2

Alternative Vehicle Technologies:
Status, Potential, and Barriers

2.1 INTRODUCTION AND OVERALL FRAMEWORK FOR ANALYSES

Virtually all light-duty vehicles on U.S. roads today have internal combustion engines (ICEs) that operate on gasoline (generally mixed with about 10 percent ethanol produced from corn) or diesel fuel. To achieve very large reductions in gasoline use and greenhouse gas emissions from the light-duty fleet, vehicles in 2050 must be far more efficient than now, and/or operate on fuels that are, on net, not based on petroleum and are much less carbon-intensive. Such fuels include some biofuels, electricity, and hydrogen. This chapter describes the vehicle technologies that could contribute to those reductions and estimates how their costs and performance may evolve over coming decades. Chapter 3 considers the production and distribution of fuels and their emissions.

Improving the efficiency of conventional vehicles, including hybrid electric vehicles (HEVs), is discussed first.1 It is, up to a point, the most economical and easiest-to-implement approach to saving fuel and reducing emissions. It includes reductions of the loads the engine must overcome, specifically vehicle weight, aerodynamic resistance, rolling resistance, and accessories, plus improvements to the ICE powertrain and HEV electric systems However, if improved efficiency was the only way to meet the goals, then, for the expected vehicle miles traveled (VMT) in 2050, the average on-road fleet fuel economy would have to exceed 180 mpg.2 Since that is extremely unlikely, at least with currently identifiable technologies, additional options will be needed. Options considered by the committee include biofuels (discussed in Chapter 3), plug-in hybrid electric vehicles (PHEVs), battery-electric vehicles (BEVs [PHEVs and BEVs are collectively referred to as plug-in vehicles, PEVs]), fuel cell electric vehicles (FCEVs), and ICE vehicles (ICEVs) using compressed natural gas (CNGVs).

ICEVs and PHEVs will require little or no modification to operate on “drop-in” biofuels or synthetic gasoline derived from natural gas or coal. Vehicles that are powered by electricity or hydrogen are very different from current vehicles as described later in this chapter. CNGVs are also discussed, as they require a much larger fuel tank and other modifications. Upstream impacts of producing and providing electricity, hydrogen, and CNG are discussed in Chapter 3.

All these alternative vehicle options currently are more expensive than conventional ICEVs. The rate at which research and development (R&D) improves the performance and reduces the cost of new technologies is highly uncertain. To address this uncertainty, the analysis in this chapter considers two technology success pathways. The midrange case is the committee’s best assessment of potential cost and performance should all technologies be pursued vigorously. The committee also developed a stretch case with more optimistic, but still feasible, assumptions about advances in technology and low-cost manufacturing. Details of the technology assessments are in Appendix F.

The committee’s estimates are not based on detailed evaluations of all the specific technologies that might be used by 2050. It is impossible to know exactly which technologies will be used that far in the future, especially since major shifts from current technology will be necessary to meet this study’s goals for reduced light-duty vehicle (LDV) petroleum

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1All fuel economy (mpg) and fuel consumption numbers discussed in Chapter 2 are based on unadjusted city and highway test results or simulations, and do not include in-use efficiency adjustments.

2To meet the goal of 303 million metric tons of carbon dioxide equivalent (MMTCO2e), 80 percent reduction from the 1514 light duty fleet emissions in 2005, with gasoline responsible for 10.85 kilograms CO2e/gallon (8.92 from the tail pipe, the rest from refining and other upstream activities), at most only 28 billion gallons/year could be used (vs. 125 billion now). VMT in 2050 is expected to be about 5 trillion miles (see Chapter 5). Therefore, if the goal were to be met only with efficiency and no advanced vehicle or fuel technology, average economy would have to be 180 mpg. For this case only, the 80 percent oil reduction goal (28 billion gallons) is identical to the GHG goal.



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2 Alternative Vehicle Technologies: Status, Potential, and Barriers 2.1  INTRODUCTION AND OVERALL FRAMEWORK currently identifiable technologies, additional options will FOR ANALYSES be needed. Options considered by the committee include biofuels (discussed in Chapter 3), plug-in hybrid electric Virtually all light-duty vehicles on U.S. roads today have vehicles (PHEVs), battery-electric vehicles (BEVs [PHEVs internal combustion engines (ICEs) that operate on gasoline and BEVs are collectively referred to as plug-in vehicles, (generally mixed with about 10 percent ethanol produced PEVs]), fuel cell electric vehicles (FCEVs), and ICE vehicles from corn) or diesel fuel. To achieve very large reductions (ICEVs) using compressed natural gas (CNGVs). in gasoline use and greenhouse gas emissions from the light- ICEVs and PHEVs will require little or no modification to duty fleet, vehicles in 2050 must be far more efficient than operate on “drop-in” biofuels or synthetic gasoline derived now, and/or operate on fuels that are, on net, not based on from natural gas or coal. Vehicles that are powered by elec- petroleum and are much less carbon-intensive. Such fuels tricity or hydrogen are very different from current vehicles as include some biofuels, electricity, and hydrogen. This chap- described later in this chapter. CNGVs are also discussed, as ter describes the vehicle technologies that could contribute they require a much larger fuel tank and other modifications. to those reductions and estimates how their costs and perfor- Upstream impacts of producing and providing electricity, mance may evolve over coming decades. Chapter 3 considers hydrogen, and CNG are discussed in Chapter 3. the production and distribution of fuels and their emissions. All these alternative vehicle options currently are more Improving the efficiency of conventional vehicles, includ- expensive than conventional ICEVs. The rate at which ing hybrid electric vehicles (HEVs), is discussed first.1 It is, research and development (R&D) improves the performance up to a point, the most economical and easiest-to-implement and reduces the cost of new technologies is highly uncer- approach to saving fuel and reducing emissions. It includes tain. To address this uncertainty, the analysis in this chapter reductions of the loads the engine must overcome, spe- considers two technology success pathways. The midrange cifically vehicle weight, aerodynamic resistance, rolling case is the committee’s best assessment of potential cost and resistance, and accessories, plus improvements to the ICE performance should all technologies be pursued vigorously. powertrain and HEV electric systems However, if improved The committee also developed a stretch case with more efficiency was the only way to meet the goals, then, for optimistic, but still feasible, assumptions about advances the expected vehicle miles traveled (VMT) in 2050, the in technology and low-cost manufacturing. Details of the average on-road fleet fuel economy would have to exceed technology assessments are in Appendix F. 180 mpg.2 Since that is extremely unlikely, at least with The committee’s estimates are not based on detailed evaluations of all the specific technologies that might be used 1  All fuel economy (mpg) and fuel consumption numbers discussed in by 2050. It is impossible to know exactly which technolo- Chapter 2 are based on unadjusted city and highway test results or simula- tions, and do not include in-use efficiency adjustments. gies will be used that far in the future, especially since major 2  To meet the goal of 303 million metric tons of carbon dioxide equivalent shifts from current technology will be necessary to meet this (MMTCO2e), 80 percent reduction from the 1514 light duty fleet emissions study’s goals for reduced light-duty vehicle (LDV) petroleum in 2005, with gasoline responsible for 10.85 kilograms CO2e/gallon (8.92 from the tail pipe, the rest from refining and other upstream activities), at most only 28 billion gallons/year could be used (vs. 125 billion now). VMT in 2050 is expected to be about 5 trillion miles (see Chapter 5). Therefore, if the goal were to be met only with efficiency and no advanced vehicle case only, the 80 percent oil reduction goal (28 billion gallons) is identical or fuel technology, average economy would have to be 180 mpg. For this to the GHG goal. 15

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16 TRANSITIONS TO ALTERNATIVE VEHICLES AND FUELS use and GHG emissions.3 The optimistic and midrange slowed down to ensure that the estimates stayed well short estimates reflect the committee’s appraisal of the overall of the limits. development challenges facing the general pathways, and the On the other hand, learning occurs primarily because promise of the various technologies that might be employed manufacturers are very good at coming up with better and to meet the challenges. These estimates do not consider more efficient incremental improvements. For example, issues of market acceptance, which are addressed in Chapters 10 years ago technology that uses turbochargers to boost 4 and 5, and are not based on specific policies to encourage exhaust gas recirculation (EGR) was virtually unknown for market acceptance. Both estimates assume that policies are gasoline engines. This new development, enabled by sophis- adopted that are sufficiently effective to overcome consumer ticated computer simulations and design, has the potential and infrastructure barriers to adoption. to improve overall ICEV efficiency by about 5 percent. The committee reviewed a wide range of studies on Certainly some of the currently known technologies will not technology potential and cost but was not able to find a pan out as planned, but it is equally certain that there will study based on up-to-date technology assumptions and a be incremental improvements beyond what we can predict consistent methodology for all types of technologies through now. The estimates in this chapter reflect an effort to strike 2050. The 2017-2025 light duty fuel economy standards a careful balance between these considerations. were based on analyses that included major improvements Learning also applies to cost. Historically, technol- in data and estimation of technology benefits and costs, but ogy costs have continuously declined due to incremental assessed technology only through 2025 (EPA and NHTSA, improvements. For example, 6-speed automatic transmis- 2011). The 2009 MultiPath study (ANL, 2009) used a con- sions, currently the most common type, are cheaper to sistent methodology through 2050, but it lacked this recent manufacturer than 4-speed automatic transmissions, thanks data. Thus, the committee performed its own assessment of to innovative power flow designs that allow additional gear technology effectiveness and costs, as described below and combinations with fewer clutches and gearsets. in Appendix F. Although significant continuing R&D yielding sustained In order to compare technologies, all costs discussed in progress and cost reduction in all areas is essential, the this chapter assume the economies of scale from high volume technology estimates used for the committee’s analyses do production even in the early years when production is low. not depend on any unanticipated and fundamental scientific The modeling in Chapter 5, which estimates the actual costs breakthroughs in batteries, fuel cell systems, lightweight of following specific trajectories, modified these costs for materials, or other technologies. Therefore the estimates for early and low-volume production. improvements may be more readily attained, especially for Great care was taken to apply consistent assumptions to 2050, when technology breakthroughs are quite possible. all of the technologies considered. For example, the same For example: amount of weight reduction was applied to all vehicle types, and vehicle costs were built up from one vehicle type to the · Batteries beyond Li-ion were not considered for next (e.g., hybrid costs were estimated based on changes from PEVs because the challenges facing their develop- conventional vehicles, and PEV costs were based on changes ment make their availability highly speculative. from hybrid vehicles). This approach does not reduce the · Fuel cell efficiency gains were much less than large uncertainty in forecasting future benefits and costs, theoretically possible, based on the assumption that but it does help ensure that the relative differences in costs developers will consider reducing the cost of produc- between different technologies are appropriately assessed ing a given power level to be more important. and are more accurate than the absolute cost estimates. · Reducing weight with carbon fiber materials was not The committee made every attempt to ensure accurate included in the analyses, because the committee was technology assumptions. Fundamental limitations for all uncertain if costs would be low enough by 2050 for technologies were considered for all future assessments, mass market acceptance. such as the ones discussed below for lithium-ion (Li-ion) · The annual rate of reduction for the various vehicle battery chemistry and for engine losses. As these limits energy losses was assumed to diminish after 2030, were approached, the rate of technology improvement was usually to about half of the historical rate of reduction or the rate projected from 2010 to 2030. This reflects reaching the limits of currently known technology 3  The committee did not assess GHG emissions from the production of and implicitly assumes that the rate of technology vehicles or include such emissions in its analyses of emissions trends later improvements will slow in the future, despite the in this report. Given that vehicles are expected to last about 15 years, any current trend of accelerating technology introduction. differences in production emissions will not make a large difference in lifetime emissions. In addition, data on emissions from the production of · Only turbocompounding was considered for waste vehicles is poor, and estimates for advanced vehicles in several decades will heat recovery, even though other methods with much be even more uncertain.

