Mark A. Delucchi

Institute of Transportation Studies

University of California

Davis, California 95616

October 1997

Acknowledgments and Disclaimer

Table of Contents

Acknowledgments and Disclaimer i

Table of Contents ii

Introduction 1

The need for this effort 1

Overview 2

Input and output 3

Input cells 3

Projections of energy use and emissions 3

Format of output 3

Emissions by greenhouse gas 4

EV emissions by region 4

CO2 emissions from biofuels 4

BTU energy use per mile 4

One-step scenario analysis and table printout 4

CO2-equivalency factors 5

Fuels 8

Composition of gasoline 8

Oxygenates in reformulated gasoline 8

CO2 from biomass-derived ETBE 9

Mixtures of reformulated gasoline and conventional gasoline 9

Mixtures of alcohols and gasoline 10

Mixtures of soy diesel and petroleum diesel 10

LPG intermediate results 10

Source of LPG 10

Heating value, carbon content, sulfur content, and ash content of coal 11

Carbon content, specific gravity, and sulfur content of crude oil 11

Composition of refinery gas 12

Composition of natural gas 12

Characteristics of soy diesel 12

Motor vehicles: energy use, fuel storage, weight, and materials 12

Fuel economy, drive cycle, and vehicle weight 12

Formula to calculate energy efficiency of AFVs 14

Electric vehicles 15

Range and fuel storage of heavy-duty vehicles 16

Soy diesel vehicles: range, fuel storage, and energy use 17

Vehicle weight 17

High-pressure hydrogen storage 17

Choice of LNG or CNG and LH2 or CH2 17

Materials in vehicles 18

Materials in electric-vehicle batteries 18

Lifetime of HDVs 18

Motor vehicles: emissions 18

Emission-factor model 18

Emission-factor parameters for CO, NMOC, and NOx emissions from light-duty gasoline vehicles 20

Emission-factor parameters for N2O emissions from LDVs 21

Emission-factor parameters for CH4 emissions from LDVs 21

Emission factors for AFVs: relative to gasoline and diesel 21

Input of heavy-duty vehicle emission factors: g/bhp-hr vs. g/mi 22

Emissions of refrigerant 22

Petroleum refining 23

Refinery energy required to produce conventional and reformulated gasoline 23

Refinery energy use: meaning of BTU/BTU measure 23

Projections of refinery energy use 23

Allocation of refinery energy to specific products 24

Sale or transfer of electricity 24

Crude used as fuel gas or petroleum coke in refineries 24

Emissions of NMOCs, CO, NOx, SO2, and PM from process areas 25

CH4 and total carbon emissions from process areas 25

N2O emissions 27

Electricity generation 27

Efficiency of electricity generation 27

National average mix of fuels used to generate electricity 28

Marginal mix of power used to recharge electric vehicles 28

High-renewables generation scenario 29

Uncontrolled emissions from utility boilers 29

Emission-reduction factor due to emission controls 29

Nuclear fuelcycle 32

Greenhouse-gas emissions at hydropower facilities 32

Production of alternative fuels 33

Feedstock and process energy use of methanol, ethanol, and SNG plants 33

Feedstock and process energy use of corn-to-ethanol plants 34

Coproducts of the corn-to-ethanol conversion process: conceptual background 37

GHG emissions displaced by the DDGS coproduct of dry-mill ethanol plants 38

The co-product displacement credit for wet-mill plants 43

Co-products of wood-to-alcohol production 44

Electricity displaced by electricity exported from wood-to-ethanol and grass-to-ethanol plants 44

Co-products of the soy-diesel production process 45

Hydrogen produced from biomass: process energy requirements 46

Hydrogen produced from water: energy efficiency of electrolysis 46

CH4 emissions from methanol plants 47

Emission factors for alcohol-fuel production 47

Emission factors for wood-waste combustion in boilers 47

Production of corn, soybeans, trees, and grasses 48

Where will the marginal corn come from? 48

Use of fertilizer for corn and soybeans 49

Use of pesticides on corn and soybeans 52

Energy inputs to corn and soybean farming 53

Collection, grinding, baling, and transport of corn residue 55

Inputs to woody-biomass production (SRIC) 55

Inputs to the production of perennial grasses 56

Energy used to manufacture agricultural chemicals 57

The lifecycle of nitrogen, phosphate, and potash fertilizers 57

Potash 58

Phosphate 61

Nitrogen 64

Energy used to manufacture pesticides 66

Summary of estimates and assumptions regarding energy in the lifecycle of agricultural chemicals 66

