-even prices for alcohol fuel for 5 tractors and 2 dual-fuel methods for a large-size farm . . . . . . . . . . Ethanol break-even prices for gasoline tractor with minor mOdi fications O O I O O O O O O O O O I O O O O 0 O O O O O Ethanol break-even prices for gasoline tractor with increased compression . . . . . . . . . . . . . . . . . . . Ethanol break-even prices when dual-fueling with spray injection is used 0 O 0 O O O 0 O O I O O O O O O O O O O 0 Ethanol break-even prices when dual-fueling with carburated ethanol is used . . . . . . . . . . . . . . . . Ethanol break-even prices for 2 recovery periods and 4 conversion methods (conventional fuel prices Of $0.40 per 1iter O 0 O O O O O O O O O O O O O O O O O O O O O O O 0 Diesel prices required to allow ethanol to be economically feasible with a production cost Of $0.46 per liter . . . . Page 89 90 91 92 94 94 95 96 97 99 99 100 101 LIST OF FIGURES Figure Page 1 Model flowchart . . . . . ....... . . . ...... 39 2 Specific fuel consumption as a function Of engine load . 53 3 Tractor usage levels and ethanol break-even prices for gasoline and diesel prices Of $0.40 per liter . . . . . . 102 ACAF ACC AKPL ALOG ALUSE AREA BC FEPA CAn CAP CAREA ccn crc crp cruse CLP Clll cn co coucos car ocou DRAFT EFC LIST OF SYMBOLS, ABBREVIATIONS AND NOMENCLATURE discount rate annual fuel cost annual conversion cost average fuel consumption natural logarithm alcohol use area bite length break-even price of alcohol draft parameter capacity area covered draft parameter conventional fuel cost conventional fuel cost conventional fuel use LP gas consumption centimeter draft parameter carbone monoxide conversion cost capital recovery factor diesel fuel consumption implement draft effective field capacity xi EFF ENNE EXP FCHA FCP FD FLPH FR GCON ha ICN ICOTY ID IDEN IFACT IST LOAD NB NK NN NOP NOx uaovs PAR machine field efficiency power requirement exponential fuel consumption per hectare alcohol fuel consumption parameter field distance fuel consumption per hour feed rate gasoline fuel consumption hour hectare soil surface condition conversion type identification variable for grain drills crOp density load ranges soil type engine‘load Operation number Operation number number Of bottoms number of knives recovery period Operation number nitrates number Of rows alcohol fuel consumption parameter xii PAVA PREO PTO $1 SLIP SPEED TD TE TCOSTA TCOSTD TDRAFT TTOTA UDRAFT USE YIELD v WIDTH NM power available power required power take Off revolution Spark ignition wheel slip field speed working depth tractive efficiency alcohol fuel costs conventional fuel costs total implement draft total alcohol fuel use unit draft machine use crop yield implement weight implement width machine weight xiii CHAPTER 1 INTRODUCTION In Spite Of public awareness of limited petroleum availability, conservation Of energy is not being practiced by the majority Of farmers (Ozkan, et al. 1979). In the last 25 years, the population increase has forced most nations to continue to search and to improve technology. Much Of the new technology is much more energy dependent. For example, in an agricultural production system, more energy is now utilized to replace labor through use of chemicals, and large electrical and field machines than was used 25 years ago. The world petroleum price has increased in an unexpected rate in the last 8 years. With the increased price, uncertainties about the availa- bility of fossil fuels is a major concern not only for the producers but also for the consumers. Agriculture is known as one of the few industries that produces more energy than it uses. Despite this fact, improvements can be Obtained through using more energy efficient methods of crap production. Farmers, by adopting new machinery systems such as conservation and no-tillage systems can not solve the energy problem, but they may be better prepared for future shortages. The events Of the last 8 years suggest that availability and cost Of energy will play an increasingly important role in crOp production. The competition with other sectors Of society and diminishing petroleum reserves will produce higher fuel costs in the future. Agriculture consumes only 3 percent Of the U.S. total energy consumption, but modern agriculture is highly dependent on fuels and petroleum based products of pesticides and fertilizers. 2 In 1973 we eXperienced an energy crisis which increased interest in the energy demand Of crOps. The total energy input Of a particular practice not only includes the fossil fuel used directly, but also the energy used in manufacturing, marketing and repairing equipment as well as the manual labor required to perform the Operations. The amount of energy used indirectly in the production process, may be difficult to lower. More efficient machines and tractors can be designed, and more important, the total use of energy for field Operations for crOpping systems can be reduced considerably. Primary tillage has always been one Of the larger power consuming Operations on a farm (202, 1974). Over the years the moldboard plow has been the most accEpted primary tillage tool; only recently has it been challenged by various systems Offering reduced tillage. Tractors are prime movers for agriculture and are used in most farming Operations. Although the major portion Of fuel and Oil used on the farm is consumed by the farm tractor, consideration should also be given to other machines, such as combines, trucks and self-prOpelled machines. From the U.S. government reports, in 1973, an average Of 157 liters Of refined petroleum fuel (gasoline, diesel, and liquefied petroleum gas) per hectare was used for all crops in the United States. Fuel use varied from 28 liters per hectare for pasture and hay to over 468 liters per hectare for Irish potatoes and fruit. In 1974 the tOp three crops in the U.S. in terms Of hectares grown were: corn for grain, soybeans, and wheat. These accounted for over half Of all fuel used in crOp pro- duction (Gunkel et al., 1974). Better management decisions can be made if better data for field Operations, crOps, crOpping systems, and machines are available for the farmers and decision makers. According to Hunt (1968) one third of crap production costs can be attributed to machinery costs. This makes the selection Of a compliment Of machines and machine replacement decisions, the major decisions facing machinery managers. Hayfield et al., (1980), report the costs per hour for a 121 Kw tractor. Fuel and lubrication had a cost of $3.20 per hour in the spring season Of 1977 and this accounted for 30 percent Of the total tractor cost. In the fall season Of 1980 the fuel and lubrication costs accounted for 37 per- cent Of the total tractor costs, with a cost Of $7.93 per hour. This shows not only the importance of the fuel and lubrication costs in total tractor costs, but also the rising cost of petroleum fuels. Present fuel consumption figures do not easily permit calculations and comparisons with Speed and load conditions under which most tractors Operate (Persson, 1969). Tractor engines Operate predominantly under part load and varying speed conditions. The determination Of tractor field performance such as wheel slip, tractive efficiency, fuel economy, and fuel costs require detailed models for accurate prediction. Fuel requirements for a specific Operation can, and do, vary widely from one state to another, from one section Of the state to another, from one farm to another, and even within the same farm. This is due to a number Of factors, such as the following: 1. Weather . Variations in the soil type . Topography . Size of field 2 3 4. Soil condition (drainage) 5 6 Depth Of tillage 7 . Machine type (physical characteristics) 8. Operating speed 9. Match between power unit and implement 10. Soil surface condition 11. Operator working habits and management ability All the above factors make the recommendation Of the amount of fuel for field Operations very difficult to be presented in a short range. White (1974) reported that it takes 8.5 to 35.0 liters Of diesel fuel to plow one hectare of land in the state Of Michigan. A study where all the above factors are included requires a systems approach. The intensive search for energy independence has led many in the United States to consider using alcohol, and vegetable Oils as an extender or replacement for gasoline and diesel fuels. These alter- native fuels are produced from renewable resources. Alcohol, par- ticularly ethanol and methanol, have long been considered as potential fuels for internal combustion engines. Recently they have received more attention because Of rapidly increasing costs and serious future depletions of non-renewable petroleum resources in the United States. Four basic methods are available for using alcohol in spark-ignition and diesel engines. These include the following: 1. Use Of alcohol in gasoline engines after minor modifications such as a carburetor change or replacement to provide a correct air/fuel ratio for alcohol. 2. Use Of alcohol in gasoline engines after a major modification Of rebuilding the engine with increased compression as well as carburetor changes. 3. Use of alcohol in diesel engines, when alcohol is sprayed into the intake air by pressurized air from the turbocharger. 4. Use Of alcohol in diesel engines where alcohol is aspirated into the intake air through a carburetor system. The idea Of using alcohol as a motor fuel is as Old as the automo- bile itself. Methanol is today used in racing cars because Of its spe- cial characteristics such as higher octane rating, allowing higher compression ratios which deliver more power out Of the engine. Correon in 1928 wrote "it may not be long before the world will have to grow its motor fuel rather than depend on Oil wells." Alcohol is viewed by some as the most promising substitute as a motor fuel. Alcohol burns very well when engines are designed for alcohol fuel. Research and road tests have shown that alcohol does not have to be pure to be used in Spark-ignition engines. These engines work well on alcohol containing up to 15 percent water. Diesel engines burn fuels by compression heating the air-fuel mix- ture to the ignition temperature. Because of this, a wide variety Of burn very well on unmodified diesel engines due to uncontrolled igni- tion. Alcohol can, however, be used as a supplement in diesel engines through dual-fueling. In the future, engines may be redesigned for alcohol use. Since most farm tractors are diesel fuelled, a long period Of time will be required for alcohol engines to replace diesel engines. The dual-fuel systems may be a good way of displacing part Of the diesel fuel, in field Operations. Substitution rates of 30 to 45 percent can be Obtained by using the dual-fuel systems. CHAPTER 2 OBJECTIVES The overall Objective Of this work was to study the fuel consumption on typical farms to determine the feasibility Of using alcohol as an alternative fuel. TO Obtain this overall Objective, the following spe- cific Objectives were set: 1. TO write a computer program to model the fuel consumption for tractors, combines, trucks, and self-prOpelled machines per- forming different Operations on Michigan farms. TO validate the fuel consumption model by comparing modeled fuel requirements for different machinery sets and crOp rotations to actual farm fuel requirements. TO determine the portion Of the machinery fuel requirement which can be met with alcohol fuel based upon the available methods Of using alcohol fuel and the efficiencies of these methods. To determine a break-even price for producing alcohol in order tO allow tractor conversion and utilization Of alcohol to be economically feasible. CHAPTER 3 LITERATURE REVIEW 3.1 Energy consumption for field Operations. In the last 10 years several researchers have studied fuel use for specific field Operations. comparisons between some Of the results are made in Tables I through 6. Fuel consumption in liters of diesel fuel per hectare are summarized for field Operations from soil preparation to tranSportation. Most Of the information was Obtained from Extension Bulletins as referenced on the tables. Several researchers studied tractor performance under field con- dition in order to determine the energy requirements for realistic situations. Ricketts (1961) instrumented a tractor for field tests and measured the amount Of power required for farm Operations. With the test results and information Obtained by COOperating farmers, he deter- mined the Optimum combinatin Of power and engine speed for farm Operations. This was a relevant contribution because some farm Opera- tions require part load, part throttle conditions, likewise there are others which require near full load and full governed speeds. Gunkel et al. (1974) made an engineering analysis Of farm Operations. The information on the engineering aspect Of fuel use is composed of two parts. The first section outlines the fuel needs Of various agriculture Operations for tillage, chemical application, planting, cultivation and harvesting. The second section adds the appropriate Operations to determine the fuel needs for each of the various crOps grown in the state of New York. 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Loaaoa m=a> wa.m~ wa.o~ .cmxmzmv Loamo>cmg aascm mosh a~.ma a~.ma Emamo>cog mpaoaomm> mn.ma m~.ma Loamo>gug ammn Luasm a~.ma «m.¢a cm.¢a Loamm>go= oamaoa go; So ms .Lmucagm m~.aa m~.aa mn.aa Loxuaa new Lm—Fmgm-gmxuaa :Lou ~m.m ~m.o ~m.m 3o; 5 a .Loucagm Lexuaa can gmpamgmngoxuaa cgou ma.m ea.a ma.m so on .meuaq cgoo am.m am.m am.m m~.oH me.ma 30L 5 a .Loxupa :Lou mn.ma ma.m~ ma.ma :02 so on .mcaamasaa; eaou coaamsoqo camcoumaz cage agzommaz camaguaz oxca «vase—u macaw .e.a=ou. m apnea 14 me .am .mm .sm mwucmgoamm umwugsom -.~ mcamgm agoqmcmgp mm.o mamasaz ~m.~ memonxam mm.m cgou cameo ea.¢m wmmpam cgou mm.m omega» cmogu m~.oa oo.m oe.m sagas .aas uaaam mmpqaa .maogu wanaaomm> a~.o~ em.m em.m .eeou uoaaagm .e.aem apasm mmaegmsu .maoon gmmsm ma.~m Na.a~ Nm.A~ maoaaaoa .amaasag .ama__a eeou :oaaagmqo camcoumaz cage cauaguaz azoa macaw ..eLaL an» saga 2! m.