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ALTERNATIVE VEHICLE TECHNOLOGIES: STATUS, POTENTIAL, AND BARRIERS 17 higher potential waste heat recovery rates are being erly assessed and that the modeled efficiency results do not researched (Ricardo, 2012). violate basic principles. · Radical new ICE combustion techniques with poten- The committee estimated conventional powertrain tially higher thermal efficiency were not considered improvements using the results of sophisticated simulation due to uncertainty about cost and durability. In fact, modeling conducted by Ricardo (2011). This modeling was the assumptions for thermal energy in the commit- used by the U.S. Environmental Protection Agency (EPA) to tee’s modeling for the 2030 optimistic and 2050 mid- help set the proposed 2025 light-duty vehicle CO2 standards. range cases were very similar to the efficiency levels Ricardo conducted simulations on six different vehicles, considered achievable by Ford’s next generation three cars and three light trucks, which examined drivetrain Eco-Boost engine with “potentially up to 40% brake efficiency (not load reduction) in the 2020-2025 timeframe. thermal efficiency . . . at moderate cost” (Automotive The simulations were based on both existing cutting-edge Engineering, 2012). technologies and analyses of technologies at advanced stages of development. EPA post-analyzed Ricardo’s simulation runs and appor- 2.2  VEHICLE FUEL ECONOMY AND COST tioned the losses and efficiencies to six categories—engine ASSESSMENT METHODOLOGY thermal efficiency, friction, pumping losses, transmission efficiency, torque converter losses, and accessory losses. The 2.2.1  Fuel Economy Estimates committee used these results as representative of potential This committee’s approach to estimating future vehicle new-vehicle fleet average values in 2025 for the optimistic fuel economy differs from most projections of future ICE case and in 2030 for the midrange case. The 2050 mid-level efficiency, which have generally assessed the benefits of and 2050 optimistic vehicles were constructed by assuming specific technologies that can be incorporated in vehicle that the rates of improvement in key drivetrain efficiencies designs (see Appendix F). Such assessments work well for and vehicle loads would continue, although at a slower rate, estimates out 15 to 20 years, but their usefulness for 2050 based on the availability of numerous developing technolo- suffers from two major problems. One is that it is impossible gies and limited by the magnitude of the remaining oppor- to know what specific technologies will be used in 2050. tunities for improvement. The traditional approaches taken to assess efficiency, such Baseline inputs for 2010 ICEVs were developed by as PSAT and ADVISOR, depend on having representative the committee from energy audit data that corresponded engine maps, which do not exist for the engines of 2050. with specific baseline fuel economy. The model calculates The second is that as vehicles approach the boundaries of changes in mpg based on changes in input assumptions over ICE efficiency, the synergies, positive and negative, between EPA’s test cycles. Additional details of the model are in different technologies become more and more important; that Appendix F. The results were averaged to one car and one is, when several new technologies are combined, the total truck for analysis in the scenarios, but the analysis for all six effect may be greater or less than the sum of the individual vehicles is in Appendix F. contributions. Starting with the results for ICEVs, the energy audit The three-step approach used here avoids these problems. model was then applied to the other types of vehicles consid- First, for ICE and HEV technologies, sophisticated computer ered in this report for each analysis year and for the midrange simulations conducted by Ricardo were used to establish and optimistic scenarios. PHEVs were assumed to have fuel powertrain efficiencies and losses for the baseline and 2030 economy identical to their corresponding BEVs5 while in midrange cases.4 These simulations fully accounted for charge-depleting mode (that is, when energy is supplied by synergies between technologies. Second, the efficiencies and the battery) and to HEVs in charge-sustaining mode (when losses of the different powertrain components and catego- energy is supplied by gasoline or diesel). Natural gas vehicles ries were determined. Using these categories to extrapolate were assumed to have the same efficiency as other gasoline efficiencies and losses allowed the committee to properly fueled vehicles. assess synergies through 2050. Third, the estimates of future Care was taken to use consistent assumptions across the efficiencies and losses were simultaneously combined with different technologies. For example, the same vehicle load modeling of the energy required to propel the vehicle as reduction assumptions (weight, aero, rolling resistance) were loads, such as weight, aerodynamics, and rolling resistance, applied to all of the drivetrain technology packages. were reduced. This approach ensures that synergies are prop- 5  The BEVs evaluated have a 100 mile range. BEVs with longer range 4  The committee accepts the Ricardo results. However, it should be noted would have substantially heavier battery packs (and supporting structures), that they are based in part on input data that has not been peer reviewed adversely affecting vehicle efficiency. PHEVs might have higher electric because it is proprietary. efficiency than long-range BEVs.

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18 TRANSITIONS TO ALTERNATIVE VEHICLES AND FUELS Variables considered by the model (not all variables were ICE technology includes a vast array of incremental used for each technology) were the following: engine, transmission, and drivetrain improvements. Past experience has shown that initial costs of new technologies · Vehicle load reductions: can be high, but generally drop dramatically as packages of —Vehicle weight, improvements are fully integrated over time. The incremental —Aerodynamic drag, cost of other technologies was compared to future ICE costs —Tire rolling resistance, and (FEV, 2012). —Accessory load; For HEVs, costs specific to the hybrid system were added · ICE: to ICE costs, and credits for smaller engines and compo- —Indicated (gross thermal) efficiency, nents not needed were subtracted to arrive at the hybrid cost —Pumping losses, increment versus ICE. Similarly, the other vehicle costs —Engine friction losses, were derived from ICEVs by adding and subtracting costs —Engine braking losses, and for various components as appropriate. Battery, motor, and —Idle losses; power electronics costs were assessed separately for electric · Transmission efficiency; drive vehicles. · Torque converter efficiency; · Electric drivetrain: 2.3  LOAD REDUCTION (NON-DRIVETRAIN) —Battery storage and discharge efficiencies, TECHNOLOGIES —Electric motor and generator efficiencies, and —Charger efficiency (BEV and PHEV only); Many opportunities exist to reduce fuel consumption · Fuel cell stack efficiency, and CO2 emissions by reducing vehicle loads, as shown in — lso the FCEV battery loop share of non- A Table 2.1. The load reduction portion of improved efficiency regenerative tractive energy; will benefit all the propulsion options by improving their · Fraction of braking energy recovered; and fuel efficiency, reducing their energy storage requirements, · Fraction of combustion waste heat energy recovered. and reducing the power and size of the propulsion system. This is especially important for hydrogen- and electricity- Details of the input assumptions for alternative tech- fueled vehicles because battery, fuel cell, and hydrogen nologies and of the operation of the model are described in storage costs are quite expensive and scale more directly Appendix F. with power or energy requirements than do internal combus- tion powertrain costs. In particular, load reduction allows a significant reduction in the size and cost of electric vehicle 2.2.2  Vehicle Cost Calculations battery packs. Future costs are more difficult to assess than fuel con- sumption benefits. The committee examined existing cost assessments for consistency and validity. Fully learned out, high-volume production costs were developed as described in this chapter and in Appendix F. The primary goal was to treat the cost of each technology TABLE 2.1  Non-drivetrain Opportunities for Reducing type as equitably as possible. The vehicle size and utility Vehicle Fuel Consumption were the same for all technology types. Range was the same Light weighting Structural materials for all vehicles except for BEVs, which were assumed to Component materials have a 100 mile real-world range. Care was taken to match Smart design the cost assumptions to the efficiency input assumptions. Rolling resistance Tire materials and design Results from the efficiency model were used to scale the size Tire pressure maintenance of the ICE, electric motor, battery, fuel cell, and hydrogen Low-drag brakes and CNG storage tanks (as applicable). Consistent assump- Aerodynamics Cd (drag coefficient) reduction tions of motor and battery costs were used for HEVs, PHEVs, Frontal area reduction BEVs, and FCVs. Costs were calculated separately for cars Accessory efficiency Air conditioning and light trucks. Efficient alternator For load reduction, the cost of lightweight materials, Efficient lighting aerodynamic improvements, and reductions in tire rolling Electric power steering Intelligent cooling system resistance were assumed to apply equally to all vehicles and technology types.  

