F

Vehicles

This appendix is an addendum to Chapter 2 of the main report, providing additional information on subjects discussed there. Section F.1 discusses efficiency technologies for internal combustion engine (ICE) vehicles (ICEVs) and hybrid electric vehicles (HEVs). Some of these technologies also apply to other types of vehicles. Section F.2 discusses the modeling techniques uses to estimate future fuel consumption. Two spreadsheet models are also included in the electronic version of this appendix. The Vehicle Input Spreadsheet shows the committee’s estimates of the reduction in energy losses over time for the six vehicles analyzed. The Vehicle Cost Summary estimates the cost of the various vehicles analyzed (6 models each of ICEVs, HEVs, battery-powered electric vehicles [BEVs], and hydrogen fuel cell electric vehicle [FCEVs]). Section F.3 elaborates on the battery vehicle section of Chapter 2, and Section F.4 on the hydrogen fuel cell electric vehicle section.

F.1 EFFICIENCY TECHNOLOGIES FOR CONVENTIONAL VEHICLES

F.1.1 Load Reduction Technologies Applicable to All Vehicles

F.1.1.1 Mass Reduction

This discussion is focused on the potential benefits of reducing the mass of vehicles to improve fuel economy. The government’s fuel economy standards are footprint based and provide no incentive for downsizing vehicles. Potential effects on safety, fuel economy, and vehicle costs are discussed for scenarios where mass reduction is accomplished entirely through material substitution and smart design that can reduce mass without changing a vehicle’s functionality or safety performance and maintains structural strength.

Fuel Economy Benefits

The engineering rule of thumb, assuming appropriate engine resizing is applied and vehicle performance is held constant, is that a 10 percent curb weight reduction results in a 6-7 percent fuel consumption savings (NHTSA-EPA, 2010). For this committee’s analysis, the fuel consumption from weight reduction is calculated as one of the inputs into an energy audit model.

Potential for Mass Reduction

The National Highway Traffic Safety Administration (NHTSA) and the Environmental Protection Agency (EPA) examined mass reductions of 15-30 percent for the 2017-2025 timeframe (NHTSA-EPA, 2010). The automobile manufacturers’ position, as characterized in the Technical Assessment Report (TAR), was that mass reduction plans for 2017-2025 were focused on increased use of high strength steel and some additional aluminum with resulting mass reductions of 10-15 percent. Manufacturers generally



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F Vehicles This appendix is an addendum to Chapter 2 of the main report, providing additional information on subjects discussed there. Section F.1 discusses efficiency technologies for internal combustion engine (ICE) vehicles (ICEVs) and hybrid electric vehicles (HEVs). Some of these technologies also apply to other types of vehicles. Section F.2 discusses the modeling techniques uses to estimate future fuel consumption. Two spreadsheet models are also included in the electronic version of this appendix. The Vehicle Input Spreadsheet shows the committee’s estimates of the reduction in energy losses over time for the six vehicles analyzed. The Vehicle Cost Summary estimates the cost of the various vehicles analyzed (6 models each of ICEVs, HEVs, battery-powered electric vehicles [BEVs], and hydrogen fuel cell electric vehicle [FCEVs]). Section F.3 elaborates on the battery vehicle section of Chapter 2, and Section F.4 on the hydrogen fuel cell electric vehicle section. F.1 EFFICIENCY TECHNOLOGIES FOR CONVENTIONAL VEHICLES F.1.1 Load Reduction Technologies Applicable to All Vehicles F.1.1.1 Mass Reduction This discussion is focused on the potential benefits of reducing the mass of vehicles to improve fuel economy. The government’s fuel economy standards are footprint based and provide no incentive for downsizing vehicles. Potential effects on safety, fuel economy, and vehicle costs are discussed for scenarios where mass reduction is accomplished entirely through material substitution and smart design that can reduce mass without changing a vehicle’s functionality or safety performance and maintains structural strength. Fuel Economy Benefits The engineering rule of thumb, assuming appropriate engine resizing is applied and vehicle performance is held constant, is that a 10 percent curb weight reduction results in a 6-7 percent fuel consumption savings (NHTSA-EPA, 2010). For this committee’s analysis, the fuel consumption from weight reduction is calculated as one of the inputs into an energy audit model. Potential for Mass Reduction The National Highway Traffic Safety Administration (NHTSA) and the Environmental Protection Agency (EPA) examined mass reductions of 15-30 percent for the 2017-2025 timeframe (NHTSA-EPA, 2010). The automobile manufacturers’ position, as characterized in the Technical Assessment Report (TAR), was that mass reduction plans for 2017-2025 were focused on increased use of high strength steel and some additional aluminum with resulting mass reductions of 10-15 percent. Manufacturers generally 218

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indicated that universal material substitution (such as a switch from steel to aluminum body in white (BIW) 1 structures) would not be feasible across all body lines in the 2017-2025 timeframe. In the TAR covering 2017-2025 Model Years, the government stated that “the ability of the industry to reduce mass beyond 20% while maintaining vehicle size . . . is an open technical issue” (EPA-NHTSA-CARB, 2010, p. 3-8). The Partnership for New Generation Vehicles research effort from 1994-2002 was an early effort to conceptualize and build highly fuel efficient vehicles. The mass reduction goal was 40 percent. Actual vehicles achieved a mass reduction of 20 to 30 percent (NRC, 2001). A recent study by the University of Aachen, done for the European Aluminum Association, looked at weight reduction opportunities for aluminum versus steel for subcompact and medium-sized passenger vehicles, crossover vehicles, and small multi-purpose vehicles. The Aachen study looked at optimizing the BIW and closures with aluminum intensive designs and concluded that a 40 percent weight savings in these areas was possible. BIW and Closure Reductions of 40-45 percent translate to an incremental (taking into account aluminum content already in standard production vehicles) 10-11 percent total vehicle weight reduction and with secondary weight savings yield approximately a 15 percent reduction in total vehicle weight (Aachen, 2010). The 15 percent weight reduction of the total vehicle was repeated in detailed design studies by IBIS Associates, Inc., although secondary weight savings and use of lightweight materials in the rest of the body would result in much greater overall weight savings (IBIS, 2008). An interesting aspect of the Aachen study is that it looked specifically at the use of the aluminum-intensive parts from the standpoint of vehicle stiffness (handling, comfort, noise) and strength needed for managing crash energies and constrained the proposed design to meet or exceed current vehicle BIW performance when it quantified weight reduction opportunities. Lotus showed similar conclusions to the Aachen study regarding BIW weight savings (Lotus, 2010). The Lotus study evaluated the total vehicle design and hypothesized a “high development” vehicle using an aluminum/magnesium intensive design with an overall weight reduction of about 40 percent. The primary areas of mass reduction are: • Body in white and closures—44 percent, • Interior—20 percent, and • Suspension/chassis—33 percent. The aluminum industry sponsored studies, which looked strictly at weight reduction for the BIW and closures with associated secondary weight reduction, are in agreement with the Lotus study for similar areas of the vehicle. Lotus also used increased aluminum as part of the suspension and chassis optimized design. Polymer-matrix composites (PMC, e.g., carbon fiber) have the potential to make a significant further contribution to reducing mass if the production costs of such materials can be reduced with mass production. “Conservative estimates are that carbon fiber PMC can reduce the mass of a steel structure by 40-50 percent . . .” (NRC, 2011, p. 102). However, there are currently production concerns for using carbon fiber in mass-produced vehicles. Currently, there still is not a known substitute for the existing carbon fiber process, which is too expensive for high-volume applications. Because of this uncertainty, the committee has not included carbon fiber in the 2050 mass reduction scenarios. A key factor when evaluating design strategies for reducing mass is the corresponding secondary weight savings from rationalizing chassis, suspension, and drivetrain performance for the reduced mass. Estimates of the synergistic effects of mass reduction and the compounding effect that occurs along with it can vary significantly. In comments to various U.S. Corporate Average Fuel Economy (CAFE) rulemaking proposals, the Auto-Steel Partnership estimates that these secondary mass changes can save 1 Body in white is the term for the stage in vehicle manufacture when all the fixed sheet metal components are fastened together. It does not include moveable parts such as doors, hood, and trunk (closures). 219