¢. agaaoag can pose pmmmau no mgoaap :. moamam a Low mcoaaogmao coaaeacoamcoca Lou :oaaae=m=ou Foam .m manna 15 followed to determine the fuel consumption per Operation: 1. The range Of draft requirements and speed from the ASAE year- bOOk were selected. 2. The power-take Off requirements for each Operation as outlined in the ASAE yearbook (1974) were calculated. 3. A tractor size most closely meeting this need was selected from Nebraska Tractor Test data. 4. The fuel efficiency was used to calculate the fuel requirements. 5. A 10 percent increase in fuel use was given to account for mismatching of tractor and implement. Three values for fuel requirments were given; a low value for muck soils and some sand soils, an average value for clay loam soils, and a high value for heavy clay soils. The tractive efficiency is a very important variable when deter- mining the power that can be delivered by a tractor under field conditions. Burt et al., (1979) found that the net traction, input and output power are functions of dynamic load and travel reduction. They showed that tractive efficiency can be improved under field conditions by selecting the apprOpriate dynamic load for a particular soil condition. Sulek and Lane (1968) pointed out that in most cases the Nebraska PTO full economy data are used incorrectly. Statistical analyses were done by using the Nebraska PTO varying power and fuel consumption test to evaluate the fuel economy Of tractor models. A poor correlation was found. Fuel consumption comparisons between different sizes, models and brands Of tractors are frequently made in connection with the purchase 16 Of tractors (Persson, 1969). Because engines Operate predominantly under part load and varying speed conditions. Persson developed an empirical relationship between fuel consumption and power. The fuel consumption for crawler, 2 wheel drive, and 4 wheel drive tractors was given as a function Of the net heat value Of fuel, engine speed, engine displacement, engine power as measured at the PTO shaft, and engine constants determined from Nebraska PTO test data. The same equation was used by Macnab (1976) to determine the fuel consump- tion Of tractors under field conditions. Better information to assist farmers, fuel suppliers, and others concerned with agricultural production is needed in estimating fuel requirements, both for specific farming Opeations and for the overall Operation Of the total farm enterprise (White, 1974). White presented the fuel requirements for farm tractors when working at approximately 75 percent load. Tractors are normally designed so that this is the best load in terms Of fuel efficiency, safety, and reduced engine wear. Farmers sometimes need the job done in a certain period Of time, so they have large machines. Mismatching is difficult to avoid and tractors work underloaded or overloaded during many Operations. Fuel consumption for field Operations, from soil preparation to transportation, to produce corn for silage in the state Of Michigan is presented by White (1974) as 76.9 liters of diesel fuel per hectare. Christenson (1977) stated that 78.3 liters of diesel fuel per hectare were required to do the same Operations outlined by White. Madex and Bakker-Arkema (1978) presented fuel requirements to produce and dry corn for grain in the state Of Michigan. According to them, it takes 57.26 liters Of diesel fuel per hectare to perform the field operations (drying is not included). The approximate energy requirementsfor corn 17 production per hectare are presented in Table 7. The requirements for New York state major crops are presented by Gunkel et al. (1974) in Table 8. Christenson (1977) presented the fuel requirements (for the state Of Michigan) for 4 crOpping systems. The fuel consumption for these field Operations is listed in Table 9. Several researchers have studied the energy requirements for speci- fic soil types and for specific implements. Collins et al., (1978) studied the energy requirements for tillage systems on Costal Plain soils. Speeds for minimizing draft have been determined where draft is . related to the cone index. Collins presented field machinery data for corn production on two soil types (loamy sand and silty loam). Table 10 shows the fuel requirements for corn production systems. Based on the results a regression analysis was made to determine the unit draft. The relationship between unit draft and speed for a soil type was found. The results showed that the least energy requirements (l/ha) for a no- tillage planter was Obtained with the speed of 12.63 Km/h, while a disk tiller with seeding attachment was 9.81 Km/h. 18 Table 7. Approximate energy requirements for corn production per hectare (Madex and Bakker—Arkema, 1978) Operations Diesel fuel (l/ha) Moldboard plow Disk Harrow Plant Spray Anhydrous ammonia application Combine Transport 0 C O I 0 HH H \I NHOHmNU‘IN I O C mNmU'IquNl-I 0 w moomosoouoo TOTAL 01 Table 8. Energy requirements for New York state agriculture (Gunkel et al., 1974 . Enterprise Diesel fuel equivalent (l/ha) 1. Corn 63.5 2. Soybeans* 49.8 3. Wheat 52.4 4. Corn silage 102.7 5. Dry beans 103.5 6. Hay bale 66.2 7. Hay silage 77.3 8. Oats 64.1 9. Rye 26.2 10. Barley 64.1 * = no cultivation 19 pawn: u M £52. ES: n N mummn Lam-am n H mccmnxom u 3 FE”. u c ¢¢.¢c cm.~c mm.oc co.oa Lama cc.~m~ cc.¢~a mm.oc Am.occ eoaacaog maccoa m~.mH mammn Lcmsm acaamm>ccz m~.ma mammn Lcmam acaaaoh cma.~ mcaazcz -~.H aaa.a meaaacz aom.om cca.¢a mo.ma mo.oe acaascx ~¢.am om.- . meccacscc am.m~ c=_aao=c mc.c¢a acaccac m=._cc cc.c¢a ceaccac meazocc=_z aac om.n mccmn >5c: acazocccaz mcappsa ma.m coaacu—aaac mcauaaummca ma.” cm.a mo.a aa.~ coaacoaaaac oc.oaacc= am.m ac.~ ¢~.~ mm.c cgaa=c= Lc~___acac ao.ca ca.aa ca.aa mm.c coaacuaaaac Lac.._acca o¢.¢a o~.~ coaacsaa_=c ma.c~ oc.m ac.m A~.m mecaecaa am.cc ma.a¢ ac.- aa.- coaccccacca cecs mammn Lcmam a mcoaacgmao acmsa .mccmnwa>mz mcmnmomwcgou mac—am econ, xczwcmacma< msmamxw mccaum: Emmiamzc ammmav mo mcmaaa ca coaaaasmcou pmau .Assma .comcmamacgu. :cmaguaz co macaw msa ca msmamxw acaqaocu a so» mcoaacgmno camam com coaaae=m=ou pmzu .m mpncp 20 co.aa ca.¢c cm.mc cc.c as.om a~.cm macaoa mo.¢ ma.~ mc.~ sccam .c Am.~a ca.~a am.~a Nc.c Nc.c cc.c accaa .L ma.c ma.c guzeasasa .c AA.¢ ca.c mo.¢ mo.¢ gaooa meccam .m Nc.c Nc.c Oman .e ¢~.oa ma.c ma.c cc.c Swag .m c¢.o~ cc.ma zoaa panagc .N oa.c~ c¢.o~ zoaa cacoacao: .a _F_a oz zo_a acmagc zoaa ccconcaoz .aac a: scan acmagc zoaa ceconcaoz meoaaccaao saop xaaam cccm xacoa mamamaw mac—paa ucc mmaxa Paom .awnma ..pc am mcaapou. c: cma pmac ammmac co mgmaaa ca mamamxw coaausuogq ccou com macmsmcazamc .mau .oa manca 21 Smith and Fornstrom (1978) studied the energy requirements of selected dryland wheat crOpping systems. NO till represented a poten- tial method of saving energy. The energy requirements on various imple- ments provide a basis for selection Of implements and crOpping rotations. On farm, fuel consumption data were gathered by several researchers in several states. Kramer et al., (1978) present the results Of studies done on Kansas-Nebraska farms. Myers, et al., (1979) present the preliminary studies of fuel consumption on Michigan farms. 3.2 Machinery models. Review was done for machinery selection models, economic models, and energy models. 3.2.1 Machinery selection models. Kjelgaard and Quade (1975) presented a system model of forage transport and handling. The diversity Of machine alternatives and inter-dependence Of machine functions within forage systems make it dif- ficult to select and schedule the system mechanical elements. The model contains variables for machine types, harvesting rates, and transport distances. The outputs Of the system are: daily capacity for transport and handling machines, mechanical energy, and labor requirements. Hughes and Holtman (1976) develOped a machinery selection model based on time constraints. The model selects machines and power units which have the capacity to perform the required field Operations at a rate which ensures the target dates for successful crops are met. The com- puter model was composed Of four major segments: system power require- ment determination, tractor selection, field machine selection, and cost analysis. 22 Singh et al., (1979) develOped an algorithm for machinery selection for multicrop farms. The algorithm designs a machinery system based upon field work specifications, field Operations date constraints, machine capacity relations and field work conditions. The algorithm Specifies the size and number Of each component, prepares a detailed week-by-week work schedule, gives distribution Of labor needs, calcula- tes fuel requirements for each Operation, and makes a detailed cost ana- lysis for the selected machinery set. Singh et al., (1979) studied the field machinery requirements as influenced by crop rotations and tillage practices. They used a previously designed algorithm to determine the machinery requirements and costs for 29 cash crOp production systems Of Southern Michigan. 3.3.2 Economic models. Miller (1980) determined the minimum machinery cost compliment for various situations. A model was develOped to determine the number and sizes Of tractors. The equipment capacity and the days available for work were included in the model in such a way that the best equipment size could be determined. Edwards and Boehlje (1980) studied the risk-return criteria for selecting farm machinery. Risk preferences were introduced into machi- nery selection by estimating the mean and standard deviation for total costs, including timeliness costs, associated with various machinery sets. A machinery selection model was develOped. Ten machinery sets were chosen, representing the best combination Of machines and power units. Several risk-return criteria were tested using the cost distri- bution data generated by the simulation model. The criteria were: expected cost; standard deviation frontiers; stochastic dominance; 23 least-cost, least variance, and upper confidence limit criteria. These criteria were compared in terms of applicability, results and prac- ticability Of use. For small farms (8O - 160 ha) most of the criteria were consistent by selecting the same machinery set for least-cost, except for the expected mean, standard deviation that chose several machinery sets. For large farms (320 - 360 ha) only the least-cost, least variance; and upper confidence limit (0.9) criteria were con- sistent and chose only one machinery set. The least-cost, least variance criterion is relatively simple to use and produced results con- sistent with those Of the other criteria tested. Mayfield et al., (1980) develOped a model to estimate farm machinery Operating costs. The model used a depreciation schedule based on replacement list prices rather than initial list prices. The model has been used since early 1977 to estimate farm machinery Operating costs in the state Of Alabama. The Alabama COOperative Extension Service issued, in October Of 1980, a Bulletin where farm machinery Operating costs are listed in dollars per hour. The cost per hour for different usage levels are also listed. Computerized machinery cost analysis programs were also developed by Moore et al., (1980). The computer program develOped estimates a single machine's cost, an Operation's cost with twO machines, or a total job cost using up to 5 power units and 5 pulled units plus labor. Both com- puter programs give the costs per hour for several usage levels. Chancellor and Cervinka (1975) presented a costing procedure for combines. Costs related to the speed of combine Operation, and costs pro- portional to years Of ownership were presented. Basic input information were developed such as combine grain losses, timeliness coefficient for harvest, and combine parameters such as size, Speed, etc. Conclusions 24 about combine management, crOp research, and combine develOpment were presented. Cervinka and Chancellor (1975) also presented the costs for rice production in California. Economic and physical aspects of major increases in intensity of farm machinery use were examined. Peterson and Milligan (1976) presented an economic-life analysis for machinery replacement decisions. A method for determining fixed and Operating costs was presented. A computer model was develOped which com- puted and tabulated costs for all likely combinations Of machinery acquisition and retirement ages. An example for a potato harvester was presented. Kolarik et al., (1979) presented a performance analysis Of farm machinery. The computer program is described as: Farm Machinery Availability and Cost Simulation (FMACS) model, which is a two level (system-subsystem) simulation model. The simulation model considers usage requirements, multiple working conditions, Operating aspects, sub- system failure and detection, service, maintenance, repair and costs associated with Operation, service, maintenance, repair and timeliness. The model was designed for specific Operating conditions and with the idea of helping designers and manufacturers to balance out system and subsystem designs. Krutz et al., (1980) described the equipment analysis with farm management models. TwO linear programming farm management models were described: Purdue Model 8-93 (Purdue CrOp Budget, 1976) and the International Harvester Pro-Ag Program (Pro-Ag Model, 1977). The model allows the user to evaluate alternative sets and sizes of machinery. 25 3.2.3 Energy models. An empirical relationship was developed by Persson (1969) to deter- mine the fuel consumption in Kg per hour. This relationship was uSed by Macnab (1976) as part Of a computer model. Tractor performance and fuel consumption could be Obtained by using as input the tractor characteristics and working conditions. Three relationships are pre- sented in the ASAE Yearbook (1978). These relationships use the engine load to determine the diesel, gasoline, and Liquified Petroleum gas consumption in a l/Kw-h basis. These are the relationships used in this study to determine the engine fuel consumption as a function Of load (a correction factor was included). Many researchers have develOped SOphisticated fuel meters to deter- mine the fuel consumption for field operations. The power required to pull a determined implement has also been a major concern for years, but relatively little data are available to check the validity Of these relationships. The relationships are general and few parameters are included. When data are obtained and compared with results calculated by these relationships, differences are sometimes tOO high to be acceptable. Pimentel et al., (1973) delineated the energy inputs to corn produc- tion as: labor, machinery manufacturing, fuel, nitrogen, phosphorus, potassium, seed, irrigation (if required), insecticides, herbicides, grain drying, electricity, and transportation. Clark and Johnson (1975) presented an energy budget for grain sorghum tillage systems. A procedure for develOping energy budgets for tillage systems is illustrated. Draft, fuel, and energy requirements for field Operations used in tillage systems are also presented. 