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ALTERNATIVE VEHICLE TECHNOLOGIES: STATUS, POTENTIAL, AND BARRIERS 19 2.3.1  Light Weighting looked at weight increases for a variety of safety regulations, including proposed rules that would affect vehicles through Reducing vehicle weight is an important means of reduc- 2025 and estimated a potential weight increase of 100-120 ing fuel consumption. The historical engineering rule of pounds (EPA and NHTSA, 2011). That is about a 3 percent thumb, assuming appropriate engine resizing is applied and mass increase, which was factored into the committee’s vehicle performance is held constant, is that a 10 percent assessment of weight reduction potential. weight reduction results in a 6 to 7 percent fuel consump- tion savings (NHTSA/EPA/CARB, 2010). The committee Mass Increases for Additional Comfort and Accesso- specifically modeled the impact of weight reduction for ries  Vehicle weight decreased rapidly in the late 1970s and each technology type, as this rule of thumb was derived for early 1980s because of high fuel prices and implementation conventional drivetrain vehicles and other technologies may of the initial CAFE standards, then increased significantly differ in their response to weight reduction. during the period from the mid 1980s to the mid 2000s A variety of recent studies (see Appendix) have evaluated when fuel prices fell and fuel economy standards were kept the weight reduction potential and cost impact for light duty constant (EPA, 2012). Thus, projecting weight trends into vehicles through material substitution and extensive vehicle the future is very uncertain.7 Continued weight increases redesign. The long-term goal of the U.S. DRIVE Partnership are inconsistent with the assumptions driving this study, sponsored by the U.S. Department of Energy DOE) is a 50 i.e., a future that emphasizes improved vehicle efficiency, percent reduction in weight (DOE-EERE, 2012).6 Lotus increased fuel costs, and strong policies to reduce fuel Engineering projects a 2020 potential for about a 20 percent consumption. Not only will manufacturers have strong weight reduction at zero cost and 40 percent weight reduc- incentive to reduce weight, but the historical increase in tion potential at a cost of about 3 percent of total vehicle comfort and convenience features is likely to slow and his- cost, from an aluminum/magnesium intensive design (Lotus torical increases in weight associated with emission control Engineering, 2010). technology should not continue.8 The committee estimated that weight increases associated with additional comfort and 2.3.1.1  Factors That May Affect Mass Reduction Potential accessories for the midrange scenarios would be roughly half of the historical annual weight increase during a period Towing Capacity  Mass reduction potential for some light of fixed fuel economy standards, or 5 percent by 2030 and trucks will be constrained by the need to maintain towing 10 percent by 2050. This adjustment was applied after the capacity, which limits the potential for engine downsizing weight reductions considered here for lightweight materials. and requires high structural rigidity. Towing capacity is the The optimistic cases did not include weight increases for only advantage of body-on-frame over unibody construction, additional comfort and accessories. thus it was assumed that the historical trend for conversion of minivans and sport utility vehicles (SUVs) from body- Mass Reductions Related to Smart Car Technology  In the on-frame to unibody construction would continue and all 2050 timeframe, a significant portion of LDVs may include vehicles that did not need significant towing capacity would crash avoidance technology and other features of smart car convert to unibody construction. The committee accounted technology. Although it is possible that such features might for towing capacity by reducing the weight of body-on- lead to weight reduction, that is speculative and was not con- frame trucks (pickups and some SUVs) by only 80 percent sidered. The committee also did not consider driverless (or of the mass reduction of passenger cars and unibody trucks (minivans and most SUVs). In other words, if a car in 2050 7  addition to weight increases, improvement in powertrain efficiency In is estimated to be 40 percent lighter, a corresponding mass has been used to increase performance instead of improving fuel economy reduction for a body-on-frame truck would be limited to 32 in the past. The committee concluded that, as for weight discussed above, percent. power is unlikely to grow significantly under the conditions postulated for this study. Past performance increases occurred primarily during periods of Mass Increases Due to Safety Standards  Weight associated little regulatory pressure, and this study assumes that strong regulations or with increased safety measures is likely to be lower than in high gasoline prices will be required to reach the levels of fuel economy discussed here. In addition, the average performance level of U.S. vehicles the past. The preliminary regulatory impact analysis for the already is high, and many drivers aren’t interested in faster acceleration. 2025 Corporate Average Fuel Economy (CAFE) standards Finally, the advanced vehicles expected in the future are likely to operate at high efficiency over a broader range than current engines, so high power 6  U.S. DRIVE is a government-industry partnership focused on advanced engines will detract less from fuel economy. Hence the committee decided automotive and related energy infrastructure technology R&D. The partner- that performance increases may not happen to a great degree and, if they did, ship facilitates pre-competitive technical information to accelerate technical would likely not have a significant impact on fuel economy in the future. progress on technologies that will benefit the nation. Further information can 8  Future emission reductions will be accomplished largely with improved be found at http://www1.eere.energy.gov/vehiclesandfuels/pdfs/program/ catalysts and better air/fuel ratio control—neither of which will add weight us_drive_partnership_plan_may2012.pdf. to the vehicle.

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20 TRANSITIONS TO ALTERNATIVE VEHICLES AND FUELS autonomous) vehicles because it is not clear what the impact table also includes carbon fiber in 2050 for context, even on fuel use may be. While they may lead to smaller cars and though the committee considers it unlikely that costs will mass reduction because of improved safety, and driving a drop sufficiently for widespread use in vehicles and it was given route may be more efficient with computer controlled not used in the vehicle benefit and cost analyses. As noted acceleration and braking and continuous information on above, the midrange case includes some weight growth from congestion, people may be encouraged to live further away additional consumer features. from their workplaces and other destinations because they The costs of weight reduction are ameliorated by the cost can use the time in their vehicles more productively. More savings associated with the corresponding secondary weight information on the potential impact of autonomous vehicles savings from downsizing chassis, suspension and engine and is in Appendix F. transmission to account for the reduced structural require- ments and reduced drivetrain loads from the reduced mass. Although estimates of the secondary savings vary, they may 2.3.1.2 Safety Implications approach an additional 30 percent of the initial reduction Any effects of fleet-wide weight reduction on safety will (NRC, 2011). depend on how the reductions are obtained and on the dis- tribution of weight reduction over different size classes and 2.3.2  Reduced Rolling Resistance vehicle types. However, the footprint-based standards imple- mented in 2005 for light trucks and 2011 for cars eliminate Rolling resistance, and the energy required to overcome any regulatory incentive to produce smaller vehicles, and it, is directly proportional to vehicle mass. The tire rolling there are few indications that substantial weight reduction resistance coefficient depends on tire design (shape, tread through the use of lightweight materials and design opti- design, and materials) and inflation pressure. Reductions mization will have significant adverse net effects on safety in rolling resistance can occur without adversely affecting (DOT, 2006). Advanced designs that emphasize dispersing wear and traction (Pike Research and ICCT, 2011). The fuel crash forces and optimizing crush stroke and energy manage- consumption reduction from a 10 percent reduction in roll- ment can allow weight reduction while maintaining or even ing resistance for a specific vehicle is about 1 to 2 percent. improving safety. Advanced materials such as high strength If in addition the engine is downsized to maintain equal steel, aluminum and polymer-matrix composites (PMC) performance, historically fuel consumption was reduced 2.3 have significant safety advantages in terms of strength ver- percent (NRC, 2006). sus weight. The high strength-to-weight ratio of advanced In 2005, measured rolling resistance coefficients ranged materials allows a vehicle to maintain or even increase the from 0.00615 to 0.01328 with a mean of 0.0102. The best size and strength of critical front and back crumple zones and is 40 percent lower than the mean, equivalent to a fuel con- maintain a manageable deceleration profile without increas- sumption reduction of 4 to 8 percent (8 to 12 percent with ing vehicle weight. Finally, given that all light duty vehicles engine downsizing). Some tire companies have reduced their likely will be down-weighted, vehicle to vehicle crash forces rolling resistance coefficient by about 2 percent per year for should also be mitigated, and vehicle handling may improve at least 30 years. Vehicle manufacturers have an incentive to because lighter vehicles are more agile, helping to avoid provide their cars with low rolling resistance tires to maxi- crashes in the first place. mize fuel economy during certification. The failure of owners to maintain proper tire pressures and to buy low rolling resis- tance replacement tires increases in-use fuel consumption. 2.3.1.3  Weight Reduction Amount and Cost For this study, scenario projections of reductions in light- Table 2.2 summarizes the weight reductions and costs per duty new-vehicle-fleet rolling resistance for the midrange pound saved that are used in the committee’s scenarios. The case average about 16 percent by 2030, resulting in about a TABLE 2.2  Summary of Weight Reduction and Costs Relative to Base Year 2010 Cars and Unibody Light Trucks Body-on-Frame Light Trucks Weight Reduction with Weight Reduction with Reduction Cost Weight Growth Reduction Cost Weight Growth Year (%) ($/lb) (%) (%) ($/lb) (%) 2030 25 1.08 Midrange 20 20 0.86 Midrange 15 Optimistic 25 Optimistic 20 2050 40 1.73 Midrange 30 32 1.38 Midrange 22 Optimistic 40 Optimistic 32 2050 carbon fiber 50 6.0 Optimistic 50 40 6.0 Optimistic 40  