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an additional 0.7 to 1.8 times the initial mass change. Comments by the Aluminum Transportation Group have estimated a factor of 64 percent for secondary mass reduction (NHTSA, 2010). The 2011 National Research Council (NRC) report Assessment of Fuel Economy Technologies for Light-Duty Vehicles pointed out the importance of secondary weight reduction “as the mass of a vehicle is reduced . . . other components of the vehicle can be reduced . . . for example brakes, fuel system, powertrain, and even crash management structures” (NRC, 2011, p. 113). It discussed a rule of thumb that for every pound saved in the design through material substitution or structural modifications, an additional 30 percent of the weight savings in secondary systems could be saved (NRC, 2011). Potential Cost Impacts Cost estimates for reducing vehicle mass have varied significantly. One difference is the cost savings from secondary weight reduction which can offset some of the costs related to lightweight materials and improved structural design. In this context, the net costs for mass reduction should include the secondary weight and drivetrain downsizing that are directly related to mass efficient vehicle designs. The impacts of weight reduction on drivetrain costs are discussed below. NHTSA and EPA summarized three studies, which were first used in the 2012-2016 CAFE rulemaking, that concluded that weight could be reduced for approximately $1.50 per pound. Additionally, Sierra Research estimated a 10 percent reduction, with secondary weight reduction, could be accomplished for $1.01 per pound. The Massachusetts Institute of Technology (MIT) estimated that the weight of a vehicle could be reduced by 14 percent with no secondary weight reduction, for a cost of $1.36 per pound. The final NHTSA/EPA cost estimate for the 2012-2016 rulemaking was $1.32 per pound and was based on the average of the three referenced studies (NHTSA/EPA, 2010). The 15 percent reduction in total vehicle weight estimated by IBIS for the Aluminum Transportation Group discussed above was estimated to cost $0.18 per pound. This cost was significantly less than the $1.32 per pound used in NHTSA/EPA’s rulemaking analysis—an estimate that did not account for secondary weight savings. Downweighting is even more cost-effective for battery-powered vehicles (or other high-cost propulsion systems) because of the potential savings in battery/energy storage. The Aachen and IBIS reports produced detailed designs using aluminum intensive BIW and Closures with weight savings of 19 percent of total vehicle weight. The increased cost of aluminum was estimated at $630. Cost savings in the study were estimated at $450-$975 for the batteries (using $375/kWh). The Lotus study estimated that a 21 percent mass reduction could be achieved by 2020 using high-strength steel with no cost impact. A 38 percent mass reduction could be achieved by 2020 with a moderate cost growth (e.g., a 3 percent increase in vehicle cost using aluminum, magnesium, and composites; Lotus, 2010). For the 2017-2025 proposed rule, NHTSA and EPA updated their analysis of existing cost studies. Currently the government is proposing a formula that assumes mass reduction increases in cost as the absolute size of mass reduction increases, e.g., $4.32 × % weight reduction. Table F.1 shows the results over a range of mass reduction. Down-weighting battery powered (or other high cost propulsion systems) vehicles is even more cost effective because of the potential savings in battery/energy storage (Ricardo, 2011). Carbon fiber/plastics may also make a significant impact on mass reduction if costs are reduced: “Conservative estimates are that carbon fiber PMC can reduce the mass of a steel structure by 40 to 50 percent (Powers, 2000)” (NRC, 2011, p. 102). The 2011 NRC report states “that the price of carbon fiber has to fall to $5 to $7 per pound (about 50 percent) before it can be cost competitive for high-volume automobiles (Carpenter, 2008)” (NRC, 2011, p. 102). Research conducted at ORNL suggests that if a vehicle design with a weight reduction of 50 percent was achieved with a 50/50 mix of plastic resin (1.00 $/#) and carbon fiber (7.00 $/#), then an average cost for using carbon fiber/plastic would be $3 to $4 per pound at a high production volume (10 million pounds per year) (ORNL, 2008). 220

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TABLE F.1 Cost of Mass Reduction MassR $/lb Incremental $/lb 10% $0.43 $0.43 20% $0.86 $1.30 30% $1.30 $2.16 40% $1.73 $3.02 Table 2.2 in Chapter 2 summarizes the weight reductions and costs that are used in the committee’s scenarios. It includes carbon fiber in 2050 for context, even though the committee considers it unlikely that costs will drop sufficiently for widespread use in vehicles. For the midrange cases, 5 percentage points of the weight reduction were countered by weight increases due to increased vehicle features in 2030, and 10 percentage points in 2050. Predicted reductions of new car weight are 18-22 percent in 2030 and 28-37 percent in 2050. For light trucks, they are 17-20 percent in 2030 and 23-33 percent in 2050. The cost estimates in Table 2.2 do not include secondary weight reductions. In general, secondary weight reductions are free or even reduce costs, as they reduce component size. However, available estimates for secondary weight reductions generally include powertrain size reduction, in addition to chassis and suspension weight reductions. As the cost benefits of powertrain size reductions are being calculated elsewhere in the analysis and the amount of secondary weight reduction for the chassis and suspension alone is uncertain, no adjustments were made to lightweight material costs. Safety Implications The 2011 NRC report said the following: “Vehicle mass can be reduced without compromising size, crashworthiness, and [noise/vibration/harshness] . . .” NRC (2011, p. 100). The NHTSA/EPA Final Rule stated that “the agencies believe that the overall effect of mass reduction in cars and LTVs may be close to zero, and may possibly be beneficial in terms of the fleet as a whole.” 2 This statement was based on an analysis which looked at historical experience and tried to separate out size and weight differences and how they affect real world safety performance based on vehicle designs of the 1990s, which were not optimized with innovative designs using improved, lighter weight, stronger materials, and improved structural design (NHTSA/EPA (2010b). NHTSA/EPA issued the proposed rule “2017 and Later Model Year Light-Duty Vehicle Greenhouse Gas Emissions and Corporate Average Fuel Economy Standards” (NHTSA/EPA, 2011c), which discussed an updated statistical analysis (Kahane, 2011). NHTSA created a common, updated database for statistical analysis that consists of crash data of model years 2000-2007 vehicles in calendar years 2002-2008, as compared to the database used in prior NHTSA analyses, which was based on model years 1991-1999 vehicles in calendar years 1995-2000. The study found that decreasing weight (while maintaining footprint) generally decreased fatalities in rollovers and collisions with fixed objects for all vehicles. In the other type of crashes, weight reduction in smaller vehicles tended to increase fatalities and in larger vehicles tended to decrease fatalities. NHTSA/EPA concluded, however: “The effect of mass reduction while maintaining footprint is a complicated topic and there are open questions whether future designs will reduce the historical correlation between weight and size. It is important to note that while the updated database represents more current vehicles with technologies more representative of vehicles on the road today, they still do not fully represent what vehicles will be on the road in the 2017-2025 timeframe.” 3 2 NHTSA/EPA, Final Rule, Federal Register, Volume 75, Number 88, May 7, 2010, p. 25383. 3 NHTSA/EPA, Proposed Rules, Federal Register, Volume 76, Number 231, December 1, 2011, p. 74955. 221