26 Ozkan and Frisby (1979) presented the develOpment and application Of a linear programming model to maximize the overall energy efficiency Of a multi-crop, example farm. A computer model gave the fuel and energy consumption for field Operations, and fuel and energy consumption for selected crops. A method for determining the total energy input for agricultural practices was developed by Bridges and Smith (1979). The energy required for a particular practice included the fossil fuel used, energy used in manufacturing, marketing, and repairing equipment as well as the manual labor required to perform the Operation. The approach and an example were presented. The model used was developed by Loewer et al., (1977). 3.3 Alcohol utilization. The utilization Of alcohol in mixture with gasoline or even pure alcohol is not a new adventure. Alcohol has been used as motor fuel, in the form Of blends since the first automobiles were made. Alcohol has also been used in racing because of its special characteristics. Strong (1911) and several other researchers looked for new ways Of replacing fossil fuels. Alcohol Obtained from plants containing sugar and starch proved to be a good fuel and was economically feasible in case Of a shortage Of petroleum. This review presents some Of the research done with gasoline and diesel engines using alcohol as a blend or in its straight form. 3.3.1 Alcohol use in spark-ignition engines. The first report on the use Of alcohol was published in 1907 by the U.S. Department of Agriculture, entitled "Use of Alcohol and Gasoline in 27 Farm Engines." In 1926, in Britain, ROSS and Ormandy published a paper on the use Of alcohol fuel in internal combustion engines. The following includes a review Of the use Of alcohol in spark ignition engines, in blends with gasoline or in its straight form. 3.3.1.1 Alcohol use in blends with gasoline. Zimmerman (1924) conducted tests with alcohol gasoline blends. Correon (1928) used commercial alcohol (190 proof) mixed either with gasoline or kerosene as fuel for gas engines. He concluded that most farm gas engines could Operate with gasoline, kerosene or mixtures of gasoline and alcohol without structural changes. Gray in 1933 and in 1934 used alcohol with gasoline blends and Obtained more power by increasing the compression. This was explained as making better use Of the higher octane rating of alcohol. Similar results were Obtained by Miller (1933). In 1936, Bridgeman published a paper on the “Utilization of Ethanol and Gasoline Blends." In 1938, the U. S. Department Of Agriculture published a booklet on “Motor Fuel from Farm Products." Since the second world war few studies were done and most Of them were related to the use Of alcohol in blends with gasoline. In the 70's work was done by Ingamels et al., (1975), Chui et al., (1979), Sheller (1977), Owens (1977), Baker (1977), Pishinger et al., (1979), and Stephenson (1980). Conclusions which can be drawn are that both methanol and ethanol can be used as an octane booster. For unmo- dified engines, as the alcohol concentration is increased, driveability decreases and corrosion problems occur. Sheller presented four reasons for blending alcohol with unleaded gasoline: increased octane number, positive volume charge of mixing, reduced fuel consumption, and few 28 pollutants in the exhaust. Test results showed an advantage (lower fuel consumption) for ethanol due tO its higher Kcal content, when compared to methanol. 3.3.1.2 Straight alcohol use in gasoline engines. Ingamells (1975) Showed in his tests that methanol could be used effectively in special vehicles designed to handle its corrosion, water absorption, and vaporization characteristics. Chui (1977) using two engines (1.4 L and 2.3 L) performed tests with neat ethanol. Improvements in power were due primarily to differences in equivalence ratio and fuel octane rating. TO get a comparable equivalence ratio the metering jets in the carburetor were enlarged. Cold start was not possible when the temperature was below 5°C. Adding gasoline to the fuel bowl extended cold start capability downward to 0°C. He stated that higher compression engines, carburetor adjustments, spark timing and cold starting should be given attention when redesigning engines to use neat ethanol. The redesigned engine had a higher thermal efficiency and increased power. The use Of ethanol fuel decreased NOx and increased fuel exhaust emissions. C0 emissions were similar. The most Significant differences in the unburned fuel emissions were the presence Of unburned ethanol and substantial amounts of aldehydes. Owens (1977) reported that using methanol in Spark ignition engines at low temperatures increased the rate of wear Of the piston rings and cylinder bore, when conventional lubricant was used. Baker (1977) reported the potential advantages of methanol relative to gasoline, were most evident when it was used in the neat form. Some Of the advantages are: increased power through increased compression, 29 reduced specific fuel consumption, and extended lean misfire limit, reduced NOx and increased fuel octane quality. McCormack (1977) performed tests on a four-cylinder, 2.3 L spark ignition engine. Five configurations Of intake manifold, and fuel injection systems were examined. Gains were seen in fuel economy for all Of the methanol fueled systems ranging between 6 and 30 percent in the urban cycle and between 10 and 30 percent on the highway. Johnson (1977) performed tests using straight methanol in a single cylinder Spark ignition engine. Methanol and methanol + 5 percent water exhi- bited efficiency increases Of 2 - 3 percent for the range of test con- ditions. For constant manifold heat conditions (sustantially lower mix- ture temperature) methanol and methanol + 5 percent water produced 5 - 7 percent more power than gasoline. Hunt (1979) said "We have shown that you don't have to use pure alcohol in spark ignition engines. These engines work nicely on alcohol containing 16 percent water.“ Hunt ran a modified spark ignition engine on 167 proof alcohol (83.5 percent ethanol and 16.5 percent water), and concluded that ethanol/water solutions worked fine in spark ignition engines. Pishinger (1977) wrote that the use Of straight alcohol for vehicle use in Brazil goes back to 1923. Ethanol fueled cars used 12.68 liters of fuel per 100 Km compared to 10.37 liters per 100 Km for gasoline (a 22.3 percent increase). Stephenson (1980) performed tests in an air-cooled, four-cycle, single-cylinder, Spark-ignition engine, using 100 percent ethanol Of 200, 190, and 180 proofs. The higher octane rating Of ethanol was an advantage at the increased compression and it was consistent for 100 percent ethanol. 30 Swarr (1981) used ethanol and distilled water solutions of 100, 95, 90, 85, 80, 75, and 70 percent ethanol in a Ford 2000, three cylinder gasoline tractor. The modifications included the replacement Of a gaso- line carburetor with a carburetor designed for use with ethanol. Ignition timing was advanced, and the spark plugs and fuel pump were replaced. He measured power output, thermal efficiency and fuel effi- ciency and compared performance with ethanol to that with gasoline. AS the water content in the fuel increased, more fuel was necessary to pro- vide a given torque level. The fuel efficiency for 90 percent ethanol was a little less than for 100 percent ethanol. He concluded that the best ethanol fuel as far as engine performance as well as economical value contains 10 percent water. Increases in fuel consumption Of 32 percent were Obtained when using an 8:1 compression in the engine. A high compression (12:1) with fuel injection engine can be called the true alcohol engine. This efficient engine was tested in September of 1941 at the National Experiment Station at Bellevue, France as the Brandt System. Some characteristics of this engine are the following: a) Higher thermal efficiencies when compared to conventional SI engines. b) Smaller engines are required to deliver the same amount Of power. c) Higher fuel consumption due to lower caloric value Of alcohol can be compensated by higher engine output (Kw-h/l) due to the higher octane rating of alcohol. This allows higher compression which will give higher thermal efficiencies for the true alcohol engine. 31 3.3.2 Alcohol use in diesel engines. Most Of the research done was using alcohol through dual-fueling, where minor engine modifications are required. When the dual-fueling method is used, up to 45 percent Of the diesel fuel can be replaced by alcohol. 3.3.2.1 Alcohol use through dual-fueling. Holmer (1977) selected the dual-fuel diesel engine as the best compromise and studied it when using methanol dual-fueled with diesel. Holmer used a turbocharged diesel engine, with a displacement Of 10 L and compression ratio Of 15 to 1. A separate alcohol fuel system was used. He concluded that diesel engines can easily be converted to a dual-fuel engine and attain good performance and low emissions Of smoke, HC, and noise. Panchapakesan (1977) used a alcohol-diesel engine, where alcohol was the main fuel, aiming to achieve the maximum use Of alcohol with the best possible thermal efficiency and output. The results Showed that it was possible to derive as much as 70-80 percent of the total energy requirements of the engine from alcohol for most of the load range. Extensive work on the use Of alcohol as a principal fuel in diesel engi- nes by dual-fuel Operation has been investigated also by Harvermann and others at the Indian Institute of Science. Some advantages Of alcohol/diesel engines are: a. The engine permits the use Of alcohol (renewable fuel) as the main fuel. b. The engine using alchol can achieve substantially higher peak power outputs. 32 c. The engine using alcohol can attain better thermal efficiency. Scott (1977) investigated the extent to which methanol could replace normal diesel fuel in truck type engines. The substitution rate was limited by both quench and knock. The maximum substitution was 80 percent and it was only reached at 36.7 r/s, by inlet mixture heating to 30°C and 2 percent amyl nitrate as fuel additive. The main problem was igntion delay. This was also a problem for Panchasepakesan in his research. A turbocharged engine would have more suitable characteristics teristics for Operation on methanol. Pishinger (1979) develOped an ignition Spray concept for dual- fueling a diesel engine with methanol, and some conclusions on his work are listed below: I a. The engine presented less visible smoke. b. The engine emissions Of gaseous pollutants was reduced. c. A large portion Of Oil can be substituted by methanol. d. The engine presented better thermal efficiency. e. The engine thermal and mechanical Stresses were reduced. f. The engine compression ratio can be varied over a wide range (14.5:1 to 19.5:1). Berg and Holmer (1979) used two separate systems in a turbocharged engine to investigate the use Of ethanol and methanol. Several alcohol proofs were tested. The conclusions were similar as the above. The dual-fuel system broadens the use of the engine permitting the utiliza- tion Of a broad range Of light liquid fuel. Cruz et al., (1980) found that carburated alcohol can supply 50 per- cent Of the fuel energy for diesel engines Operated in a dual-fuel mode. The direct injection proved to be a better way to use alcohol than with a precombustion chamber. Cruz (1979) also found that 47 percent Of the 33 total energy requirements could be supplied by carburated methanol. Similar problems like rate Of substitution which was limited by knock were encountered Cruz (1981). 3.3.2.2 Straight alcohol use in diesel engines. Little work has been done in the area Of alcohol use in diesel engi- nes in its straight form. Alcohol powered tractors are being tested in Brazil. Heavy weight trucks were recently put into the market in Brazil. The tractors and trucks are running on straight alcohol pro- duced from sugar cane. The “alcotractors” are being tested under dif- ferent field working conditions in several agricultural states Of Brazil. The tractor engines were redesigned to Operate with a Spark- ignition system and decreased compression. CHAPTER 4 MODEL FORMULATION Model formulation is divided into two major phases: Feasibility study and model description. 4.1 Feasibility study. This phase of the model formulation is divided into three subphases: needs analysis, system identification, and problem formulation. 4.1.1 Needs analysis. According to the ASAE Yearbook (1978) the draft requirements vary considerably from one soil type to another. For example, for each square centimeter Of sandy soil plowed, 2.5 Newtons of draft are required while 9.0 Newtons are required to plow clay soils, using the same speed of 6.0 Km/h. White (1974) reported that it takes 8.5 to 34.0 liters Of diesel fuel to plow one hectare Of land in the state of. Michigan. Other factors such as those discussed in chapter 1.0 make it difficult to calculate the exact amount of fuel required for a specific Operation under Specific conditions. A close determination Of the amount of fuel to be used can be done if data related to the soil type, soil conditions, working depth, machine speed, and other variables are considered. Some Of the needs are listed below: a. Better knowledge concerning the energy needs for specific field Operations, crOpS, tillage and crOpping systems. D. Systems analysis by using a computer program where equations listed in the ASAE Yearbook (1978) would be used to determine 34 35 the energy requirements for field Operations. c. Check results from the computer program with results collected from the farm. d. A computer program that calculates the energy and fuel require- ments for most of the Operations performed on Michigan farms. e. A computer program that requires only relevant information as input data, easy to be Obtained and produces valid results. f. A computer program that analyzes the influence Of alcohol (as motor fuel) used in several ways in gasoline and diesel engines, and in several crOpping systems. 