Miscellaneous 66

Trace gas emissions related to cultivation and the use of fertilizer 67

N2O and NOx emissions from nitrogen fertilizer 67

CO2 from soil and biomass 68

Methane emissions from soil 72

Environmental impacts of corn farming 72

Production of oil, gas, and coal 73

Projected supply and disposition of crude oil 73

Venting and flaring of associated gas 73

Emissions of CO2 removed from raw gas 74

Emission factors for gasoline and diesel industrial engines 76

Emission factors for large stationary diesel engines 76

Emissions of methane from coal mining. 76

Evaporative emissions of VOCs and CH4 from the crude oil cycle. 76

Energy used in mining 78

Documentation of miscellaneous parameter values 79

Natural gas transmission 81

Energy intensity of natural gas transmission 81

Leaks of natural gas 81

Emission factors for gas-turbine and gas-engine pipeline compressors 84

Work and energy use of gas-turbine and gas-engine compressors 84

Note on natural gas storage 85

Shipment of feedstocks, Fuels and vehicles 85

Distribution of coal, crude oil, and petroleum products: general method 85

International waterborne shipment of crude oil, and petroleum products: estimated tons-shipped/ton-produced, and average length of haul 87

Domestic waterborne shipment of crude oil and petroleum products: estimated tons-shipped/ton-produced, and average length of haul 90

Domestic waterborne shipment of coal, crude oil, and petroleum products: energy intensity 90

Pipeline shipment of crude oil and petroleum products: estimated tons-shipped/ton-produced, and average length of haul 91

Truck shipment of petroleum products: ton miles and average length of haul 91

Truck distribution of methanol, ethanol, and LPG: average length of haul 93

Train, water, truck, and pipeline transport of coal 93

Distribution of ethanol and methanol from biomass 94

Transport of corn from farm to corn-to-ethanol facility 94

Future energy consumption of rail, ship, and truck transport 95

Fuel marketing and dispensing 95

Upstream NMHC emissions from gasoline marketing 95

Gas leaks from gaseous-fuel stations 96

Electricity use at liquid bulk-storage facilities and service stations 96

CNG compression energy 97

Hydrogen compression energy 97

Emission factors for trains, engines, industrial boilers, etc. 98

Organic compounds 98

PM and SO2 emissions 98

Control of emissions from trains, ships, boilers, engines, etc. 98

Industrial boilers 99

Trains 100

Ships 100

Indirect energy use 101

Other 102

"Own-use" of fuel 102

Background 102

The original method 103

Estimation of own-use 104

Development of an equivalent, simpler method 107

Application of the new method 110

Related changes 110

Results from the revised GHG emissions model 110

Energy efficiency of vehicles. 110

Energy intensity of fuelcycles 111

Kinds of process fuel used 111

Leaks of methane and CO2 111

Electricity generation: efficiency and mix of fuels, 112

Fuelcycle emissions from the use of electricity 112

Emissions per unit of fuel delivered, by fuel-cycle stage 112

Gram-per-mile emissions by vehicle/fuel/feedstock combination, and stage of the fuelcycle. 112

Gram-per-106 BTU emissions by stage and feedstock/fuel combination. 112

Summary of major remaining uncertainties 113

Acknowledgment 114

References 115

 

TABLES

Table I. Estimates of the Total Global Warming Potential (GWP) and Economic Damage Index (EDI) of non-CO2 Greenhouse Gases 131

Table II. Composition (volume %) and properties of conventional and reformulated gasoline 134

Table III. Projections of coal quality 135

Table IV. Mile/BTU efficiency of alternative-fuel-vehicle powertrains relative to that of conventional petroleum vehicles 136