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Safety is primarily a design issue. Advanced designs that emphasize dispersing crash forces and optimizing crush stroke and energy management can allow weight reduction, while maintaining or even improving safety. In a crash, occupant protection is provided by designing the vehicle structure to absorb energy in a managed way and prevent intrusion into the occupant compartment. Advanced materials such as high-strength steel, aluminum, and polymer-matrix composites (PMC) have significant advantages in terms of strength versus weight. For example, pound for pound, aluminum absorbs two times the energy in a crash compared to steel and can be up to two and a half times stronger. The high strength-to-weight ratio of advanced materials allows a vehicle to maintain, or even increase, the size and strength of critical front and back crumple zones without increasing vehicle weight and maintain a manageable deceleration profile. And, given that all light-duty vehicles (LDVs) likely will be down weighted, vehicle-to-vehicle crashes should also be mitigated. Lastly, assuming mass reduction without size reduction, vehicle handling (exacerbated by smaller wheel bases, for instance) is not an issue. In fact, lighter vehicles are more agile, helping to avoid crashes in the first place. Several significant engineering studies on mass/safety are in progress: • NHTSA has issued a contract proposal for an engineering down-weighting design and crash simulation analysis. • California Air Resources Board is having Lotus look at the crash worthiness of the recent design study on down weighting. And EPA is having FEV, Inc., conduct crash simulations on a high strength steel design. • The U.S. Department of Energy (DOE) has several research studies planned. One will be looking at the amount of mass reduction that is technically feasible. A second, more ambitious project will be an actual vehicle build of a light weighted vehicle identified as a multi-material vehicle. DOE has also asked Lawrence Berkeley National Laboratory to look at mass reduction versus safety. F.1.1.2 Reduced Rolling Resistance About one-third of the energy delivered by the drive-train to the wheels goes to overcoming rolling resistance. Rolling resistance, and the energy required to overcome it, is directly proportional to vehicle mass. It is calculated by multiplying the tire rolling resistance coefficient times the weight on the tire. Thus if a tire with a coefficient of 0.01 is supporting 1,000 pounds, the force resisting rolling is 10 pounds. The tire rolling resistance coefficient depends on tire design (shape, tread design, and materials) and inflation pressure. According to a 2006 NRC study, reductions in rolling resistance can occur without adversely affecting wear and traction (NRC, 2006). This study estimated the fuel consumption reduction from a 10 percent reduction in rolling resistance at 1-2 percent. Additional savings from the reduced power requirement (at constant performance) result in a total reduction of 2-3 percent. Measured rolling resistance coefficients provided by manufacturers for commercial LDV tires in 2005 ranged from 0.00615 to 0.01328, with a mean of 0.0102. The best is 40 percent lower than the mean, equivalent to a fuel consumption reduction of 4-8 percent. Vehicle manufacturers have an incentive to provide their cars with low rolling resistance tires to maximize fuel economy during certification. The failure of owners to maintain proper tire pressures and to buy low rolling resistance replacement tires increases in-use fuel consumption. Average future improvements by 2030 are estimated to provide 20-28 percent reduction in rolling resistance relative to 2010 for a fuel consumption reduction of 5-8 percent at a cost of $25. By 2050, rolling resistance could be reduced by 35-41 percent for a fuel consumption reduction of about 10 percent. Since tires are usually replaced several times over a vehicle’s lifetime, achieving such fuel consumption improvements may depend on ensuring that replacement tires are as efficient as the vehicle’s original tires. 222

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F.1.1.3 Improved Aerodynamics The fraction of the energy delivered by the drive-train to the wheels going to overcoming aerodynamic resistance depends strongly on vehicle speed. The drag resistance, D = ½CdρAV2 where Cd = drag coefficient ρ = density of air A = vehicle frontal area V = vehicle velocity. Unlike rolling resistance, the energy to overcome drag does not depend on vehicle mass. It does depend on the size of the vehicle as represented by the frontal area. For low-speed driving, about one- fourth of the energy delivered by the drivetrain goes to overcoming drag; for high-speed driving, one-half of the energy goes to overcoming drag. Vehicle drag coefficients vary considerably, from 0.195 for the General Motors EV1 to 0.57 for the Hummer 2. Vehicle drag can be reduced through both passive and active design changes. The drag coefficient can be lowered by more aerodynamic vehicle shapes, smoothing the underbody, wheel covers, active cooling aperture control (radiator shutters). Active ride height reduction reduces frontal area and improves tire coverage. Narrower tires reduce frontal area. A 10 percent reduction in drag can give a 2.5 percent reduction in fuel consumption—more at high speeds, less at low speeds. A combination of technologies can reduce drag by 17-25 percent by 2030, and 30-38 percent by 2050. Improved aerodynamics could reduce fuel consumption by about 4 percent by 2030 and 8-9 percent by 2050. These changes could be implemented at low cost. F.1.1.4 Improved Accessory Efficiency • Heating, ventilation, and air conditioning—Air conditioning accounts for about 4 percent of LDV fuel consumption (EPA-NHTSA-CARB, 2010). Since the air conditioner is not operating during vehicle certification testing, there has been little incentive for manufacturers to improve air conditioning. EPA mileage labeling, however, does include air conditioner use, and new fuel economy and greenhouse gas regulations credit improved air conditioner efficiency. Multiple technologies exist for improving the efficiency of air conditioning systems, in particular in the compressor, air handling fans, and refrigeration cycles. These are estimated to reduce air conditioning related fuel consumption by 40 percent by 2016. Better cabin thermal energy management through use of solar-reflective paints, solar-reflective glazing, and parked car ventilation is projected to reduce air conditioner-related fuel consumption by 26 percent (Rugh et al., 2007). This study estimates 2030 fuel consumption reduction for improved air conditioning and thermal load management at 2 percent. BEVs and FCEVs do not have access to ICE waste thermal energy for heating. Heat pump technology can provide these vehicles both cooling and heating with improved efficiency. • Efficient lighting—The use of light emission diodes is claimed to reduce CO2 emissions by 9 gm/mi (Osram Sylvania, 2011). This is equivalent to a fuel consumption reduction of 2.6 percent while the lights are in use. • Power steering—The traditional hydraulic pump draws power from the engine whether the vehicle is turning or not. Replacing it with an electric motor, which operates only when needed, saves 2-3 percent of fuel consumption. Some weight reduction is realized and costs are similar to hydraulic systems. Both pure electric and hydroelectric systems have been used. Systems are not yet available for the largest 223