4.1.2 System identification. The farm is the system under study. Machinery is a subsystem made up Of tractors, combines, trucks, and self-prOpelled machines which are the major components of the system. Implements are considered com- ponents Of the system as well. Linkages are present between components Of the system. A tractor pulling a plow is an Operation in which the two components are linked by energy requirement (plow) and energy availability (tractor). The linkages are represented by mathematical relationships giving the amount Of energy or amount Of power required to perform an Operation. When self-prOpelled machines, such as combines, trucks, and windrowers, etc. are used, mathematical relationships are used to determine the amount of power and thus fuel requirement for that specific component. The major inputs for our system are the machinery set specifications such as Size of machines and power units, soil type, and Operating conditions. The major outputs Of the system are the energy and fuel requirements, machine load, and fuel costs for specific 36 farm Operations. System parameters are used to make the system more general and most Of them are stored in a subroutine block data and used whenever necessary. The weather is the most important environmental (exogenous) input for agricultural systems. In this program no constraints are put on time available to finish a certain Operation. We assume the farmer knows which Operations he is going to perform and the machinery sets are large enough to complete the Operations by a certain date. Weather is not considered in this program. More attention to the input, parameters, and outputs will be given in chapter 5.0. The following is a brief description of the input and outputs Of the model. 4.1.2.1 Model inputs. Lines Of input data can be SUpplied interactively or by cards. The following are the input data. a. General input data. This includes prices Of fuels, number Of machines, discount rate and number Of years to depreciate the machine conversion costs, and total farm area. b. Input for each machine. This includes fuel types, decision to convert an engine to alcohol, conversion type, number Of Opera- tions to be performed, power and weight Of machine, and opera- tion to be performed by a machine. c. Input data for each field Operation. These inputs are supplied by a group Of Operations. The Operation groups are the following: seeding, cultivating, fertilizer and chemical application, harvesting, and transportation Operations. The following are the inputs to be supplied for each Operation: implement size, depth Of work, implement weight, number Of rows, machine 37 Speed, soil type and conditions, area to be covered, crop density and feed rate, and for transportation (crOp yield, transport distance, fuel consumption in Kilometers per liter, and truck and wagon capacity). 4.1.2.2 Model outputs. When conventional fuels are used the following outputs are Obtained. Output for each field Operation includes: Wheel slip and tractive efficiency, total implement draft, power required, engine load, fuel consumption per hour, effective field capacity, number Of hours to complete the job, machine accumulated use, fuel consumption per hectare, total fuel use, total fuel cost, and fuel cost per hectare. When alcohol fuel is used in the system the same outputs as the above are given plus the following: amount of alcohol used, fossil fuel savings, cost Of alcohol fuel per hectare, and breakeven price for alco- hOl. 4.1.3 Problem formulation. After analyzing the needs and identifying the system, the problem is formulated in order to find a feasible solution. Based on the infor- mation generated during system identification, we develOp what the system must do in order to satisfy the determined needs. The problem formulation will be: tO determine the machine performance under field conditions (i.e., determine the wheel slip, tractive efficiency, energy requirements to pull implements or power requirements for self-prOpelled machines, machine loads, fuel consumption and costs Of fuel, explore the use Of alcohol as alternative fuel, determine break-even prices for alcohol fuels, etc.), such that the identified outputs are provided, the results are correct, and the results can be validated. 38 4.2 Model description. The computer program is made up Of five subroutines which perform the calculations according to the flowchart Shown in Figure I. The first subroutine calculates the energy needs and machine loads for field Operations. The second calculates fuel consumption, effective field capacity, and machine use. The third calculates alcohol utilization when either one of four conversion methods is used. The fourth calcula- tes the conventional and alernative fuel costs. The fifth subroutine contains information such as machine field efficiency, draft parameters, tractor conversion costs, alcohol fuel consumption parameters, and alpha numeric code for machine and Operation names. ' 4.2.1 Energy subroutine. This subroutine computes the energy needs for field Operations from soil preparation to transportation. The field Operations are divided into six groups: tillage, seeding, cultivating, fertilizing and Spraying, harvesting, and transportation. 4.2.1.1 Draft requirements for tillage Operations. Sixteen field Operations are modeled in this group. Draft is defined as the force required in the horizontal direction Of travel to pull an implement. The following equations calculate only functional draft (soil and crap resistance). Draft requirements for moldboard plows are modeled as the product Of unit draft and cross-sectional area of cut. The draft per unit cross- section Of furrow slice is for bottoms equipped with high speed moldboards, coulters, and landsides. The implement draft is modeled using the following equations: READ INFO FARM, MACH. AND FIELD OPERATIONS. CALCULATE: _______q. SLIP, TE, MACH. EFF., F... ENERGY REQ., “ AND DRAFT MACHINE LOAD. PARAMETERS. V CALCULATE: FUEL CONS., MACHINE CAP. AND USE. IS ALCOHOL NO CALCULATE: FUEL CONS. ALCOHOL FUEL PARAMETERS CONS. AND 5" ‘ FOR ALCOHOL CONV. SAVING. FUELS. i NEXT OPERATION NEXT MACHINE CALCULATE: FUEL COSTS. ? CALCULATE: MACHINE TOTAL MACH . <— CONVERSION FUEL, COSTS, COSTS. BREAK-EVEN. O CALCULATE: TOTAL FARM FUEL USE AND COSTS. (m?) Figure 1. Model flowchart 40 DRAFT 3 CAREA * UDRAFT (1) Where DRAFT is the implement draft in Newtons, CAREA is the area covered in cm2, and UDRAFT is the unit draft in Newtons/cmz. CAREA is calcu- lated by multiplying the implement width by the working depth, both in cm. The unit draft (UDRAFT) is given by the following equation: UDRAFT = C1(IST) + CC1(IST) *SPEED ** 2 (2) Where CI and 001 are constants and their values depend on the soil type. A list of all the constants used in this model are presented in Table 13. Values for several soil types are stored in the block data subroutine. IST is the input variable for soil type which can assume values from 1 to 7. SPEED is the maChine speed in Km/h. Soil moisture and apparent specific gravity parameters are not included in this model. Disk plows were modeled similar to moldboard plows. The draft per unit cross-section of furrow slice for a 66 cm diameter disk with a tilt angle of 0.38 rad and a horizontal angle of 0.75 rad is modeled by two equations similar to Equations (1) and (2). Constants CZ and 002 are stored for two different soil types and IST can assume values of 1 or 2. Draft requirements for listers were modeled as the product of number Of bottoms and working depth to the second power. The draft per 36 cm bottom at 6.76 Km/h is modeled by the following equation: DRAFT = C3*NB*TD**2 (3) Where N8 is the number Of bottoms, T0 is the working depth in cm, and C3 is a constant for silty clay loam soils. 41 Draft requirements for disks harrows are modeled as a function Of implement mass. The implement draft at any speed, and typical working depth is modeled by the following equation: DRAFT = C4(IST)*W (4) Where C4 is a constant which can assume three values to calculate the draft for clay, silt loam, and sandy soils. IST is the input variable for SOil type, assuming values Of 1, 2, and 3. W is the implement mass in Kg. The draft requirements for chisel plows are modeled as a function Of the number Of tOOls and field speed. Equations derived from data pre- sented by Frisby and Summers, 1979 were prefered over the ASAE yearbook equations. The draft requirements for chisel plows and field cultiva- tors according to the ASAE yearbook equations were too high to be used for Michigan soil conditions. The following equation was used to calcu- late the draft for loam, sand, and clay soils when tools are Spaced at 31 cm. DRAFT = NB*(C5(IST)+CC5(IST)*SPEED) (5) Where DRAFT is the implement draft in Newtons at 30.7 cm depth, N8 is the number Of tools, 05 and 005 are constants for three soil types (loam, sand, and clay), IST and SPEED are the same as defined above. The draft requirements for field cultivators are modeled Similar to chisel plows. Data from Frisby and Summers, 1979 were used to derive Equation (6). Equation (6) calculates the draft requirements for field cultivators when working at 20.5 cm depth and the tools are spaced by 16 CHI. 42 DRAFT = NB*(CFC1(IST)+CFC2(IST)*SPEED) (6) Where CF01 and CF02 are draft parameters derived from experimental data. The draft requirements for rotary tillers are modeled as the product Of unit draft and cross-sectional area Of cut. The effective draft per unit cross-section Of furrow slice, 45 cm diameter rotor, 10 cm depth, 6.7-11.7 r/s is modeled for dry silt loam soils as follows: DRAFT = CAREA*UDRAFT (7) UDRAFT = C6(IST)/BL**O.46 (8) Where DRAFT is the draft in Newtons, CAREA is the area covered in cm2, and BL is the bite length in cm. The draft requirements for one way disks with seeder attachments are modeled as the product Of unit draft and implement width. The draft for a tillage depth Of 7.5 cm, including rolling resistence for three soil types is modeled by the following equations: DRAFT 8 1000.0*UDRAFT*WIDTH (9) Where UDRAFT = C7(IST)+CC7(IST)**SPEED (10) WIDTH is the machine width in m, UDRAFT is the unit draft in Kilonewtons/m, C7 and 007 are constants for clay, clay loam, and loam soils, other variables were already defined above. The draft requirements for subsoilers are modeled Similar to chisel plows and field cultivators. The total draft as a function Of the number Of shanks and working depth is given by the following equation: DRAFT 8 NB*(C8(IST)*TD) (11) 43 Where N8 is the number Of shanks, T0 is the working depth in cm, 08 is the constant for soil types, and IST is the input variable for soil types (from clay to sandy loams). The draft requirements for minor tillage tools as a function Of implement width is modeled according to the following equation: DRAFT = CA(IST)*WIDTH (12) Where CAIO, CA11, CAIZ, CA13, and CA14 are the constants for land plane, spike tooth harrow, spring tooth harrow, rod weeder, and roller and packer, respectively. The equation for the stalk shredder is the same only the constant is 016. WIDTH is the machine width in m. 4.2.1.2 Draft requirements for seeding Operations. Four seeding Operations are included in the program, including row crop planters and grain drills. The draft requirements for row crOp planters (seeding only) as a function of the number of rows for good seedbed, including the rolling resistence is given by the following equation: DRAFT = 017(IST)*NROWS (13) Where NROWS is the number Of rows. Three values are stored (high, medium, and low) for 017, depending on the value Of IST (1, 2, and 3). The draft requirements for row crOp planters (seeding, fertilizer, and herbicide) as a function Of the number Of rows is given by Equation (13) where 018 is the constant used. The draft requirements for grain drills as a function Of the number of furrow Openers (number Of rows), including rolling resistence is 44 given by Equation (13). 019 contains the constant values for regular furrow and 0019 contains values for deep furrow. An input variable (10) is used to specify which method is used. The draft requirements for nO-till planters are modeled by a similar equation as Equation (13) where the constant is 020. 4.2.1.3 Draft requirements for cultivation Operations. Three cultivation Operations are included in the program. The draft requirements for row and lister cultivators as a function Of working depth and implement width for all typical speeds is given by: DRAFT = C( IST)*TD*WIDTH (14) Where 021 is the constant for row cultivators and 022 for a lister cultivator. T0 is the working depth in cm, WIDTH is the machine width in m, and the constants C can assume high, medium, and low values for clay, silty, and sandy soils, respectively. The draft requirements for rotary hoes as a function of implement width and speed is given by: DRAFT = 023+0023*SPEED*WIDTH (15) Where DRAFT, SPEED, and WIDTH were defined above, and 023 and 0023 are constants (draft parameters). 4.2.1.4 Draft requirements for fertilizer and chemical application. Equations for anhydrous ammonia applicators, fertilizer distributors, and pesticide Sprayers were used. The draft requirements for anhydrous ammonia applicators as a function of the number Of knives is given by: 45 DRAFT 3 C24*NK (16) Where DRAFT is the draft is Newtons, NK is the number of knives, and 024 is a constant. The power requirements for fertilizer distributors and pesticide Sprayers include both the rolling resistence Of the implement plus hydraulic power. The hydraulic power usually is very low, SO only the rolling resistence Of the implement was considered. The draft as a function Of implement weight and soil surface conditions is given by the following equation: DRAFT = 9.8*W*(1.2/025(IST)+0.04) (17) Where W is the implement mass in Kg, 025 is a constant assuming dif- ferent values for soil surface conditions. 