Table V. the drivetrain efficiency of EVs relative to that of gasoline ICEVs 138

Table VI. Projections of EV and battery parameters 139

Table VII. EV Batteries: present and future characteristics 140

Table VIII. Fuel storage, weight, and range of alternative-fuel-vehicles 141

Table IX. Materials in electric-vehicle batteries 142

Table X. Emissions from petroleum and alternative-fuel vehicles 144

Table XI. Mix of electric power used to recharge electric vehicles 148

Table XII. Feedstock and process energy requirements of methanol, ethanol, and SNG plants 150

Table XIII. Fertilizer use in corn and soybean farming 153

Table XIV. Inputs to energy-crop farming 155

Table XV. The energy lifecycle of agricultural chemicals 158

Table XVI. Venting and flaring of gas from coal mines 160

Table XVII. Production of natural gas and Natural gas liquids, 1982, 1987, 1992 (103 tons) 161

Table XVIII. Energy intensity of natural gas transmission, year 2015 162

Table XIX. Parameters in the estimation of emissions from the natural gas system, 1992 164

Table XX. Water and pipeline shipment of petroleum, 1994 165

Table XXI. Primary sources of data on domestic coal transportation 167

Table XXII. Data used to calculate ton-miles of shipment of petroleum products by truck, 1992 169

Table XXIII. Calculation of electricity and fuel use in SICs 517, 554, 55 (except 554) and 75, in 1987 170

Table XXIV. Energy use per unit of activity 172

Table XXV. Emission factors for natural gas and diesel-fuel use by buildings 174

Table XXVI. Emission factors for components of refinery gas, relative to factors for natural gas, in industrial boilers 175

Figure 1. The market displacement effect of byproducts of production processes 176

TABLE 2. Calculated weight and efficiency of vehicles 177

TABLE 3a. Energy intensity of fuelcycles: BTUs of process energy consumed per net BTU of fuel to end users 179

TABLE 3B. Energy consupmtion of fuelcycles: BTUs of process energy consumed per mile of travel by vehicles 181

TABLE 4a. Type of process energy used at each stage of the fuelcycle: feedstocks 183

TABLE 4b. Type of process energy used at each stage of the fuelcycle: fuels 185

TABLE 5. Venting, flaring, and leaks of CH4 and CO2 187

Table 6a. Efficiency of Electricity Generation, by Fuel Type 188

Table 6b. Source of Electricity, by Share (2015) 188

TABLE 6c. fuelcycle CO2-equivalent emissions from power plants 189

TABLE 7. CO2-equivalent emissions per unit of energy delivered to end users, by stage of the fuelcycle 191

TABLE 9. Gram-per-mile emissions by vehicle/fuel/feedstock combination, and stage of the fuelcycle 193

TABLE 10. Gram-per-106 BTU emissions of each individual gas, by stage and feedstock/fuel combination. 200

 

appendix a: energy use and emissions from the biodiesel fuel cycle

Biodiesel as a Heavy Duty Vehicle Fuel 1

Biodiesel Production 1

Byproducts from Biodiesel Production 4

Biodiesel Demonstrations, Fuel Consumption and Maintenance 4

Biodiesel Combustion and Emissions 6

References 8

Table A-1: Chemical properties of representative diesel and biodiesel fuels 10

Table A-2: Energy Inputs Into Soy and Rape Oil Esterification Process 11

Table A-3: Energy Used in Soy Methyl Ester Production Process in the U.S. 12

Table A-4: Byproducts and Energy Credits from U.S. Soydiesel Production 14

Table A-5: Emissions from Representative Diesel and Biodiesel Blendsa 15

Table A-5 (cont'd): Emissions from Representative Diesel and Biodiesel Blendsa 17

Table A-5 (cont'd): Emissions from Representative Diesel and Biodiesel Blendsa 19

Figure A-1. Energy and chemical input and output in the biodiesel fuelcycle 21

Introduction

This report documents and summarizes the results from a recently revised version of the greenhouse-gas emissions model originally documented in Emissions of Greenhouse Gases from the Use of Transportation Fuels and Electricity, ANL/ESD/TM-22, Volumes 1 and 2, Center for Transportation Research, Argonne National Laboratory, Argonne, Illinois (DeLuchi, 1991, 1993). The model calculates CO2-equivalent emissions of carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), chlorofluorocarbons (CFC-12), nitrogen oxides (NOx), carbon monoxide (CO), reactivity-weighted non-methane hydrocarbons (NMHCs), sulfur oxides (SOx, and particulate matter (PM) from most stages of the lifecycle of fuels and vehicles, for a wide range of vehicle and fuel types.

