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Review of the Research Program of the Partnership for a New Generation of Vehicles: Sixth Report 5 Major Crosscutting Issues This chapter first briefly reviews some advantages of a technology partnership, such as the PNGV program, and provides definitions of program success. The remainder of the chapter examines the major achievements and barriers, the adequacy and balance of the program and potential future directions, issues raised by the Tier 2 emission standards, and timely consideration of fuels issues for new automotive power plants. BACKGROUND The PNGV Concept The basic concept underlying the automotive industry/government partnership is the fulfillment of automobile-related societal goals, as perceived by the federal government, with minimum disruption to the industry’s ability to meet marketplace demands. The PNGV was formed to develop technology through cooperative research among the three automobile companies and federal research entities that would enable a substantial improvement in the fuel economy of new vehicles without sacrificing desirable market characteristics. If the PNGV program is successful, it would avoid the conflicts inherent in “technology-forcing” regulations, which run the following risks: requiring that technologies be introduced before predictable field performance and reliability have been established, possibly causing undesirable, and sometimes unexpected, consequences
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Review of the Research Program of the Partnership for a New Generation of Vehicles: Sixth Report increasing costs, causing a decrease in new car sales, thereby limiting the rate of improvement in the societal benefits of new technologies causing significant undesirable economic effects on the industry and the country A partnership for technology development has several advantages. The resources of both the industry and a variety of government laboratories and universities provide a broad base for research and create a shared understanding of the solutions and trade-off possibilities. The lessons learned from the program could be used to inform future public policy decisions that may be less disruptive to industry facing regulatory requirements. Ultimately, this approach might be extended to enable a more rapid deployment of effective solutions to a broad range of societal problems, and, at the same time, promote a better understanding of potential side effects of changes. Definitions of Program Success PNGV’s approach has been to set one “stretch” goal with specific criteria and a 10-year deadline for “production-ready” technology together with a “best-efforts” fuel economy target of 80 mpg (gasoline equivalent). The program also set two other goals to encourage the near-term application of research results. Success, therefore, can be defined in many ways. The committee used the following criteria for determining success: the attainment of all aspects of the “stretch” Goal 3, namely, the development by 2004 of a production prototype midsize sedan that meets all emission and safety standards, has a fuel economy up to 80 mpg, and costs no more than conventional 1994 family sedans, adjusted for economics the development of vehicles by 2004 with a fuel economy and cost trade-off that maximize potential market penetration and meet Tier 2 emission requirements the transition of as much of the technology developed as possible to a wide range of production vehicles (Goal 2) with significant progress toward a state of technology beyond 2004 that will be much more fuel efficient In the committee’s view, the simultaneous attainment of the three critical requirements (emissions, fuel economy, and cost) of Goal 3 by 2004 is very unlikely. Although the 80-mpg fuel economy level appears to be technically feasible, the cost requirement is clearly unattainable with known or projected technological development in the program schedule (2004). Also, it appears that meeting the Tier 2 emissions standard will result in a fuel economy well below
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Review of the Research Program of the Partnership for a New Generation of Vehicles: Sixth Report 80 mpg, and, even then, it will be difficult to achieve in production vehicles with adequate probability for meeting the certification period of 100,000 miles. The development of vehicles of radical design (e.g., a fuel-cell vehicle) for mass production by 2004 is also highly optimistic. The second definition of success, although it does not include the cost parity envisioned in the original goal, recognizes that the ultimate objective of reducing fuel consumption would be served by achieving large market penetration of the new technologies. In effect, 60 mpg instead of 80 mpg would still represent a major reduction in fuel consumption. For a car traveling 15,000 miles per year, the baseline vehicle would use 560 gallons, the 60-mpg car 310 gallons, and the 80-mpg car 190 gallons. In the third definition, success is reflected by the commercial introduction of radically new technology, such as a fuel-cell power plant, rather than the construction of a specific short-term prototype production vehicle. MAJOR ACHIEVEMENTS AND TECHNICAL BARRIERS Goals 1 and 2 Although most of the discussion about achievements and barriers is directed toward Goal 3, the committee found evidence of continuing and significant progress toward achieving goals 1 and 2: the successful completion of a project to demonstrate continuous cast sheets of Series 5000 aluminum for body structures and a follow-up project to develop similar processes for exterior body parts several smaller efforts to expand aluminum manufacturing and assembly capabilities and an alliance between the automotive and aluminum industries to address standardization, scrap recovery, and other issues cost reduction of carbon-fiber composites, improvement of their properties, and development of new manufacturing techniques, as well as the recycling and design of hybrid material bodies the development of techniques for predicting aluminum springback Goal 3 Achievements Substantial technical progress has been made in reducing the energy required to propel the vehicle (e.g., reduced mass, drag, etc.) and supplying auxiliary loads (e.g., heating, air conditioning, etc.). Simultaneous efforts have resulted in continued improvements in the efficiency and performance of power plants (e.g., 4SDI engines, fuel cells), performance and life of energy storage devices (batteries), and in the development of modeling and simulation techniques. The