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ALTERNATIVE VEHICLE TECHNOLOGIES: STATUS, POTENTIAL, AND BARRIERS 21 4 percent decrease in fuel consumption, and about 30 percent system. Moving parts create frictional losses, intake air is in 2050, for about a 7 percent fuel consumption decrease. For throttled (called “pumping” losses), accessories are powered, the optimistic case, rolling resistance reductions were pro- and the engine remains in operation at idle and during decel- jected to be about 25 percent in 2030 and 38 percent in 2050. eration. In the transmission, multiple moving parts create friction, and pumps and torque converters create hydraulic losses. Also, when the vehicle brakes, much of the potential 2.3.3 Improved Aerodynamics energy built up during acceleration is lost as heat in the fric- The fraction of the energy delivered by the drive-train to tion brakes. Many or most of these losses and limitations the wheels that goes to overcoming aerodynamic resistance can be reduced substantially by a variety of technological depends strongly on vehicle speed. Unlike rolling resistance, improvements. The technologies discussed below are just a the energy to overcome drag does not depend on vehicle few of the options. More information can be found in Appen- mass. It does depend on the size of the vehicle, as repre- dix F. Note that biomass-fueled vehicles are being treated as sented by the frontal area, and on how “slippery” the vehicle conventionally powered vehicles in this study. is designed to be, as represented by the coefficient of drag. For low speed driving, e.g., the EPA city driving cycle, about 2.4.1  Conventional Internal Combustion Engine Vehicles one-fourth of the energy delivered by the drivetrain goes to overcoming aerodynamic drag; for high speed driving, one- 2.4.1.1  Gasoline Engine Drivetrains half or more of the energy goes to overcoming drag. Under average driving conditions, a 10 percent reduction in drag Engines will improve efficiency in the future by increas- resistance will reduce fuel consumption by about 2 percent. ing the maximum thermal efficiency and reducing friction Vehicle drag coefficients vary considerably, from 0.195 for and pumping losses. There are multiple technology paths for the General Motors EV1 to 0.57 for the Hummer 2. The accomplishing these improvements. Mercedes E350 Coupe has a drag coefficient of 0.24, the Although the dominant technology used to control fuel lowest for any current production vehicle (Autobloggreen, flow in gasoline engines currently is port fuel injection, 2009). Vehicle drag can be reduced by measures such as engines with direct injection of fuel into the cylinders have more aerodynamic vehicle shapes, smoothing the underbody, been rapidly entering the U.S. fleet. Gasoline direct injec- wheel covers, active cooling aperture control (radiator shut- tion (GDI, or just DI) systems provide better fuel vaporiza- ters), and active ride height reduction. tion, flexibility as to when the fuel is injected (including For this study’s scenarios, reduction in new-vehicle-fleet multiple injections), more stable combustion, and allow aerodynamic drag resistance for the midrange case is esti- higher compression ratios due to intake air charge cooling. mated to average about 21 percent (4 percent reduction in Direct injection reduces fuel consumption across the range fuel consumption) in 2030 and 35 percent (7 percent reduc- of engine operations, including high load conditions, and tion in fuel consumption) in 2050. For the optimistic case, increases low-rpm torque by allowing the intake valve to be the aerodynamic drag reductions are estimated to average open longer. Future GDI systems using spray-guided injec- about 28 percent in 2030 and 41 percent in 2050. tion can deliver a stratified charge allowing a lean air/fuel mixture (i.e., excess air) for greater efficiency. One approach that is rapidly penetrating the market is 2.3.4  Improved Accessory Efficiency to combine direct injection with down-sized turbocharged Accessories currently require about 0.5 horsepower from engines. Turbocharging increases the amount of fuel that the engine for most vehicles on the EPA city/highway test can be burned in the cylinders, increasing torque and power cycle. While small, this is a continual load that affects fuel output and allowing engine downsizing. The degree of turbo- economy. Accessory load reductions were assessed using charging is enhanced by GDI because of its cooling effect on Ricardo simulation results and the EPA Energy Audit data, the intake (air) charge and reduction of early fuel detonation. as described above. Overall, test cycle accessory loads were Further efficiency improvements are available with more reduced about 21-25 percent by 2030 and 25-35 percent by sophisticated turbocharging techniques (e.g., dual-stage 2050. turbochargers) and combining turbocharging with some combination of variable valve timing, lean-burn, Atkinson cycle, and cooled and boosted EGR. 2.4  DRIVETRAIN TECHNOLOGIES FOR REDUCING Ricardo developed engine maps specifically for an EGR FUEL CONSUMPTION DI turbo system, which uses the turbocharger to boost EGR Currently, conventional gasoline-fueled ICE drivetrains in addition to intake air. This recirculates additional cooled generally convert about 20 percent of the energy in the gaso- exhaust gas into the cylinder to reduce intake throttling (and line into power at the wheels. The engine cannot operate at pumping losses), increase compression ratio, enable higher peak efficiency most of the time. Within the engine, energy boost and further engine downsizing, and reduce combustion is lost as heat to the exhaust or transferred to the cooling temperatures and early fuel detonation (Ricardo, 2011). This

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22 TRANSITIONS TO ALTERNATIVE VEHICLES AND FUELS engine is projected to have a fuel economy benefit of 20 to 25 will also improve with the perfection of dry clutches and percent, compared to the baseline port fuel injected, naturally other improvements, with an additional reduction in internal aspirated engine, by 2020-2025. losses (beyond advanced automatic transmissions) of about Turbocharging with GDI engines is likely to become very 20 percent. Their cost should also be lower than advanced common by 2030 because the costs are modest and the fuel automatic transmissions. economy improvement significant. Engine friction is an important source of energy losses. 2.4.1.2  Estimation of Future Internal Combustion Engine Friction reduction can be achieved by both redesign of key and Powertrain Efficiency Improvements engine parts and improvement in lubrication. The major sources of friction in modern engines are the pistons and As discussed earlier in Chapter 2, the committee esti- piston rings, valve train components, crankshaft and crank- mated conventional powertrain improvements using the shaft seals, and the oil pump. Key friction reduction measures results of sophisticated simulation modeling on six differ- include the following (EEA, 2007): ent vehicles conducted by Ricardo for baseline (2010) and future (2025) vehicles. EPA post-analyzed Ricardo’s simula- · Low mass pistons and valves, tion runs and apportioned the losses and efficiencies to six · Reduced piston ring tension, categories—engine thermal efficiency, friction, pumping · Reduced valve spring tension, losses, transmission efficiency, torque converter losses, and · Surface coatings on the cylinder wall and piston skirt, accessory losses. · Improved bore/piston diameter tolerances in The committee directly used EPA’s 2025 results for the manufacturing, 2030 midrange case to ensure adequate time for the technolo- · Offset crankshaft for inline engines, and gies to fully penetrate the entire fleet. These results were also · Higher-efficiency gear drive oil pumps. extrapolated to 2050 by assuming that the percent annual improvements in each of the six categories after 2030 would Over the past two and one half decades, engine friction has be at most half the percent annual improvement calculated been reduced by about 1 percent per year (EEA, 2007). Con- for 2010 to 2030. Optimistic estimates were calculated the tinuing this trend would yield about an 18 percent reduction same way, except that the Ricardo runs were used for 2025 by 2030, but considerably greater reduction than this should instead of delaying the results until 2030. The total reduc- be possible, especially with continued aggressive vehicle tions for the various vehicles and losses are shown in Tables efficiency requirements. For example, surface technologies 2.9, 2.10, and 2.11, and in Appendix F. such as diamond-like carbon and nanocomposite coatings can reduce total engine friction by 10 to 50 percent. Laser 2.4.1.3 Diesel Engines texturing can etch a microtopography on material surfaces to guide lubricant flow, and combining this texturing with ionic This report has not explicitly considered diesel engines. liquids (made up of charged molecules that repel each other) Today’s diesels are about 15-20 percent more efficient can yield 50 percent or more reductions in friction. than gasoline engines, which would seem to mandate their There will also be improvements to transmission effi- inclusion in a study of greatly improved fuel economy. The ciency and reductions in torque converter losses. The pri- committee ultimately decided, however, that a diesel case mary advanced transmissions over the next few decades would not add significant value to the results of the study, are expected to be advanced versions of current automatic primarily because the efficiency advantage of the diesel will transmissions, with more efficient launch-assist devices be much smaller in the future as gasoline engines improve. and more gear ratios; and dual-clutch automated manual Current diesels have a much higher level of technology than transmissions (DCTs). Transmissions with 8 and 9 speeds gasoline engines in order to address diesel drivability, noise, have been introduced into luxury models and some mass smell, and emission concerns, such as direct fuel injection, market vehicles, replacing baseline 6-speed transmissions. sophisticated turbocharging systems using variable geometry The overdrive ratios in the 8- and 9-speed transmissions or dual turbochargers, and cooled EGR systems. As this same allow lower engine revolutions per minute (rpm) at highway level of technology is added to the gasoline engine, the effi- speeds, and the higher number of gears allows the engine to ciency advantage of the diesel will be much smaller. Another operate at higher efficiency across the driving cycle. A 20 to consideration is that combustion technology by 2050 may 33 percent reduction in internal losses in automatic trans- blur, if not completely eliminate, the distinction between missions is also possible by 2020-2025 from a combination diesel and gasoline engine combustion. For example, diesel of advances, including improved finishing and coating of engines are reducing compression ratio in order to increase components, better lubrication, improvements in seals and turbocharger boost and reduce emissions, while gasoline bearings, and better overall design (Ricardo, 2011). Dual engines are increasing compression ratio due to improve- clutch transmissions, currently in significant use in Europe, ments in combustion chamber design, increasing use of

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ALTERNATIVE VEHICLE TECHNOLOGIES: STATUS, POTENTIAL, AND BARRIERS 23 variable valve timing, and better control of EGR. Another systems for the future hybrid efficiency and cost assessments example is development of homogenous charge compression (see Appendix F). ignition engines, which combine features of both gasoline About 60 percent of the fuel energy in an ICE is rejected and diesel engines. as heat, roughly evenly divided between the engine cooling system (through the radiator) and the exhaust. Some of this heat can be recovered and used to reduce fuel consumption, 2.4.2  Conventional Hybrid Electric Vehicles especially from the exhaust, which is at a high temperature. HEVs combine an ICE, electric motor(s), and a battery Turbines, such as used for turbo-chargers, can generate or ultracapacitor. All the energy comes from the fuel for the electric power or transfer power to the crankshaft. Alterna- ICE. HEVs reduce fuel consumption by: tively, thermoelectric couples can generate electric power directly, reducing fuel consumption by about 2 to 5 percent. · Turning off the engine during idling, deceleration, HEVs would likely benefit more than ICEVs from waste and coasting; heat recovery, as generated electric power could be used in · Capturing a percentage of the energy that is normally their hybrid propulsion systems or to recharge the battery. lost to friction braking (i.e., regenerative braking); This analysis assumes waste heat recovery systems will be · Engine downsizing (because the electric motor applied starting in 2035, and only to HEVs. More efficient provides a portion of the maximum tractive power forms of waste heat recovery, such as Rankine cycle devices, required); were not included in the analyses. · Allowing easier electrification of accessories such as There is some uncertainty about the fuel consumption power steering; benefit of advanced hybrid systems in the future. While · Allowing the engine to operate more efficiently. By hybrid systems will improve (more efficient components, using the electric motor to drive the wheels at low improved designs and control strategies), advanced engines load, or by operating the engine at a higher power will reduce some of the same losses that hybrids are designed (and higher efficiency) during low loads and captur- to attack (e.g., advanced engines will have reduced idle ing excess energy in the battery; and and braking fuel consumption, yielding less benefit from · By allowing the use of efficient engine cycles, e.g. stopping the engine during braking and idling). In addi- Atkinson cycle, that are impractical for conventional tion, even as hybrid drivetrains improve, conventional ICE drivetrains. fuel consumption will shrink, and the actual volume of fuel saved will go down. As done for ICEVs, the committee used The simplest HEV configuration has a “stop-start” system the Ricardo simulations of 2025 hybrid vehicles to directly which shuts off the engine when idling and restarts it rapidly estimate losses and efficiency for the optimistic case in 2025 when the accelerator is depressed. These “micro-hybrids” and for the midrange case in 2030. Unfortunately, Ricardo need a higher capacity battery and starter motor than ICEVs. did not conduct simulations of baseline hybrid systems, so Stop-start systems are rapidly growing and are likely to be the annual rate of improvement from 2010 to 2025/2030 was universal by 2030 because they are a relatively inexpensive assessed using Ricardo’s ICE baseline simulations and dif- way to achieve substantial fuel economy improvements. The ferences in the 2025 simulations for ICE and hybrid vehicles benefits of stop-start systems are included in the committee’s to establish baseline hybrid energy losses. The committee’s calculations for future ICEV efficiency. The hybrid vehicle estimates are shown in Table 2.3. projections assess the incremental efficiency above that of the stop-start system. More complex systems that allow electric drive and substantial amounts of regenerative braking include paral- TABLE 2.3  Estimated Future Average Fuel Economy and lel hybrid systems with a clutch between the engine and Fuel Consumption the motor, commonly referred to as P2 parallel hybrids Cars Trucks (e.g., Hyundai Sonata hybrid). They have an electric motor Midrange Optimistic Midrange Optimistic inserted between the transmission and wheels, with clutches ICE HEV ICE HEV ICE HEV ICE HEV allowing the motor to drive the wheels by itself or in com- bination with the engine, or allowing the engine to drive the Average Fuel Economy (miles per gallon) 2010 31 43 31 43 24 32 24 32 wheels without motor input. Powersplit hybrids (e.g., Prius) 2030 65 78 74 92 46 54 52 64 are another approach, with two electric machines connected 2050 87 112 110 145 61 77 77 100 via a planetary gearset to the engine and the powertrain. The Average Fuel Consumption (gallons per 100 miles) committee determined that there is more opportunity for cost 2010 3.20 2.34 3.20 2.34 4.24 3.10 4.24 3.10 reduction on P2 hybrid systems in the future and used P2 2030 1.55 1.28 1.36 1.09 2.19 1.84 1.91 1.56 2050 1.15 0.89 0.91 0.69 1.64 1.30 1.30 1.00  