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vehicles, but are likely well before 2030. Electric power steering is required on vehicles with any electric drive mode. • Intelligent cooling system—The use of an electric coolant pump allows speed control and optimal operation. Engine friction is reduced by facilitating engine operation at the optimum temperature. An electric radiator fan, already used in most LDVs, is part of the system. Fuel consumption reduction is about 3 percent. • Energy generation (vehicle specific)—Vehicles with batteries for energy storage (HEVs, plug-in hybrid electric vehicles [PHEVs], BEVs, and FCEVs) provide an opportunity for charging from on-vehicle solar cells. The value of this technology in reducing fuel consumption depends strongly on vehicle location over a 24-hour period. With a nominal power level of 100 watts (W), a reduction of fuel consumption of 0.5 to 2.5 percent is projected, but is not considered in this study. Overall, energy consumption by accessories is estimated to drop 21-25 percent by 2030 and 30- 36 percent by 2050. F.1.2 Internal Combustion Engine and Powertrain Efficiency Improvements F.1.2.1 Engine Technologies Gasoline Direct Injection Engines Although the dominant technology used to control fuel flow in gasoline engines has been port fuel injection, engines with direct injection (DI) of fuel into the cylinders have been rapidly entering the U.S. fleet. Gasoline direct injection (GDI) systems provide better fuel vaporization, flexibility as to when the fuel is injected (including multiple injections), and more stable combustion. The rapid evaporation of the direct-injected fuel spray cools the in-cylinder air charge, reducing engine knock and allowing for higher compression ratios and higher intake pressures with reduced levels of fuel enrichment. Direct injection reduces fuel consumption across the range of engine operations, including high load conditions. Although current U.S. GDI systems are stoichiometric—the air/fuel ratio is set to provide exactly the amount of oxygen needed to combust the fuel, with no excess—future systems using spray-guided injection can deliver a stratified charge (delivering more fuel close to the spark plug) and can operate with a lean air/fuel mixture (e.g., excess air). This reduces the need to throttle the air intake, reducing pumping losses and fuel consumption. Such a system would require additional NOx controls beyond a three-way catalyst, such as a lean NOx trap, and would likely shift to stoichiometric operation at high load conditions. Ricardo (2011) projects a 3 percent benefit for stoichiometric DI engine, 8-10 percent benefit for stoichiometric DI turbo engines, 8-10 percent benefit for a lean DI engine, and 20-22 percent benefit for lean DI turbo engines in the 2020-2025 timeframe. Direct injection enables more effective turbocharging and engine downsizing. In a turbocharged engine, exhaust gases are allowed to drive a turbocharger turbine that compresses the air entering the engine cylinders. This increases the amount of fuel that can be burned in the cylinders, increasing torque and power output, and allows engine downsizing. The degree of turbocharging is enhanced by GDI because of its cooling effect on the intake charge and delay of knock. Ricardo (2011) expects turbocharged engines in the 2020-2025 time frame to have overcome many of the issues often associated with turbocharging (e.g., minimal turbo lag and a smooth acceleration feel), with one likely solution being two-stage series sequential turbocharger systems building on systems tested by General Motors (Schmuck-Soldan et al., 2011 from Ricardo report). Another engine/turbocharger combination, exhaust gas recirculation (EGR) DI turbo, recirculates cooled exhaust gas into the cylinder to reduce intake throttling (and pumping losses) and to manage combustion knock and exhaust temperatures (Ricardo, 2011). This engine allows operation without 224

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enrichment over a wider range of load and speed and by reducing knock still further, allows a higher compression ratio over that of a stoichiometric GDI engine, thus allowing even more downsizing. Ricardo (2011) projects a 2020-2025 benefit for this engine of 15-18 percent. Diesel Engines This report has not explicitly considered diesel engines. The committee considered at length whether or not to include separate calculations for diesel and gasoline engines. The current efficiency advantage of the diesel is widely known, and diesels have about 50 percent of the light duty market share in Europe, both of which argue for inclusion. It was ultimately decided that a diesel case would not add significant value to the results of this study, primarily because the efficiency advantage of the diesel will be much smaller in the future as gasoline vehicles improve. Current diesels have a higher level of technology than most gasoline engines, as it was needed to address drivability, noise, smell, and emission concerns. As this same level of technology (direct injection, sophisticated turbocharged systems, dual-path and cooled EGR) is added to the gasoline engine, the efficiency advantage of the diesel will be much smaller. Also, BMEP can be higher on gasoline engines than on diesels, at least without additional reinforcement of the diesel engine block (cost and weight), so more downsizing is possible with gasoline. Another consideration is that combustion technology by 2050 may blur, if not completely eliminate, the distinction between diesel and gasoline engine combustion. Given the reduced efficiency advantage of the diesel in the near future and the uncertainty about the relative benefits in the long term, there is little to be gained by adding a diesel case. It is also not at all clear that diesels will gain significant market share in U.S. LDVs. Diesels are inherently more expensive than gasoline engines. In addition, they always operate with a lean air/fuel mixture, requiring expensive NOx aftertreatment, and the late fuel injection creates a lot of particulates, requiring expensive particulate traps. It is expected that diesels will cost $1,500 to $2,500 more than equivalent performance gasoline engines. In most countries in Europe, gasoline taxes are higher than diesel taxes, so diesel vehicles can recoup this additional cost fairly quickly in fuel savings. However, in the United States, diesel fuel prices are higher than gasoline due to a worldwide imbalance between gasoline/diesel demand and refinery capacity. This makes for a much longer payback period that may not be acceptable to U.S. customers, especially as gasoline engine efficiency improves and hybrid alternatives come down in cost. Engine Friction Reduction Engine friction is an important source of energy losses. Engine friction reduction can be achieved by both redesign of key engine parts and improvement in lubrication. The major sources of friction in modern engines are the pistons and piston rings, valve train components, crankshaft and crankshaft seals, and the oil pump. Key friction reduction measures include the following (EEA, 2006): • Low mass pistons and valves, • Reduced piston ring tension, • Reduced valve spring tension, • Surface coatings on the cylinder wall and piston skirt, • Improved bore/piston diameter tolerances in manufacturing, • Offset crankshaft for inline engines, and • Higher efficiency gear drive oil pumps. 225

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Over the past two and one half decades, engine friction has been reduced by about 1 percent per year (EEA, 2006). Continuing this trend would yield about a 20 percent reduction by 2030, but considerably greater reduction than this should be possible. For example, surface technologies such as diamond-like carbon and nanocomposite coatings can reduce total engine friction by 10-50 percent. Laser texturing can etch a microtopography on material surfaces to guide lubricant flow, and combining this texturing with ionic liquids (made up of charged molecules that repel each other) can yield 50 percent or more reductions in friction. F.1.2.2 Transmission Technologies The primary advanced transmissions over the next few decades are expected to be advanced versions of current automatic transmissions with more efficient launch-assist devices and more gear ratios and dual clutch transmissions (DCTs). Transmissions with 8 and 9 speeds have been introduced into luxury models and some large mass market vehicles, replacing baseline 6-speed transmissions. The overdrive ratios in the 8- and 9-speed transmissions allow lower engine rpm at highway speeds, and the higher number of gears allows the engine to operate at higher efficiency across the driving cycle. Ricardo (2011) projects a 20-33 percent reduction in internal losses in automatic transmissions by 2020-2025 from a combination of advances, including improved finishing and coating of components, better lubrication, improvements in seals and bearings, better overall design, and so forth. Dual clutch transmissions, currently in significant use in Europe, will also improve with the perfection of dry clutches and other improvements, with an additional reduction in internal losses (beyond advanced automatic transmissions) of about 20 percent. F.1.2.3 Engine Heat Recovery (Vehicle Specific) About two-thirds of fuel energy is rejected as heat, roughly evenly divided between the engine cooling system (through the radiator) and the exhaust. Because the exhaust is at a higher temperature, heat recovery has been focused on this energy source. Most activity in this area has been focused on diesel engines used in trucks and off-road vehicles (NRC, 2010). These technologies are not applicable to BEVs or FCEVs. • Mechanical turbocompounding attaches a power turbine to the exhaust to extract energy, which is coupled to the engine crankshaft. This technology, applied to a diesel engine, is in production with a reduction in fuel consumption of 3 percent. A potential for up to 5 percent reduction is claimed. Performance is best at high load operation. The technology should be applicable to gasoline engines, which have higher exhaust temperatures than diesel engines but have the disadvantage of typically operating at lower loads. • Electric turbocompounding is similar to mechanical turbocompounding, but the power turbine drives a generator. The electricity can be used to supplement engine power through an electrical motor to drive accessories or to charge a battery in a hybrid system. Up to 10 percent fuel consumption reduction is predicted with 5 percent more commonly quoted. Such units are not yet available commercially. • Thermoelectric power generation utilizes a direct energy conversion device, for example Bi2Te3, located in the engine exhaust. BMW has demonstrated this technology on a gasoline engine vehicle and projects fuel consumption reduction of 2-3 percent on the U.S. combined cycle at a power level of about 100 W (BMW, 2009). At high-load conditions, reductions of 5-7 percent are projected. For LDV application, the most promising are the electric turbocompounding and thermoelectric technologies, used with hybrid propulsion systems, which have the necessary electric energy storage and 226