4.2.1.5 Power requirements for harvesting Operations. Equations to calculate power requirement for combines, self- propelled machines, and tractors performing harvesting Operations Of soybeans, small grain, corn, cotton, potatoes, sugar beets, forage, and hay are listed as follows: The power requirements for harvesting soybeans and small grain is modeled as a function of feed rate by the following equation: ENNE = 026+0026*FR (18) Where ENNE is the power required in Kw, FR is the feed rate in Kg/s of typical material (wet basis), and 026 and 0026 are constants. 46 The power requirements for corn haresting is modeled similar to soybeans and small grain harvesting. The result Of Equation (18) is multiplied by 1.1 to Obtain an estimated power requirement for corn harvesting. The power requirement for harvesting windrowed small grains is modeled similar to soybeans and small grain harvesting. Equation (18) is used and the result is multiplied by 0.9.. The power requirement for cotton pickers, cotton strippers, and beet toppers are modeled as a function Of the number Of rows and given by: ENNE = C(IDEN)*NROWS (19) Where 027 is a constant for a cotton picker, 028 is a constant for a cotton stripper, and 029 is a constant for a beet tOpper. IDEN is an input variable for crOp density and can assume values of 1, 2, and 3. The constant C has three values stored; high, medium, and small to model corresponding crOp densities. Beet harvestors and potato diggers are pulled by tractors and the PTO power requirement is given by the following equation: ENNE = C(IDEN)*NROWS (20) The variable 0 in Equation (20) can be 032 for a beet harvestor and 033 for a potato digger. The draft requirement to pull the harvesting machine is given by: DRAFT = 00(IDEN)*NROWS (21) Where DRAFT is the implement draft in Newtons, 00 can be 0032 for a beet harvestor and 033 for a potato digger. 47 The power requirments for a cutterbar mower (for alfalfa) is given by: ENNE = 034*WIDTH (22) Where ENNE is the power requirement in Kw, 034 is a constant, and WIDTH is the machine width in meters. The power requirements for a cutterbar mower-conditioner (for alfalfa) as a function of crap density and implement width is given by: ENNE = 035(IDEN)*WIDTH (23) Where IDEN is the crop density and 035 is a constant. The power requirements for a flail mower conditioner (for alfalfa) as a function Of feed rate is given by: ENNE = C36+CC36*FR ' (24) Where FR is the feed rate Of typical material, in Kg/s, wet basis. The power requirements for conditioner only (for alfalfa) are modeled simi- lar to the cutterbar mower. The constant is 037. The power requirements fora 2.44 m side delivery rake as a function of machine Speed is given by: ENNE = C38+CC38*SPEED (25) Where 038 and 0038 are constants and SPEED is the machine Speed in Km/h. The power requirements for rectangular and round balers used to bale normal hay or straw is given by: ENNE = C*FR (26) 48 Where 0 is 039 for a rectangular baler and 040 for a round baler, and FR is the feed rate in Kg/s. The power requirement for a flail type forage harvester, for green forages is given by Equation(24). Equation (24) multiplied by a factor Of 2.0 gives the power requirements for a flail type forage harvester, for other forages. The power requirement for a shear bar type forage harvester, for corn is given by: ENNE = C43+0043*FR (27) Where the variables are the same as the ones defined above. Equation (27) multiplied by a factor Of 1.33 gives the power requirements for a shear bar type forage harvester, for green forage. Equation (27) multiplied by a factor Of 2.0 gives the power requirements for a shear bar type forage harvester, for low moisture forage and hay. The draft requirements for pulling, windrowing, and pulling- windrowing beans as a function of the number Of rows is given by: DRAFT = 0*NROWS (28) Where 0 is 046 for a bean puller, 047 for a bean windrower, and 048 for a bean puller-windrower. 4.2.1.6 Energy requirements for transportation. The program calculates the amount of fuel used in transportation for short distances (from field to farm storage or from farm storage to field, and from farm storage to market or field to market). TwO transportation Operations are allowed. Transportation with trucks or with wagons pulled by farm tractors. 49 The fuel used to transport a determined amount Of product using a truck is determined as follows: TFU = 2.0*FD*(AREA*YIELD/CAP)/AKPL (29) Where TFU is the total fuel used in liters, F0 is the field distance in Km, AREA is the area in hectares, YIELD is the crap yield per hectare in Kg, CAP is the truck capacity in Kg, AKPL is the average fuel con- sumption Of the truck in Km/l, and 2.0 is a constant to model a round trip over a given distance. Equation (17) is used to calculate the draft requirements to pull wagons. 4.2.1.7 Load determination. Equations (1) through (29) calculate the draft requirements or power required to pull an implement or machine when performing field Operations. The rolling resistence of the implement was included whe- never necessary. The equations do not include the rolling resistence Of a tractor when pulling an implement. The energy required to overcome the rolling resistence can be considerable, especially in soft, plowed soils. In order to calculate the tractor total load, the wheel slip and tractive efficiency were modeled by including a coefficient of rolling resistence. A loss Of power occurs between the power arriving and power leaving the tractor powered wheels. A loss of power due to slippage also is inevitable. In order to quantify these losses, the wheel slip and trac- tive efficiency were calculated. The wheel slip was used to calculate the tractive efficiency and the latter was used to calculate the total power required to pull an implement under field conditions. When 50 equations are used to calculate power requirements in Kw, the tractor or machine rolling resistence is calculated, transformed into Kw, and the ratio Of PTO power required to maximum PTO power available was determined. When equations calculated the draft requirements the following calculations were made: SLIP = 1.0/(0.3*025(ICN)*ALOG(0.75-((TDRAFT/9.8)IWM+(1.2/025(ICN) +0.04)))) (30) TE = (1.0-SLIP)*(1.0-(1.2/025(ICN)+0.04)/(0.75*(1.0-EXP(-0.3*025 (ICN)*SLIP)))) (31) PREQ . 0.0002778*DRAFT*SPEED/(0.96*TE) (32) RATIO = FREQ/PAVA (33) LOAD = 100.0*RATIO (34) Where SLIP is the wheel slip in percentage, TDRAFT is the total draft in Newtons, WM is the machine dynamic weight in kg, TE is the tractive efficiency in percentage, PREQ is the PTO power required in Kw, PAVA is the maximum PTO power available in Kw, SPEED is the machine speed in Km/h, RATIO is the PTO power required divided by maximum PTO power available, TLOAD is the machine load in percentage, and 025 (ICN) is the constant for different soil surface conditions. 4.2.2 Fuel consumption subroutine. The value for RATIO calculated in the energy subroutine is used to calculate the specific fuel consumption in l/Kw-h. Values for field efficiencies which are stored in the subroutine block data are used to calculate the machine effective field capacity in ha/h. The fuel con- sumption in liters per hectare was then calculated. 51 The diesel, gasoline, and liquified petroleum gas consumption are calculated with the following equations: DCON = 2.64*RATIO +3.91-0.2*(738.0*RATIO+173.0)**0.5 (35) GCON = 2.74*RATIO+3.15-O.2*(697.0*RATIO)**O.5 (36) CLP = 2.69*RATIO+3.14-0.2*(646.0*RATIO)**O.5 (37) Where DCON, GCON, and CLP are the diesel, gasoline, and liquified petroleum gas consumption in l/Kw-h and RATIO as defined above is the PTO power required divided by maximum PTO power available. Equations (35) and (36) were checked against the Nebraska Tractor Test data and were found to overestimate the Specific fuel consumption for most tractor models. The Specific fuel consumption for 13 diesel tractors was Obtained from Nebraska Tractor Test data and are listed in ,Table 11. The Specific fuel consumptions (l/Kw-h) at 50, 75, and 100 percent load were compared with the results from Equation (35). AS 75 percent is the best load for engines to Operate a 13 percent decrease in the specific fuel consumption Of Equation (35) was given and the new Equation (35) is listed as follows: DCON = 2.3*RATIO+3.4-0.174*(738*RATIO+173)**0.5 (35) The specific fuel consumption for 13 gasoline tractors was also Obtained from Nebraska Tractor Test data as listed in Table 12. The same procedure as described for diesel tractors was used. A correction factor Of 0.92 was used for Equation (36). The new Equation (36) is given as follows: GCON = 2.521*RATIO+2.898-0.184*(697*RATIO)**0.5 (36) 52 Figure 2 presents the curves for three engine types described by Equations (35), (36), and (37). The specific fuel consumption for diesel and gasoline engines using a correction factor is also plotted in Figure 2. Equation (37) was not changed because not enough information about new LP gas tractors was available in the Nebraska Tractor Test data. Table 11. Specific fuel consumption for 13 diesel tractors (Nebraska Tractor Test data) Tractor Specific fuel consumption (l/Kw-h) number 50% load 75% load 100% load 1 0.491 0.414 0.387 2 0.522 0.445 0.417 3 0.500 0.424 0.406 4 0.504 0.432 0.407 5 0.522 0.453 0.426 6 0.497 0.426 0.417 7' 0.503 0.417 0.375 8 0.533 0.447 0.421 9 0.492 0.417 0.381 10 0.507 0.439 0.442 11 0.540 0.456 0.424 12 0.507 0.425 0.393 13 0.551 0.447 0.407 Average 0.513 0.434 0.408 Stand. dev. 0.019 0.014 0.019 Equation (35) 0.574 0.499 0.513 Difference (%) 10.627 13.026 20.468 SPECIFIC FUEL CONSUMPTION (l/Kw.h) 1.9 0.4 53 *—*—* Gasoline engine ‘ .—._. Gasoline engine with correction factor D—G—IU Diesel engine I-——._- Diesel engine with correction . factor 10 20 3O 40 SO 60 7O 80 90 100 PERCENT LOAD Figure 2. Specific fuel consumption as a function of engine load. 54 Table 12. Specific fuel consumption for 13 gasoline tractors (Nebraska Tractor Test data). Tractor Specific fuel consumption (l/Kw-h) number 50% load 75% load 100% load 1 0.720 0.579 0.546 2 0.731 0.592 0.562 3 0.623 0.532 0.520 4 0.675 0.566 0.518 5 0.603 0.512 0.491 6 0.808 0.669 0.567 7 0.686 0.577 0.540 8 0.630 0.550 0.541 9 0.646 0.535 0.523 10 0.757 0.651 0.648 11 0.741 0.651 0.569 12 0.769 0.632 0.567 13 0.604 0.538 0.510 Average 0.692 0.538 0.546 Stand. dev. 0.068 0.050 0.039 Equation (36) 0.786 0.632 0.609 Difference (%) 11.959 7.753 10.492 The specific fuel consumption is then multiplied by the power required to Obtain the fuel consumption in liters Of fuel per hour. FLPH = ESPFC*PREQ (38) Where FLPH is the fuel consumption in liters per hour, ESPFC is the spe- cific fuel consumption in l/Kw-h, and PREQ is the PTO power required in Kw. The effective field capacity is given by the following equation: Table 13. Values for the parameters used in the fuel consumption model. Parameters Values 01 7.000 6.000 4.800 3.000 3.800 2.800 2.000 011 0.049 0.053 0.024 0.020 0.032 0.013 0.013 02 5.200 2.400 002 0.039 0.045 03 21.500 04 14.700 11.700 7.800 05 500.000 500.000 500.000 005 206.000 86.000 194.000 CF01 300.000 300.000 300.000 CF02 50.000 70.000 35.000 06 43.900 0.140 07 2.000 1.700 1.600 007 0.170 0.130 0.130 08 280.000 228.000 190.000 175.000 155.000 120.000 CA10 11600.000 8000.000 4400.000 0A11 730.000 585.000 440.000 CA12 2190.000 11825.000 1460.000 CA13 1830.000 1355.000 880.000 CA14 880.000 660.000 440.000 016 2926.000 017 800.000 625.000 450.000 018 2000.000 1550.000 1100.000 019 450.000 290.000 130.000 0019 670.000 502.000 335.000 020 2800.000 2400.000 2000.000 021 230.000 173.000 115.000 022 2200.000 1465.000 730.000 023 440.000 0023 21.700 024 1800.000 025 50.000 30.000 20.000 15.000 026 7.500 0026 7.500 027 11.000 9.300 7.500 028 2.200 1.900 1.500 029 5.200 4.450 3.700 032 3.000 2.300 1.500 0032 4000.000 3000.000 2000.000 033 1.500 1.100 1.750 0033 3500.000 2900.000 2200.000 034 1.200 035 4.900 4.300 3.700 56 Table 13. (cont'd) Parameters Values 036 8.200 0036 2.130 037 2.450 038 -0.186 0038 0.052 039 2.950 040 2.950 043 1.500 0043 3.300 046 1668.000 047 448.000 048 1668.000 FCP 1.4401 1.2802 PAR 0.720 0.740 0.840 0.760 0.9403 0.860 0.920 0.890 0.860 0.8004 1 and 2 = Parameters for 180 proof alcohol. 3 = Parameters for 100 proof alcohol. 4 = Parameters for 160 proof alcohol. EFC = WIDTH*SPEED*EFF(NOP)/10.0 (39) Where EFC is the effective field capacity in ha/h, WIDTH is the machine width in m, SPEED is the machine speed in Km/h, EFF is the field effi- ciency for field Operations, and NOP is the Operation number. Machine use is calculated by dividing the area (AREA) by the effec- tive field capacity (EFC). USE = AREA/EEC (40) The fuel consumption in liters per hectare (FCHA) is then given by: FCHA = FLPH/EFC (41) 57 If any of the engines are converted to run on alcohol fuel then the alcohol subroutine is called, otherwise the variables are used to calcu- late the costs in the cost subroutine. 4.2.3 Alcohol subroutine. This subroutine allows alcohol to be used in either one of the following tractor conversion methods: 1. Use of alcohol in gasoline engines after minor carburetor modifications. 2. Use Of alcohol in gasoline engines after major modifications for increased compression. 3. Use Of alcohol through dual-fueling of diesel engines where alcohol is Sprayed into the intake air by pressurized air from the turbocharger. 4. Use Of alcohol through dual-fueling of diesel engines where alcohol is aSpirated into the intake air through a carburetor system. The alcohol consumption for the first and second conversion methods is calculated by the following equation: ALUSE = CFUSE*FCP (42) Where ALUSE is the alcohol use in liters, 0FUSE is the conventional fuel use in liters, and FCP is the alcohol fuel consumption parameter. Different parameters for ethanol are stored in the subroutine block data. The third and fourth conversion methods are modeled by the following equation: ALUSE = CFUSE*PAR(IFACT) (43) 58 Where IFACT is the values assigned for different load ranges. Five load ranges are used for each conversion methods and for each alcohol type. PAR is the alcohol fuel consumption parameter. 