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24 TRANSITIONS TO ALTERNATIVE VEHICLES AND FUELS FIGURE 2.1  Historical and projected light-duty vehicle fuel economy. NOTE: All data is new fleet only using unadjusted test values, not in-use fuel consumption. While the gains projected by the committee are clearly on body-on-frame light trucks in order to maintain towing ambitious, the rate of improvement for conventional vehicles capacity. Weight and other load reductions were incorpo- (including use of stop-start systems and advanced alterna- rated into calculations of the size of the engine, motor, and tors) is about 3 percent/year from 2010-2050. Light-duty battery pack for each of the six vehicles. Credits associated trucks are expected to improve almost as much. Figure 2.1 with engine downsizing and eliminating the torque converter compares these rates of improvement to past experience were subtracted. Except for the battery pack, hybrid system and the 2016 and 2025 CAFE standards. All of the vehicle costs were based on detailed and transparent tear-down cost modeling was assessed as percentage improvements over assessments conducted by FEV, Inc., on current production baseline vehicles. These results were adjusted by the ratio HEV vehicles, with learning factors and suitable design of the baseline used for the modeling in Chapter 5 to the improvements applied to future HEV vehicles (FEV, 2012). average efficiency of the baseline vehicles used in Chapter 2. Batteries are discussed in Section 2.5, below. The committee estimated HEV costs by adding the cost Currently, an HEV costs about $4,000 to $5,000 more of the battery pack, electric motor, and other hybrid system than an equivalent ICEV, mostly for the battery, electric components to the cost previously estimated for conventional motor, and electronic controls. The committee’s total direct vehicles. Credits were also applied for engine downsizing manufacturing cost increments for hybrids, compared with and deletion of the torque converter and original equipment 2010 reference vehicles, are shown in Table 2.4. Details on alternator, with the exception that engine size was not reduced projected costs for hybrid systems are in Appendix F. Retail TABLE 2.4  Efficiency Cost Increment Over Baseline 2010 Vehicle Cars Trucks Midrange Optimistic Midrange Optimistic ICE HEV ICE HEV ICE HEV ICE HEV 2010 $0 $4,020 $0 $4,020 $0 $4,935 $0 $4,935 2015 $435 $3,510 $376 $3,006 $460 $4,228 $400 $3,601 2020 $986 $2,989 $867 $2,485 $1,059 $3,516 $939 $2,890 2025 $1,652 $3,017 $1,473 $2,590 $1,798 $3,446 $1,618 $2,942 2030 $2,433 $3,280 $2,195 $2,765 $2,676 $3,711 $2,436 $3,160 2035 $2,675 $3,357 $2,432 $2,973 $2,978 $3,834 $2,734 $3,408 2040 $2,960 $3,638 $2,713 $3,267 $3,332 $4,171 $3,085 $3,770 2045 $3,288 $3,949 $3,036 $3,577 $3,738 $4,540 $3,487 $4,142 2050 $3,659 $4,347 $3,403 $3,960 $4,196 $5,022 $3,941 $4,611  

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ALTERNATIVE VEHICLE TECHNOLOGIES: STATUS, POTENTIAL, AND BARRIERS 25 price markups are discussed in Chapter 5. Additional infor- tions and would take prohibitively long to charge. At $450/ mation on how the committee arrived at its estimates of fuel kWh, the current battery pack cost estimate (see Section economy improvements and direct manufacturing costs are 2.5.3 below), a 78 kWh battery costs $35,000. Prospects for in Appendix F. reducing the cost are discussed below. Other considerations for plug-in vehicles include the range that can be achieved in an affordable vehicle and the 2.5  PLUG-IN ELECTRIC VEHICLES time required for recharging. As vehicle weight, aerody- Three distinctly different configurations that utilize namic resistance, and rolling resistance are improved, range battery power for propulsion are in production: HEVs, can be improved for the same battery size, or a smaller, less discussed in the previous section; PHEVs; and BEVs. Each expensive battery may be used for the same range. Many has a rechargeable battery designed for a specific service. PHEVs and BEVs can be plugged in at home overnight on The Chevrolet Volt is the first mass-produced PHEV,9 and regular 110 or 220 volt lines. Gradual charging is generally Nissan’s Leaf the first mass produced BEV10 introduced best for the batteries, and night-time charging is best for into the U.S. market. Other manufacturers are introducing the power supplier, as power demand is lower than during electric vehicles of both types over the next several years. the day and excess generating capacity is available (see Improvements in battery technology will be critical to the Chapter 3). Fast charging is more challenging for batteries, success of electric vehicles. requires more expensive infrastructure, and is likely to use Plug-in hybrids are conceptually similar to HEVs. The peak-load electricity with higher cost, lower efficiency, and same set of improvements in fuel economy that will benefit higher GHG emissions. HEVs will also benefit PHEVs. PHEV batteries have about 4-20 kilowatt-hours (kWh) of stored energy that can be 2.5.1  Batteries for Plug-In Electric Vehicles charged from the grid. PHEVs can travel 10 to 40 miles on electricity before the engine is needed. Thus a driver who There is general agreement that the Li-ion battery will be does not exceed the electric range and charges the vehicle the battery of choice for electric vehicles for the foreseeable before using it again will use little or no gasoline. However, future. It was developed for the portable electronics industry when driven beyond the charge depletion mode of the first 20 years ago because of its light weight, superior energy 10 to 40 miles, the vehicles operate as conventional hybrid storage capability, and long cycle life, attributes, which also vehicles (in a charge sustaining mode), eliminating the are important for electric vehicles. Cell performance has range anxiety associated with BEVs. PHEV efficiency was increased steadily by improvements in the internal electrode assumed to be the same as BEV efficiency when operating structure and cell design and manufacturing processes, as on the battery pack and the same as HEV when the engine well as the introduction of higher performance anode and is running. cathode materials. A BEV has no engine, a significant cost savings relative There are several Li-ion chemistries that are being inves- to PHEVs, but currently the battery pack for even a small, tigated for use in vehicles, but none offers an ideal combina- short-range vehicle is likely to be at least 20 kWh, and a tion of energy density, power capability, durability, safety, large SUV might require 100 kWh for a range of 200 miles. and cost. HEVs are also shifting to Li-ion from the original The Nissan Leaf has a battery of 24 kWh. Battery cost will nickel-metal-hydride chemistry. HEV batteries, which are thus be a key determinant for the success of PHEVs and optimized for high power, may differ from those for PHEVs BEVs. Based on the energy modeling described earlier in and BEVs, which will be optimized for high energy and this chapter, a car that today gets 30 mpg would, if built as low cost. a BEV, require about 26 kWh/100 miles. For a range of 300 Development of the cylindrical 18650 Li-ion cell for the miles, the battery would need at least 78 kWh of available portable electronics industry is representative of how auto- energy.11 With current technology and costs, this would be motive batteries may develop. In 1991, the cost of the 18650 prohibitively expensive, heavy, and bulky for most applica- was $3.17/Wh. Twenty years later, the same cell costs $0.20/ Wh, while the charge capacity of the cell went from 1 Amp- 9  The Volt’s all-electric range is certified by EPA as 38 miles. General hour (Ah) to over 3 Ah in the same volume (see Figure 2.2). Motors refers to the Volt as an extended range electric vehicle because all These improvements resulted from the introduction of new, power to the wheels is delivered by the electric motor, unlike, say, Toyota’s high-performance materials, improvements to the cell and Prius PHEV. However, both are hybrids in that they have two fuel sources. electrode structure design, and high volume production pro- 10  The EPA certified range is 73 miles, but estimates vary widely; also, range is extremely sensitive to weather, driving conditions, and driver cesses with reduced wastage. As a rule of thumb for highly behavior. automated cell production, cell materials account for about 11  Available energy is typically less than nameplate battery pack capacity 60 to 80 percent of the cell cost in volume production.12 because batteries may not completely discharge to avoid damage to battery life and loss of power. In addition, available energy could effectively be reduced by energy required to offset the loss of vehicle efficiency caused 12  As used here, “materials” means processed materials ready for cell by the additional weight of a larger battery for longer range. manufacture. It does not mean raw materials, which may be much cheaper.