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drives. These technologies are at an early stage of development but should be commercially available by 2030. HEVs would likely benefit more than ICEVs from waste heat recovery, as generated electric power could be used in their hybrid propulsion systems or to recharge the battery. This analysis assumes waste heat recovery systems will be applied starting in 2035, and only to HEVs. The committee concluded that only mechanical turbocompounding is sufficiently advanced to be included in the study, and more efficient forms of waste heat recovery, such as Rankine cycle devices, were not included in the analyses. This report projects that 1 percent of the available combustion energy can be recovered in the midrange case and 2 percent in the optimistic case in 2050 at a cost of $200. F.1.2.4 Performance Versus Fuel Economy Historically, much of the improvement in efficiency has been diverted toward higher performance (i.e., weight and power), instead of improving fuel economy. It is difficult to assess the sensitivity of fuel economy to changes in performance, but it is clear that in the past up to 50 percent of the efficiency benefits may have been lost to performance increases. The committee considered the impacts of further performance improvements in the future on the calculated efficiency estimates. It concluded that the effect of performance on fuel economy trade-off will be very different in the future for the following reasons: 1. The historical performance increases occurred primarily during periods of little regulatory pressure. The committee’s goals can only be achieved with aggressive policies, including stringent efficiency standards. Such policies will influence manufacturers to emphasize fuel economy improvements over performance improvements. 2. The average performance level of vehicles in the United States is very high, both when compared historically and when compared with other countries. Certainly additional performance increases are possible, but it is reasonable to assume that performance expectations by the average consumer are not insatiable and will eventually reach a plateau. 3. The impact of power on efficiency will decrease in the future. The downsized, boosted engines needed to meet stringent efficiency standards will have a much larger region of high efficiency operation. Currently, powerful engines running at light load are operating at much lower efficiency. Future, downsized engines will maintain much better efficiency at these low load points. In addition, hybrid systems have the ability to turn the engine off and run on the motor alone, avoiding the lowest engine efficiency regions entirely. Thus, the fuel economy impact of increasing power or engine displacement will be much smaller on future engines. 4. The fuel cell stack is more efficient at low loads. This means that more powerful fuel cell stacks will have higher efficiency during normal driving, the reverse of the ICE situation. 5. Motors are also more efficient at lower loads, so a more powerful motor will also have higher efficiency during normal driving. The effect is smaller than it is for fuel cell stacks, plus a more powerful BEV likely needs a larger battery pack, which means more weight. But, overall, there is likely to be little or no tradeoff between power and efficiency on BEVs. Based upon the above, the committee decided that performance increases may not happen to a great degree and, if they did, would likely not have a significant impact on fuel economy in the future. More probable, under the assumptions of this study, is a reduction in performance. Some common metrics of performance that have a direct relationship to fuel consumption include interior volume, footprint, weight, acceleration (0-60 mph time), and hill climbing (gradeability at 65 mph). Additional performance metrics, not directly related to fuel consumption but often valued by consumers, include turning radius, smoothness of ride, noise, vibration, handling, braking, headlights, seat comfort, safety, ground clearance, load carrying, towing capacity, cabin cool-down time, and more. 227

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Fuel consumption decreases linearly with weight. Model year 2010 cars that, in general, weighed 10 percent less than average used 9 percent less fuel than average. For trucks, a 10 percent reduction in weight would yield a fuel consumption reduction of 8.3 percent. A reduction of footprint (product of the wheelbase and track distances) by 10 percent is associated with a reduction in fuel consumption of 13.1 percent for cars and 6.5 percent for trucks. In addition, a 10 percent reduction in car interior volume came with a 1.3 percent decrease in fuel consumption. Large fuel consumption reductions are available from downsizing at a purchase cost savings. Technology will play a role in making smaller vehicles as safe as the vehicles they replace. The attractiveness of smaller cars will be enhanced by including qualities common to larger vehicles, albeit at an increased cost. F.1.3 Modeling Hybrid Electric Drivetrains HEVs combine an ICE, electric motor(s), and a battery or ultracapacitor. All the energy comes from the fuel for the ICE. HEV types range from simple stop-start systems using a belt drive motor- generator 4 (or, more simply, a more powerful starter motor) and larger battery to more complex systems that allow electrical assist and/or electric drive with regenerative braking. The more complex systems, include P2 Parallel Hybrids (e.g., Hyundai Sonata hybrid), which has an electric motor inserted between the transmission and wheels, with clutches allowing the motor to drive the wheels by itself or in combination with the engine, or allowing the engine to drive the wheels without motor input; and powersplit hybrids (e.g., Prius), with two electric machines connected via a planetary gearset to the engine. There is disagreement about the fuel consumption benefit of advanced hybrid systems in the future, because hybrid systems will improve (more efficient components, and improved designs and control strategies), but advanced engines will reduce the same losses that hybrids are designed to attack (e.g., advanced engines will have reduced idle and braking fuel consumption, yielding less benefit from stopping the engine during braking and idling). Ricardo projects 2020-2025 city cycle fuel consumption (and CO2) benefits of 18-22 percent for P2 hybrids, 22-33 percent for power split hybrids, and some highway benefits, all compared to advanced DI engines with stop-start (Ricardo, 2011). F.1.3.1 Estimating Hybrid System Costs The committee considered three primary sources of information: the MIT 2007 report (Kromer and Heywood), the 2011 NRC report, and tear-down costs assessments conducted by FEV (FEV, 2012). The MIT report contains the following hybrid systems costs for a projected 2030 Toyota Camry ( Kromer and Heywood, 2007, Tables 51 and 53): • $300: Hybrid transmission/integration, • $200: Wiring and connectors, and • ($100): Credit for eliminating the conventional starter and alternator. Table F.2 contains cost estimates for the manufacturing cost (without retail price equivalent) for a high-volume Prius powersplit system (2025 costs calculated based on 2008 current cost estimate and assuming 2 percent annual cost reductions through 2025 for the electric air conditioning, high voltage cables, and the body/chassis/special components and 1 percent annual cost reductions for the other components) (NRC, 2011). 4 The belt-drive generator system may allow some engine boosting, thus a small degree of engine downsizing. 228