4.2.4 Cost subroutine. The cost subroutine calculates the conventional and alternative fuel costs. The following relationship is used: CFC = CFUSE*CFP/AREA (44) Where CFC is the conventional fuel cost in dollars per hectare and CFP is the cost Of fuel in dollars per liter. A Similar equation is used for alcohol fuel costs. In order to calculate the alcohol break-even price the following were taken into consideration: Annual cost due to machine conversion, conventional fuel cost, and alcohol fuel consumption. The calculations were made on an annual basis. A capital recovery factor was calculated in order to determine the annual conversion cost. The following equations were used to calculate the annual machine fuel cost and alco- hol break-even price. CRF = A*(1.0+A)**NN/((1.0+A)**NN-1.0) (45) Where CRF is the capital recovery factor. A is the discount rate in decimal. MN is the number Of years for recovery Of investment. The annual conversion cost was calculated by the following equation: ACC = CONCOS(ICOTY)*CRF (46) 59 Where A00 is the annual cost to be recovered, and CONCOS is the conver- sion cost depending on the conversion type ICOTY. The conversion cost includes the cost for parts and cost for labor when converting engines to alcohol. Annual fuel cost for an alcohol fueled engine was determined by: ACAF = TO0STO+TCOSTA+A00 (47) Where ACAF is the annual fuel cost. TCOSTD and TCOSTA are the cost of conventional fuel (in the case of dual fuel engines) and alcohol fuel costs. A break-even price for alcohol fuel was then Obtained by using Equation (48). BEPA = (TCOSTF-TCOSTD-ACC)/TTOTA (48) Where BEPA is the break-even price for alcohol fuel in dollars per liter, TCOSTF is the annual cost for conventional fuel, and TTOTA is the total alcohol use in liters. CHAPTER 5 DATA COLLECTION AND VALIDATION 5.1 Validation by Operation. Two types Of data were collected. Field data and data from a Michigan Energy Audit Study. 5.1.1 Data collection. It was decided that one way Of validating the model was through a comparison between the model results and field data collected for field Operations on Michigan farms. Michigan farms were evaluated in the fall season Of 1980. The first farm chosen to collect data (farm one) was a cash crOp farm located in Ithaca, Michigan. Five crOps were grown on a total of 340 hectares. Data were collected for six field Operations including: Pulling and windrowing navy beans, combining navy beans, combining corn, combining soybeans, moldboard plowing, and chisel plowing. The machine sizes, performance and fuel consumption data are listed in Tables 14 and 15. 60 61 mcm meflwomcm amc mmpu mucccsm vac; xgm> vac xamocc Luxecgm ma. 3x msa .ammcac mmc .sco. scecm SN am.¢ omom a\~ aa_acmcm> .Loaccca a=_zo_a ammagc .c aaaucacu camac .meoaaoa cc xx maa .acmc.c mmc .Ecop xvccm Nu so.m ceaN ~\~ mpaacmcm> .Loaucch acazoaa ccconcpoz .m muccgsm ac: caaa_a 18:82 me 3x ma .maaa .mcm mmacammg .zcau T mm.m occm N .a cmccmao .mcaneou ccmnxdm acacansou .e muccczm am: maaa_a 18:82 av xx ma .maaa .mca mmscammc .xvccm . em.~ ooem N .m cmccmpo .mcaaeou ccou acacaanu .m haaucacu amzoL my Ex ma .mcma .mcm campy .zvccm . mm.m ocem N .u cmccmpo .mcaneou mccmn >5c: acacaneou .N xaaucacu Anzac a. 3x No .vnma .amc c_c_c .Acccm c ac.~ coca c .oooa c282 .Loaucea acazoac=_z-m=_.P=a .H :oaaaceou Asa“ gaamc as. mnam .cmma amcoe cec .maxa aaom caxgoz aemsmpaea 2am Lcmw maxa mcazucz mac: coaaccmao .omoa co comcmm pace msa ca meo conga: sec» Lou mucceLoCLma ccc mnam xgmcagucz .ea mpach 62 .ea m—nca ca vmamaa mac mcoaaccmao mmmga soc umms mmcazuce map mcoaacemao vamp; scam umcasgmama II M +92 xooagcm» uccg ecmasom mmav—mmL .xcpu . oo.¢ omma o mcmmo czoc .Loauccp cmaccv meaxmaa .N »a_ucacu camac zxcc.ficma.Pcmcac.o~o¢ Aaeaamm>cc= eccnsam mmsu—mmL .xcau . oo.¢ oo- m mcmmo snow .Loaocch smaccv meaxmac .a coaaavcou “sum :aamv Rev mnam cmma pmuos vac .maxa aaom caxco: acmemaasa 2am Lcmo maxa meagocz mac: coaaccmao .omma co comcmm pace mga ea oza amass: aecc soc moccscoccmq ucc m~_m xgmcagucz .ma m—ac» 69 .QH mpnuh :w voumpp QLQ meowumsmno mmwsa LOh tam: gouomgu ugh u h ~4.Aa cc.ma oa.o mm.c om aeazoaa caconcaoz .A Lacaxmcc Emaccc a~.~a mm.ca cc.a cc.c oc acazoaa acm_gc .c .aeaxmac Lmacc. ~a.a A~.ca ac.a ac.c cc a=.zo_a acmagc .m ASELLALc Lcacc. Ao.a ac.oH Aa.a ca.m cc cease—a acm.=c .e ameaxm_c Lmacc. am.a mm.ma Ac.a em.c cc acazo_a acmagc .m mo.” cc.aa m~.m Aa.¢a cc cam» ceoumm .aeaxmac .N .mcaamm>cc= ecmnxdm cc." cm.aa ca.~ ~c.a cc Lance. aeaxmao .a Lc=\_. .=\a. ,=\cgv L=\sxv IA. coaaqE=mcou amau emu ummam Adamauaccm camau mac: :oaaccmno .OmmH kc :Omwmm ——w% wsv Cw O)» LwnEsc ngk Low covvnfismcou PwSh 3:6 OUCMELO$st XKOszuwZ .NH OPQMH 70 The tractor worked for 24 minutes in the first test and spent 4.55 liters Of diesel fuel. In the second test, the same amount of work was done in 22 minutes with 4.35 liters Of diesel fuel. The second Operation performed was chisel plowing. Three tractors were tested in this Operation. A John Deere 4020, a Case 830, and a Ford 7700. The chisel plow contained 7 shanks, with a 2.44 m width. The Operation was performed after disking. The same area was covered with the John Deere 4020 and Case 830 tractors. The working depth was approximately 30 cm. The following were the tractor speeds for the three tractors tested: the average speed was 8.54 Km/h for the John Deere 4020, 5.96 Km/h for the Case 830, 8.39 Km/h for the Ford 7700 in high gear, and 6.82 Km/h for the Ford 7700 in low gear. The standard deviation for the above tests were the following: 0.15, 0.09, 0.10, and 0.09 Km/h. The John Deere 4020 worked for 27 minutes and used 7.00 liters Of . diesel fuel. The Case 830 worked for 37 minutes and did the same amount Of work as the John Deere 4020 with 6.55 liters Of diesel fuel. The Ford 7700 worked for 32 minutes in high gear and used 8.67 liters Of diesel fuel. When working in low gear the Ford 7700 worked for 39 min- utes and Spent 10.62 liters Of diesel fuel. The last Operation was moldboard plowing. The Operation was per- formed with a Ford 7700 tractor working in 4th gear at approximately 2100 RPM. The moldboard plow was 1.78 m wide and worked at approxima- tely a 22 cm depth in a clay soil. The average speed was 6.35 Km/h. The tractor worked for 48 minutes and Spent 12.6 liters of diesel fuel. 71 5.1.2 Validation. The data collected on farm number one and farm number two were used as input for the computer program. Table 18 presents the results Of the computer program for farm number one. The fuel consumption in liters of diesel fuel per hectare from the field Observation, average fuel con- sumption on Michigan farms, and average fuel consumption for other sta- tes are also listed in Table 18. The results from the computer program are close enough to the actual data to Show that the model is reasonably accurate for modeling fuel requirements. A difference Of less than 20 percent was Obtained for most of the operations. Where the results Of the computer model are not close to the results from field Observations, they are generally close to the Michigan average. The highest difference was Obtained for pulling and windrowing navy beans. This can be attributed to the high parameter used for the implement draft equation. The equation does not take into consideration the soil type. Part of the difference could be attributed to error in the field observation measurement since only one test was done. The fuel consumption for corn harvesting was higher than the average for Michigan farms. More energy was required to harvest corn, since the corn was grown using irrigation giving an approximate yield Of 9140 Kg per hectare. Table 19 presents the results of the computer program for farm number two. The fuel consumption in liters of diesel fuel per hectare from field Observations, average fuel consumption on Michigan farms, and average fuel consumption for other states are also listed in Table 19. The results from the computer program for farm number two are also close to those from field Observations. The disking Operation was done on soybean ground which contained a high level Of residue on the surface. 72 .caaxca zacoz cec .ceozc—xo .oagcaco .xco> zmz .camcouma: .aczommaz .cxmccamz .czoa co mmacam u a .AmELcc Nm co mmccm>cv xvaam aac=< xmcmcm :cm_=OPz Ease u m .acmac>a=am ammmac oa mcapomca aLm>=ou oa emu: ac: N.o co Loaucc c .mgcaomg Lma amsc ammmac co mcmaap ca ma :oaaa53mcou pmac mg» n N .ma ccc ea mmpnca ca cmamap mLc m=o_accmao mmmga Lou cm»: macmsmaqea uec mmcagucs mew u a aa.oa NN.NH mm.ma mm.¢a mcazoaa ammagu a¢.Na ma.ma am.wa wa.ma meazopa ccconcaoz m¢.m om.aa a~.o . m¢.NH ccmnxdm acaamm>ccz ac.Na Na.¢a aa.ca Na.aa econ meaamm>cc= m¢.a om.aa cm.c ma.c mecca sac: ceaammsccz ma.m om.¢ mm.m No.c mecma zscc acazogucaz vac meap—sa emmacam cmgao c.a>c =ca.gu.z .Aca c_m_L Pace: meoaacgmao Nac:\p. coaaa53meou pmam a .mco Lmae=c sccc co meoaaccmao cam.» soc coaaae=mcou pmau .ma mpnch .caoxco zacoz ccc .cEOgcpxo .oaccaco .xco> zmz .camgoumaz .aesommaz .cxmccnmz .czoa co mmacam .AmeLcc Nm co mmccm>cv zvaam aav=< xmcmcu ccmaguaz scam .mccaum; emu amsm pmmmac co mcmaa— ca ma coaaae=mcou pmsc mza .Na ccc ca mmpnca =_ cmamap mac mcoaaccmao camac mmmga Lou umma macmsmaasa ucc meoaucca msa II '4va 73 a¢.Aa ma.ca NS.AL Ho.AH c=_zo.a caconc_oz ma.oH ~A.Na SN.NL cc.aa acazoaa acm_=u ao.oa NN.NL Nm.a ac.ma acazoaa aam_=c ma.oH NA.NH No.a ca.oa aeazoaa acmagc aa.oA NN.NL am.a cm.aa acazoaa acmagc co.c oc.c cc.” Am.e meaxm_o co.c oA.c cc." ca.e m=_cmaa emmacam cmgao m.m>c ccaazoaz .mno v—mau amcoz amcoaacgmao Nac=\a. eoaaa53mccu amam .oxa amass: accc co mcoaaccmao camac Lou coaaassmcou amam .ma maaca 74 The parameters used to calculate the enrgy requirements were obtained from the ASAE yearbook. The same formula was used for disking stalks, but with the parameters reduced by 70 percent as indicated by White, 1977. The model results for some chisel plowing Operations were higher than the field Observations. Only three formulas were available for chisel plowing, so the most appropriate one was used. Differences in the soil type could increase the draft by 20 percent. The computer program in general produced representative results for Specific situations. In the next section we present the results from three Michigan farms, where more will be concluded about the models usefulness. 5.2 Whole farm validation. 5.2.1 Michigan Energy Study Study data. Three farms were selected from a Michigan Energy Audit Study to make the energy comparison to the computer program. The first was a small-size farm with four crops as shown in Table 20. The soil was a loamy type. Table 21 presents the machine power units used for field Operations on farm number three in 1979. The next farm studied was a medium-size farm. Three crOps were grown on a total of 200 hectares. The soil was a loamy type. Tables 22 and 23 present the crOps, area, and machines used on the farm in 1979. 75 Table 20. Crops grown on the small-size farm in 1979. CrOps Area (ha)- Corn 40.0 Oats 3.6 Wheat 4.4 Hay 31.0 Total 79.0 76 Table 21. Power units used on the small-size farm. Machine type Power (Kw) Fuel type Tractor NO. 1 74.74 Diesel Tractor No. 2 52.15 Diesel Tractor No. 3 45.18 Diesel Table 22. Crops grown on the medium-Size farm. Crops Area (ha) Corn 59.0 Oats 31.0 Wheat 84.0 Hay 26.0 Total 200.0 77 Table 23. Power units used on the medium-size farm in 1979. Machine type Power (Kw) Fuel Effic. Fuel type ' (Km/l) Tractor NO. 1 70.00 Diesel Tractor NO. 2 93.78 Diesel Combine 70.00 Gasoline Truck NO. 1 1.30 Gasoline Truck No. 2 2.00 Gasoline Truck NO. 3 1.50 Gasoline Table 24. Crops grown on the large-size farm in 1979. Crops Area (ha) Corn 139.0 Wheat 60.0 Navy beans 97.0 Soybeans 213.0 Sugar beets 38.0 Hay 3.0 Total 550.0 78 The final farm was a large farm of 550 hectares. The soil was loam and Six crops were produced. Tables 24 and 25 present the crOps, area, and machines used on the large size farm. Table 25. Power units used on the large-Size farm in 1979. Machine type Power (Kw) Fuel Effic. Fuel type (Km/l) Tractor NO. 1 138.83 Diesel Tractor NO. 2 46.93 Gasoline Tractor NO. 3 74.74 Diesel Tractor NO. 4 93.78 Diesel Tractor NO. 5 112.24 Diesel Tractor NO. 6 130.95 Diesel Combine 95.00 Diesel Truck NO. 1 6.38 Gasoline Truck No. 2 3.20 Gasoline Truck NO. 3 1.35 01959] Truck No. 4 1.65 Gasoline Truck No. 5 4.05 Gasoline Truck NO. 6 4.44 Gasoline Truck No. 7 1-10 Gasoline 79 5.2.2 Validation. The data collected for farms number three, four, and five as described in section 5.2.1 were used as input data for the computer program. The results are presented as small, medium, and large-size farms. 5.2.2.1 Small-size farm. Table 26 presents the results from the computer program for the three tractors used on the farm. These results Show that the average Table 26. Tractor usage and fuel consumption for the small-size farm. Machine Power (Kw) Ave. load Ave. FLPH1 TUSE2 F0HA3 Tractor NO. I 75 37 15.0 348 10.0 Tractor No. 2 52 32 10.8 96 4.8 Tractor No. 3 45 32 8.4 15 5.1 1 = Average fuel consumption (l/h) 2 = Machine annual use (h) 3 = Average fuel consumption (l/ha) load for all the tractors was low. According to Figure 2, diesel trac- tors are very efficient at low load when compared to gasoline and LP gas tractors but the highest fuel efficiency for diesel tractors occurs when they are Operated at 80 percent load. Tractor number one, with the highest power rating had the highest yearly use. Tractors number two and three had a low yearly use and a lower fuel consumption (l/h and l/ha). Table 27 presents the fuel consumption by Operation group. The 80 Table 27. Fuel consumption by Operation group for a small-size farm. Operation group Total fuel (1) l/ha % of total Tillage 961 12.2 21 Seeding 179 2.3 4 Cultivating 91 1.2 2 Spraying, fertililzer 24 0.3 1 Harvesting 2,945 37.3 64 Transporting 369 4.7 8 Total 4,569 58.0 100 total fuel use for the small size farm was 4,569 liters compared to 4,282 liters reported by the farmer. The highést fuel use was for har- vesting Operations which included corn silage and hay harvesting. Tillage Operations had a low fuel use because in this particular year no soil was prepared for alfalfa planting. The average fuel consumption for the farm was 58.0 liters of diesel fuel per hectare. Table 28 presents the fuel consumption per enterprise for the small farm. Corn was grown for silage on this farm and the fuel consumption was 67.2 liters per hectare. Wheat and oats had a very low fuel use because few Operations were reported by the farmer, and the harvesting Operations were done through custom hire. Hay was the second highest energy consumer with 56.6 liters of diesel fuel per hectare. 