I have revised the model considerably since the publication of the original ANL report in 1993. These revisions, and the results therefrom, are documented in two reports: this one, and an accompanying report by Delucchi and Lipman (1996).

A). This report summarizes all changes made to the model: changes to input and output; changes to data assumptions and model structure; emission sources added; fuelcycles added; and much more. It summarizes but does not detail changes in emission factors for gases other than CO2; those details are given in Delucchi and Lipman (1996). It presents tables of results for CO2-equivalency factors, the efficiency of and emissions from power plants and motor vehicles, energy intensity by stage, fuel use by stage, CO2-equivalent emissions by stage, and emissions by individual greenhouse gas and stage of the fuelcycle.

B). Delucchi and Lipman (1996) contains documentation of most of the emission factors for greenhouse gases other than CO2, and a re-analysis of the CO2-equivalency factors. It does not discuss the data used to estimate energy intensity.

The need for this effort

Many scientists now believe that an increase in the concentration of greenhouse gases will increase the mean global temperature of the earth. In 1995, an international team of scientists, working as the Intergovernmental Panel on Climate Change (IPCC), concluded that "the balance of evidence suggests that there is a discernible human influence on global climate" (IPCC, 1996a, p. 5). In the long run, this global climate change might affect agriculture, coastal developments, urban infrastructure, human health, and other aspects of life on earth (IPCC, 1996b).

Highway vehicles, of course, are a major source of the greenhouse gases thought to be responsible for global warming. Over the past five years, policy makers have become increasingly interested in developing alternative fuels and vehicle technologies to reduce emissions of greenhouse gases from the transportation sector. For example, the "Climate Change Action Plan" proposed by President Clinton and Vice President Gore in 1993 calls on the "National Economic Council, the Office on Environmental Policy, and the Office of Science and Technology Policy to co-chair a process...to develop measures to significantly reduce greenhouse gas emissions from personal motor vehicles, including cars and light trucks" (Clinton and Gore, 1993, p. 30). The Energy Information Administration (Alternatives to Traditional Transportation Fuels 1994, Volume 2: Emissions of Greenhouse Gases, 1996) of the U. S. Department of Energy has published an analysis of emissions of greenhouse gases from alternative fuels, based mainly on an earlier version of the revised model described here.

Given the growing consensus that greenhouse gases will cause global warming, and the growing interest in alternative fuels and vehicle technologies, it is useful to keep the greenhouse-gas emissions model, which has been widely used and cited, up to date. Hence this first major revision of the model, documented in the two reports outlined above.

Overview

Because this report documents changes made to the model presented originally in DeLuchi (1991, 1993), it references all changes to the relevant tables and sections of the original report. For each change described in this report, the relevant table or appendix of the original ANL report (DeLuchi, 1991, 1993) is indicated in parentheses. Tables that are new to this report are numbered in Roman numerals. For example, in the statement "The CO2 equivalency factors have been revised (Table 8)," the parenthetical reference is to Table 8 of Volume 1 of Emissions of Greenhouse Gases from the Use of Transportation Fuels and Electricity (DeLuchi, 1991). In the statement "The new estimates of CO2-equivalency factors are summarized in Table I below," Table I is in this report. So that readers may compare the present input data and final results with those of the original model, the numbering of the major tables of results in this report follows that in Volume 1 of the original ANL report (DeLuchi, 1991).

The structure and input data of the model have been completely overhauled. For example, the inputs and model structure for vehicle emissions, vehicle fuel economy, feedstock recovery, transportation of feedstocks, fuel production, and distribution of fuels have been redone to be more detailed, flexible, consistent, and realistic. Many data on energy use, fuel characteristics, and emissions have been projected for every year from 1995 to 2015.

The output has been cleaned up and presented in considerably more detail. Estimates of g/106 BTU emissions are presented for each GHG (without the GWP weighting), for each stage of all of the fuelcycles. Fuelcycle GHG emissions for electric vehicles are calculated for the U.S. and each of six regions. A new macro runs the model for up to 20 different years and prints all of the main results in publication-ready tables.