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FIGURE F.12 Breakdown of compressed hydrogen storage system costs at high-volume production using 2010 technology. SOURCE: Hua et al. (2011). F.4.1.6 Vehicle Safety The two primary features that distinguish FCEVs from conventional ICE vehicles with respect to safety are high-voltage electric power and hydrogen fuel. Safety of high-voltage electric power is managed on FCEVs similarly to HEVs, where safety requirements have resulted in on-road safety comparable to conventional ICE vehicles. Experience from decades of safe and extensive use of hydrogen in the agriculture and oil refining industries has been applied to vehicle safety and verified in vehicle maintenance and on-road demonstration programs. Fire risk is mitigated by the high dissipation rate of hydrogen, which is greater than gasoline fumes, and regulatory provisions for fuel system monitoring. Safety of high pressure onboard gaseous fuel storage has been demonstrated worldwide in decades of use in natural gas vehicles. Comparable safety criteria and engineering standards, as applied to ICEs, HEVs, and natural gas vehicles, have been applied to FCEVs (for example, Society of Automotive Engineers industry specifications: J1766, J2578, J2579, J2600, J2601, and J2719; and International Organization for Standardization specifications 14687-2, 15869, and 20100). The United Nations has drafted a Global Technical Regulation for hydrogen-fueled vehicles to provide the basis for globally harmonized vehicle safety regulations for adoption by member nations. F.4.2 FCEV Cost and Efficiency Projections 2020-2050 F.4.2.1 2020-2030 Fuel Cell System Cost Detailed analyses of current costs and expected technology advances that are already under demonstration have resulted in a fuel cell system cost estimate of $39/kW for a high-volume FCEV commercial introduction in 2015 (James et al., 2010). This estimate reflects recent advances in technology and material costs; for example, in both the cost and loading of precious metal in fuel cell 294

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6% Controls/ MEA Sensors Gaskets 18% BOP Stack 15% Bipolar Plates 22% Fuel Loop Air Loop $17/kW $22/kW 10% 45% GDLs Membranes 12% 12% Coolant Loop 27% 45% 55% Electrodes 33% FIGURE F.13 Breakdown of fuel cell system costs at high-volume production using 2015 technology (stack power density 1000 mW/cm2 with 0.15 mg/cm2 Pt loading). SOURCE: James et al. (2010). electrodes. The platinum (Pt) loading in an earlier-generation stack with ~80 g Pt at $32/g (2005 Pt price) would cost ~$2,500. If only 10 g Pt were required in a higher-technology alloyed-Pt stack, the cost would be only ~$600, even at the higher 2011 Pt price of $58/g. Figure F.13 shows the main sources of costs expected in 2015 for high-volume production. The total cost then is projected to be $39/kW. This report assumes $40/kW for the midrange in 2020. The optimistic case for 2020 is $36/kW, anticipating additional cost benefit from potential near-term technology developments, which are shown in Table F.29. All costing assumes commercial introduction of FCEVs at annual production volumes over 200,000 units, with the primary economy of scale occurring at 50,000 units (James et al., 2010). Estimates for 2030 costs of fuel cell systems vary with optimism for the timing of technology advances currently under development. Projections of fuel cell system cost up to 2030 are linked to the achievement of technology advances already under development (see Table F.29, “Near-Term” and “Mid- Term”). An important and unique attribute of the automotive fuel cell system is the early stage in its development and application for on-road vehicles. Historically, gains in weight, volume, efficiency, and cost between successive early generations of a new technology are much more substantial than between more mature generations as early designs and materials are rapidly simplified, transformed and refined. Estimates of 2-3 percent per year reductions in high volume cost in early generations of a technology and 1 percent per year in later generations have commonly been observed (EPA, DOT, CARB, 2010). Therefore, for purposes of this report, technology-driven cost reduction from 2020 to 2030 of 2 percent per year is midrange, and 3 percent per year is optimistic. These advances are considerably less than the recent rate of fuel cell cost reduction (Figure F.10), because observed documented trends in technology cost apply to technologies that are market ready, not to technologies in a pre-commercial prototype stage of development. The technology-driven cost projections for fuel cell systems are summarized in Table F.30. The fuel cell system costs are traditionally expressed as $/kW, because the change in cost of a system has generally been proportional to changes in vehicle power over the limited ranges of power currently used in FCEVs (James et al., 2010). However, significant deviation from a linear dependence of cost on net system power over a large range of vehicle power is expected for significant variations in vehicle power. This nonlinearity is difficult to project and is not included in cost estimation for this report. Nonlinearities are currently thought to be of secondary significance, 52 but there is little experience or analysis to substantiate that assumption. 52 The committee received confidential input from vehicle manufacturers and suppliers. 295

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TABLE F.29 Currently Recognized Opportunities for Technology Development for Improved Energy Efficiency and Cost Near Term (2020) 1. Storage—reduced carbon fiber usage in storage systems—improved winding patterns 2. Storage—improved methods for tank production 3. Storage and fuel cell system—simplified design (fewer and cheaper components) 4. Storage and fuel cell system—improved manufacturing processes 5. Fuel cell system—reduced use of platinum (platinum alloys; new catalyst structures) 6. Fuel cell system—reduced transport losses by refined management of reactant flows and hydration and improved electrode structure 7. Fuel cell system—optimized stack and balance of plant (BOP) with optimized battery supplement for transient power 8. Fuel cell system—reduced BOP size and complexity from optimized reactant flow fields (for decreased stoichiometry and resultant lower mass flow rates) 9. Fuel cell system—reduced BOP size and complexity from membranes tolerant of lower humidity and/or higher temperature operation (simplified water management, lower pressure, and smaller radiator) 10. Fuel cell system—catalyst structures that increase and maintain the effective surface area of chemically active materials 11. Fuel cell system—higher temperature membranes for increased activity with less catalyst Mid-Term (2030) 1. Storage—reduced cost of carbon fiber—new production and processing methods 2. Storage—reduced carbon fiber usage in storage systems—smaller or lower-pressure vessels (associated with increased fuel cell system efficiency) 3. Storage—efficient low pressure cryo-storage 4. Fuel cell system—new durable membrane materials for low cost volume manufacture, thin design and low resistance 5. Fuel cell system—rapid manufacturing techniques for layered materials and for integration of layered materials into unit pieces for quick assembly 6. Fuel cell system—low cost, conductive, chemically stable plate materials 7. Storage and fuel cell system—capacity downsizing related to reduction in vehicle weight and increased efficiency of fuel cell system 8. Further progress in near-term opportunities Long Term (2050) 1. Fuel cell system—catalysts that do not use precious metals 2. Fuel cell system—capability for efficient operation at less than 1.2 stoichiometry 3. Fuel cell system—novel, low cost thermal management 5. Fuel cell system—refined designs for fluid flow in fuel cell stacks 6. Fuel cell system—new membrane materials and processing methods 7. Fuel cell system—novel processing techniques for catalyst substrates, impregnation and integration With layered materials 8. Storage—new low cost, high strength composite materials 9. Further progress in near-term and mid-term opportunities 296