81 Table 28. Fuel consumption by enterprise for the small-Size farm. Enterprise Total fuel (1) l/ha Corn 2,689 67.2 Oats 18 5.9 Wheat 109 24.8 Hay 1,753 57.6 Total 4,569 5.2.2.2 Medium-size farm. Table 29 presents the results from the computer program for the power units used on the medium size farm. The smaller tractor was only used for Spraying and fertilizing Operations, and therefore, had a low average load and low fuel consumption (l/h and l/ha). The value for the combine represents liters of gasoline fuel used. Tractor number two had a higher usage (486 hours). This tractor was used fOr most of the field Operations. The tractor load was higher for tillage Operations and lower for other Operations so the average load was still a little low. The combine presented a high load for corn harvesting, but the average load was still low. Table 30 presents the fuel consumption (diesel equivalent) by Operation group. The medium size farm used 13,521 liters Of diesel fuel compared to 13,484 liters reported by the farmer. An average Of 67.6 liters of diesel fuel per hectare was obtained. As expected tillage required more than half Of the fuel used on the farm. The second fuel consuming Operation group was harvesting which used 18 82 Table 29. Machine usage and fuel consumption for the medium-size farm. Average Avera e Machine Power (Kw) Load FLPH TUSEZ FCHA3 Tractor NO. 1 70 22 10.8 160 3.9 Tractor NO. 2 94 41 20.9 485 8.7 Combine4 70 46 24.6 181 18.8 1 = Average fuel consumption (l/h) 2 a Machine annual use (h) 3 = Average fuel consumption (l/ha) 4 = Gasoline combine Table 30. Fuel consumption by Operation group for the medium-size farm. Operation group Total fuel (1) l/ha % Of total Tillage 7,518 37.6 56 Seeding 832 4.2 6 Cultivating 289 1.4 2 Spraying, fertililzer 1,903 9.5 14 Harvesting 2,474 12.4 18 Transporting 505 2.5 4 . Total 13,521 67.6 100 83 Table 31. Fuel consumption by enterprise for the medium-size farm. Enterprise Total fuel (l) l/ha Corn 4,651 78.8 Wheat 3,342 107.8 Soybean 5,304 63.1 Cover crOp 224 8.6 Total 13,521 expected tillage required more than half of the fuel used on the farm. The second fuel consuming Operation group was harvesting which used 18 percent of the fuel used on the farm. The third highest was spraying and fertilizing which used 14 percent of the fuel used on the farm. Table 31 presents the fuel consumption by enterprise. Wheat presented the highest energy use. This occurred because chisel plowing was per- formed twice and several Spraying Operations were performed on the wheat crop. Corn consumed 78.8 liters of diesel fuel per hectare, soybeans consumed 63.1 liters Of diesel fuel per hectare, and the cover crOp, rye, used 8.6 liters/ha Of diesel fuel. 5.2.2.3 Large-size farm. Table 32 presents the results from the computer program for the power units used on a large farm. These are the Simulated results from the computer program for 1979. The tractors had a higher average load than the tractors in the small and medium size farms. Better tractor 84 Table 32. Machine usage and fuel consumption for the large-size farm. Average Avera e Machine 1 Power (Kw) Load FLPH TUSE2 FCHA3 Tractor NO. 1 139 58 37.8 177 16.6 Tractor NO- 2 47 45 16.3 3 13.2 Tractor NO. 3 75 29 13.3 346 5.9 Tractor NO. 4 94 32 17.8 426 6.4 Tractor NO. 5 112 57 30.4 276 12.0 Tractor NO. 6 131 57 35.6 277 9.2 Combine4 95 32 18.4 408 12.0 Average fuel consumption (l/h) Machine annual use (h) Average fuel consumption (l/ha) Gasoline combine DUMP- u u u II and implement matching was possible since 6 tractors were available. Tractor number two, a gasoline fueled tractor, was used only for one Operation. Tractors number three and four were still too large for the Operations assigned for them. The combine had a higher load for corn harvesting, but a lower load for wheat, navy beans, and soybean harvesting. Table 33 presents the fuel consumption by Operation group. Tillage and harvesting were the two groups with higher fuel use. Tillage Opera- tions consumed 50 percent of the fuel used on the farm. Harvesting Operations consumed 20 percent of the total fuel used on the farm. The large farm consumed 37,717 liters of diesel fuel for field Operations 85 Table 33. Fuel consumption by operation group for the large size farm. Operation group Total fuel (l) l/ha % Of total Tillage 19,137 34.8 50 Seeding 3,178 5.8 8 Cultivating 3,029 5.5 8 Spraying, fertililzer 2,646 4.8 7 Harvesting 7,729 14.0 20 Transporting 1,998 3.6 7 Total 37,717 68.5 100 from soil preparation to transportation. This value was within 4 per- cent the value rEported by the farmer (39,166 liters of diesel fuel). The average fuel consumption was 68.5 liters of diesel fuel per hectare Table 34 presents the fuel consumption per enterprise. Sugar beets had the highest fuel consumption (103.4 liters Of diesel fuel per hectare). Navy beans and soybean consumed about the same amount of fuel per hectare. Corn and wheat had about the same amount of fuel used. Only three hectares of hay were grown on the farm. The fuel consumption per hectare for hay therefore, is not a representative result Since the farmer did not report all Operations performed for the hay crOp. Table 34. Fuel 86 consumption by enterprise for the large-size farm. Enterprise Total fuel (l) l/ha Corn 8,029 57.8 Wheat 3,426 57.1 Navy beans 6,925 71.4 Soybean 15,283 71.7 Hay 126 41.9 Sugar beets 3,928 103.4 Total 37,717 CHAPTER 6 ETHANOL AS TRACTOR FUEL 6.1 Conversion methods. The use of alcohol by using the following four tractor conversion methods was investigated. 1. The use of alcohol in gasoline engines after minor modifica- tions such as carburetor change or replacement to provide a carburetor Specially designed for alcohol engines. 2. The use of alcohol in gasoline engines after major modifica- tions of rebuilding the engine with increased compression. 3. The use of alcohol through dual-fueling diesel engines where alcohol is Sprayed into the intake air by pressurized air from the turbocharger. 4. The use of alCohOl through dual-fueling diesel engines where alcohol is aspirated into the intake air through a carburetor system. Table 35 lists the parameters used for each conversion method. The fuel consumption parameters were Obtained from lab tractor tests carried out in the Agricultural Engineering Department (Cruz, 1981; Swarr, 1981) of Michigan State University. As part of the ethanol research project two tractors were converted to run on ethanol. For the first and second conversion methods a Ford 2000 tractor was converted. For the third and fourth conversion methods a Ford 7700 tractor was tested with ethanol through dual-fueling. The fuel consumption parameters for the third and fourth conversion methods were functions of engine load. The parameters are listed in Table 13. 87 88 Table 35. Parameters used for 4 conversion methods. Conversion Methods Parameters First Second Third Fourth Cost ($) 200 1,800 1,200 1,400 Discount rate(%) 12 12 12 12 Recovery period (years) 5 5 5 5 Alcohol proofl 180 180 100 160 1 = The alcohol used for all methods was ethanol. 6.2 Ethanol use on farms. 6.2.1 Small-Size farm. For the small farm described in chapter 5, section 5.2.1, the possibi- lity of converting either one or both of the tractors was investigated. Tractor number two presented a lower usage (96 hours of use in 1979). The conversion of this tractor to alcohol as an alternative to save diesel fuel was not feasible because the annual conversion cost is higher than the fuel savings by using alcohol. Tractor number one which pre- sented a higher annual use (348 hours) was studied for conversion. Two conversion methods were considered available (dual-fueling) for tractor number one. Both methods as described above will replace part Of the diesel fuel. Table 36 shows the amount Of fuel used by tractor number one when Operating under the conventional or dual-fuel mode. When the third conversion method is used 22 percent of the diesel fuel can be replaced by ethanol and when the fourth conversion method is used 44 89 Table 36. Fuel consumption for tractor number one using 2 conversion methods in a small-size farm. Dual-fuel (l) Conversion Diesel (l) Diesel Ethanol Third 3,565 2,770 1,322 Fourth 3,565 2,010 2,548 percent of the diesel fuel can be replaced by ethanol. . Table 37 shows the break-even prices for alcohol fuel when either one Of the third and fourth conversion methods are used on tractor number one. The break-even prices are given for 200 proof alcohol (ethanol). The economics of using alcohol fuel in tractor number one are not promising. For the third conversion method, negative break-even prices were Obtained. This means that if diesel fuel prices are less than $0.40 per liter, the amount of money saved by using alcohol is less than the amortized cost of conversion. For diesel priCes greater than $0.40 per liter, alcohol should not cost more than 36 percent Of the diesel cost when diesel prices are at $1.06 per liter. Better results were Obtained when the fourth conversion method was used. For today's diesel fuel prices ($0.33/l) alcohol should not cost more than 19 per- cent Of the diesel cost. For diesel prices of $.79 per liter, alcohol should not cost more than 42 percent Of the diesel cost. If conversion is to be made the fourth convesion method which can save up to 34 per- cent Of the total farm fuel use would have to be chosen. Considering a corn yield Of 6276 Kg per hectare and an alcohol yield of 0.357 liters 90 Table 37. Break-even prices for alcohol fuel for 2 conversion methods on a small-size farm. Break-even prices Of ethanol ($/l) Diesel price (ill) Third conversion Fourth conversion 0.26 - 0.10 0.01 0.33 - 0.05 0.05 0.40 - 0.01 0.09 0.46 0.03 0.13 0.53 0.07 0.17 0.79 0.22 0.33 1.06 0.38 0.49 per Kg Of corn grain, 1.14 hectares of corn should be planted to supply the 2548 liters of alcohol used by tractor number one. This represents 2.9 percent of the corn area and 1.4 percent of the total farming area. 6.2.2 Medium-size farm. The possibility of converting either one or both of the tractors used on this farm was investigated. Tractor number one presented a low usage (160 hours in 1979). The conversion of tractor number one as an alternative to save diesel fuel was not feasible because the annual con- version cost was higher than the fuel savings possible using alcohol. Tractor number two which presented a high annual use (486 hours) was studied for future conversions. Two methods were considered available (third and fourth type) for tractor number two. Table 38 shows the 91 Table 38. Fuel consumption for tractor number two using 2 conversion methods on a medium-size farm. Dual-fuel (l) Conversion Diesel (1) Diesel Ethanol Third 8,970 6,802 3,582 Fourth 8,970 5,061 6,476 amount Of fuel used by tractor number two when Operating under conven- tional or dual-fuel mode. When the third conversion_method was used a 24 percent saving in diesel fuel was Obtained. When the fourth conver- sion method was used a 44 percent saving in diesel fuel could be obtained. Table 39 shows the break-even prices for alcohol fuel when diesel fuel prices vary from $0.26 per liter up to $1.06 per liter. The break- even price for alcohol fuel considering today's diesel price ($0.33/l) is $0.11 per liter for the third conversion method and $0.15 per liter for the fourth conversion method. This means that alcohol should not cost more than 33 percent of the diesel price for the third conversion method and 45 percent of the diesel price for the fourth conversion method. If diesel prices go up to $0.79 per liter, than alcohol can cost up to 49 percent of the diesel cost for the third conversion method and up to 54 percent of the diesel cost for the fourth conversion method. If conversion is to be made, the fourth conversion method which can save up to 29 percent Of the total farm fuel use for field opera- tions should be used. ‘Considering a corn yield of 6276 Kg of corn per hectare and an alcohol yield Of 0.357 liter per Kg of corn grain, 2.87 92 Table 39. Break-even prices for alcohol fuel for tractor number 2 on a medium-size farm. Break-even prices of ethanol ($/l) Diesel price ($/l) Third conversion Fourth conversion 0.26 0.06 0.11 0.33 0.11 0.15 0.40 0.15 0.19 0.46 0.19 0.23 0.53 0.23 0.27 0.79 0.39 0.43 1.06 0.55 0.59 93 hectares of corn should be planted to supply the 6,476 liter of alcohol needed to run tractor number two. This rcpresents 4.9 percent of the corn area and 1.4 percent of the total farming area. 6.2.3 Large-size farm. Five tractors were converted to alcohol by using the third and fourth conversion methods. Table 40 presents the amount of diesel and alcohol fuel used when the third conversion method was used. Table 41 presents the amount of diesel and alcohol fuel used when the fourth con- version method was used. From Table 40, the highest rate of substitu- tion (25 percent) was Obtained when tractors number one and five were converted. From Table 41, the highest rate of substitution (45 percent) was Obtained when tractor number six was converted. The break-even pri- ces for alcohol fuel are listed in Table 42. The fourth conversion method proved to be better for all the tractors converted. If tractors are to be converted to alcohol the sequence would have to be the following: The first tractor to be converted is tractor number Six, then tractor number five, then tractor number one, and then tractor number four. Last would