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Review of the Research Program of the Partnership for a New Generation of Vehicles: Sixth Report three concept vehicles described in Chapter 4 show the results to date of these substantial efforts. Major achievements for specific components are detailed below. Vehicle Engineering A number of accomplishments have been achieved in vehicle engineering, including the following: the fabrication and testing of a lightweight hybrid material body to validate weight reduction of more than 40 percent the completion of an energy-efficient occupant-comfort project with a 75 percent reduction in required energy achieved, for example, by reduced thermal mass of the vehicle interior, improved efficiency of the heating and cooling systems, and optimized thermal management the completion of a lightweight interior project demonstrating a 157-lb (71-kg) interior weight reduction initiation or continuation of projects to address issues for a high (42 percent) payload/curb weight ratio, low rolling resistance (run-flat) tire, underbody airflow management, and energy-efficient side window development Engines and Fuels The following accomplishments have been achieved in the engines and fuels areas: New collaborative projects have been initiated in advanced combustion and emission controls (e.g., Detroit Diesel and Johnson-Matthey; Cummins Engine Company and Engelhard). Other continuing projects are advancing the understanding of catalysts, as well as defining fuels issues. SNL has developed a new catalyst with lower “light-off” temperature and better NOx reduction. SNL is also pursuing a novel means for reducing PM emissions, improving the effectiveness of EGR, and gaining a better understanding of combustion processes. LANL has developed a new zeolite-supported catalyst to improve NOx reduction and has formed promising microporous catalysts. A project by Industrial Ceramic Solutions has resulted in a PM filter that can remove up to 90 percent of diesel particulates and can be regenerated at idle using microwave techniques. Southwest Research Institute has demonstrated that fuel formulation could reduce diesel PM emissions by 50 percent and NOx by 10 percent. ORNL is using its refinery models to evaluate the impact of various formulations on the cost of diesel fuel.
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Review of the Research Program of the Partnership for a New Generation of Vehicles: Sixth Report PNNL has developed and tested a plasma catalyst that shows high conversion rates even in the presence of sulfur. Batteries Accomplishments in the battery area include the following: receipt and evaluation of a 50-V NiMH module from VARTA receipt of four Li-ion modules from SAFT for testing the initiation of a project to build a 300-V system at SAFT the identification of a Li-ion electrochemistry projected to increase calendar life from two years to three to five years better understanding of failure mechanisms and abuse tolerance issues the incorporation of NiMH batteries in the Prodigy concept vehicle the incorporation of Li-ion batteries in the ESX3 concept vehicle the incorporation of NiMH (and later lithium-polymer) batteries in the Precept concept vehicle Power Electronics The power electronics and electrical systems area has made progress in the following areas: SNL is improving DC high-voltage-bus capacitors. Results to date indicate that improved performance and reduced cost are feasible. A project at ORNL is helping to assess the mechanical reliability of electronic ceramic devices and to identify less expensive alternatives through mechanical characterization. ANL and ORNL are working to develop processes to fabricate neodymium-iron permanent magnets with up to 25 percent higher magnetic strengths than with available magnets. A facility has been completed and characterization has begun. ORNL has developed a 100-kW inverter with a power density of 11 kW/kg and is working with ORNL, Wright Patterson Air Force Base, the Electric Power Research Institute, the U.S. Department of Defense, and SNL on a 100-kW, reduced cost, motor controller. Fuel Cells The following significant fuel-cell developments have been made: the operation of an Epyx gasoline (fuel-flexible) fuel processor in conjunction with a 10-kW Plug Power PEM stack
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Review of the Research Program of the Partnership for a New Generation of Vehicles: Sixth Report the demonstration of microchannel fuel processing of iso-octane (PNNL) the demonstration of a new higher temperature nonair-sensitive fuel reformer catalyst (ANL) the demonstration of a much more CO-tolerant anode (LANL) industry demonstrations of a high power density stack (AlliedSignal), low-cost composite bipolar plates (Institute for Gas Technology), and low-cost membrane electrode assemblies (3M) continued improvements in modeling and simulation (ANL, LANL) the demonstration of production techniques for low-cost molded bipolar plates (LANL, Premix, Inc.) Goal 3 Barriers In spite of substantial accomplishments in virtually every area of PNGV activities, formidable barriers remain in virtually every area. New business arrangements, such as the Daimler-Chrysler merger and the Delphi spin-off from GM, as well as the fact that the program has moved into the prototype-development phase, have made reaching consensus on precompetitive projects more difficult. Neither aluminum nor composite materials are yet projected to reach costs competitive with steel for most major vehicle components. Nevertheless, aluminum and composite materials are essential to meeting the weight reduction targets. To meet projected emission requirements, CIDI engines will require a new fuel (e.g., with low sulfur and aromatics), a low-cost after-treatment system with NOx reduction efficiencies of more than 75 percent, at least a 50-percent effective PM trap, and a minimal effect on fuel economy. New sensor and control technology will be necessary, as well as cost reductions for common-rail fuel injection, for all 4SDI engines. For advanced CIDI engines, spark-ignition, direct-injection engines, and gasoline-fueled fuel-cell systems, either a low-sulfur fuel (e.g., <10 ppm) or an onboard method of removing sulfur will be necessary to avoid the deactivation of catalysts. EPA recently proposed a diesel fuel sulfur control requirement of no greater than 15 ppm beginning June 1, 2006 (EPA, 2000). Costs of batteries are still projected to be at least three times targeted costs. Both life and abuse tolerance issues must also be resolved. System complexity and operation under all ambient conditions are major problems for gasoline (fuel-flexible) fuel-cell systems, and projected costs are still about six times too high for a cost-competitive power plant.