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F.4.2.2 2050 Fuel Cell System Cost Projections for 2050 shown in Table F.30 are based on technology achievements and refinements outlined in Table F.29 and on historical trends for cost improvement with advancing generations of mature technologies and manufacturing refinements (EPA, DOT, CARB, 2010). Historical trends include continuing technology advancement with further research and advances in new materials, analysis, simulation, and testing tools. Because of the expected major focus of fuel cell R&D on cost reduction prior to 2030, it is expected that subsequent cost reduction rates will not exceed norms for more mature generations of technologies (EPA, DOT, CARB, 2010). Therefore both midrange and optimistic cost estimates for 2050 include the 1 percent per year cost reduction rate associated with maturing technologies after 2030. Evaluation of potential world Pt supply to support FCEVs as 50 percent of the on-road LDV sales by 2050 was conducted by TIAX (Carlson et al., 2003), assuming the conservative achievement of 15 g Pt per FCEV by 2050. Key documented findings are the following: (1) there are sufficient Pt resources in the ground to meet long-term projected Pt demand; (2) the Pt industry has the potential for expansion to meet demand for 50 percent market penetration of FCEVs (15 g Pt/vehicle) by 2050; and (3) the price of Pt may experience a short-term rise in response to increasing FCEV penetration, but is expected to return to its long-term mean once supply adjusts to demand. Scaled to 10 g Pt per FCEV (already achieved by 2010), the same conclusions apply to 80 percent penetration of the LDV sales by 2050. F.4.2.3 2020-2050 Fuel Cell System Efficiency Near-term technology developments for fuel cell systems are expected to be focused on reduction in fuel cell system cost without significant gain in fuel cell efficiency. Therefore, the midrange 2020 fuel cell system efficiency is taken to be 53 percent, which is equivalent to the 2010 estimated on-road fuel cell system efficiency. The optimistic 2020 fuel cell system efficiency is taken to be 55 percent, reflecting minimal expectation for efficiency gains while resources are focused on cost reduction. 55 percent is consistent with a minimal 0.5 percent per year improvement in the loss fraction over the nominal 2010 efficiency in the DOE demonstration fleet. Due to the primary focus on cost reduction, projections for both 2030 and 2050 midrange and optimistic efficiencies are expected to reflect only minimal 0.5 percent per year reduction in the loss fraction from the respective 2020 values. Fuel cell system efficiency projections are summarized in Table F.31. TABLE F.30 Summary Fuel Cell System Cost Projections ($/kW) 2010 2020 2030 2050 Midrange 51 40 33 27 Optimistic 51 36 27 22 TABLE F.31 Summary of Fuel Cell Efficiency Projections 2010 2020 2030 2050 Midrange 53% 53% 55% 60% Optimistic 53% 55% 57% 62% 297

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F.4.2.4 2020-2030 Hydrogen Storage Cost The cost of a CFRC hydrogen storage tank varies with the pressure and volume capacity. At present, nominal storage of 5.6 kg of 70 MPa hydrogen costs ~$3,500 (Hua et al., 2011). Reduction in the cost of tanks can be expected from new manufacturing/design techniques and smaller hydrogen storage systems. Storage systems get smaller as vehicle demand for fuel is reduced with improved vehicle efficiency (vehicle weight, aerodynamics, rolling resistance and powertrain efficiency). Significant cost reduction from technology advancement within the 2010-2020 period is not expected due to current plans and capabilities of manufacturers for onboard storage. 53 The midrange hydrogen storage cost for 2020 is derived from the 2010 estimated cost by scaling the system to contain the volume of hydrogen needed to maintain vehicle driving range with the vehicle efficiency projected for 2020. The scaling is accomplished by recognizing that roughly 75 percent of storage cost is proportional to the volume of stored hydrogen (variable cost); the remaining 25 percent of cost (boss and valve hardware) is not changed by the quantity of stored hydrogen (fixed cost is not sensitive to vehicle efficiency) (Hua et al., 2011). This assumes that a reduction in volume of stored hydrogen is accomplished by reducing tank size rather than eliminating a tank. This is consistent with consideration of packaging constraints for moderate reductions in vehicle demand. Dividing the cost into fixed and variable fractions is a means of approximating nonlinearities in the dependence of the storage system cost on its volumetric capacity when variations in that capacity are not small. Estimates for midrange and optimistic 2030 technology-driven costs of hydrogen storage differ because of different estimates of the timing of technology advances currently under development (Warren, 2009) (Table F.29, “Near-Term” and “Mid-Term”). Several improvements in processing techniques have been identified (Warren, 2009) that are expected to reduce the cost of carbon fiber used in CFRC by 25 percent. That reduction is applied as a 1 percent per year midrange cost improvement from 2020 until 2040 to accommodate the technology development and its phased-in implementation into high-volume production. The 2030 optimistic cost projection assumes 2 percent per year technology- driven cost reduction from 2020 to 2030 in the variable cost fraction to accommodate full deployment of these new techniques for manufacture of carbon fiber by 2030. However, less expensive manufacturing techniques are needed for producing carbon fiber from polyacrylonitrile or other precursor materials and for manufacturing storage tanks from the carbon fibers. Project success and commercialization of redesigned storage systems by 2030 are not certain but eventually could reduce storage costs significantly. The fixed cost fraction, which is associated with flow-control equipment, is expected to have modest potential for cost reduction, because the technologies are mature. Therefore, a 1 percent per year cost reduction is applied to be consistent with historical improvements (EPA, DOT, CARB, 2010) in the design and materials used in mature technologies as they are applied in new areas, such as the 70 MPa compressed hydrogen application. The result is a projected 10 percent cost reduction in the fixed cost fraction over the 2020-2030 period. In addition to these technology-related cost projections, additional reductions can be expected when the storage system is downsized—when the volume of hydrogen that needs to be stored for full vehicle range is reduced in response to increased vehicle efficiency. This reduction in the variable fraction of the storage cost is directly proportional to the reduced vehicle load. The difference between cost projections with and without downsizing of the storage system is illustrated by the difference between Tables F.32 and F.33. 53 The committee received confidential input from vehicle manufacturers and suppliers. 298

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TABLE F.32 Technology-Driven Storage Cost Projections (constant 5.6 kg hydrogen capacity) 2010 2020 2030 2050 Midrange 5.6 5.6 5.6 5.6 Cost $ 3,500 3,500 3,165 2,589 $/kg-H2 625 625 565 462 $/kWh 19 19 17 14 Optimistic Cost $ 3,500 3,500 2,936 2,232 $/kg-H2 625 625 524 399 $/kWh 19 19 16 12 TABLE F.33 Illustrative Hydrogen Storage System Cost Projectionsa from Technology Advances (Design, Material, and Manufacturing) and Reduced Size (Hydrogen Capacity) 2010 2020 2030 2050 Midrange Capacity (kg) 5.5 4.6 3.8 2.8 Cost ($) 3,453 3,031 2,402 1,618 $/kg-H2 628 659 632 578 $/kWh 19 20 19 17 Optimistic Capacity (kg) 5.5 4.4 3.3 2.4 Cost ($) 3,453 2,938 2,055 1,326 $/kg-H2 628 668 623 553 $/kWh 19 20 19 16 a Costs based on illustrative hydrogen storage capacity requirements. F.4.2.5 2050 Hydrogen Storage System Cost The midrange estimate for 2050 hydrogen storage cost results from continuation of the technology-driven 1 percent per year cost improvement over the 2030-2050 period in recognition of research into improvements in CRFC winding patterns 54 and expectation of further improvements in manufacturing costs from added experience with high-volume production using new techniques (Warren, 2009). The result is an accumulated technology-driven cost reduction from 2020 to 2050 of 26 percent. As before, additional cost reductions result when the variable fraction of the storage system cost is scaled to accommodate the downsizing of storage associated with continually improving vehicle efficiency. The optimistic estimate for 2050 hydrogen storage cost assumes a more aggressive technology- driven 2 percent per year cost improvement applied to the variable cost fraction for an additional 10-year 54 The committee received confidential input from vehicle manufacturers and suppliers. 299