be tractor number three which presented nega- tive break-even prices for alcohol for diesel prices up to $0.40 per liter. For today's diesel price ($0.33/l) the break-even price for alcohol fuel for tractor number Six is $0.14 per liter. This means that alcohol should not cost more than 42 percent of the diesel cost. For diesel prices Of $0.79 per liter alcohol should not cost more than $0.44 per liter (57 percent of the diesel cost). If all the five tractors are converted to run on dual-fuel (fourth conversion method) 35 percent of the total farm fuel used for field Operations would be replaced by alco- hol. This would require 9.6 hectares Of corn to supply the 21,506 liters 94' ' Table 40. Diesel and alcohol fuel use when Spray injection was used for 5 different tractors. Dual-fuel (l) Tractor NO. Diesel fuel (l) Diesel Ethanol Savings (%) 1 5,940 4,455 2,495 25 3 3,264 1 2,522 1,231 23 4 5,363 4,158 3,107 22 5 7,449 5,587 3,107 25 6 8,150 6,171 3,095 24 Table 41. Diesel and alcohol fuel use when the carburated dual-fuel system was used for 5 different tractors. Dual-fuel (l) Tractor No. Diesel fuel (1) Diesel Ethanol Savings (%i 1 5,940 '3,327 4,229 44 3 3,264 1,859 2,370 43 4 5,363 3,053 3,851 43 5 7,449 4,155 5,291 44 6 8,150 4,458 5,765 45 95 Table 42. Break-even prices for alcohol fuel for 5 tractors, and 2 dual- fuel methods for a large-size farm. Break-even prices (S/l) for 5 tractors Tractor number Conventional Conversion fuel prices ($/l) type 1 3 4 5 6 0.26 Third 0.02 -0.11 -0.01 0.05 0.06 Fourth 0.07 -0.01 0.06 0.09 0.10 0.33 Third 0.06 -0.07 0.03 0.09 0.10 Fourth 0.11 0.03 0.10 0.13 0.14 0.40 Third 0.10 -0.03 0.07 0.13 0.15 Fourth 0.16 0.07 0.14 0.18 0.19 0.46 Third 0.14 0.01 0.11 0.17 0.19 Fourth 0.19 0.11 0.17 0.21 0.23 0.53 Third 0.18 0.05 0.15 0.21 0.23 Fourth 0.24 0.15 0.22 0.26 0.27 0.79 Third 0.34 0.21 0.31 0.37 0.40 Fourth 0.40 0.30 0.37 0.42 0.44 1.06 Third 0.50 0.37 0.46 0.53 0.57 Fourth 0.56 0.46 0.53 0.59 0.61 Of ethanol needed to run the five tractors. With the same assumptions as the ones made for the small and medium size farm, for corn and alco- hol yields, 6.9 percent of the corn area and 1.7 percent of the total farming area should be planted on corn for ethanol production. 6.3 Tractor use and ethanol feasibility. Computer simulation was done to find the ethanol break-even prices for four usage levels (250, 500, 750, and 1000h/yr). A 75 Kw tractor with an average load Of 50 percent was used for the simulation. The four conversion methods were simulated for four usage levels and the results are presented in the following section. 96 6.3.1 Gasoline tractor with minor modifications. Table 43 presents the break—even prices for ethanol for gasoline prices from $0.33 to $1.06 per liter. The break-even prices were constants for almost all usage levels. This occurred because Of the low conversion costs for this conversion method. Figure 3 shows the plotted results for this and the three other conversion methods. Table 43. Ethanol break-even prices for gasoline tractors with minor modifications. Gasoline prices Usage levels(h) (3/1) 250 500 750 1000 0.33 0.25 0.25 0.25 0.25 0.40 0.30 0.30 0.31 0.31 0.46 0.35 0.35 0.35 0.35 0.53 0.40 0.40 0.41 0.41 0.79 0.60 0.61 0.61 0.61 1.06 0.81 0.81 0.82 0.82 6.3.2 Gasoline tractor with increased compression. Table 44 presents the break-even prices for the second conversion method. The same usage levels and gasoline prices as in the first con- version method were used. As the usage level increased the break-even prices also increased. For gasoline prices of $0.33 per liter the break-even price for ethanol is 79 percent of the gasoline price if the tractor is used 750 hours per year. Figure 3 shows this conversion 97 Table 44. Ethanol break-even prices for gasoline tractor with increased compression. Gasoline prices Break-even prices (S/l) for 4 usage levels(h) (5/1) 250 500 750 1000 0.33 0.20 0.25 0.26 0.27 0.40 0.27 0.31 0.32 0.33 0.46 0.32 0.36 0.38 0.38 0.53 0.38 0.42 0.44 0.44 0.79 0.60 0.65 0.66 0.67 1.06 0.84 0.88 0.90 0.90 method being better than the first one, when the tractor is used more than 350 hours. 6.3.3 Dual-fueling with spray injection. Table 45 presents the break-even prices for four usage levels. The break-even prices for ethanol increased as the usage level increased, for all the fuel prices. For gasoline prices of $0.33 per liter the break-even price for ethanol is $0.12 per liter (36 percent of the gaso- line price), when the tractor is used 500 hours. Figure 3 shows the lower break-even prices for ethanol when compared to the first and second conversion methods. 98 6.3.4 Dual-fueling with carburated alcohol. Table 46 presents the break-even prices for ethanol fuel for four usage levels. As the usage level increased the break-even prices also increased. The increases were less evident when the tractor was used 1000 h. Figure 3 Shows this conversion method giving higher break-even prices for all usage levels. The change in ethanol break-even prices by changing the recovery period from 5 to 10 years is presented in Table 47. Conventional fuel prices Of $0.40 per liter were used for the calculations. The changes were higher for the dual-fuel methods. The break-even prices had a higher increase for lower usage levels, except for the gasoline engine with minor modifications, where the break-even prices remained essentially the same. A 5 year recovery period is recommended because data is not availabe to Show that converted engines will last 10 years, especially under high annual use. Table 48 shows the prices that diesel fuel should be at the present time considering a ethanol production cost of $0.46 per liter. In most cases diesel pPices Should be at least twice the ethanol production cost. AS mentioned above, all tractors used for field Operations on the selected farms were diesel, so dual-fueling was the conversion recom- mended. Carburated ethanol presented lower diesel prices for economical use of ethanol as tractor fuel. ‘ If a true alcohol engine is available the following could be concluded: Ethanol break-even prices equal to gasoline may be obtained. This occurs as mentioned in the literature review, because the thermal efficiency is quite high providing an alcohol fuel consumption similar to gasoline. This engine will have higher thermal efficiency and higher power outputs. 99 Table 45. Ethanol break-even prices when dual-fueling with Spray injec- tion is used. Diesel prices Break-even prices ($/l) for 4 usage levels(h) (5/1) 250 500 750 1000 0.33 -0.02 0.12 0.15 0.17 0.40 0.02 0.16 0.20 0.22 0.46 0.06 0.20 0.24 0.25 0.53 0.11 0.25 0.28 0.30 0.79 0.27 0.41 0.45 0.47 1.06 0.47 0.59 0.63 0.65 Table 46. Ethanol break-even prices when dual-fueling with carburated ethanol is used. Diesel fuel rices Break-even prices (S/l) for 4 usage levels(h) ($/li 250 500 750 1000 0.33 0.07 0.16 0.18 0.19 0.40 0.11 0.20 0.23 0.24 0.46 0.15 0.24 0.27 0.28 0.53 0.20 0.29 0.31 0.33 0.79 0.35 0.45 0.49 0.50 1.06 0.54 0.68 0.67 0.69 100 mN.o «N.o MN.o ma.o eN.o MN.o oN.o aa.o poccgam cmaccznccu MN.o NN.o oN.o aa.o NN.o cN.o ma.o No.o :oaaumnca accam em.o mm.o Nm.o om.o mm.o Nm.o am.o AN.o mcoaacuamacoe Lance gap: mcamcm mzaaomcw am.o am.o om.o om.o am.o am.o om.o om.o mcoaacuacacos Locas :aaz.m:_m=m mcapomcu mesa; coca ems oom omN mesa: coca ems com omN coacma xgm>oumc 2cm» oa coacma >gm>oome Lcma m A_\». emu—La =m>mixcmca aoccsau mcogams :oamcm>=ou .Lcoa_a Lea oe.oe co mecca Pmac accoaaem>cou. meosams :oamcm>:oo v ccc muoacmg xgm>oums N com mmuacq cm>muxcmcn Poccgau .Ne manca 101 Table 48. Diesel prices required to allow ethanol to be economically feasible with a production cost of $0.46 per liter. Diesel prices for Farms Spray injection Carburated ethanol ($/l) ($/l) Small farm (79 ha) 1.18 1.00 Medium farm (200 ha) 0.91 0.86 Large farm (550 ha) Tractor NO. 1 1.00 0.89 Tractor NO. 3 1.21 1.05 Tractor NO. 4 1.06 0.93 Tractor No. 5 0.95 0.86 Tractor NO. 6 0.89 0.82 ETHANOL BREAK-EVEN PRICE (S/l) 102 7 - First conversion method *- Second conversion method .- Fourth conversion method 0' Third conversion method 250 500 750 1000 USAGE LEVEL (h) Figure 3. Tractor usage levels and ethanol break-even prices for gasoline and diesel prices of $0.40 per liter. CHAPTER 7 SUMMARY A computer program to simulate the machine performance and calculate the energy requirements for 50 field operations from soil preparation to transportation was develOped. The model performs the calculations based upon input parameters including machinery sets (machine sizes, types, working depths, and field Speeds), soil type and conditions, and field size. Tractor performance such as wheel slip and tractive efficiency are determined, and energy requirements for conventional fuel (diesel, gasoline, and LP gas) for field Operations are calculated. An alcohol subroutine was written where alcohol fuel consumption and conventional fuel consumption are determined for converted tractors. Four tractor conversion methods are allowed to be used in this model. An economic analysis is included in the main program to compare each of the conversions on an economic basis. Break-even prices for alcohol fuel (ethanol) were determined. The computer model was validated by comparing the results from the computer program with field data collected on two Michigan farms in the fall season of 1980. Data from the Michigan Energy Audit Study which contained the average fuel consumption of 52 Michigan farms was also used to validate the model. Three Michigan farms were used as case studies. Results of fuel consumption by machine, by Operation group, and by enterprise were pre- sented for a small (79 ha), medium (200 ha), and large (550 ha) farm. Large farms presented a better matching between tractors and implements. The results from the computer model for fuel consumption were within 6.2, 0.3, and 3.8 percent of the results reported by the farmer for the small, medium, and large farms, respectively. 103 104 The use of alcohol in gasoline engines after major modification of rebuilding the engine with increased compression proved to be the best way Of using alcohol. Most of the farm tractors are diesel powered so this conversion method can only replace a small percentage of the conven- tional fuels used on the farms. The use of alcohol in diesel engines where alcohol is fueled in a dual-fuel system by aspirating the alcohol into the intake air through a carburetor system presented substitution rates around 45 percent. This proved to be a better way Of using alcohol in diesel engines when com- pared to Spray injection. Tractors with high annual use which used either spray injection or dual-fueling with carburated ethanol presented break-even prices closer to those when ethanol was used in gasoline engines. Because of the higher difference in heat content between diesel and ethanol than between gasoline and ethanol, the break-even prices for ethanol will always be lower when ethanol is used in diesel engines. CHAPTER 8 CONCLUSIONS 1. A computer program was develOped which models the fuel consump- tion for 50 field Operations from soil preparation to transportation involving the use of tractors, trucks, combines and self-propelled machines. The program models fuel consumption with conventional and alcohol fuels. 2. The computer model produced results close to those from field Observations to Show that the model was valid. For the three farms studied the model results were within 6.2, 0.3, and 3.8 percent of the results reported by the farmer for the small (79 ha), medium (200 ha). and large (550 ha) farms. 3. Alcohol substitution rates of 34, 29, and 35 percent of the total fuel used on the farm were Obtained for a small, medium, and large farm, respectively. Corn should be planted on 1.4, 1.4, and 1.7 percent Of the total farming area if the rates of substitution are to be met for the small, medium, and large farms. 4. Larger farms would normally present more potential for economi- cal use Of alcohol, because of the high annual use of tractors. 5. If alcohol is to be used in a gasoline engine at the present time, the cost per liter should not be more than $0.25, considering gasoline prices at $0.33 per liter. 6. 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Problems with the Use of Ethanol as Fuel for Commercial Vehicles. Paper 2-3 presented at the International Symposium on Alcohol Fuel Technology, Wolfsburg, Germany, November. Scott, W. M. and D. R. Cummings. 1977. Dual-Fueling the Truck Diesel with Ethanol, paper 2-5 presented at the International Symposium on Alcohol Fuel Technology, Wolfsburg, Germany, November. Owens, E. C. 1977. Methanol-Fuel Effects on Spark Ignition Engine Lubrication and Wear. Paper 2-6 presented at the International Symposium on Alcohol Fuel Technology, Wolfsburg, Germany, November. Baker. R. E. 1977. Utilization Of Methanol as an Automotive Fuel, Paper 2-7 presented at the International Symposium on Alcohol Fuel Technology, Wolfsburg, Germany, November. Chester K. A., et al. 1977. The Effects of Blending Methanol with Gasoline on the Lean Misfire Limit of a Multicylinder Carburated Engine. Paper 4-1 presented at the International Symposium on Alcohol Fuel Technology, Wolfsburg, Germany, November. McCormack, M. and R. K. Pefley. 1977. Alternative Air-Fuel Induction System Contrasts in Terms of Fuel Economy and Exhaust Emissions for Simulated Driving Cycles with Methanol and Indolene. Paper 4-2 presented at the International Symposium on Alcohol Fuel Technology, Wolfsburg, Germany, November. Johnson, R. T. 1977. A Comparison of Gasoline, Methanol and Methanol/Water Blend as Spark Ignition Fuels. Paper 4-3 presented at the International Symposium on Alcohol Fuel Technology, Wolfsburg, Germany, November. Zimmerman, A. C. 1924. Alcohol and Gasoline Mixtures. U. S. Air. Ser. Cir. 5:45. . Strong, R. M. 1911. Commercial Deductions from Comparisons of Gasoline and Alcohol Tests on Internal Combustion Engines, U. S. Bureau of Mines Bul. 32. Hunt, 0. 1968. Farm Power and Machinery Management, Iowa State University Press, Ames, Iowa 292 pp. Myers, 0. A., et al. 1979. Annual Report for Phase I-Michigan Farm Energy Audit Study. 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