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Review of the Research Program of the Partnership for a New Generation of Vehicles: Sixth Report The size and weight of fuel-cell fuel processors are still much too high. No liquid fuel-cell system tests, or even projections of known technologies, indicate start-up times of less than several minutes, which will not be acceptable to consumers. Better oxygen reduction catalysts and higher CO tolerance will be necessary to move towards fuel-cell cost and performance targets. An efficient, lightweight, low-cost, quiet, fuel cell compressor/expander has not yet been designed. High-volume, low-cost manufacturing techniques will have to be developed for much of the power electronics. Integrated thermal management for power electronics, which will be necessary for efficiency, life, size, cost, and performance, is still complex and costly. Fuel supply infrastructures for fuels other than gasoline have yet to be put in place. ADEQUACY AND BALANCE OF THE PNGV PROGRAM Distribution of Funding Figure 5-1 shows an industry analysis of funding by technology for PNGV from the DOE Office of Advanced Automotive Technologies over the life of the PNGV. The decrease in funding for hybrid propulsion systems since 1998 is substantial, as is the corresponding increase in funding for fuel cells. The decrease in hybrid systems was apparently caused by the conclusion of the DOE contract for the Hybrid Propulsion System Development Program and was more than compensated for by the increase in industry effort on hybrid systems for the 2000 concept cars. The increase in funding for fuel cells was apparently the result of optimism about their eventual success. The committee believes government funding for longer range, precompetitive research and industry efforts focused more on near-term development are entirely appropriate. Figure 5-1 shows that total DOE funding in 2000 is expected to be approximately $128 million. This, of course, is not the entire funding for PNGV, and DOE’s allocation among technologies does not represent the overall distribution of effort among technologies for the PNGV. About another $110 million of PNGV-related funding is expected to be provided by other government agencies (the U.S. Department of Commerce, EPA, U.S. Department of Transportation, National Science Foundation), perhaps half of which will go to emissions control and half to long-range research. The committee was informed that USCAR solicited its members, on a confidential basis, for overall figures on expenditures for “PNGV-related research” and arrived at a total investment for 1999 of
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Review of the Research Program of the Partnership for a New Generation of Vehicles: Sixth Report FIGURE 5-1 Distribution of DOE’s Office of Advanced Automotive Technologies budget for PNGV (by technology). Source: PNGV, 1999b. $982 million. The three USCAR companies estimated that their investments for each of the previous three years of the program was approximately the same. This very large investment (far above the program’s expected 50/50 government/ industry matching level) represents a major effort on the part of the industry partners to develop the concept cars for 2000.