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FIGURE 2.4  Continuing system simplification contributes to cost reduction. SOURCE: James et al. (2010). 31

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32 TRANSITIONS TO ALTERNATIVE VEHICLES AND FUELS $200 Fire risk is mitigated because hydrogen dissipates much $180 faster than do gasoline fumes and by regulatory provisions Tiax $160 for fuel system monitoring. The safety of high-pressure on- Stack Cost ($/kW) Ballard $140 DOE board gaseous fuel storage has been demonstrated worldwide $120 $100 in decades of use in natural gas vehicles. Comparable safety $80 criteria and engineering standards, as applied to ICEVs, $60 HEVs, and CNGVs, have been applied to FCEVs with adap- $40 tation of safety provisions for differences between properties $20 of natural gas and hydrogen. The United Nations has drafted $0 a Global Technical Regulation for hydrogen-fueled vehicles 2000 2002 2004 2006 2008 2010 2012 to provide the basis for globally harmonized vehicle safety Year regulations for adoption by member nations (UNECE, 2012). 2-5.eps FIGURE 2.5  Historical progression of high-volume fuel-cell stack Codes and standards will also be required for hydrogen fuel- cost projections. ing stations, as discussed in Chapter 3, but DOE has greatly SOURCES: Kromer and Heywood (2007),Cost Fuel Cell Stack NRC (2005, 2008), and reduced its work in developing them. Carlson et al. (2005). 2.6.2  FCEV Cost and Efficiency Projections bon fiber, priced at roughly $30/kg of the hydrogen stored, accounts for most of the cost of the CFRC wrapped layers Detailed analyses of current fuel cell costs and near- that provide the structural strength of the storage system. The term improvements yield an estimated fuel cell system cost remaining costs are primarily attributed to flow-regulating estimate of $39/kW for a high volume FCEV commercial hardware. introduction in 2015 (James 2010). This estimate reflects recent advances in technology and material costs, especially sharp reductions in the loading of precious metal in fuel cell 2.6.1.6 Vehicle Safety electrodes. The platinum (Pt) loading in an earlier-generation The two primary features that distinguish FCEVs from 100 kW stack with ~80 g Pt at $32/g (2005 Pt price) would ICEVs with respect to safety are high-voltage electric power cost ~$2,500. For the 2010 loading of only 10 g Pt in a and hydrogen fuel. The safety of high voltage electric power higher-technology alloyed-Pt 100 kW stack, the cost would is managed on FCEVs similarly to HEVs, where safety be only ~$600 even at the higher 2011 Pt price of $58/g. requirements have resulted in on-road safety comparable The committee estimates a midrange fuel cell system cost to that of ICEVs. Experience from decades of safe and of $40/kW in 2020, and an optimistic cost of $36/kW, assum- extensive use of hydrogen in the agriculture and oil refining ing additional cost benefit from potential near term technol- industries has been applied to vehicle safety, and verified in ogy developments. All cost estimates assume commercial vehicle maintenance and on-road demonstration programs. introduction of FCEVs at annual production volumes over $300 2010 2015 $270 System Cost ($/kWnet) $240 $210 $180 $150 $120 $90 $60 $30 $0 0 100,000 200,000 300,000 400,000 500,000 600,000 Annual Production Rate (systems/year) 2-6.eps FIGURE 2.6  Progression of fuel cell system costs with production volume. SOURCE: James et al. (2010). Fuel Cell System Cost

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ALTERNATIVE VEHICLE TECHNOLOGIES: STATUS, POTENTIAL, AND BARRIERS 33 60 50 40 Cost, $/kW Mid-range 30 Optimistic 20 10 0 2000 2010 2020 2030 2040 2050 2060 FIGURE 2.7  Fuel cell system estimated costs. 200,000 units, with the primary economy of scale occurring TABLE 2.6  Fuel Cell Efficiency Projections at 50,000 units (James, 2010). 2010 2020 2030 2050 Costs are likely to drop more rapidly in the earlier years Midrange 53% 53% 55% 60% of deployment because automotive fuel cell systems are in Optimistic 53% 55% 57% 62% an early stage of development. Historically, reductions in   weight, volume and cost and improvements in efficiency between successive early generations of a new technology are much more substantial than between more mature gen- erations. Reductions of 2.3 percent per year in high volume the same conclusions apply to 80 percent penetration of the cost in early generations of a technology, and 1 percent per light-duty sales by 2050. year in later generations have commonly been observed. For the foreseeable future, technology developments Therefore, for purposes of this report, technology-driven cost for fuel cell systems are expected to prioritize reducing the reductions from 2020 to 2030 of 2 percent per year were used cost of producing a given level of power (kW), rather than for the midrange case and 3 percent per year for the optimis- efficiency improvements. Therefore, even though significant tic case. This report assumes that improved technology will gains in fuel cell efficiency are theoretically possible, this reduce costs by 2030 to $33/kW for the midrange and $27/ report assumes only modest improvements from the 2010 kW for the optimistic scenarios. level of 53 percent as shown in Table 2.6.15 Because of the major focus of fuel cell research and The cost of a CFRC hydrogen storage tank varies with development on cost reduction prior to 2030, the committee the pressure and volume capacity. In addition, there is a expects that subsequent cost reduction rates will be slower, fixed cost, independent of size, from equipment such as at 1 percent per year. By 2050, the midrange cost estimate valves, pressure regulators and sensors. Reduction in the is $27/kW and the optimistic is $22/kW. Cost estimates are cost of CFRC tanks can be expected from two sources: new shown in Figure 2.7. The supporting analysis is in Appen- manufacturing/design techniques and the decreasing size of dix F. tanks as demand for fuel is reduced with improved vehicle An evaluation of potential world Pt supply to support efficiency. FCEVs as 50 percent of the on-road light-duty vehicle sales Significant cost reduction from technology advancement by 2050 assumed the conservative achievement of 15 g Pt per is not expected by 2020, but several improvements in pro- FCEV by 2050. Key documented findings are that (1) there cessing techniques are expected to reduce the cost of carbon are sufficient Pt resources in the ground to meet long-term fiber used in CFRC by 25 percent by 2030. The fixed cost projected Pt demand; (2) the Pt industry has the potential for fraction, which is associated with flow-control equipment, is expansion to meet demand for 50 percent market penetration expected to have modest potential for cost reduction because of FCEVs (15 g Pt/vehicle) by 2050; and (3) the price of Pt the technologies are mature. Therefore, a 1 percent per year may experience a short-term rise in response to increasing cost reduction is applied to the fixed cost fraction, resulting FCEV penetration, but is expected to return to its long-term mean once supply adjusts to demand (TIAX LLC, 2003). 15  Theefficiency improvements in Table 2.6 were included in assessing Scaled to 10 g Pt per FCEV (already achieved by 2010), the size and cost of the fuel cell stack.

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34 TRANSITIONS TO ALTERNATIVE VEHICLES AND FUELS TABLE 2.7  Illustrative Hydrogen Storage System Cost and reduce tailpipe GHG emissions.16 A key driver of recent Projections interest in natural gas vehicles is the potential from shale- 2010 2020 2030 2050 based resources using hydraulic fracturing (“fracking”), and the likelihood that natural gas prices will remain well Midrange Capacity (kg) 5.5 4.6 3.8 2.8 below gasoline prices for the foreseeable future. The supply Cost ($) 3,453 3,031 2,402 1,618 of natural gas, and its potential for conversion into liquid $/kg-H2 628 659 632 578 fuels, electricity, or hydrogen, are discussed in Chapter 3. $/kWh 19 20 19 17 This section considers its direct use as a fuel in CNGVs with Optimistic conventional ICE engines. Capacity (kg) 5.5 4.4 3.3 2.4 Adding a compressed gas storage tank is a larger problem Cost ($) 3,453 2,938 2,055 1,326 for ICE vehicles than for fuel cell vehicles. This is because $/kg-H2 628 668 623 553 $/kWh 19 20 19 16 vehicle interior space is highly optimized and the large CNG tank compromises the interior space and utility. In   contrast, FCEVs eliminate the internal combustion engine in a 10 percent cost reduction in the fixed cost fraction over and drivetrain, plus the fuel cell stack can be configured in the 2020-2030 period. many different ways to optimize interior space. This allows The midrange estimate for 2050 hydrogen storage cost additional room and flexibility for hydrogen storage tanks. results from continuation of the technology-driven 1 per- Some vehicles have been converted to burn CNG, but until cent per year cost improvement over the 2030-2050 period recently the only dedicated CNG light-duty vehicle sold new in recognition of research into improvements in CRFC in the United States was the Honda Civic Natural Gas vehicle winding patterns and expectation of further improvements (formerly called the GX). Chrysler has just introduced a in manufacturing costs from added experience with high- CNG pickup, and Ford and General Motors are expected to volume production using new techniques (Warren, 2009). follow soon. CNGVs have been much more popular in other Hence, improved technology is estimated to reduce costs by countries, especially Italy, although sales recently plum- 26 percent between 2020 and 2050. Research on cost reduc- meted in Italy after the end of incentives. tion of structural CFRC is expected to accelerate with the new market driver of its broadened application to airplane 2.7.1 Fuel Storage fuselages, and other forms of hydrogen storage could become commercially viable. The key issue is the vehicle storage tank. In order to store Due to the difficulty in confirming promise among early enough natural gas for a reasonable driving range, it must stage research possibilities for manufacturing carbon fibers be compressed to high pressure. CNGVs can be fast-filled derived from polyacrylonitrile (PAN), or replacing it as the at fueling stations that have natural gas storage facilities and precursor for carbon fiber, the committee did not assume large compressors, or they could be filled overnight, typically dramatic cost reductions for CFRC even by 2050. However, at a rate of 1 gallon of gasoline equivalent per hour (gge/hr it is noted that a reduction in storage cost associated with where gge is the amount of energy equivalent to a gallon of achievement of a targeted <$10/kg carbon fiber and pressure gasoline) at home, tapping into the residential natural gas shift to 50 MPa would be consistent with a cost reduction of service and employing smaller compressors.17 35 to 40 percent, the optimistic technology-driven projection At 3,600 psi and 70°F, a CNG tank is about 3.8 times in Table 2.7. larger than a gasoline tank with the same energy content. In addition to these technology-related cost projections, CNG tanks also are heavier in order to manage the high additional reductions can be expected when the storage sys- pressure. The cheapest solid steel (type 1) cylinders weigh tem is down-sized. The volume of hydrogen that needs to be 4 to 5 times as much as the same capacity gasoline tank; stored for full vehicle range declines as vehicle efficiency advanced (Type 3) cylinders with thin metal liners wrapped increases. This reduction in the variable fraction of the stor- with composite weigh about half as much as Type 1 tanks, age cost is directly proportional to the reduced vehicle load. though at higher cost. Tanks with polymer liners weigh even Promising areas for research and future technology less, but at higher cost. The tank on the 2012 Honda Civic development for improved energy efficiency, performance NG vehicle holds about 8.0 gge of CNG at 3,600 psi, giv- and cost of fuel cell systems and hydrogen storage are listed ing the vehicle a range of 192 miles (EPA city) to 304 miles in Appendix F. 16  CNGV emits about 25 percent less CO than a comparable vehicle A 2 operating on gasoline. Upstream emissions of methane, including leakage, 2.7  COMPRESSED NATURAL GAS VEHICLES are discussed in Chapter 3. 17  The natural gas must be of sufficiently high quality; Honda does not Increasing the use of natural gas in U.S. LDVs would recommend home refueling at this time because of concern over moisture displace petroleum with a domestic fuel, reduce fuel costs, in the fuel in some parts of the country.

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ALTERNATIVE VEHICLE TECHNOLOGIES: STATUS, POTENTIAL, AND BARRIERS 35 (EPA highway), while taking up half of the vehicle’s trunk TABLE 2.8  Comparison of the Honda Civic NG with space. Higher pressure tanks (up to 10,000 psi) can reduce Similar Vehicles fuel storage space, though at added cost and increased energy Civic NG Civic LX Civic Hybrid required to compress the gas. MSRPa $26,805 $18,505 $24,200 In the future, it may be possible to store CNG at 500 mpg 27/38 28/39 44/44 psi (within the 200-1500 psi range of the pressure of gas Fuel cost $1,050 $1,800 $1,300 in natural gas transmission pipelines) in adsorbed natural Power 110 HP 140 HP 110 HP gas (ANG) tanks using various sponge-like materials, such Cargo (cubic feet) 6.1 12.5 10.7 Weight (pounds) 2848 2705 2853 as activated carbon. This technology, which is still under CO2 (grams/mile) 227 278 202 development, could allow vehicles to be refueled from the natural gas network without extra gas compression, reducing aManufacturer’s suggested retail price. SOURCE: American Honda Motor Company; available at http://www. cost and energy use and allowing the fuel tanks to be lighter. honda.com/. Also, at lower pressure, the shape of the tank can be adjusted as needed to fit the space available, thus minimizing the impact on cargo space. The committee did not include ANG tanks in its modeling. some extent by the higher compression ratios possible with the high octane of the fuel. For the analysis in this report, CNGVs are assumed to operate with the same efficiency 2.7.2 Safety as gasoline-powered vehicles, including future efficiency When used as an automobile fuel, CNG is stored onboard improvements. CNG engines were assumed to be 10 percent vehicles in tanks that meet stringent safety requirements. larger than other ICE engines for the purpose of calculating Natural gas fuel systems are “sealed,” which prevents spills engine cost at the same power output. or evaporative losses. Even if a leak were to occur in a fuel CNGV vehicles currently are sold in very low volumes system, the natural gas would dissipate quickly up into the and, partly due to that, cost significantly more than their atmosphere as it is lighter than air—unlike gasoline, which gasoline-powered counterparts. For example, the base price in the event of a leak or accident pools on the ground and of the 2012 Honda Civic NG vehicle is about $8,000 more creates a cloud of evaporated fuel that is easily ignited. than a similarly equipped Civic LX. Table 2.8 compares the Natural gas has a high ignition temperature, about 1,200° F, 2012 Honda Civic NG with the LX and the Civic Hybrid. compared with about 600° F for gasoline. While fires or even The CNGV has higher up-front vehicle costs mainly explosions could occur, overall the safety of CNGVs should because its high-pressure storage tanks are bulky and expen- be no worse than gasoline vehicles and is likely to be better. sive. Currently, a CNGV might require nearly ten years to recover the higher purchase price, but these costs should come down significantly as production volume increases. 2.7.3 Emissions The large fuel tank also reduces vehicle interior space, espe- Compared with vehicles fueled with conventional diesel cially in the trunk. CNGVs could also be built as hybrids with and gasoline, natural gas vehicles can produce significantly the same incremental cost and benefits as gasoline HEVs. lower amounts of harmful emissions such as particulate matter and hydrocarbons. Natural gas has a higher ratio of 2.8  SUMMARY OF RESULTS hydrogen to carbon than gasoline, reducing CO2 emissions for the same amount of fuel consumed. However, methane is The previous sections present a variety of options for a potent greenhouse gas, so it is important to prevent meth- reducing oil use and GHG emissions in LDVs and a meth- ane leakage throughout the well-to-wheels life cycle if the odology for estimating how much might be accomplished greenhouse gas benefits of natural gas are to be realized, as by 2050. This section summarizes those results. An example discussed in Chapter 3. of how one vehicle might evolve illustrates how the benefits and costs were determined. This is followed by a series of tables showing the technology results that were input into the 2.7.4  Vehicle Costs and Characteristics energy audit model, the results of those analyses, and the data Other than the tank, CNGVs do not require significant that was input to the scenario models discussed in Chapter 5. re-engineering from their gasoline counterparts, although the Detailed results can be found in Appendix F. cylinder head and pistons must be redesigned for a higher compression ratio and the ignition system modified. These 2.8.1  Potential Evolution of a Midsize Car Through 2050 design costs are significant for low volume production, but should be almost zero at high-volume. The lower density As an illustration of how a vehicle might evolve with of the fuel means that CNG engines have lower output than increasing fuel economy technology, this section examines a gasoline engines of the same size, though this is mitigated to midsize car, one of the six vehicles the committee analyzed.

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36 TRANSITIONS TO ALTERNATIVE VEHICLES AND FUELS Both a conventional drivetrain and a hybrid electric drivetrain increase in fuel economy (50.5 mpg for the mid-level case) are traced from a baseline 2007 vehicle to a 2050 advanced with no changes in vehicle loads. With load reduction, 2030 vehicle. Similar information for a BEV and FCEV and for fuel economy levels of nearly 66 mpg (mid) and 75 mpg the other vehicle types is shown in Appendix F. This evolu- (optimistic) are possible without full hybridization. The tion assumes that there is continuous pressure (from either added benefits of the vehicle load reduction—in particular, or both regulatory pressure and/or market forces) to improve the weight reduction, which pays back about 6 to 7 percent fuel economy and reduce emissions of greenhouse gases. fuel economy improvement for every 10 percent reduction Table 2.9 shows details of the evolution of the vehicle with in weight—are quite powerful. a conventional drivetrain. As can be seen in the table, the By 2050, strong additional benefits can be gained by combination of shifting to a downsized turbocharged direct further vehicle load reductions and, within the drivetrain, injection engine with high EGR and an advanced 8-speed primarily by continued improvements in indicated effi- automatic transmission drastically reduces pumping losses ciency and reductions in friction losses. Improvements in within the engine and, to a lesser extent, reduces friction the transmission and torque converter are minor because losses and increases indicated thermal efficiency. The com- most of the possible improvements have been done by 2030, bination of idle-off and an advanced alternator allow fuel use but some further reduction in pumping losses and improve- during idling to be virtually eliminated. In addition, engine ments in accessories is possible. Successful achievements of efficiency at low loads can be improved by increasing the these improvements can yield startling levels of fuel econ- charging rate of the alternator to the battery, thereby storing omy—88.5 mpg for the mid-level case, and 111.6 mpg for the energy for later use and allowing the engine to operate at the optimistic case. Note that these estimates are for the EPA more efficient load levels. In addition, smart alternators can test cycle, and on-road results will be significantly lower. improve the capture of regenerative braking energy. There Table 2.10 tracks the evolution of the benefits of adding are also improvements in transmission and torque converter a hybrid drivetrain to the technologies already onboard the efficiency and reductions in accessory loads. advanced conventional vehicles. Note that part of the “stan- The overall result in both the 2030 mid-level and opti- dard” benefits of hybrid drivetrains are already captured by mistic case is nearly a 50 percent increase over the EPA the combination of stop-start and advanced alternators in the 2-cycle tests in overall brake thermal efficiency, and a similar conventional vehicles. While the hybrid system allows elimi- TABLE 2.9  Details of the Potential Evolution of a Midsize Car, 2007-2050 2030 2030 2050 2050 Conventional Drivetrain Baseline Midrange Optimistic Midrange Optimistic Engine type Baseline EGR DI turbo EGR DI turbo EGR DI turbo EGR DI turbo Engine power, kW 118 90 84 78 68 Transmission type 6-sp auto 8-sp auto 8-sp auto 8-sp auto 8-sp auto Drivetrain improvements Brake energy recovered through alternator, % —a 14.1 14.1 14.1 14.1 Reduction in transmission losses, % n/a 26 30 37 43 Transmission efficiency, % 87.6 91 91 92 93 Reduction in torque converter losses, % n/a 69 75 63 88 Torque converter efficiency, % 93.2 98 99 99 99 Reduction in pumping losses, % n/a 74 76 80 83 Reduction in friction losses, % n/a 39 44 53 60 Reduction in accessory losses, % n/a 21 25 30 36 % increase in indicated efficiency n/a 5.6 6.5 10.6 15.6 Indicated efficiency, % 36.3 38.4 38.7 40.2 42 Brake thermal efficiency, % 20.9 29.6 30.3 32.5 34.9 Load changes % reduction in CdA n/a 15 24 29 37 CdA (m2) 7.43 6.31 5.64 5.29 4.68 % reduction in Crr n/a 23 31 37 43 Crr 0.0082 0.0063 0.0057 0.0052 0.0047 % reduction in curb weight n/a 20 25 30 40 Curb weight, lb 3325 2660 2494 2328 1995 Fuel economy, test mpg 32.1 65.6b 74.9 88.5 111.6 NOTE: All conventional drivetrains have stop-start systems and advanced alternators that can capture energy to drive accessories. aRicardo assumed stop start and smart alternator, with 14.1 percent of braking energy recovered, resulting in fuel economy = 34.9 mpg. bFuel economy with drivetrain changes only = 50.5 mpg.

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ALTERNATIVE VEHICLE TECHNOLOGIES: STATUS, POTENTIAL, AND BARRIERS 37 TABLE 2.10  Details of the Potential Evolution of a 2.8.2  Technology Results, Performance, and Costs Midsize Car Hybrid, 2007-2050 Tables 2.11 and 2.12 and Figures 2.8 through 2.11 sum- Hybrid Drivetrain—P2 hybrid with 2030 2030 2050 2050 marize the results from the committee’s vehicle analyses. DCT8 transmission mid opt mid opt Note that fuel consumption was directly assessed only for Engine power, kW 88 82 77 68 2030 and 2050. Between 2010 and 2030 and between 2030 Drivetrain improvements and 2050, fuel consumption was assumed to have a constant % additional pumping loss reductiona 80 80 80 80 multiplicative reduction each year. % additional friction loss reductiona 30 30 30 30 Table 2.11 presents the load reductions assessed by the % tractive energy provided by regen 20 22 24 26 Brake thermal efficiency, % 33.7 34.3 36.3 38.5 committee. These reductions were applied consistently to % of waste heat recovered 0 0 1 2 the calculations of costs and benefit for all of the technology types. Note that “Trucks” in this table is the sales-weighted Fuel economy, test mpg 81.7b 95.1 115.8 150.9 average of unibody and body-on-frame light trucks from Hybrid benefit over conventional, % 25 27 31 35 Table 2.2. aAdditional from conventional drivetrain in that year. Table 2.12 presents the overall fuel economy calculated bFuel economy with drivetrain changes only = 62.6 mpg. by the committee for the average car and light truck of each type. It is presented in miles per gallon because that is the metric usually used in the United States. There are three nation of most pumping losses, the actual overall efficiency caveats with the numbers in Table 2.12. First, at very high improvement is modest as pumping losses were already mpg levels, large changes in mpg are needed to have much reduced to low levels in the conventional ICE case. Most of impact on fuel consumption (see Figure 2.1 for an illustra- the incremental efficiency gains from the hybrid system are tion of this effect). Second, Table 2.12 shows the mpg results due to the tractive energy provided by capture of regenera- of the test cycles which do not include the adjustment for tive braking energy. real-world fuel consumption. Third, the BEV and FCEV As shown in Table 2.10, the overall hybrid fuel economy numbers are for the vehicle and do not account for the benefit over the corresponding conventional drivetrain vehi- energy needed to produce the electricity or hydrogen. This cle increases from 25 to 27 percent in 2030 to 31 to 35 per- is especially important for BEVs, where there are substantial cent in 2050; however, the hybrid benefit in terms of actual losses in electricity generation. Chapter 3 adds assessments fuel consumption actually declines in the future—from about of upstream energy losses. 0.30 gallons per 100 miles for the 2030 mid-level case to Figures 2.8 through 2.11 present the incremental cost cal- 0.23 gallons per 100 miles in the 2050 optimistic case. In culated for each of the technology types. Note that these costs other words, as non-hybrid ICEVs grow more efficient, the are all incremental to a baseline 2010 conventional vehicle. actual fuel savings and monetary benefit of hybridization They are also direct manufacturing costs to the manufacturer. may decline even as hybrid systems improve. For example, as vehicle mass decreases, the potential energy savings from regenerative braking also decreases. An interesting aspect of the evolution of hybrids is the improvement in the efficiency of electric components, not TABLE 2.11  Load Reduction, Percent Relative to 2010 shown in the table but included in the fuel economy calcula- Rolling Aerodynamic tions. For example, the benefits of hybridization will increase Resistance Drag Mass with improvements in electric motor/generator efficiency, Cars Trucks Cars Trucks Cars Trucks battery in/out efficiency, and improving control strategies 2030 Midrange 26% 15% 18% 15% 20% 18% as onboard computer power increases over time. Note that 2030 Optimistic 40% 30% 31% 29% 30% 27% these benefits also apply to BEVs and FCVs. Also, the 2050 2050 Midrange 33% 23% 26% 24% 25% 23% hybrids benefit from waste heat recovery. 2050 Optimistic 46% 37% 39% 37% 40% 37%   TABLE 2.12  Estimated Miles per Gallon Gasoline Equivalent (mpgge) on EPA 2 Cycle Tests ICEV HEV BEV FCEV Cars LT Cars LT Cars LT Cars LT 2010 Baseline (mpgge) 31 24 43 32 144 106 89 65 2030 Midrange (mpgge) 64 46 78 54 190 133 122 86 2050 Midrange (mpgge) 87 61 112 77 243 169 166 115 2030 Optimistic (mpgge) 74 52 92 64 219 154 145 102 2050 Optimistic (mpgge) 110 77 146 100 296 205 206 143  

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38 TRANSITIONS TO ALTERNATIVE VEHICLES AND FUELS $18,000 $16,000 BEV $14,000 $12,000 $10,000 $8,000 $6,000 PHEV FCV HEV $4,000 $2,000 CNG(ICE) ICE $0 2010 2015 2020 2025 2030 2035 2040 2045 2050 FIGURE 2.8  Car incremental cost versus 2010 baseline ($26,341 retail price)—Midrange case. 2-8.eps Cars: Mid-Range Costs $18,000 Incremental Direct Manufacturing Costs over 2010 Baseline BEV $16,000 $14,000 $12,000 $10,000 $8,000 FCV PHEV $6,000 HEV $4,000 $2,000 CNG(ICE) ICE $0 2010 2015 2020 2025 2030 2035 2040 2045 2050 FIGURE 2.9  Light truck incremental cost versus 2010 baseline ($32,413 retail price)—Midrange case. 2-9.eps Light Trucks: Mid-Range Costs Markups for retail prices are evaluated in Chapter 5. Finally, gas, coal, wind, solar, hydroelectric, and nuclear). Three Incremental Direct Manufacturing Costs over 2010 Baseline the cost estimates assume that high volume production has primary considerations differentiate their prospects for intro- already been realized. While this is not realistic for BEV, duction and acceptance as LDVs: vehicle attributes, rate of PHEV, and FCEV production in the near term, it allows technology development, and infrastructure: all technologies to be evaluated on a consistent basis. Cost increases for near term, lower volume production are incor- · Vehicle attributes. FCEVs provide the full utility of porated into the modeling in Chapter 5. current on-road vehicles. BEVs, however, require time consuming “refueling” (recharging) and only offer limited driving range between “refuelings.” 2.9  COMPARISON OF FCEVs WITH BEVs · Rate of technology development. A key requirement FCEVs and BEVs are electric vehicles having no tailpipe for realization of projected technology advances for GHG emissions. Both are “fueled” by an energy carrier (elec- battery and fuel cell systems is the continued dedica- tricity or hydrogen) that can be produced from a myriad of tion of research and development resources. Because traditional and renewable energy sources (biofuels, natural demand for improved battery technologies is driven

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ALTERNATIVE VEHICLE TECHNOLOGIES: STATUS, POTENTIAL, AND BARRIERS 39 2-10.eps FIGURE 2.10  Car Incremental cost versus 2010 baseline ($26,341 retail price)—Optimistic case. type outlined FIGURE 2.11  Light truck incremental cost versus 2010 baseline ($32,413 retail price)—Optimistic case. 2-11.eps type outlined by their established application in portable commu- 2.10 FINDINGS nication/computer devices, prospects for short-term · Large increases in fuel economy are possible with return on R&D investments are substantial. incremental technology that is known now for both · Infrastructure is discussed in Chapter 3, but it should load reduction and drivetrain improvements. The be noted that the barriers facing hydrogen are more average of all conventional LDVs sold in 2050 formidable than those facing electricity. A brand new might achieve EPA test values of 74 mpg for the infrastructure for producing and distributing hydro- midrange case and 94 mpg for the optimistic case. gen would have to be built in concert with FCEV Hybrid LDVs might reach 94 mpg for the midrange manufacturing. Neither is viable without the other, case and 124 mpg for the optimistic case by 2050. and the investments required both for manufactur- On-road fuel economy values will be significantly ing vehicles and hydrogen are extremely large. Both lower. industries would require guarantees that the other · To obtain the efficiencies and costs estimated in this will produce as promised, and that probably will chapter, manufacturers will need incentives or regu- entail a government role.

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40 TRANSITIONS TO ALTERNATIVE VEHICLES AND FUELS latory standards, or both, to widely apply the new developments would substantially reduce the cost and technologies. lead time to meet these targets. In addition, continued · The unit cost of batteries will decline with increased research on advanced materials and battery con- production and development; additionally, the energy cepts will be critical to the success of electric drive storage (in kWh) required for a given vehicle range vehicles. The committee recommends the following will decline with vehicle load reduction and improved research areas as having the greatest impact: electrical component efficiency. Therefore battery — ow-cost, conductive, chemically stable plate L pack costs in 2050 for a 100-mile real-world range materials: fuel cell stack; are expected to drop by a factor of about 5 for the — ew durable, low-cost membrane materials: fuel N midrange case and at least 6 for the optimistic case. cell stack and batteries; However, even these costs are unlikely to allow a — ew catalyst structures that increase and maintain N mass-market vehicle with a 300-mile real-world the effective surface area of chemically active range. In addition to the weight and volume require- materials and reduce the use of precious metals: ments of these batteries, they are unlikely to be able fuel cell stack and batteries; to be recharged in much less than 30 minutes. There- — ew processing techniques for catalyst substrates, N fore BEVs may be used mainly for local travel rather impregnation and integration with layered materi- than as all-purpose vehicles. als: fuel cell stack and batteries; · BEVs and PHEVs are likely to use Li-ion batteries — nergy storage beyond Li-ion: PHEVs and BEVs; E for the foreseeable future. Several advanced battery — educed cost of carbon fiber and alternatives to R technologies (e.g., lithium-air) are being developed PAN as feedstock; that would address some of the drawbacks of Li-ion — eplacements for rare earths in motors; R batteries, but their potential for commercialization — aste heat recovery: ICEVs, HEVs, and PHEVs; W by 2050 is highly uncertain and they may have their and own disadvantages. — mart car technology. S · PHEVs offer substantial amounts of electric-only driving while avoiding the range and recharge time 2.11 REFERENCES limitations of BEVs. 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