Several new components have been added, most notably:

• data projections through the year 2015

• a more detailed calculation of emissions from the use of oxygenates;

• an estimate of emissions from energy use by service stations and marketing facilities;

• perennial grasses as a feedstock for the production of ethanol;

• a much more detailed treatment emissions from bio-fuel cycles

• a completely new fuelcycle: diesel fuel derived from soybean oil;

• PM and SO2 as greenhouse gases, and individual pollutants; and

• a new treatment of "own use" of fuel

And throughout, input assumptions regarding energy use and emissions have been updated as new data (e.g., from EPA’s AP-42, fifth edition) have become available.

Overall, the present model is more powerful, and quite a bit easier to use, than the original model. As one can see by comparing the new results presented here with the results in Volume (DeLuchi, 1991), the overall affect of all these changes documented in this update is make alternative fuels more attractive.

Input cells

In the spreadsheet, important input cells and tables now are emphasized in block letters with shadows.

Projections of energy use and emissions

In the original version of the model, the input data were for a single year -- in the base case, the year 2000. To analyze another year, the user had to estimate and input a separate set of data, for the year of interest. This made it difficult to do multi-year analyses.

As part of a major revision to the model, I have added projections of energy use and emissions, or changes in energy use and emissions, for every year from 1995 to 2015. The user now specifies any year between 1995 and 2015, and the model looks up or calculates energy-use intensities or emission factors for the specified year and uses them in the active calculations. The actual projections are discussed below, in the pertinent subject areas.

Format of output

The column headings in the main summary tables (similar to Table 9 in Volume 1 of the original report) and in other tables throughout the model now are formatted to automatically show the following: the fuel specification (methanol %, ethanol %, reformulated gasoline %, oxygenate %, propane %, butane %, low-sulfur diesel, LNG or CNG, or LH2 or CH2), the characteristics of the feedstock (oil, coal, natural gas, natural-gas liquids, refinery byproducts, corn, or wood), and the mix of the process energy used for boiler fuel or power generation (coal, natural gas, fuel oil, biomass, nuclear power, or solar power). In some major headings, the year of the analysis is shown also.

The user need only specify the fuel and feedstock characteristics in one place, and all of the main tables will change accordingly. For example, if you specify that an ethanol-fuel vehicle use 100% ethanol made from corn, and that the ethanol plant use coal for process heat, the column headings automatically will read: "Ethanol, E100 corn, C100/NG0/B0" . If you change the fuel to 85% ethanol/15% gasoline, and change the process fuel to 50% natural gas and 50% corn stover, the headings will automatically change to "Ethanol, E85 corn, C0/NG50/B50," where the "B50" part means "50% biomass". The same happens for the other fuel/feedstock combinations.

The fuelcycle stage formerly called "Compression or liquefaction" now is called "Fuel dispensing," and includes emissions from the use of energy to pump liquid fuels such as gasoline. (This pumping energy is new to the model; see the discussion below.) The stage formerly called "Fuel distribution" now is called "Fuel distribution and storage," and includes emissions from the use of energy at bulk fuel-storage facilities.

The breakdown of energy use by fuel type, by stage and fuelcycle, formerly displayed as a single table (Table 4), has been split into three tables: one for feedstock processes (agricultural chemicals, feedstock recovery, and feedstock transport), one for fuel processes (fuel production, fuel distribution and storage, and fuel dispensing), and a separate breakout of fuel distribution and storage for individual petroleum fuels.

Emissions by greenhouse gas

I added a macro to display grams of each gas emitted (without the GWP weights) per 106-BTU of energy delivered to end users,. (The macro is called "Separate_gases".)

EV emissions by region

Fuelcycle emissions for electric vehicles are calculated for the marginal mix of electricity in the entire U. S. and in each of six regions: Northeast, East Central, South East, South Central, West Central, and West. A macro command ("EVs_by_region") runs the regional results.

CO2 emissions from biofuels

Instead of displaying only the net zero CO2 emissions from biofuel vehicles (total CO2 emissions from fuel combustion less the same amount captured photosynthetically in the first place by the energy crops grown to make the biofuel), the model now displays the total actual CO2 emissions, the photosynthesis removal credit, and the net result (revised Table B.2).

BTU energy use per mile

A new table shows BTUs of process and end-use energy used per mile of travel.

One-step scenario analysis and table printout

I have added a macro, called "Print_results," that runs the model for up to 20 different target years (any year from 1995 to 2015), and then prints the results, for each target year, in ready-to-publish tables. The user identifies which tables of results she wants printed, and then, for each results table (g/mi, g/106-BTU, etc.), which target years she wants to run. The macro runs the model for the first target year and table of results, sends the table to the printer, runs the next target year, sends the table to the printer, and so on, for each target year and table of results.

The macro will run and print any of the following tables of results: fuelcycle CO2-equivalent emissions from vehicles (g/mi; Table 9 of the original report, but with more fuelcycles); fuelcycle CO2-equivalent emissions excluding end use (g/106-BTU; Table 7 of the original report); the energy intensity of fuelcycles (BTU-input/BTU-output; Table 3 of the original report); the types of process fuel used in the fuelcycles (Table 4 of the original report); fuelcycle CO2-equivalent emissions from electricity generation (g/kWh; similar to Table D.4 of the original report); emissions of individual greenhouse gases (g/106-BTU; similar to Table 10 of the original report, but with more detail, and without the CEFs applied); and input data and results regarding vehicle weight and energy use (similar to Table 2 of the original report, but with more information). The target year is printed in the title of each table.

This macro calls other macros as necessary. For example, if the user wishes to print the g/mi results for EVs, by region, for different target years, the Print_results macro will call the macro EVs_by_region, described above, for each target year. If the user wishes to print the g/106-BTU results for individual greenhouse-gases, for different target years, the Print_results macro calls the Separate_gases macro described above.

CO2-equivalency factors

In order to estimate the combined impact of emissions of all of the different greenhouse gases, mass emissions of the non-CO2 greenhouse gases -- CH4, CO, N2O, NMHCs, NOx, CFC-12, and HFC-134a -- are converted into the mass amount of CO2 emissions that would cause the same climatic or economic impact. The first of these conversion factors (which I will call CO2-equivalency factors, or CEFs), developed around 1990, equated emissions solely on the basis of global warming, and hence were called "global warming potential" factors, or GWPs. More recently, researchers have estimated equivalency factors that equate emissions on the basis of the economic impacts of the warming. The most recent estimates of GWPs and EDIs are analyzed by Delucchi and Lipman (1996) and summarized in Table I here.

Because the EDIs incorporate the present value of the economic damages of future global warming, and thereby express the impacts of emissions of different gases in a common currency -- namely, the present dollar value -- whereas the GWPs reflect only the future temperature change, the EDIs in principle are the preferred equivalency factor. However, the EDIs developed thus far do have some shortcomings: those of Reilly (1993) are based on now-outdated estimates of climate effects, and those of Hammit et al. (1996) do not include the indirect effect of CH4 or halocarbons on H2O or O3, or the effects of CO2 fertilization. As a result, one still must refer to the GWPs in order to estimate appropriate CEFs. My own assumptions or estimates of CEFs are explained in the notes to Table I, and in Delucchi and Lipman (1996).

Tthe equivalency factor for NOx has been reduced substantially, the factors for NMHCs and CO have decreased slightly, and the factor for N2O has increased. The changes to NOx and N2O equivalency factors have a major impact on fuelcycle CO2-equivalent emissions. In fact, this set of changes results in a greater change in fuelcycle CO2-equivalent emissions than does any other change or set of changes described in this report.

The CEF for NO2 is not input directly, but rather is calculated from input data on the indirect GWP due to ozone production, the fraction of NO2 that is deposited onto soils, and the fraction of deposited N that is re-emitted as N2O.

The ozone reactivities are relative to that for conventional gasoline, and are estimated on the basis of data in Delucchi (Emissions of Criteria Pollutants, Toxic Air Pollutants, and Greenhouse Gases, from the Use of Alternative Transportation Modes and Fuels, 1996) and Derwent et al. (1996). This method estimates the direct CO2 contribution of NMHC emissions exactly, and accounts reasonably well for the ozone-forming potential of different NMHC emissions. It still suffers, however, from the uncertainty in the indirect GWP/CEF.