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Review of the Research Program of the Partnership for a New Generation of Vehicles: Sixth Report Criteria for Adequacy and Balance The allocation of resources (e.g., money, people, and facilities) to the PNGV program should optimize the chance of success of the program. Critical criteria for judging the adequacy and balance of the program are listed below: Are some important projects receiving too few resources? Are some projects receiving too many resources or duplicating other efforts? In the face of limited budgets, should some projects be reduced in favor of higher priority projects? Should some projects with poor chances of success be eliminated? In short, major efforts should be devoted to solving major problems, which are listed below: Fuel economy and emissions trade-offs. Radical after-treatment technology will reduce fuel economy of the CIDI engine, and the substitution of a gasoline spark-ignition engine to make it easier to attain the emissions and cost goals will still compromise fuel economy. However, the gasoline engine uses technology that is more developed and much closer to production readiness. A comparison of the fuel economy outcome of these two engine applications would be very useful. Meeting Tier 2 emission requirements with a CIDI engine. After-treatment systems for control of NOx and PM emissions from CIDI engines are under intensive study, but the proposed systems appear to be cumbersome, expensive, and not effective enough to meet Tier 2 standards. The possible emission benefits of an HEV configuration with electric motors and batteries have not yet been determined and should be an immediate subject of study in the PNGV. Optimizing the system for emissions rather than for fuel economy should also be given immediate consideration. High costs. Cost is a serious problem in almost every area of the PNGV program. In fact, DaimlerChrysler announced that the selling price of its concept HEV, the ESX3, if put into production, would be $7,500 more than for a conventional car. Costs of most components in the proposed vehicle systems are above the target values, and rudimentary estimates of the cost penalties for complete vehicle systems are several thousands of dollars. Systems analysis. Reasonable systems analysis tools have now been developed, but, as yet, the PNGV has not applied them to the many outstanding questions of HEV design and performance. Both emissions and costs remain to be modeled. Systems analysis should be used for
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Review of the Research Program of the Partnership for a New Generation of Vehicles: Sixth Report trade-off studies, which will be critical to decisions on program direction and the actual design of systems. Battery and power electronics cost and performance. Both of these are far from their targets, which could well be a barrier to the realization of a market-acceptable HEV. Technical breakthroughs or strategies to overcome this barrier will be necessary. Figure 5-1 shows that the major DOE funding is being devoted to some of these major problems, namely, emissions after-treatment, high-power batteries, and power electronics. The development of HEV propulsion systems is the object of major efforts by industry, and the committee was reassured to see that serious concerns about costs were raised in all of the presentations at the committee meetings. It was not clear from the estimates provided to the committee whether or not systems analysis is being appropriately funded, but more effort in this area is clearly needed. Long-Range vs. Short-Range Research and Development If one adopts the first definition of success (meeting all aspects of Goal 3 with a production prototype by 2004), then the PNGV has very little time and faces immense challenges. To satisfy this definition of success, PNGV would have to focus more on the major problems listed above, which probably would require cutbacks in other longer-range projects, assuming funding did not increase. If one adopts the second definition of success (fuel economy/cost trade-off to maximize market penetration and meet Tier 2 standards), then development can proceed along more orderly lines with a broader program, a better chance of achieving breakthroughs, and a better chance of having a marketable product with reliable performance. To satisfy this definition of success (which is favored by the committee), the federal administration and Congress (if they want to promote the early deployment of the high fuel economy PNGV-type vehicles) may have to evaluate the advisability of temporary incentives (e.g., tax rebates) to offset the higher initial vehicle costs. Adopting the third definition of success (to pursue Goal 2 aggressively and work toward fuel efficiency beyond 2004) would leave time to solve the major problems listed above and would allow for a more deliberate allocation of resources for Goal 2 and a drastic reduction in funding, or perhaps the abandonment of projects that have limited chances of success. Fuel-cell vehicle research could be the major focus of continuing efforts because fuel-cell vehicles appear to be far from production-ready at this time. The committee encourages the PNGV leadership to develop specific objectives for the production-prototype phase of the program with the following objectives in mind. First, each automotive company should develop production-feasible
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Review of the Research Program of the Partnership for a New Generation of Vehicles: Sixth Report vehicles that come as close as is practical to the original vehicle performance objectives of Goal 3, meet the mandated emission requirements, and balance the inevitable shortfalls in fuel economy, vehicle performance, and affordability to maximize potential market acceptability. Second, production-feasible versions of new PNGV component technologies that can, in an evolutionary way, be incorporated into new vehicle designs under Goal 2, should be developed. The first objective will continue to “stretch” the new technologies and system concepts that have the potential to provide large improvements in fuel economy in the vehicle fleet. The second objective will prompt the development and application of component technologies critical to improving fuel economy. In the committee’s judgment, the Tier 2 NOx and PM emission standards as currently promulgated could potentially exclude the CIDI internal combustion engine, with its significant fuel economy benefit, from early introduction in the United States. Even if it is not excluded, measures to meet the Tier 2 standards may reduce the CIDI engine’s fuel economy to such an extent that it is no longer more efficient than