Internal combustion engines (ICEs) operating on petroleum fuels have powered almost all light-duty vehicles (LDVs) for a century. The dominance of ICEs over steam and batteries has been due to their low cost, high power output, readily available fuel, and ability to operate for long distances in a wide range of temperatures and environmental conditions. Although ICEs can run on many fuels, gasoline and diesel have remained the fuels of choice because of their low cost and high energy density, allowing hundreds of miles of driving before refueling. Crude oil has remained the feedstock of choice for these fuels because production has kept pace with demand and world reserves have actually been expanded as a result of ongoing technological progress. The co-evolution and co-optimization of ICE and petroleum-based fuel technology, infrastructure, and markets have proven resilient to challenges from market forces such as oil price spikes in a geopolitically complex world oil market as well as environmental policies such as tailpipe pollution reduction requirements.
For nearly 40 years, energy security concerns have motivated efforts to reduce the use of petroleum-based fuels. LDVs consume about half the petroleum used in the United States, and about half is imported, tying Americans to a world oil market that is vulnerable to supply disruptions and price spikes and contributing about $300 billion to the nation’s trade deficit (EIA, 2011).
More recently, concerns have been growing over emissions of carbon dioxide (CO2), the most important of the greenhouse gases (GHGs) that threaten to cause serious problems associated with global climate change.1 Petroleum use is the largest source of GHG emissions in the United States. Because LDVs account for the single largest share of U.S. petroleum demand and directly account for 17 percent of total U.S. GHG emissions (EPA, 2012), they have become the subject of policies for mitigating climate change.
For these reasons, U.S. policy makers seek to both improve the fuel efficiency of LDVs and promote the development and adoption of alternative fuels and vehicles (AFVs). Here “alternative fuels” refers to non-petroleum-based fuels, including plant-based fuels that are otherwise essentially identical to gasoline or diesel fuel, and to powertrains much more efficient than today’s or capable of using alternative fuels, including non-liquid energy carriers such as natural gas, hydrogen, and electricity. Numerous studies have addressed these issues over the years, reflecting the interest in these goals. Substantial but uneven progress has been made on LDV efficiency, and a small but significant penetration of hybrid electric vehicles in the marketplace has contributed to this goal. Otherwise little progress has been made on AFVs in the marketplace beyond the quantities of ethanol still used almost exclusively in gasoline blends.
Since its beginnings over 100 years ago, the automotive sector has succeeded through a combination of private market forces and public policies. The energy use and GHG emissions challenges with which we now are grappling are the unintended and largely unforeseen by-products of that success.
This report is the result of a study by a committee appointed to evaluate and compare various approaches to greatly reducing the use of oil in the light-duty fleet and GHG emissions from the fleet. As specified in the statement of task (Appendix A), the Committee on Transitions to Alternative Vehicles and Fuels was charged with assessing the status of and prospects for technologies for LDVs and their fuels, and with estimating how the nation could meet one or both of two goals:
1As used in this report, GHG means the total of all greenhouse gases, as converted to a common base of global warming potential, i.e., CO2 equivalent (CO2e). For tail pipe emissions, CO2 is used.
