EPA/AA/CTAB/PA/81-16 REV. //1/Oct 81 Technical Report Gasoline Equivalent Fuel Economy Determination for Alternate Automotive Fuels by Craig A. Harvey August, 1981 revised October, 1981 NOTICE Technical Reports do not necessarily represent final EPA decisions or positions. They are intended to present technical analysis or summaries of programs from work which is currently being conducted. The purpose in the release of such reports is to facilitate the exchange of technical information and to inform the public of programs and technical developments which may form the basis for a final EPA decision, position or regulatory action. Control Technology Assessment and Characterization Branch Emission Control Technology Division Office of Mobile Source Air Pollution Control Office of Air, Noise and Radiation U.S. Environmental Protection Agency 2565 Plymouth Road Ann Arbor, Michigan 48105 ------- -2- GASOLINE - EQUIVALENT FUEL ECONOMY DETERMINATION Abstract Due to the growing interest in and use of alternate automotive fuels, it is necessary that EPA provide a method of calculating fuel economy values for these vehicles than using fuels so that average fuel economies of manufacturers can be determined. The relevant legislation is reviewed, and various methodologies are discussed. Possible fuel equivalency factors are presented for Diesel fuel, ethanol, methanol, gasohol, and natural gas. A methodology is recommended that takes into account the energy content of the fuel, the energy required to manufacture the fuel, and the value of the raw material used to make the fuel. I. Introduction A. Recommendation In order to comply with the provisions of the Energy Policy and Conservation Act (EPCA, PL 94-163) (1)* and the Chrysler Corporation Loan Guarantee Act (PL 96-185) (2), which call for a determination of "... that quantity of any other fuel which is the equivalent of one gallon of gasoline," it is recommended that for the purpose of calculating the ?uel Econonry Values for vehicles fueled wich fuels which differ substantially from gasoline, a methodology similar to that used by Department of Energy (DOE) for electric vehicles (3) be applied. This methodology would account for fuel energy content and final processing energy requirement, and indirectly for energy input in the earlier processing steps. In essence, this methodology would consist of taking the mile-per-gallon result from a vehicle test on an alternate (non-gasoline) liquid fuel and adjusting it by (1) the energy content ratio of gasoline to the alternate fuel (LIIV, BTU/gal), (2) the ratio of processing energy efficiency of the alternate fuel to the efficiency of a petroleum refinery, and (3) the ratio of raw material costs of gasoline to those of the alternate fuel. * Numbers in parentheses indicate references at the end of the report ------- -3- The equation is: FE = MPGalt. x LHVgas. x Salt, x Vgas. LHValt. Egas. Valt. where: FE = gasoline equivalent Fuel Economy MPGalt. = Mile per gallon test result for Alternate Fuel LHVgas. = Lower heating value, standard test gasoline (BTU/gal) LHValt. = Lower heating value, alternate fuel (BTU/gal) Ealt. = Energy efficiency of processing plant, alternate fuel Egas. = Energy efficiency of petroleum refinery (%) Vgas. = Raw material value, gasoline (^/million BTU) Valt. = Raw material value, alternate fuel (^/million BTU) ------- -4- B. Purpose of Report With the increasing national emphasis on energy conservation and energy independence, in conjunction with rapidly rising gasoline; costs, the transportation industry, the energy industry, the U.S. Government, and other interested parties are putting more attention on development of vehicles/engines that either utilize petroleum fuels more efficiently or make more use of fuels derived from domestic energy resources. Some examples of this are the increased production of Diesel vehicles, the marketing of Gasohol, the development of alcohol-fueled vehicles, and the development of electric vehicles. This report is intended to provide some of the basis for a decision on the most appropriate methodology for calculating the gasoline "equivalent fuel economy of a vehicle that uses fuel other than gasoline. Once this methodology has been determined, it will provide vehicle manufacturers with a way to gauge the effects of alternative marketing options on their average fuel economy. C. Background C.I. Legislation a) The Energy Policy and Conservation Act The Energy Policy and Conservation Act (EPCA) mandates that the Secretary of Transportation establish average fuel economy standards for major automobile manufacturers and importers (production above 10,000 cars per year) beginning with the 197.8 model year, as shown in Table 1. The 1980 standard was 20.0 mpg. The standard will increase progressively until the average fuel economy is 27.5 mpg, as required in 1985. The standard is to be met by each manufacturer and by each importer and applies to the total number of cars produced or imported. Civil penalties are prescribed for a violator of the law: $5 for each tenth of a mile-per-gallon that their corporate average falls below the ------- -5- Table 1. Automotive Average Fuel Economy Standards Under the Energy Policy and Conservation Act Model Year Standard (mpg) 1978 1979 1980 1981 1982 1983 1984 1985 and thereafter 18.0 19.0 20.0 22.0 24.0 26.0 27.0 27.5* *The Secretary of Transportation may alter this to the "maximum feasible average fuel economy", but such action may be disapproved by Congress for levels below 26.0 mpg or above 27.5 mpg. ------- -6- year's standard, multiplied by the number of cars produced orr imported that year. The National Energy Conservation Policy Act, P.L. 95-619, grants the Secretary of Transportation the authority to raise this penalty up to $10 for each tenth of a mile-per-gallon beginning in the 1981 model year. Credits for exceeding the standard are calculated in a similar manner. For purposes of EPCA, "The term 'fuel economy' means the average number of miles traveled by an automobile per gallon of gasoline (or equivalent amount of other fuel) consumed, as determined by the EPA Administrator in accordance