alternative engines. Therefore, the new emissions requirements may require PNGV to shift its development efforts away from the highly efficient CIDI engine and toward the adaptation of other internal combustion engines that have more potential for extremely low emissions. USCAR and the government agencies involved in the PNGV should begin serious discussions about whether lesser improvements in fuel economy with the alternative engines available for the next phase of the program (the 4SDI spark-ignition engine and the port fuel-injected gasoline spark-ignition engine), which have significantly better potential for meeting the Tier 2 emission levels, is an appropriate trade-off from a national perspective. A wiser choice might be to extend the deadline for meeting the fuel economy target and lower emissions objectives and allow more time for the development of new fuel economy technology. PNGV will have to clarify the objectives of the production prototype phase of the program, especially in light of the changed emission standards. Constraints Budgeted federal expenditures are an obvious constraint to PNGV’s overall efforts, as well as to some individual projects. PNGV management does not have complete control over these amounts. By the same token, they have little control over the expenditures of industry in support of PNGV. In 1999, the industry clearly put a tremendous effort into developing and producing the concept vehicles, which have addressed nearly all of the major problems and made a giant leap toward satisfying the PNGV goals and defining the remaining challenges. Adequacy of Resources The adequacy of funding of PNGV is difficult to assess because the funding
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Review of the Research Program of the Partnership for a New Generation of Vehicles: Sixth Report figures provided to the committee are incomplete. It could be said that, because progress toward Goal 3 appears to be insufficient to attain the objectives by 2004, the resources are inadequate. However, the industry partners have stated that the greatest limitation they face is the lack of talented people rather than the lack of money and that new ideas (breakthroughs) are needed more than dollars. The committee is inclined to agree, although increased funding might accelerate some projects and support a broader program with more likelihood of breakthroughs. However, the committee could find no specific areas in the PNGV program that are starving for funds. Therefore, the committee concluded that the overall supply of resources is appropriate. Balance of Resources The balance of resources in PNGV is even more difficult for the committee to assess than funding because no data are available on the industry distribution of funding by project. The balance shown in Figure 5-1 appears to be appropriate based on the past history of PNGV, if government funding is supposed to be applied mainly to long-range R&D. The committee assumed that, in the course of their development of the concept vehicles, industry resources were directed heavily toward solving the major problems of HEV optimization. However, looking ahead to 2004, a different balance of effort will be required, and the new balance will depend heavily on the course each company chooses to follow. For example, if the companies choose to continue working toward production prototypes with a CIDI engine in an HEV configuration, then a major effort will have to be mounted on emissions control for that power plant and a determination made of the benefit of optimizing that system for emissions control rather than for efficiency. This determination will also determine the fuel economy and cost penalties of meeting the Tier 2 emission standards with whatever technology can be developed. If the companies choose to replace the diesel engine with a gasoline spark-ignition engine, which they have said can meet the Tier 2 requirements, then the optimized fuel economy of that configuration can be compared to the fuel economy of the diesel system. The gasoline system will probably have a somewhat smaller cost penalty than the diesel configuration and reach production readiness more quickly. The committee believes that both of these options should be investigated using the best systems analysis and experimental evidence available, and the balance of future R&D should be adjusted according to the results. Cost obviously remains a serious problem in almost all areas of PNGV and will have to be addressed between now and 2004. Although the problem of cost has received more attention in the past year by the PNGV technical teams, no major changes in resource allocation have been made as a result. The federally funded longer term research shown in Figure 5-1 may well be continued in anticipation that breakthroughs useful to the industry will be made. However, industry representatives have complained that much of this research is
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Review of the Research Program of the Partnership for a New Generation of Vehicles: Sixth Report not likely to be helpful in the near term. Better communication between the federally funded researchers and industry engineers might correct this problem. With no breakthroughs, the committee now believes that the likely outcome for 2004 will be an HEV system that approaches the Tier 2 emission standards but has a fuel economy somewhat lower than that of the concept cars and a cost several thousand dollars higher than conventional vehicles. Based on the data presented to the committee, the fuel-cell vehicle program (and its required infrastructure) appears to be on a separate, longer range schedule that extends beyond the 2004 production-prototype development time frame. The federal resources for fuel-cell vehicles seem to be appropriate for this longer range technology, and industry appears to be devoting substantial resources to fuel cells. Because work on the fuel-cell vehicles has made considerable progress and is still considered promising for beyond the 2004 milestone, the committee sees no reason for reallocating those resources. Recommendation Recommendation. At this stage of the program, PNGV should direct its program toward an appropriate compromise between fuel economy and cost using the best available technology to ensure that a market-acceptable production-prototype vehicle can be achieved by 2004 that meets Tier 2 emission standards. FUEL ECONOMY AND EMISSIONS TRADE-OFFS Although the emission levels for the new generation of vehicles expected to result from the PNGV program were not quantified in goals 1, 2 or 3, it was stated that they would be the emission standards in place for 2004 for a PNGV-type vehicle. At the outset of the PNGV program, the emission design targets were 