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1 Introduction Internal combustion engines (ICEs) operating on petro- of total U.S. GHG emissions (EPA, 2012), they have become leum fuels have powered almost all light-duty vehicles the subject of policies for mitigating climate change. (LDVs) for a century. The dominance of ICEs over steam For these reasons, U.S. policy makers seek to both and batteries has been due to their low cost, high power improve the fuel efficiency of LDVs and promote the output, readily available fuel, and ability to operate for long development and adoption of alternative fuels and vehicles distances in a wide range of temperatures and environmental (AFVs). Here “alternative fuels” refers to non-petroleum- conditions. Although ICEs can run on many fuels, gasoline based fuels, including plant-based fuels that are otherwise and diesel have remained the fuels of choice because of essentially identical to gasoline or diesel fuel, and to pow- their low cost and high energy density, allowing hundreds ertrains much more efficient than today’s or capable of using of miles of driving before refueling. Crude oil has remained alternative fuels, including non-liquid energy carriers such as the feedstock of choice for these fuels because production natural gas, hydrogen, and electricity. Numerous studies have has kept pace with demand and world reserves have actually addressed these issues over the years, reflecting the interest in been expanded as a result of ongoing technological progress. these goals. Substantial but uneven progress has been made The co-evolution and co-optimization of ICE and petroleum- on LDV efficiency, and a small but significant penetration of based fuel technology, infrastructure, and markets have hybrid electric vehicles in the marketplace has contributed to proven resilient to challenges from market forces such as this goal. Otherwise little progress has been made on AFVs oil price spikes in a geopolitically complex world oil market in the marketplace beyond the quantities of ethanol still used as well as environmental policies such as tailpipe pollution almost exclusively in gasoline blends. reduction requirements. Since its beginnings over 100 years ago, the automo- For nearly 40 years, energy security concerns have moti- tive sector has succeeded through a combination of private vated efforts to reduce the use of petroleum-based fuels. market forces and public policies. The energy use and GHG LDVs consume about half the petroleum used in the United emissions challenges with which we now are grappling are States, and about half is imported, tying Americans to a the unintended and largely unforeseen by-products of that world oil market that is vulnerable to supply disruptions success. and price spikes and contributing about $300 billion to the This report is the result of a study by a committee nation’s trade deficit (EIA, 2011). appointed to evaluate and compare various approaches to More recently, concerns have been growing over emis- greatly reducing the use of oil in the light-duty fleet and GHG sions of carbon dioxide (CO2), the most important of the emissions from the fleet. As specified in the statement of task greenhouse gases (GHGs) that threaten to cause serious (Appendix A), the Committee on Transitions to Alternative problems associated with global climate change.1 Petroleum Vehicles and Fuels was charged with assessing the status use is the largest source of GHG emissions in the United of and prospects for technologies for LDVs and their fuels, States. Because LDVs account for the single largest share of and with estimating how the nation could meet one or both U.S. petroleum demand and directly account for 17 percent of two goals: 1. Reduce LDV use of petroleum-based fuels by 50 percent by 2030 and 80 percent by 2050. 1 As used in this report, GHG means the total of all greenhouse gases, as 2. Reduce LDV emissions of GHGs by 80 percent by converted to a common base of global warming potential, i.e., CO2 equiva- lent (CO2e). For tail pipe emissions, CO2 is used. 2050 relative to 2005. 11
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12 TRANSITIONS TO ALTERNATIVE VEHICLES AND FUELS The 2050 petroleum reduction goal is easier to meet than optimistic. Midrange goals for cost and performance are the 2050 GHG goal because more options can be employed. ambitious but plausible in the committee’s opinion. Meeting In fact, reducing GHGs by 80 percent is likely to require this level will require successful research and development reducing petroleum use by at least 80 percent. Petroleum and no insurmountable barriers, such as reliance on critical use by the light duty fleet was 125 billion gallons gasoline materials that may not be available in sufficient quantities. in 2005 (EIA, 2011), so the targets are 62.5 billion gallons The more optimistic goals are stretch goals: possible without in 2030 and 25 billion in 2050. fundamental technology breakthroughs, but requiring greater GHG emissions from the LDV fleet in 2005 were 1,514 R&D and vehicle design success. All the vehicle and fuel million metric tons of CO2 equivalent (MMTCO2e) on a cost and performance levels are based on what is achievable well-to-wheels basis (EPA, 2012). An 80 percent reduction for the technology. from that level means that whatever fleet is on the road in Other factors also will be very important in determining 2050 can be responsible for only 303 MMTCO2e/year. That what is actually achieved. In particular, government policy is the budget within which the fleet must operate to meet will be necessary to help some new and initially costly the goal. technologies into the market, consumer attitudes will be Achieving an 80 percent reduction in LDV-related emis- critical in determining what technologies are successful, sions is only possible with a very high degree of net GHG and of course, the price and availability of gasoline will be reduction in whatever energy supply sectors are used to important in determining the competitiveness of alternative provide fuel for the vehicles. In short, it is not possible to vehicles and fuels. greatly “de-carbonize” LDVs without greatly de-carbonizing the major energy supply sectors of the economy. 1.1 APPROACH AND CONTENT The committee determined potential costs and perfor- mance levels for the vehicle and fuel options. Because of the To analyze all these issues, the committee constructed great uncertainty in estimating vehicle cost and performance and analyzed various scenarios, combining options under the in 2050, the committee considered two levels, midrange and midrange and optimistic cost and performance levels to see BOX 1.1 Analytical Techniques Used in This Report The committee relied on four models to help form its estimates of future vehicle characteristics, their penetration into the market, and the impact on petroleum consumption and GHG emissions. Chapter 2 and Appendix F describe two of the models. One is an ICEV model developed by a consultant that projects vehicle efficiency out to 2050 by focusing on reduction of energy losses, rather than the usual technique of adding efficiency technologies until the desired level is reached. The committee’s approach avoids the highly uncertain predictions of which technologies will be employed several decades from now and ensures that efficiency projections are physically achievable and that synergies between technologies are appropriately ac- counted for. The second is a spreadsheet model of technology costs developed by the committee, which focused on applying consistent assumptions across all of the different powertrain types. The analytical approach for both models is fully documented and the data are available in Appendix F. The methodology and results for both of these models were intensively reviewed by the committee, the committee staff, another consultant, and experts from FEV, Inc., an engineering services company. Reviewers of this report were also selected for their ability to understand this approach, which they endorsed. The VISION and LAVE-Trans models are described in Chapter 5 and Appendix H. VISION is a standard model for analyzing transportation scenarios for fuel use and emissions. It is freely available through the U.S. Department of Energy. The committee modified it for consistency with the committee’s assumptions such as on vehicle efficiencies and usage and fuel availability. The committee carefully monitored the modifications and reviewed the results, which are consistent with other analyses. LAVE-Trans is a new model developed by a committee member for an analysis of California’s energy future and expanded to the entire nation by the committee. It is unique among models in that it explicitly addresses market responses to factors such as vehicle cost and range, aversion to new technology, and fuel availability. It analyzes the effectiveness of policies in light of these market responses. The committee and staff spent considerable time reviewing LAVE-Trans and its results. In addition to presentations and discussions at committee meetings, one committee member and the study director spent a day going over the model with the developer and his associates. Another committee member examined intermediate calculations as well as model outputs. The results were also compared to VISION results for identical inputs and assumptions. These examinations led to recalibra- tions and changes in model assumptions. Reviewers of this report were also selected for their ability to understand the model, and they confirmed its validity.
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INTRODUCTION 13 how the petroleum and GHG reduction goals could be met. Chapter 6 discusses policies that could enable the vari- It also explored how consumers might react to new technolo- ous options and encourage their penetration into the market gies. Then the committee compared the technological and as needed to implement the scenarios. Finally, Chapter 7 economic feasibility of meeting the goals using the available discusses the committee’s suggested policy options that are options, the environmental impacts of implementing them, drawn from Chapter 6. Several current policies are encour- and changes in behavior that might be required of drivers aging actions that will reduce GHG emissions and petro- to accommodate new technologies. Finally, the committee leum use. The Corporate Average Fleet Economy (CAFE) examined the policies that might be necessary to implement standards require vehicle manufacturers to sell efficient the scenarios. vehicles. The Renewable Fuel Standards mandate the use of Vehicle options are explored in Chapter 2 and fuels in biofuels. Box 1.2 briefly describes these policies. In addition, Chapter 3. Chapter 4 discusses factors that will affect con- tax credits for battery vehicles encourage consumers to buy sumer choices in considering which vehicles to purchase, them. Fuel taxes, carbon reduction measures such as carbon and Chapter 5 describes how the scenario modeling was done taxes, and other standards and subsidies also could be used. and the results. Box 1.1 briefly describes the models used in State and local policies may also be important, particularly Chapters 2 and 5 and how they were validated. in the absence of activist federal policies, but the focus of BOX 1.2 U.S. Policies Directly Affecting Fuel Consumption U.S. Corporate Average Fuel Economy (CAFE) Standards From the mid-1970s through 2010, the United States had one set of standards that applied to passenger cars and another set that applied to light-duty trucks. These standards were administered by the National Highway Traffic Safety Administration (NHTSA) of the U.S. Department of Trans- portation, following requirements in legislation passed by the U.S. Congress in 1975. They first became effective in the 1978 model year. The standard for passenger cars that year was 18.0 miles per gallon (mpg). The standard increased to 27.5 mpg for the 1985 model year and varied between that level and 26.0 mpg from model year 1986 through model year 1989. In model year 1990 it was raised again to 27.5 mpg and remained at that level through model year 2010. The first combined light truck standard applied to model year 1985 vehicles and was set at 19.5 mpg. The light truck standard ranged between 20.0 and 20.7 mpg between model years 1986 and 1996, remained at 20.7 mpg for model years 1996 through 2004, and increased to 23.5 mpg by model year 2010. More recently, the federal government implemented two new sets of standards. In 2010, complementary standards were set by the Environmental Protection Agency (EPA) based on greenhouse gas (GHG) emissions and by NHTSA based on fuel economy. NHTSA’s CAFE standard for 2016 was set at 34.1 mpg for cars and light trucks. In 2012, new standards were set by EPA and NHTSA through 2025, although the NHTSA standards for 2022-2025 are proposed and not yet final, pending a midterm review. NHTSA’s CAFE standard for 2025 is 48.7-49.7 mpg. If flexibilities for paying fines instead of complying, flexible fuel vehicle (FFV) credits, electric vehicle credits, and carryforward/carryback provisions are considered, NHTSA estimated that the CAFE level would be 46.2-47.4 mpg. This does not consider off-cycle credits, which could further reduce the test cycle results by up to 2-3 mpg. Thus, for comparison purposes, the committee used 46 mpg as the tailpipe mpg levels comparable to the committee’s technology analyses in Figure 2.1. Also note that on-road fuel economy will be significantly lower—the committee used a discount factor of 17 percent in assessing in-use benefits in Chapter 5. The standards are discussed in more detail in Chapter 5. In particular, see Box 5.1. Renewable Fuel Standard The federal Renewable Fuel Standard (RFS) was created under the Energy Policy Act of 2005 because Congress recognized “the need for a diversi- fied portfolio of substantially increased quantities of . . . transportation fuels” to enhance energy independence (P.L. 109-58). The RFS was amended by the Energy Independence and Security Act (EISA) of 2007 which created what is referred to as RFS2. RFS2 mandates volumes of four categories of renewable fuels to be consumed in U.S. transportation from 2008 to 2022. The four categories are: · Conventional biofuels—15 billion gallons/year of ethanol derived from corn grain or other biofuels. · Biomass-based diesel—currently 1 billion gallons/year are required. · Advanced biofuels from cellulose or certain other feedstocks that can achieve a life-cycle GHG reduction of at least 50 percent. · Cellulosic biofuels, which are renewable fuels derived from any cellulose, hemicellulose, or lignin from renewable biomass and that can achieve a life-cycle GHG reduction threshold of at least 60 percent. In general, cellulosic biofuels also qualify as renewable fuels and advanced biofuels.
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14 TRANSITIONS TO ALTERNATIVE VEHICLES AND FUELS this report is on actions the federal government can take. Although the committee is generally skeptical of the value Chapters 6 and 7 estimate the relative effectiveness of U.S. of the government picking winners and losers, the goal of policies in achieving the goals of this study. drastically reducing oil use inherently entails a premise of The vehicle and fuel options discussed in this report gen- picking a loser (oil) and developing (and perhaps promoting) erally are more expensive and/or less convenient for consum- winners among a set of vehicles and fuel resources. ers than those that are available now. The societal benefits In turn, implementation of such policies is likely to they provide (in particular, lower oil consumption and GHG depend on a strong national imperative to reduce oil use and emissions) will not, by themselves, be sufficient to ensure GHG emissions. The committee has not studied such an rapid penetration of the new technologies into the market. imperative but notes that, given the length of time needed to Therefore strong and effective policies will be necessary to make major changes in the nation’s light-duty vehicle fleet, meet the goals of this study. By “strong public policies,” the additional policies will be needed soon to meet the goals. committee means options such as steadily increasing fuel standards beyond those scheduled for 2025, measures to 1.2 REFERENCES substantially limit the net GHG emissions associated with the production and consumption of LDV fuels, and large- EIA (Energy Information Administration). 2011. Annual Energy Review 2010. Washington, D.C.: U.S. Department of Energy. scale support for electric vehicles or fuel cell vehicles to help EPA (Environmental Protection Agency). 2012. Inventory of U.S. Green- them overcome their high initial cost and other consumer house Gas Emissions and Sinks:1990-2010. Available at http://www. concerns. It also may be necessary to have policies that epa.gov/climatechange/Downloads/ghgemissions/US-GHG-Inventory- ensure that the fuels required by alternative powertrains are 2012-Main-Text.pdf. readily available.