with procedures established under section 503 (d)." Section 503 (d) contains the EPA mandate for activity on the fuel equivalency issue: " (1) Fuel economy for any model type shall be measured, and average fuel economy of a manufacturer shall be calculated, in accordance with testing and calculation procedures established by the EPA Administrator, by rule..." and " (2) The EPA Administrator shall, by rule, determine that quantity of any other fuel which is the equivalent of one gallon of gasoline." Therefore, it is necessary to know what is meant by "equivalent" and what factors are included in it. Other references to equivalency in EPCA are as follows: Section 105 (b)(l) "... an average daily volume of 1,600,000 barrels of crude oil, natural gas liquids equivalents, and natural gas equivalents. (2) one barrel of natural gas equivalent equals 5,626 cubic feet of natural gas measured at 14.73 pounds per square inch (MSL) and 60 degrees Fahrenheit. (3) one barrel of natural gas liquids equivalent equals 1.454 barrels of natural gas liquids at 60 degrees Fahrenheit." These values for quantities of natural gas and natural gas liquids that are equivalent to 1 barrel of crude oil are determined simply from the ratio of average energy content (heating value) of the fuels. There is no attempt to include any additional factors such as processing or transport energy requirements. ------- -7- In Title III, Part B of EPCA, which deals with consumer products in general, these definitions are given: Section 321(a)(4) "The term 'energy use' means the quantity of energy directly consumed by a consumer product at point of use, determined in accordance with test procedures under section 323. (5) The term 'energy efficiency' means the ratio of the useful output of services from a consumer product to the energy use of such product, determined in accordance with test procedures under section 323." Section 322(6)(2)(B) "The Btu equivalent of one kilowatt-hour is 3,412 British thermal units." From this it is apparent that the scope of consideration for these products includes only the energy consumed at the final point of use, and equivalency is determined by the direct conversion factor without including any additional energy input factors. The objective of EPCA is to accomplish the purposes listed below: "SEC.2. The purposes of this act are- (1) To grant specific standby authority to the President, subject to Congressional review, to impose rationing, to reduce demand for energy through the implementation of energy conservation plans, and to fulfill obligations of the United States under the international energy program; (2) to provide for the creation of a Strategic Petroleum Reserve capable of reducing the impact of severe energy supply interruptions; (3) to increase the supply of fossil fuels in the United States, through price incentives and production requirements; ------- -8- (4) to conserve energy supplies through energy conservation programs, and, where necessary, the regulation of certain energy uses; (5) to provide for improved energy efficiency of motor vehicles, major appliances, and certain other consumer products; (6) to reduce the demand for petroleum products and natural gas through programs designed to provide greater availability and use of this Nation's abundant coal resources; and (7) to provide a means for verification of energy data to assure the reliability of energy data." Examining EPCA, it is apparent that each of these points has been dealt with by specific sections of EPCA. For instance, points three and six, above are dealt with in Title I, "Matters Related to Domestic Supply Availability", Part A, "Domestic Supply" and in Title IV, "Petroleum Pricing Policy and Other Amendments to the Allocation Act"; point one is dealt with in Title II, "Standby Energy Authorities", and in Title V, part C, "Congressional Review". Point seven is dealt with in Title V, Part A, "Energy Data Base and Energy Information". The above mentioned points do not deal with automotive fuel use' at all, except in a very indirect way, which leaves points four and five. Point four is covered by Title III, Parts A - E of EPCA, which provide energy conservation programs for the automotive sector, other consumer products, state energy use, industrial energy use, and federal energy use. Point five is a narrower application of point four and is dealt with in the first two parts of Title III, which are (A) "Automotive Fuel Economy" and (B) "Energy Conservation Program for Consumer Products Other Than Automobiles". The average fuel economy program is one of the programs called for in point four, and it is the only program from EPCA that addresses energy use by currently available automobiles. Average fuel economy as put forth in EPCA for gasoline-fueled vehicles, addresses only the energy efficiency of the ------- -9- vehicle itself in terms of miles per gallon. It does not include any provision for considering the energy efficiency of drilling, refining or fuel transport operations. Therefore, there is nothing in EPCA itself which provides for the inclusion of factors other than vehicle energy efficiency in the calculation of fuel economy. However, there is a House-Senate conference report (4) which accompanied the bill to make EPCA law. That report explained the differences between the House and Senate versions of the bill and explained what the compromise version ("conference substititue") was. Regarding fuel equivalency the conference report states, "It is anticipated that the EPA Administrator, in determining 'equivalent amount of other fuel1 will make such determination on the basis of BTU equivalency of different quantitities of various fuels, taking into account energy required to process such fuels". Since EPCA itself does not explicitly specify the inclusion of fuel processing energy in fuel equivalency calculations, but the conference report "anticipates" such inclusion, methods will be presented in Part II of this report to cover each of these possible approaches. b.) The Energy Tax Act of 1978 The Energy Tax Act of 1978, P.L. 95-618 (5), imposes an excise tax on fuel- inefficient vehicles ("gas guzzlers") which may have an even more profound impact on the strategy employed by the automobile manufacturers to comply with the fuel economy standards than the $5 to $10 per tenth of a mile-per-gallon penalty contained in EPCA. Table 2 shows the severity of this tax. Imposition of the tax begins with vehicles whose fuel economy is approximately 5 mpg less than the current year's average fuel economy standard. The tax is steeply graduated, ranging in 1986, from $500 for each vehicle whose fuel economy is 5 to 6 mpg below the 1986 standard to $3850 for each vehicle whose fuel economy is over 15 mpg below the standard. ------- -10- Table 2 The Gas Guzzler Tax (in dollars) Year (Fuel Economy Standard) Vehicle Fuel Economy 1980 EPA Composite MPG (20.0) Greater than 22.5 21.5-22.5 Greater than 21.0 0 20.5-21.5 20.0-21.0 0 19.5-20.5 19.0-20.0 0 18.5-19.5 18.0-19.0 0 17.5-18.5 17.0-18.0 0 16.5-17.5 16.0-17.0 0 15.5-16.5 15.0-16.0 Q/ 14.5-15.5 / 14.0-15.0 200 13.5-14.5 13.0-14.0 300 12.5-13.5 Less than 13.0 550 Less than 12.5 1981 1982 (22.0) (24.0) 0 0 0 0 0 0 0 0 0 / / 200 o/ / 350 '200 450 ( 350 600 450 / 750 550 ' 1 950 650 / / 1200 1983 1984 (26.0) (27.0) 0 xO~ o x x o / 0 / o 0 450 350 600 500 750" 650 x / 950 /800 / 1150 1000 1450 1250 1750 1550 2150 1985 1986 (27.5) (27.5) _____ fl 500 0 650 500 850 600 1050 800 1300 _ 1000 *" ~" 1500 1200 1850 1500 2250 1800 2700 2200 3200 2650 ^ - " ' ' 3850 Standard minus 5 mpg Standard minus 10 mpg Standard minus 15 mpg ------- -11- More interesting is the effect on a given model which is retained unchanged in a manufacturer's line. For example, if a vehicle's fuel economy is 15.1 mpg in 1980, it would not be subject to a gas guzzler tax. Beginning in 1981, it would have an ever-increasing tax levied$350 in 1981, $600 in 1982, £800 in 1983, $1150 in 1984, $1500 in 1985, and $2250 in 1986. It is assumed that the effect of this tax will be to reduce the sale of gas guzzlers. This progressive increase in penalty will probably result in earlier discontinuance of production of the less fuel-efficient vehicles in a manufacturer's line. Fewer very fuel-efficient vehicles will then be needed to achieve the average fuel economy standard. The result will be a tighter clustering of vehicles around the standard. c) The Chrysler Corporation Loan Guarantee Act of 1979 The Chrysler Corporation Loan Guarantee Act of 1979 (P.L. 96-185) established: "a seven-year evaluation program of the inclusion of electric vehicles ... in the calculation of average fuel economy ... to determine the value and implications of such inclusion as an incentive for the early initiation of industrial engineering development and initial commercialization of electric vehicles in the United States." The Administrator of EPA was, in consultation with the Secretaries of Energy and Transportation, to promulgate "regulations to include electric vehicles in average fuel economy calculations ..." by March 7, 1980. The Secretary of Energy has proposed "equivalent petroleum based fuel economy values" for various classes of electric vehicles, and final values have been promulgated (10 CFR Part 474). These equivalent values are to be reviewed annually and revised as necessary. ------- -12- These "equivalent petroleum based fuel economy values" for electric vehicles were to be determined taking into account the following parameters : "(i) The approximate electrical energy efficiency of the vehicles considering the vehicle type, mission, and weight; (ii) The national average electricity generation and transmission efficiencies; (iii) The need of the Nation to conserve all forms of energy, and the relative scarcity and value to the Nation of all fuel used to generate electricity; (iv) The specific driving patterns of electric vehicles as compared with those of petroleum fueled vehicles." According to the final rule issued by DOE, equivalent petroleum based fuel economy values for electric vehicles will be calculated in the following manner: FE = FEee x DPF x et x AF x Etotal where : FE = the equivalent petroleum-based fuel economy FEee = the energy-equivalent fuel economy value (miles per gallon) (ref. 5) conversion factor: 1 13, 300 BTU x 1 KWH gal 3412 BTU DPF = driving pattern factor (1.00) ------- -13- e = average national electricity transmission efficiency ( = 0.91) AF = Accessory Factor (= 1.00, no accessories; 0.90, heater; 0.81, heater plus air conditioning) E ^ = total amount of electricity generated from all fuel sources for the model year (quadrillion BTU, or quads) I. = input energy of fuel used to generate electricity from fuel source- i (quads) V. = relative value factor of fuel source i In section II. D of this paper the adaptation of the above procedure to alternative automotive fuels is discussed. C. 2. Current Equivalency Methodologies Up to now, tentative solutions to the equivalency issue have only been provided for two specific areas - Diesel fueled vehicles and electric vehicles. The documents that cover these provisions are: 1) Methodology for Calculation of Diesel Fuel to Gasoline Fuel Economy Equivalence Factors, Technical Support Report for Regulatory Action, January 1976 (Revised May 1976), EPA-ECTD report. (7) 2) Federal Register, Sept. 10, 1976, "Fuel Economy Testing; Calculation and Exhaust Emissions Test Procedures for 1977-1979 Model Year Automobiles." 3) Final Rule, 10 CFR Part 474, "Electric and Hybrid Vehicle Research, Development, and Demonstration Program; Equivalent Petroleum-Based Fuel Economy Calculation"; 1981. (3) ------- -14- There has been much written on the subject of Diesel/gasoline fuel equivalency but, so far, the solution has been to weight them equally. In other words, the correction factor applied to Diesel fuel economy test results is effectively 1.0. This is because the higher energy content of Diesel fuel tends to be balanced by the decrease in refinery energy consumption with increasing Diesel fuel production. In attempting to characterize the increase in energy availability (decrease in refinery energy consumption) with increasing Diesel fuel production percentage, many variables enter into the calculation. For instance, there are refinery-to-refinery differences, variations in refinery product mix with time, and variations in raw material (such as the sulfur content of the crude oil) with time and between refineries, all of which affect the process energy requirements at any given Diesel/gasoline production ratio. There are some specific problems with using the current Diesel/gasoline equivalency methodology as a basis for future equivalency determinations, arid these issues are discussed in part II. B. of this report. Regarding equivalent petroleum-based fuel economy calculations for electric vehicles, the methodology in use was discussed previously in Section C.l.c) of this report. ------- -15- II. Possible Methodologies for Determining Equivalent Fuel Economies for all Fuels Following are three methodologies for calculating equivalent petroleum-based fuel economies for a wide variety of potential automotive fuels. One objective of this investigation is to determine a methodology that is consistent for all automotive fuels, so a range of possible solutions is presented including one solution (C) that is recommended due to its consistency with the various legislative provisions outlined above. Method A. Fuel Energy Content Considered The simplest solution that would be in line with EFCA, but not necessarily with the conference report as discussed in Part I, would be to use the ratio of the heat content of a fuel to that of gasoline as a correction factor to the actual mile per gallon test result. This would effectively rank vehicles on the basis of miles per BTU of fuel used by the vehicle itself. Here is an example of this methodology as applied to a methanol-fueled vehicle: In the fuel economy test assume a vehicle gets 20 miles per gallon of methanol, as compared to a similar, but gasoline-fueled, car getting 30 miles per gallon. Since the heat content of methanol is 56,123 BTU/gal, the methanol-fueled vehicle is getting 35.6 miles per 100,000 BTU. Typical gasoline has a heat content of 113,300 BTU/gal, so 30 mpg gasoline equals 26.5 miles per 100,000 BTU. In order to adjust the mile per gallon value for methanol (20 mpg) to correct for the difference in heat content between methanol and gasoline, it would be multiplied by the ratio of the heat content of gasoline to that of methanol. FE = MPGalt. x LHVgas. LHValt. ------- -16- FE = 20 mpg x 113,300 BTU/gal gasoline* 56,123BTU/galmethanol(S) FE = 20 mpg x 2.02 FE = 40.4 mpg In this case, for purposes of fuel economy calculations, the 20 mpg methanol car could be rated at 40.4 mpg when converted to a gasoline-equivalent basis. Another fuel that should be mentioned with respect to Method A is Diesel fuel. Since Diesel fuel #2 has a 15% higher heat content than gasoline (130,650 (7) vs. 113,300 BTU/gal), the equivalent gasoline-based fuel economy of a 35 mpg Diesel vehicle, for instance, would be; FE - 35 mpg x 113,300 BTU/gal gasoline 130,650 BTU/gal Diesel FE = 30.4 mpg Table 3 lists the fuel equivalency factors for various fuels calculated with this methodology. FEF is the resultant adjustment factor, for methanol for example, the value for FEF is 2.02. * Today's motor gasolines range in BTU/gallon from about 112,000 BTU/gallon to 115,000 BTU/gallon. ------- -17- Table 3 Fuel Equivalency Factors Based on Energy Content alone * Energy Content Fuel (BTU/gal) FEF Gasoline leaded regular 113,300 1.0 unleaded regular 113,300 1.0 unleaded premium 113,300 1.0 Diesel Fuel #2 130,650 0.87 #1 126,100 0.9 Methanol 56,123 2.02 Ethanol 78,987 1.43 Gasohol 109,869 1.03 Natural Gas (1080 BTU/ft3) ** *Lower Heating Value ** FE = Miles/BTU nat. gas x 113,300 BTU/gal. gasoline The use of this methodology for Diesels could be taken to represent a 13% penalty that could discourage use of Diesel vehicles (9). However, when combined with the 30% average fuel economy benefit for Diesels over comparable gasoline vehicles (10), there is still a 17% benefit for Diesels. The only possible liability of this methodology is that, by itself, it does not address the issue of energy used in processing fuels. This area of concern is addressed in the next two methodologies. ------- -18- Method B. Energy Content Plus Refining Energy Considered A second possible approach to determining gasoline equivalent fuel economies would be one that includes the efficiency of the final fuel processing steps, (eg. refinery efficiency for petroleum fuels). In this methodology an additional factor is included in the fuel equivalency calculation. In the case of Diesel vehicles this additional factor adjusts the fuel economy value to reflect the refinery energy savings that occur when the Diesel fuel output of a refinery is increased relative to the gasoline output. The most recent investigation of this phenomenon is described by Amoco in reference (11). In the Amoco study it is concluded that decreasing the Gasoline/Distillate (G/D)* production ratio from 1.6 to 0.7 would decrease the energy consumption of the refinery by 13.7% - 16.8%, depending on the octane of the gasoline produced. The equation which characterizes this methodology for finding the gasoline- equivalent fuel economy of a Diesel vehicle is: FE = MPGD x LHVgas x DEO LHVD DEO - RES where: The subscript D indicates Diesel fuel DEO is the Diesel fuel energy output RES is the Refinery Energy Savings when producing additional Diesel fuel * G/D ratio is the volume of motor gasoline divided by the volume' of total distillates - Diesel fuel, fuel oils, kerosene and jet fuels. It is commonly used to describe refining operations. U.S. refineries currently average about 1.6 G/D ratio, but the ratio may vary among refineries and with season from about 1.0 to 2.0 ------- -19- The combination of LHV gas x Diesel Energy Output adjusts the Diesel fuel energy output at any G/D ratio to the equivalent gasoline energy output. The term in the denominator reflects the refinery energy savings that occur when producing additional Diesel fuel. This increases the Diesel equivalency factor because it gives the Diesel fuel energy output credit for the refinery energy saved. Using this methodology Amoco then developed the following table of Diesel Equivalency Factors (DEF), which would be used in this formula: FE = MPGD x DEF DIESEL EQUIVALENCY FACTORS BASED ON ALL DIESEL Fuel PRODUCED Pool Gasoline/Distillate Ratio RM/2 Octane* . 1.6 1.3 1.0 0.7 80 0.88 0.91 0.92 0.92 82 0.88 0.91 0.92 0.92 84 0.88 0.91 0.92 0.93 86 (Base) 0.88 0.92 0.93 0.92 88 0.89 0.94 0.94 0.94 90 0.89 0.96 0.97 0.96 92 0.90 0.98 0.97 0.98 * RM/2 = Anti-knock Index (AKI) = Research Octane + Motor Octane 2 ~~ From the MVMA national gasoline survey, the difference between Research and Motor octane (sensitivity) of unleaded gasoline typically ranges from 9.0 for regular to 9.6 for premium. So 91 Research Octane unleaded would have an AKI of about 86.5. For any fuel equivalency methodology, a specific base fuel needs to be used as a reference point. Unleaded 91 Research Octane gasoline is the most suitable choice for such a reference fuel. ------- -20- DIESEL EQUIVALENCY FACTORS BASED ON ADDITIONAL DIESEL FUEL ONLY Pool Gasoline/Distillate Ratio RM/2 Octane 1.6 1.3 1.0 0.7 80 0.88 0.93 0.93 0.93 82 0.88 0.94 0.93 0.93 84 0.88 0.94 0.94 0.93 86 (Base) 0.88 0.95 0.94 0.93 88 0.89 0.99 0.96 0.95 90 0.89 1.02 0.99 0.98 92 0.90 1.04 1.00 1.00 It should be mentioned that Amoco also calculated a set of DEF's that included the expected fuel economy advantage for gasoline-fueled vehicles attributable to increasing gasoline octane number (1.5 mpg per RM/2). However, it would be incorrect to include this effect in the Diesel Equivalency Factor, since any expected fuel economy change, if valid, would show up in the actual mpg test results. The above factors are based on the change that would occur from what is considered the base case (86 RM/2; 1.6 G/D). Therefore, the DEF for the base case consists only of the energy content (lower heating value) of gasoline divided by the energy content of Diesel fuel. In theory it would be possible to avoid this somewhat arbitrary base case, but it would require many assumptions on allocation of the energy used in each processing unit to each product. This is due to the many interdependences of gasoline and Diesel fuel production which make it impossible to simply separate and measure the energy consumption attributable to each of the two fuels. ------- -20- DIESEL EQUIVALENCY FACTORS BASED ON ADDITIONAL DIESEL FUEL ONLY Pool Gasoline/Distillate Ratio RM/2 Octane 1.6 1.3 1.0 0.7 80 0.88 0.93 0.93 0.93 82 0.88 0.94 0.93 0.93 84 0.88 0.94 0.94 0.93 86 (Base) 0.88 0.95 0.94 0.93 88 0.89 0.99 0.96 0.95 90 0.89 1.02 0.99 0.98 92 0.90 1.04 1.00 1.00 It should be mentioned that Amoco also calculated a set of DEF's that included the expected fuel economy advantage for gasoline-fueled vehicles attributable to increasing gasoline octane number (1.5 mpg per RM/2). However, it would be incorrect to include this effect in the Diesel Equivalency Factor, since any expected fuel economy change, if valid, would show up in the actual mpg test results. The above factors are based on the change that would occur from what is considered the base case (86 RM/2; 1.6 G/D). Therefore, the DEF for the base case consists only of the energy content (lower heating value) of gasoline divided by the energy content of Diesel fuel. In theory it would be possible to avoid this somewhat arbitrary base case, but it would require many assumptions on allocation of the energy used in each processing unit to each product. This is due to the many interdependencies of gasoline and Diesel fuel production which make it impossible to simply separate and measure the energy consumption attributable to each of the two fuels. ------- -21- In order to choose the most appropriate factor(s) from these tables, it is necessary to look a little more closely at things that affect the gasoline/distillate ratio. Distillate fuels include automotive (passenger car and truck) Diesel fuels, jet aircraft fuel, residential and commercial heating oil, and industrial Diesel fuels. According to the DOE predictions in reference (12), increases that will occur in the use of distillate fuels for transportation in the next decade will be offset somewhat by decreases in the other distillate fuel uses. Due to these decreases in non-transportation distillate fuels, the net change in gasoline/distillate ratio is not as great as might be expected. Even if we assume all jet fuel is distillate, the GDR in 1985 only comes down to about 1.45, and in 1990 it would range from 1.28 - 1.34 depending on crude oil prices. Therefore, the 1.3 G1)R column would be the most appropriate one to consider through at least 1990, assuming the changes that actually occur fall within the range of the DOE predictions. The question of whether to base the DEF on all Diesel fuel produced or just on the additional Diesel fuel produced is handled in the Sobotka report (13) by simply neglecting the existence of the all-Diesel-fuel factors. However, a valid rationale does exist for using the additional-Diesel-fuel factors, as Sobotka did. The refinery efficiency credit from decreasing GDR should be credited to that portion of the distillate production which is most responsible for the change. According the DOE projections, most of the distillate increase can be attributed to the automotive sector (80% vs. 20% jet fuel) and furthermore, all of that increase can be attributed to Diesel passenger cars, since truck vehicle-miles are expected to be less in 1990 than in 1978 (12). Therefore, the Sobotka analysis was correct in using the equivalency factors based on additional Diesel fuel production only. Also, as described in the Sobotka analysis, the unleaded gasoline pool AKI is expected to increase from the base case of 86 to 88 in the 1980's and possibly 90 in the 1990's. So the range of DEF's would be 0.95 - 1.02. ------- -22- For this methodology it is recommended that, due to the uncertainties in these calculations, the fuel equivalency factor for Diesels be rounded to 1.0, thus in effect, keeping it as it has been up to this point. Another question with this type of methodology is how to apply it to other fuels, such as alcohols. It is possible to define reasonably accurate production efficiencies, and therefore energy consumptions, for the common ethanol and methanol production processes within this methodology. But it would not be possible to define a valid fuel equivalency factor directly relating alcohol to gasoline, since there is no direct relationship between alcohol and gasoline production like there is between Diesel and gasoline. Futhermore, a corresponding efficiency for gasoline by itself would not be calculable due to the refinery interdependencies mentioned above. Despite these considerations, a possible approximation of an alcohol/gasoline equivalency factor within this basic methodology could be calculated as follows: 1) let the gasoline production efficiency be approximated as simply the overall refinery efficiency. c - REO REI - REG Egas" * REI * REI where: Egas. = Energy efficiency of petroleum refinery REO = Total refinery energy output REI = Total refinery energy input REC = Refinery energy consumption ------- -23- 2) then let the alcohol production efficiency be calculated with this same equation as applied to alcohol fuel plants. The following is how this would look for ethanol. _ , PEI - PEC Eeth. = PEI where : Eeth. = Energy efficiency of alternate fuel plant (ethanol) PEI = Total plant energy input PEC = Plant energy consumption and 3) The equivalency factor would then be the fuel energy content ratio multiplied by the ratio of the two fuel processing efficiencies,. m~ , LHVgas. Eeth. FE = MPGeth. x x Due to the likelihood of change in average production efficiency with tech- nological improvements and new plant construction, it probably would be necessary to review and update these factors periodically. Example (methanol) //I Egas. = - = 0.92 (ref. 11) PEO Emeth. = - = 0.56 (ref. 14, methanol from natural gas) PEI , 113,300 BTU/gal 0.56 FE = MPGmeth. x 56>123 BTU/*al * ^ MPGmeth. x 1.23 Example (methanol) //2 Emeth. = 0.60 (ref. 15, methanol and synthetic natural gas from coal) 113,300 0.60 FE = MPGmeth. x 56>123 x ^gj = MPGmeth. x 1.32 ------- -24- Table 4 lists fuel equivalency factors determined with Method B. Table 4 Fuel Equivalency Factors Based on Fuel Energy Content & Plant Process Energy Plant Fuel Efficiency FEF* Gasoline 92% 1.00 Diesel Fuel 92% .95 - 1.02 Methanol from natural gas 56% - 70% 1.23 - 1.54 from coal 50% - 60% 1.10 - 1.32 Ethanol from corn 45% - 60% 0.70 - 0.93 Gasohol (10% of Ethanol effect) .97 - .98 Compressed Natural Gas 96% ** Liquified Natural Gas 86% ** * FEF = FEF from Table 3 x E alt. Egas. ** FE = (Miles/BTU nat. gas) x 113,300 x Plant Efficiency/92% ------- -25- Method C. Energy Content, Process Efficiency Plus Fuel Value Considered This fuel equivalency alternative is based on the Department of Energy (DOE) proposed methodology for calculation of equivalent petroleum-based fuel economies for electric vehicles which was described earlier in Section I. This methodology accounts not only for the different energy contents of the fuels themselves and the different energy efficiencies of the various fuel processing routes, but also includes a raw material cost factor to account for the energy needed to get a fuel as- far as the processing step. The raw material assumed for gasoline production is crude oil, so gasoline produced by any other means than refining of crude oil would need to have a fuel equivalency factor calculated to account for any significant differences in processing efficiencies and raw materials. The raw material cost factor would be simply a ratio of the cost of crude oil to the cost of any alternate raw material, on a dollar per BTU basis. When this factor is included in the formula for calculating FEF's, the equation looks like this: = LHVgas. x Ealt. x Vgas. LHValt. Egas. Valt. where : Vgas. = Raw Material Value for gasoline (^/million BTU of crude oil) Valt. = Raw Material Value for alternate fuel (^/million BTU) Using some projected figures for 1982 (12), Table 5 indicates the effect of including this additional factor. For methanol, the inclusion of this raw material cost factor more than compensates for the lower processing efficiency of methanol compared to petroleum products. The resulting fuel equivalency factor, 3.76 - 5.42 depending on raw material, would seem to provide a significant impetus toward development and use of methanol fueled vehicles. ------- -26- Even if a methanol fueled vehicle only achieved half the mpg of a corresponding gasoline vehicle, the FEF would result in a gasoline-equivalent fuel economy 1.88 - 2.71 times as much as the gasoline fueled vehicle. The figures for ethanol are a little surprising due to the effect of the corn cost on the FEF. The cost of the corn needed to produce one million BTU of ethanol is about 5 1/2 times the cost of the heat source, assuming coal is used. Even when credit is given for the plant output of Distillers Dried Grain (DDG) the raw material cost per million BTU output of an ethanol plant is 1.9 times as high as a petroleum refinery operating with a current product mix. So even if a pure ethanol-fueled vehicle achieved the same mpg test result as a gasoline-fueled vehicle (e.g. 25 mpg) the resulting gasoline-equivalent fuel economy would only be 1/1.9 (=0.53) times the ethanol test result (0.53 x 25 = 13.3 mpg). ------- -27- Table 5 Fuel Equivalency Factors Based on Energy Content, Plant Efficiency and Raw Material Cost Fuel Gasoline (from petroleum)** Diesel Fuel (from petroleum)** Methanol (from natural gas) (from coal) Raw Material Cost Ethanol*** (from corn) and all process energy from coal @$1.45/MMBTU for the coal Gasohol Natural Gas bu $2.25 MMBTU FEF* $6.89 MMBTU $6.89 MMBTU $2.25 MMBTU $1.45 MMBTU $3.. 