0.20 g/mile for NOx and 0.04 g/mile for PM. In October 1997, almost coincidentally with the PNGV technology selection process (the downselect process), PNGV established new research targets of 0.20 g/mile for NOx and 0.01 g/mile for PM in anticipation of more stringent regulations. These levels represented an exceedingly difficult challenge and technology stretch for the combustion and after-treatment systems under consideration. Based on the quantitative goal for vehicle fuel economy stated in Goal 3, and because significant advances were being made on the CIDI engine emissions control system, the CIDI engine was selected as the most fuel efficient power train likely to be available in the time frame of the program. A major investigation of the effects of fuel composition on the system efficiencies was also integrated into the program (see Chapter 2). Although the new emission objectives were formidable, the emerging technologies seemed to have the potential to meet them. On May 13, 1999, EPA announced its proposed Tier 2 emission standards,
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Review of the Research Program of the Partnership for a New Generation of Vehicles: Sixth Report which introduced another significant tightening of the emission targets for the PNGV vehicle. The proposed standard mandated fleet averages of 0.07 g/mile NOx and 0.01 g/mile PM, including light trucks and SUVs weighing 8,500 lbs or less. Thus, to meet the Tier 2 targets, significant reductions in NOx emissions and PM emissions would be required compared to the targets in place at the outset of the program. Although PNGV continues to work toward improving fuel economy, almost all of the CIDI/4SDI program resources have been shifted to investigating advanced emission after-treatment technologies because PNGV believes (and the committee concurs) that no combustion engine will be able to meet the Tier 2 emission levels without them. The Tier 2 standard was finalized and announced by the federal administration on December 21, 1999. Meeting the Tier 2 standards for diesel engines will likely require new catalytic materials and new emissions control concepts. These Tier 2 emission standards are clearly “technology-forcing” regulations. The data on which EPA claims to have established their feasibility are not statistically significant (Federal Register, 1999). The loss in fuel economy consequent to meeting these standards will depend on the effectiveness and cost of technologies yet to be developed. EPA has acknowledged that reduced sulfur content of the fuel, for both gasoline and diesel engines, will be necessary for the efficiency and durability of new after-treatment systems, but the mechanism for reducing sulfur content and the ultimate level of sulfur have not been determined, although EPA recently proposed a requirement for diesel fuel of no greater than 15 ppm. Although emissions of greenhouse gases to the atmosphere are not currently regulated, many concerns have been raised about their potential for contributing to climate change. If hydrocarbon fuels are the source of energy for the vehicle power train (a CIDI or any other engine), the most efficient power train will also emit the least amount of carbon dioxide, which would also help reduce the emissions of greenhouse gases to the atmosphere. Concerns about reducing emissions of greenhouse gases has stimulated a large increase in the use of diesel engines in Europe and the rest of the world, for both trucks and passenger cars. The new standards will certainly require that the PNGV program reassess the relative merits of the CIDI engine and the gasoline spark-ignition engine as its power plant of choice and will certainly reduce the likelihood of meeting the 80 mpg fuel economy goal. PNGV believes that, in the time frame of the program, the best hope of reaching the fuel economy goal of 80 mpg is with a CIDI engine. However, the engine most likely to meet the Tier 2 emissions standard is the gasoline homogeneous stoichiometric combustion engine, for which the exhaust-gas after-treatment system is the most advanced. Unfortunately, this engine also has the lowest energy efficiency of the candidate engines under investigation. The ultimate comparison between the efficiency of these two engines will be determined only when both systems have been developed and certified to meet the Tier 2 standards.
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Review of the Research Program of the Partnership for a New Generation of Vehicles: Sixth Report Fuel-cell vehicles have the potential for meeting future emission requirements, as well as providing gains in energy conversion efficiency, but not by the 2004 milestone of the PNGV program. Many technical issues for fuel-cell vehicles remain to be solved, including reducing the high cost of the technology. The level of emissions from the fuel-cell vehicle depends on whether an onboard fuel reformer is used to produce hydrogen, and which fuel is used in the reformer as the source of hydrogen (see the committee’s fourth and fifth reports for more discussion [NRC, 1998, 1999]). No meaningful data are available to assess these systems because most of the expected emissions will come from start-up and transients, and no complete and integrated systems have been operated to date. An onboard reformer would substantially reduce the overall efficiency of the fuel-cell system. Storage of hydrogen fuel would result in a more efficient power plant, but the infrastructure for dispensing hydrogen for large-scale automotive use has not been defined and could not be put in place by 2004. Recommendation Recommendation. PNGV should quantify the trade-off between efficiency and emissions for the power plants under consideration. The PNGV systems-analysis team should develop and validate vehicle emissions models of sufficient sophistication to provide useful predictions of the emissions potential for a variety of engines (e.g., the compression-ignition direct-injection engine, the gasoline direct-injection engine) and exhaust-gas after-treatment systems in various hybrid electric vehicle configurations. The models could be used to help PNGV evaluate the feasibility of meeting the Environmental Protection Agency’s Tier 2 emissions levels and the fuel economy levels that could be achieved with various vehicle system configurations. The impact on greenhouse gas emissions also should be determined. These data should then be used to help establish a plan for the next phase of the program. FUEL ISSUES Reducing automotive fuel consumption in the transportation sector will require the widespread availability of affordable vehicles and fuels that meet the requirements of these vehicles. As the committee pointed out in previous reports, the primary vehicle power plants under consideration by the PNGV program could have wide-ranging effects on the fuels industry (NRC, 1998, 1999). Thus, to ensure the availability of the required fuels, the petroleum industry must be involved in the program in a timely fashion. Each of the vehicle power-plant options under development in the PNGV program for achieving the fuel economy goal of up to 80 mpg has important