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period prior to 2050 in anticipation of aggressive research to reduce the cost of structural carbon or to find replacement materials or alternatives to compressed gaseous storage. Research on cost reduction of structural CFRC is expected to accelerate with the new market driver of its broadened application to airplane fuselages. And low pressure cryo-storage could become commercially viable. Greater cost reductions are possible with manufacturing breakthroughs for carbon fiber, but that is not assumed here. However, it is noted that a reduction in storage cost associated with achievement of a targeted <$10/kg carbon fiber and pressure shift to 50 MPa would be consistent with a cost reduction of 35-40 percent, the optimistic technology-driven projection in Table F.32. F.4.2.6 Trade-Offs with BEVs FCEVs, like BEVs, are electric vehicles having no GHG emissions. Both are “fueled” by an energy carrier (electricity or hydrogen) that can be produced from a myriad of traditional and renewable energy sources (biofuels, natural gas, coal, and solar-, hydro-, and nuclear power). Three primary considerations differentiate their prospects for introduction and acceptance as LDVs: vehicle attributes, infrastructure, and rate of technology development. • Vehicle attributes. FCEVs provide the full utility of current on-road vehicles. BEVs, however, require time consuming “refueling” (recharging) and only offer limited driving range between “refuelings.” In addition, FCEVs can be used to power a residence or business (or hydrogen fueling station) during electrical outages and, thereby, provide a form of back-up for the electrical grid, rather than the adding load for BEV recharging. Indeed, during an electrical outage caused by a winter storm, for example, a BEV could not be recharged to drive to a region with power and warm shelter. • Infrastructure. FCEV commercialization will require the installation of hydrogen fueling pumps (with supporting onsite fuel storage and fueling equipment) at conventional fueling stations. In addition, a significant installation of regional facilities for production of hydrogen will be required. BEV commercialization requires installation of charging stations in homes or secure and accessible locations, upgrade of neighborhood transformers, and increase in electrical generating capacity for vehicle charging outside today’s off-peak hours. Infrastructure considerations are discussed further in Chapter 3 of this report. Long-term customer acceptance of in-home, near-home, and workplace/shopping charging installations remains to be established. Home chargers can be provided with individual vehicle sales, allowing vehicle manufacturers to somewhat decouple BEV sales from reliance on an independent deployment of infrastructure. However, FCEV sales will depend on the availability of hydrogen fueling stations and, hence, will require large-scale coordination of infrastructure and vehicle producers. • Rate of technology development. A key requirement for realization of projected technology advances for battery and fuel cell systems is the continued dedication of R&D resources. Because demand for improved battery technologies is driven by their established application in portable communication/computer devices, prospects for short-term return on R&D investments are substantial. In contrast, commercial application of fuel cell systems in vehicles is not seen as an outgrowth of communication/computer technologies. Instead, it depends on the likelihood of a substantial transition of the transportation sector to hydrogen fueled vehicles. The assessment of the prospects for such a transition likely depends on whether government energy policy signals a commitment to support deployment of hydrogen infrastructure and vehicles. Otherwise, the continued dedication of substantial private R&D resources to fuel cell vehicle technologies may not continue to support the current rate of progress in fuel cell technologies. Projections of the timing and magnitude of improvements in efficiency and cost of fuel cell systems and the cost of hydrogen storage systems, as discussed in this chapter, are based on the fundamental assumption that resources—private and government—dedicated to R&D in support of fuel cell vehicles and hydrogen infrastructure are maintained at current levels or greater. 300

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F.4.3 Cost and Performance Evolution of a Fuel Cell Electric Vehicle As with BEVs, fuel cell vehicles currently are considerably more expensive than conventional ICEVs but have the potential to drop substantially in cost. The key factors in this expected cost reduction (aside from vehicle load reductions, which affect all vehicle regardless of drivetrain type) are expected improvements in efficiency and cost reductions in general electric drivetrain components (e.g., batteries and motors), expected strong increases in fuel cell efficiency, and strong expected cost reductions in fuel cell stacks and onboard storage costs. As shown in Table F.34, the overall effect of these factors will be to reduce vehicle costs by about $5,300-$6,600 by 2050, allowing fuel cell vehicles to have lower costs than their conventional ICE drivetrain competitors in 2050 (and possibly as early as 2030). Gasoline- equivalent fuel economy can range upwards of 170 mpg by 2050 and exceed 200 mpg in the optimistic case. TABLE F.34 Details of the Potential Evolution of a Midsize Fuel Cell Vehicle, 2010-2050 2010 2030 mid 2030 opt 2050 mid 2050 opt Fuel cell efficiency 53 55.3 57.5 59.6 61.6 Fuel economy, test mpge 94.1 125.8 149.5 170.4 211.3 Fuel cell power required, kW 110.8 91.6 85.6 81 71.2 Hydrogen required for 390 mile (test) range, kg 4.3 3.1 2.6 2.3 1.9 Fuel cell cost, $/kW 50 33 27 27 22 Variable hydrogen tank cost, $/kg 469 424 383 347 283 Incremental cost versus baseline, $ 8,554 3,747 2,133 3,281 1,961 Incremental cost versus conventional, $ 8,554 1,314 −62 −378 −1,442 F.5 REFERENCES Aachen. 2010. Stiffness Relevance and Strength Relevance in Crash of Car Body Components. Conducted by the Institute fur Kraftfahrzeuge at the University of Aachen for the Aluminum Association. May 2010. Available at http://www.autoaluminum.org/downloads/NHTSAESV.6.2011.pdf. Ballard Power Systems. 2006. CUTE: A Fuel Cell Bus Project for Europe Lessons Learned from a Fuel Cell Perspective. May 10 and 11. Available at http://cute-hamburg.motum.revorm.com/ download/pdf/ 1/16.30%20CUTE%20Presentation%20-%20Geoff%20Budd.pdf. Bandivadekar, A., .K. Bodek, L. Cheah, C. Evans, T. Groode, J. Heywood, E. Kasseris, M. Kromer, and M. Weiss. 2008. On the Road in 2035—Reducing Transportation’s Petroleum Consumption and Greenhouse Consumption. Available at http://web.mit.edu/sloan-auto- lab/research/beforeh2/otr2035/On%20the%20Road%20in%202035_MIT_July%202008.pdf. BMW. 2009. “Thermoelectric Power Generation—The Next Step to Future CO2 Reductions?!” Presentation by A. Eder, BMW Efficient Dynamics/Thermal Management, at the 2009 Thermoelectrics Applications Workshop on September 30. Available at http://www1.eere.energy.gov/vehiclesandfuels/pdfs/thermoelectrics_app_2009/wednesday/ eder.pdf. Carlson, E.J., M. Greenfield, Y. Huang, M. Noordzij, T. Rhodes, and J. Yurko, TIAX, LLC. 2003. Platinum Availability and Economics for PEMFC Commercialization. Subcontract Report. National Renewable Energy Laboratory. December. Summary slides available at http://www1.eere.energy.gov/hydrogenandfuelcells/pdfs/tiax_platinum.pdf. 301

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