50 1.0 0.95 - 1.02 3.76 - 4.71 5.23 - 6.27 0.60 - 0.73 0.96 - 0.97 **** FEF = FEF from Table 4 x Petroleum Cost Raw Material Cost ** from petroleum at $37,88/barrel. *** The higher FEF assumes all process energy comes from the input corn without any additional process energy source. **** Gasoline - Equivalent = Miles Fuel Economy x 113,300 BTU x plant eff. x $6.89 Btunat. gas. gal. gasoline 92% $2.25 ------- -28- Gaseous and Other Fuels The methodology discussed here could also be applied to other fuels besides those listed in the tables. For instance, it is possible to produce gasoline from coal rather than from crude oil. This would result in different raw material costs as well as different processing efficiencies for the synthetic gasoline in comparison to usual oil-derived gasoline. To get a rough idea of how a synthetic gasoline such as this would compare to the fuels considered in the tables, it could be directly compared to methanol from coal. For the purpose of this comparison, we can assume that the raw material (coal) is the same in both cases, and that the processing efficiencies are approximately the same for converting coal to either gasoline or methanol. Then the only part of the Fuel Equivalency Factor that would be different for the two fuels would be the energy content (LHV) which, for the gasoline, would be double that of the methanol. The FEF computation would look like this: Ealt. = 0.60 (using example #2, page 23) Valt. = $1.45/MMBTU (from table 5) FEF (methanol from coal) =6.27 (table 5) FEF (gasoline from coal) = 3.14 Since synthetic gasoline could- be expected to yield approximately the same measured fuel economy as conventional gasoline, the final gasoline-equivalent fuel economy of the synthetic gasoline, according to these calculations, would be approximately triple that of conventional gasoline. For liquid alternate fuels, as discussed above, the basic approach starts with measuring the fuel consumption (mile/gallon) and then multiplying it by the energy content ratio of gasoline to alternate fuel to obtain a ------- -29- gasoline-equivalent fuel economy. For gaseous fuels, the more likely starting point would be a mile per BTU measurement. This would then simply be multiplied by the energy content of gasoline (BTU/gal) to get the basic gasoline-equivalent fuel economy corresponding to Method A. The other adjustment factors for Methods B and C could then be applied as described above. ------- -30- III. DISCUSSION Three different methodologies have been presented here which cover a range of approaches for dealing with the fuel equivalency issue. Other methodologies were considered, such as basing equivalency solely on retail price per BTU, but it is felt that the methodologies presented here sufficiently encompass all the possibilities. Looking first at Method A presented above (fuel energy content only), it is apparent that the factors not accounted for would include (a) plant/refinery energy consumption, (b) fuel transport energy consumption, and (c) differences in origin of fuel (imported crude, domestic coal, corn, etc.). It should be kept in mind that the Energy Policy and Conservation Act (EPCA) itself does not specifically call for any of these factors to be taken into account for non-electric vehicles. In Method B (fuel energy content/process efficiency) the differences in fuel origin and energy consumption prior to reaching the plant/refinery are still not taken into account. (Again, these are not specifically required by EPCA.) The major inconsistency introduced by this methodology is the way Diesel fuel equivalency would be handled compared with other fuels. For the process energy of Diesel fuel relative to that of gasoline it was necessary to consider the change in overall plant efficiency when the gasoline/distillate ratio was changed from an arbitrary baseline. This approach was due to the virtual impossibility of separating the efficiencies for Diesel and gasoline production since they are produced in the same plant from the same raw material and have many interdependencies in the production process. This is in contrast to the handling of non-petroleum fuels within this methodology. For these other fuels, such as methanol, the production efficiency would be an actual, current efficiency to be compared directly ------- -31- with the current gasoline production efficiency. Not only would this be inconsistent with the handling of Diesel fuel equivalency, but it is also a very imprecise comparison due to the inability to determine an efficiency for gasoline by itself. (The overall refinery efficiency would be a composite of all the refinery products). In Method C (energy content/efficiency/raw material value), the plant energy consumption is accounted for directly, while the fuel transport energy consumption, and the differences in origin of fuel are all taken into account indirectly via the raw material cost factor (price per BTU). The more energy that is consumed in getting raw material to the plant whether crude oil, coal, or corn, the higher the cost will be. Some of the factors that could influence the cost of the raw material to the plant are a) the cost of drilling, mining or growing it in the first place: b) the cost of transporting it to the plant, whether by pipeline, ship, rail or truck; and c) any taxes such as import duties; d) any subsidies granted to domestic drilling, mining or farming activities, or direct government price controls on raw materials such as oil, coal, and corn. Since these cost factors include more than just direct energy dependent costs, the use of this factor actually goes a little beyond the legislated requirement for liquid fuels equivalency factors. Using a factor such as this would, however, be consistent with one of the parameters given for fuel equivalency calculation of electric vehicles in the Chrysler Corporation Loan Guarantee Act (PL 96-185), which takes into account the need of the nation to conserve all forms of energy, and the relative scarcity and value to the nation of various fuels. Therefore, taking into account the .various fuel equivalency methodologies and the legislative requirements, Method C seems to best serve the purposes set up for fuel equivalency determination provided all the needed input data can be accurately determined and updated when and if necessary. ------- -32- APPENDIX ------- -33 This Appendix gives some more calculations of Fuel Equivalency Factors (FEFs) for various parameters such as the efficiency of various production processes and costs of various raw materials. ------- -34- Table A-l Fuel Equivalency Factors Considering fuel energy content and process energy Methanol Plant Petroleum Refinery Efficiency 50% 60% 70% Ethanol Plant Efficiency 30% 45% 60% Natural Gas* Efficiency 96% (compressed) 86% (liquified) 88% 1.14 1.36 1.59 0.49 0.73 0.98 1.09 0.98 Efficiency 90% 1.11 1.33 1.56 0.48 0.72 0.95 1.07 0.95 92% 1.09 1.30 1.52 0.47 0.70 0.93 1.05 0.94 not expected that mile/gallon figures will be found f< fueled vehicles, the gasoline-equivalent fuel econoi .culated as follows: it miles V 113,300 BTU T717T7 Gasoline-Equivalent Fuel Economy ~ ~BTU natural gas " gal. gasoline ------- -35- Table A-2 Fuel Equivalency Factors Methanol Petroleum Refinery Efficiency and Cost Raw Plant L* 88% M* H* L 9i 0% M H L 92% M H Material/Efficiency/Cost coal/50%/L** coal/50%/M** coal/50%/H** coal/60%/L coal/60%/M coal/60%/H coal/70%/L coal/70%/M coal/70%/H 4 3 2 5 4 3 6 5 4 .77 .65 .95 .73 .38 .55 .68 .11 .14 6.36 4.87 3.94 7.64 5.84 4.73 8.91 6.81 5.52 7.95 6.08 4.92 9.55 7.30 5.91 11.14 8.52 6.89 4.66 3.57 2.88 5.60 4.28 3.47 6.53 5.00 4.04 6 4 3 7 5 4 6 5 .22 .76 .85 .47 .71 .62 .71 .66 .39 7.77 5.94 4.81 9.33 7.14 5.78 10.89 8.33 6.74 4.56 3.49 2.82 5.48 4.19 3.39 6.39 4.89 3.96 6.08 4.66 3.77 7.30 5.59 4.52 8.52 6.52 5.28 7.60 5.82 4.71 9.13 6.98 5.65 10.65 8.15 6.59 nat.gas/50%/L*** nat.gas/50%/M*** nat.gas/50%/H*** nat .gas/60%/L nat.gas/60%/M nat.gas/60%/H nat.gas/70%/L nat.gas/70%/M nat.gas/70%/H * crude oil, ** coal, $/ton *** natural gas 3 2 1 3 2 1 4 2 2 $/bbl .10 .07 .55 .72 .48 .86 .34 .89 .17 , ^/million 4.14 2.78 2.07 4.96 3.31 2.48 5.79 3.86 2.90 BTU 5.17 3.45 2.59 6.20 4.14 3.10 7.24 4.83 3.62 L 30.00 31.20 2.00 3.03 2.02 1.52 3.64 2.43 1.82 4.25 2.83 2.12 Raw 4 2 2 4 3 2 5 3 2 .04 .70 .02 .85 .24 .43 .66 .77 .83 Material M 40.00 40.80 3.00 5.06 3.37 2.53 6.07 4.04 3.03 7.08 4.72 3.54 Costs 2.97 1.98 1.48 3.56 2.37 1.78 4.15 2.77 2. 08 H 50.00 50.40 4.00 3.96 2.64 1.98 4.75 3.17 2.37 5.54 3.69 2.77 4.95 3.30 2.47 5.93 3.96 2.97 6.92 4.62 3.46 ------- Table A-3 Fuel Equivalency Factors Method C for Ethanol Petroleum Refinery Efficiency Raw Plant Material/Efficiency/Cost corn/30%/L corn/30%/M corn/30%/H corn/45%/L corn/45%/M corn/45%/H corn/60%/L corn/60%/M corn/60%/H * * crude oil, $/bbl ** coal, $/ton *** corn, ^/bushel L* .44 .40 .37 .71 .65 .60 .76 .70 .66 88% M* .58 .53 .49 .95 .87 .81 1.01 .94 .88 Raw H* .73 .67 .62 1.19 1.09 1.01 1.26 1.17 1.09 Material L 30.00 31.20 3.30 L .43 .39 .36 .70 .64 .59 .74 .69 .64 Costs 90% M H .57 .71 .52 .65 .48 .60 .93 1.16 .85 1.07 .79 .99 .99 1.23 .92 1.15 .86 1.07 M 40.00 40.80 3.50 and Cost 92% L M .42 .56 .38 .51 .35 .47 .68 .91 .63 .83 .58 .77 .72 .96 .67 .90 .63 .84 H 50.00 50.40 3.70 H .70 .64 .59 1.14 1.04 .96 1.21 1.12 1.05 I CO assuming coal is used for all the process energy ------- Table A-4 FUEL EQUIVALENCY FACTORS FOR NATURAL GAS (A) Compressed, (B) Liquified Petroleum Refinery Efficiency and Cost Raw Plant L Material/Efficiency/Cost* (A) Natural gas/96%/L Natural gas/96%/M Natural gas/96%/H (B) Natural gas/86%/L Natural gas/86%/M Natural gas/86%/H 2. 1. 1. 2. 1. 1. Gasoline - Equivalent Fuel Economy natural gas crude oil, , $/MMBTU fc/bbl 88% M 98 3.97 99 2.65 49 1.99 67 3.56 78 2.37 33 1.78 miles BTUng *Raw L 2.00 30.00 H L 4.96 2 3.31 1 2.49 1 4.45 2 2.97 1 2.23 1 113 gal Material M 3.00 40.00 .91 .94 .46 .61 .74 .31 ,300 90% M H L 3.88 4.86 2.85 2.59 3.24 1.90 1.94 2.43 1.42 3.47 4.35 2.55 2.32 2.90 1.70 1.74 2.18 1.27 BTU UAU TjtjEi 92% M H 3.80 4.75 2.53 3.17 1.90 2.37 3.41 4.26 2.27 2.84 1.70 2.12 gasoline Costs H 4.00 50.00 ------- -38- References 1. Energy Policy and Conservation Act, Public Law 94-163, 1975. 2. Chrysler Corporation Loan Guarantee Act of 1979, Public Law 96-185, Jan. 7, 1980. 3. "Electric and Hybrid Vehicle Research, Development and Demonstration Program; Equivalent Petroleum-Based Fuel Economy Calculation," Final Rule, U.S. Department of Energy, 10 CFR Part 474, (Docket No. CAS-RM-80-202). 4. Energy Policy and Conservation Act, Conference Report, U.S. Senate Report No. 94-516, December 8, 1975, page 154. 5. "Electric Vehicles and the Corporate Average Fuel Economy," The Aerospace Corporation, Report ATR-80(7766)-1, May 1980. 6. Motor Vehicle Manufacturers Association National Gasoline Survey, Summer Season - October 15, 1980, sampling date - July 15, 1980. 7. "Methodology for Calculation of Diesel Fuel to Gasoline Fuel Economy Equivalence Factors," Technical support report for regulatory action, Emission Control Technology Division, OMSAPC, U.S. EPA, January 1976 (Revised May 1976). 8. Energy From Biological Processes, U. S. Congress Office of Technology Assessment, OTA-E-124, July 1980. 9. Letter, D. K. Lawrence, Amoco, to W. A. Johnson, Sobotka & Company, Inc., October 31, 1980. 10. "Comparison of Gasoline and Diesel Automobile Fuel Economy as Seen by the Consumer," B. McNutt, U.S. DOE, SAE Paper 810387, February 1981. ------- -39- 11. "Automotive Fuels - Refinery Energy and Economics," D. Lawrence, D. Plautz, B. Keller, T. Wagner, R & D Dept. Amoco Oil Co., SAE Paper 800225, February 1980. 12. Energy Information Administration Annual Report to Congress, Volume II, III, U.S. Department of Energy, DOE/EPA-0173(79)/2,3, 1979. 13. "Review of Diesel Equivalency Factors," Sobotka & Company, Inc., December 5, 1980. 14. "Methanol From Coal: Prospects and Performance as a Fuel and as a Feedstock," IGF Inc., December, 1980. 15. "Methanol as a Major Fuel," Paul W. Spaite Co., December 8, 1980. 16. "Gasohol: Does It or Doesn't It Produce Positive Net Energy?," R. Chambers, R. Herendeen, J. Joyce, P. Penner, Science, Vol. 206, November 16, 1979. 17. "Commercial Production of Ethanol for Fuel Applications" Energy from Biomass and Wastes IV, Symposium Papers, January 21-25, 1980, Sponsor: Institute of Gas Technology, May 1980. 18. "Preliminary Perspective on Methanol," Draft ECTD Report, February 1981. 19. "Net Energy Analysis of Alcohol Fuels," American Petroleum Institute Publication No. 4312, November, 1979. 20. Marks' Standard Handbook for Mechanical Engineers, "Compressors," McGraw-Hill Book Co., New York, 1951, 1978. 21. "Liquified Natural Gas," SRI International, Energy Technology Economics Program Report No. 18, February 1981. ------- |