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Review of the Research Program of the Partnership for a New Generation of Vehicles: Sixth Report implications for the composition of fuel. The primary power plant systems under consideration are the CIDI engine in an HEV configuration and fuel cells. Fuels for CIDI Engines The CIDI engine has substantial benefits in fuel economy compared to gasoline engines, but emissions of PM and NOx are a serious problem. Modern cylinder-injection, high rail pressures, and closed-loop controls can dramatically reduce these emissions but most likely cannot meet the EPA Tier 2 standards with current diesel fuel, even with PM traps and NOx absorbers. Therefore, PNGV is investigating changes in fuel characteristics, such as volatility, aromatic content, and sulfur content, as well as the addition of oxygenates. A reduction of sulfur concentrations in the fuel to less than 10 ppm alone would require major modifications to refineries to produce significant commercial quantities of fuel and would increase the cost of diesel fuel. The low sulfur in the fuel would, in turn, improve the effectiveness of vehicle emission control systems. Thus, there are trade-offs between fuel and vehicle costs. Refineries are highly interconnected, interrelated systems, and changes in one product output affects other product outputs. In U.S. refineries today, about 50 percent of crude oil is converted to gasoline. This is accomplished by a combination of recovering gasoline fractions found naturally in crude oil, cracking high molecular weight streams to gasoline, converting low molecular weight streams to gasoline, and upgrading the gasoline to meet requirements, such as octane and sulfur level. On a volumetric basis, the amount of diesel fuel produced is about 30 percent of the amount of gasoline produced. If significantly more diesel fuel relative to gasoline were required, processing schemes would have to be modified. In addition, less hydrogen would be produced, and, if the sulfur level in diesel fuel were restricted, more hydrogen would be required to remove the sulfur as hydrogen sulfide. In many refineries, this combination of circumstances would most likely lead to a hydrogen deficiency and the need to build additional hydrogen plants. In the face of these challenges, the PNGV program has been devoting more attention to fuel composition issues and working with individual petroleum companies but has not yet established an overall coordinated mechanism to determine the commercial trade-offs between engine systems and fuel compositions. For example, a PNGV/oil company ad hoc test program has been initiated to identify diesel fuels and fuel properties that could facilitate successful use of the CIDI engine in the United States. Three auto companies, three oil companies, and DOE are involved in this program (see Chapter 2). In addition, individual auto/oil company programs have been initiated, and EPA is pursuing programs related to the regulation of fuel composition to improve air quality. CARB also has a program, the California Fuel Cell Partnership, to develop fuels for fuel cells. This program is also looking into fuel choice and infrastructure issues as well.
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Review of the Research Program of the Partnership for a New Generation of Vehicles: Sixth Report DOE has drafted a new Ultra Clean Transportation Fuels Program Plan that proposes to involve both energy and auto companies in developing fuels appropriate for advanced CIDI engines and fuel cells (Chalk, 2000). The overall mission of the program is to pursue, in cooperation with industry, technologies and systems for advanced highway vehicles that improve energy security, environmental quality, and U.S. competitiveness. The fuels in the program will include fuels from renewable energy sources, petroleum, coal, and natural gas, and the objectives include reducing smog-forming emissions and greenhouse gas emissions. As DOE finalizes the plan for this program, the committee encourages DOE to focus on longer term objectives, such as the production of biofuels, and to defer to industry on shorter term objectives, such as the production of gasoline and diesel fuels with specific sulfur levels and engine optimization studies. Programs by other government agencies could provide useful information about changes in fuel composition. Based on past experience, significant modifications required in the marketplace will take more than five years to define the commercial fuel specifications and design and build the necessary refinery facilities. For example, for gasoline-powered automobiles, the automotive and fuels industries participated in the Auto-Oil Air Quality Improvement Research Program, which investigated the effects of gasoline composition and automotive systems on automotive emissions. The cost was $40 million, and it took more than five years to complete (AQIRP, 1997). Additional time was required to implement commercial changes based on the research program. Up to now, PNGV’s top priority has been the definition of automotive systems that could achieve the goals of the program. Although this was the correct approach in the early stages of the program, it is now critically important that fuel issues be strategically addressed with the involvement of the petroleum industry. Otherwise, because of the lead time required to manufacture modified fuels, commercialization of the technologies being developed could be delayed. Hydrogen for Fuel Cells Because most fuel cells under consideration run on hydrogen,1 the method of providing this fuel is a subject of intense investigation. Two approaches are under study: (1) onboard storage of hydrogen, either as compressed gas (5,000 psi), in a chemical hydride, or as a liquid in a cryogenic tank at very low temperature (e.g., –253°C);2 and (2) the indirect storage of hydrogen as conventional liquid fuel (gasoline or methanol) from which the hydrogen is “extracted” 1 Fuel cells that run directly on methanol are also being developed. 2 Liquid hydrogen is an option that has not received much attention because it requires extremely low temperatures. Ogden (1999) has shown that the distribution of liquid hydrogen to service stations and subsequent vaporization would be one of the most expensive ways of delivering gaseous hydrogen to vehicles.
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Review of the Research Program of the Partnership for a New Generation of Vehicles: Sixth Report TABLE 5-1 Infrastructure Investment for the Production and Distribution of Hydrogen and Methanol Gaseous Hydrogen ($ billions) Methanol ($ billions) Limiteda Wideb Limiteda Wideb Production 10 230–400 3.2 84 Distribution 7.7 175 0.36 9 Note: Feedstock for production of hydrogen and methanol is natural gas. a Limited penetration = 70,000 barrels/day gasoline equivalent in 2015. b Wide penetration = 1,600,000 barrels/day gasoline equivalent in 2030. Source: Wang et al., 1997. in an onboard fuel reformer and sent to the fuel cell on demand. In the first approach, the hydrogen source must be part of the fuel infrastructure. Gasoline, of course, has the advantage of being widely available in existing service stations. Although future gasoline will probably be a naptha-type hydrocarbon, it could be made available through existing service stations. Methanol is another fuel under consideration by a number of companies. Methanol reforming technology is more advanced than the technology for reforming gasoline and has the advantage of working at a much lower temperature (260°C) than gasoline reforming (more than 600°C). Although methanol is not widely available, given adequate time to establish a distribution system and additional methanol production facilities, it could be distributed to existing service stations and dispensed to vehicles. However, issues related to its corrosive properties and potential public health effects would have to be investigated and addressed. Table 5-1 summarizes the results of a study that developed capital cost estimates for the large-scale production and distribution of six fuels, including gaseous hydrogen and methanol (Wang et al., 1997). Based on investment estimates in Table 5-1, Kalhammer et al. (1998) estimated that infrastructure investment per vehicle would be between $3,500 and $6,700 for hydrogen and between $710 and $820 for methanol.3 These high costs provide a large incentive for the development of an onboard gasoline reformer, and PNGV has devoted significant resources to this objective. 3 Infrastructure costs based on projected vehicle penetration were estimated for daily delivery of hydrogen with the energy equivalence of 70,000 barrels of gasoline in 2015 and of 1.6 million barrels of gasoline in 2030. The hydrogen-fueled vehicles were assumed to be driven 14,000 miles per year at a fuel economy equivalent to either 60 or 80 mpg (gasoline). The infrastructure costs given in the text cover the range of costs based on these assumptions.
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Review of the Research Program of the Partnership for a New Generation of Vehicles: Sixth Report However, problems abound, and no cost effective, practical system is in sight at this point. First, an onboard gasoline reformer would be expensive and would require an excessive amount of platinum. Second, start-up time for the reformer system would be on the order of minutes rather than seconds. Third, an integrated reformer/fuel-cell system has not yet been tested to evaluate operating dynamics. Fourth, gasoline molecules form soot in the reformer, suggesting that the hydrocarbon stream would have to be lighter than conventional gasoline and that sulfur levels would have to be very low. In light of the infrastructure costs of hydrogen storage and the status of the onboard reforming program, the committee feels that PNGV should assess approaches for generating hydrogen at service stations by, for example, reforming natural gas or gasoline. In effect, this would replace the mobile reformer on each car with larger, stationary reformers that could provide fuel for many vehicles. The larger size of these units would provide additional design flexibility to deal with important technical issues, such as platinum requirements and the operability of the system with gasoline. In addition, with this option, hydrogen could be generated from natural gas, a preferred reformer feedstock that would minimize cost. Finally, this approach would avoid the infrastructure costs of a gaseous hydrogen distribution system and, therefore, could be implemented more quickly. When investigating this option, PNGV should take advantage of the expertise of the National Aeronautics and Space Administration, which is developing new technology for hydrogen storage, leak detection, and firefighting. PNGV should also take advantage of the expertise of the petroleum and chemical industries, which have extensive experience in generating, storing, transporting, and using hydrogen in refineries and chemical plants. Recommendations Recommendation. Defining automotive system/fuels trade-offs and establishing the basis for planning for supplying required fuels as higher efficiency vehicles become commercially available will require extensive cooperation among automotive and petroleum industry representatives at all levels of responsibility. PNGV should expand and strengthen its cooperative efforts with the petroleum industry, including issues related to fuels for fuel cells. Government leadership will be necessary to initiate this cooperative effort and provide incentives for petroleum company involvement. Recommendation. PNGV should undertake a study to assess the opportunities and costs for generating hydrogen for fuel cells at existing service stations and storing it on board vehicles and compare the feasibility, efficiency, and safety of this option with onboard fuel reforming. This study will help PNGV determine how much additional effort should be devoted to the development of onboard fuel reforming technologies.
Representative terms from entire chapter: