3
Overall Findings and Recommendations
This chapter summarizes the committee's findings and recommendations for the overall OHVT R&D program, based on presentations on individual OHVT programs (see Chapter 2), OHVT multiyear plans for each program, OHVT road maps, workshop proceedings, presentations by outside speakers, and committee members ' personal knowledge of heavy-duty engine technology and the market. The committee recognizes that the managers of OHVT must operate under many constraints that affect the distribution of available resources. For example, Congress may pass legislation related to the program that must be implemented. Fuel prices or emission or safety standards can be changed. Policies can also be changed, which may require that the program be reoriented. The committee has tried to focus its recommendations on improving the chances for the technologies under development to meet the goals of the program and to be successful commercially over the long term. The OHVT program is responding responsibly to congressional legislation and should continue to do so. In addition, OHVT follows the legislative process and provides Congress with the technical information it needs to make reasonable decisions.
The committee applauds the cooperative activities among OHVT, other DOE programs, and the EPA on the issue of sulfur levels in diesel fuel. Continuing cooperative efforts will be essential for the United States to improve fuel economy while maintaining a clean environment and a competitive advantage in a global economy. For example, the proposed 21st Century Truck Initiative is intended to be a long-range government-industry cooperative effort. In addition, OHVT has successfully involved industry and other stakeholders in identifying needs and developing a technology road map to meet the challenges facing heavy-duty diesel-engine technology. In the past year, OHVT has also made a significant effort to reach out to stakeholders and industries important to the trucking industry and has successfully leveraged its budget through cooperative efforts with other DOE programs and with industry. However, because of outside constraints, stakeholder interests, and political realities, OHVT has changed the focus of its research in several areas toward shorter term development. In the committee' s opinion, the long-term interests of the United States would be better served if most of OHVT's R&D has a long-term focus.
As multinational corporations expand, international trade increases, and global transportation knits the global economy together, industry is rapidly becoming global in all aspects. Nevertheless, standards and test procedures for vehicular emissions are not uniform across nations. Transportation emission standards in industrialized countries are becoming more stringent, and trade-offs of reductions in fuel economy to meet emission standards will be necessary. At the same time, the cost of petroleum is likely to rise, although the time frame is difficult to predict. Because transportation costs are a significant fraction of production costs in modern economies, there is an indirect relationship between emission standards and global competitiveness related both to the cost of moving goods and the cost of importing and exporting vehicles. Since emission standards are government mandated, government and industry must work together to address fuel economy and environmental issues.
In the past, OHVT programs have appropriately focused on technologies to meet anticipated stricter emission standards. Changing emission standards and an approximate eight-year delay between the start of a research program and the appearance of its results in commercial production have complicated planning of OHVT's R&D programs. Setting priorities and continually reviewing programs to redirect R&D could be more effective if OHVT had a Go/No Go decision-making process for critical milestones.
Finding 1. Energy and environmental policies, as well as emission standards, are continually changing in response to factors beyond the control of the Office of Heavy Vehicle Technologies (OHVT). Consequently, goals, objectives, and
timetables for research and development (R&D) can become outdated. For example, an R&D program designed to achieve lower emission levels will be of little practical use for initial production vehicles unless the R&D is completed significantly in advance of new standards (i.e., in time for the results to be used in production vehicles). (However, new technologies could be brought on line for later vehicle models.)
Recommendation 1. The Office of Heavy Vehicle Technologies (OHVT) should modify its program goals to reflect a time horizon of eight years or more. The longer time frame would allow industry time to incorporate research results into products, universities to contribute more significantly to solving problems, and OHVT to adjust the balance of its resources to support research by industry, the natural laboratories, and universities.
OHVT should revise its existing programs to ensure that the basic technical information produced by each individual program will be available at least three years before the technology is scheduled for commercial production. The revised mix of programs, which should be implemented by fiscal year 2003, will shift the emphasis to new advanced technologies and away from near-term development.
Finding 2. Both light-duty and heavy-duty vehicles will require improved energy efficiency with minimum adverse environmental effects and competitiveness in a global economy. Meeting these often-conflicting goals will require that government and industry work together. The Office of Heavy Vehicle Technologies (OHVT) is successfully working with industry and other stakeholders to meet these challenges. However, the committee did not see much evidence that OHVT has established a Go/No Go decision-making process for evaluating and dealing with technical showstoppers at critical milestones.
Recommendation 2. Office of Heavy Vehicle Technologies (OHVT) programs should be updated annually, and program strategies and priorities should be reassessed. New programs should have a long-term focus. In addition, OHVT should implement a Go/No Go decision-making framework to keep OHVT programs focused on program goals and to establish or modify priorities and to change directions, as necessary.
The diesel engine is the most efficient, economical power plant available today for trucks. As integrated emissions-control technology advances, the diesel engine can be increasingly optimized to its duty cycle. From the perspective of efficiency, and therefore fuel savings, the diesel engine could play a key role in reducing the rate of increase of petroleum use in the United States. However, the fuel economy benefit of the diesel engine will not be realized unless emission standards can be met. With present technologies, both the gasoline engine and the diesel engine will require exhaust-gas after-treatment to meet the projected emission standards for 2007–2010. Therefore, OHVT programs must be sharply focused on meeting future emission standards.
Finding 3. The most critical barrier to improving fuel economy is the emission of oxides of nitrogen and particulate matter. Current activities are spread across too many areas and not focused on overcoming this critical barrier. Given available resources, a smaller number of carefully chosen projects would be more productive.
Recommendation 3. The Office of Heavy Vehicle Technologies (OHVT) should reevaluate its priorities and increase its support for projects focused on overcoming the most critical barriers to success. For example, meeting emissions standards will be critical to OHVT's program on advanced combustion engines. Therefore, emissions should be a major focus of this program. In addition, OHVT must be more proactive and forward thinking in anticipating future emission standards, and should focus on improving the understanding of the physical and chemical character of emissions. In anticipation of more stringent emissions standards than are currently planned by the Environmental Protection Agency, OHVT should undertake technology-forcing research.
To meet future emission standards, particularly for oxides of nitrogen (NOx) and particulate matter (PM), some proposed exhaust-gas after-treatment technologies will require a low sulfur content in fuel to improve NOx conversion efficiency. Sulfur compounds in the exhaust gas may also contribute to the formation of ultrafine exhaust particles. Automotive manufacturers prefer very low levels of sulfur (5 parts per million [ppm]) to benefit automotive emissions-control systems; the petroleum industry has suggested a standard of 30 ppm (average) and a 50 ppm (maximum) limit to control increases in fuel costs and avoid supply problems. EPA has a proposed regulation for sulfur concentration in diesel fuel of 15 ppm.
Finding 4. Regulations are being considered to reduce the levels of sulfur in fuel used for on-highway diesel vehicles. The sulfur levels for some current after-treatment technologies, such as NOx traps, will have to be very low and could require sulfur traps that would have to be changed periodically. Some technologies, such as selective catalytic reduction, are less sulfur sensitive but require the addition of a reductant (e.g., urea). Consequently, the economic trade-offs between sulfur levels in fuel and after-treatment technologies will be an important consideration in the development of cost-effective emission-control systems.
Recommendation 4. The Office of Heavy Vehicle Technologies should place a high priority on integrated emissions-control technology (engine combustion and after-treatment
technology) to meet future emission requirements. Research and development (R&D) should be focused on sulfur-tolerant catalysts, sulfur traps, and selective catalytic reduction, for diesel fuel with sulfur levels of 5 to 50 parts per million. R&D should be focused on both experimental work and modeling related to basic in-cylinder combustion and after-treatment technologies.
Because fuel consumption by light trucks and SUVs is increasing, “dieselization” for light trucks and SUV markets makes sense. Indeed, dieselization is a significant part of OHVT's program. However, if the diesel engine cannot meet emission standards, it will not be a viable alternative for this market segment. Although OHVT's program is focused on addressing the technical barriers to meeting emission standards with diesel engines, it should also keep abreast of progress on other engine types that could meet emission standards more easily, although with poorer fuel economy (e.g., the gasoline engine).
Finding 5. The Office of Heavy Vehicle Technologies (OHVT) is actively involved in 50/50 cost-share projects with Cummins-DaimlerChrysler, Detroit Diesel-DaimlerChrysler, and Caterpillar-Ford to develop a competitive Class 2 diesel truck engine for use in sport utility vehicles (SUVs) and light trucks. OHVT's funding is being used to facilitate interactions between the heavy-duty engine industry and automotive manufacturers, and research on these projects is being done by the partnering companies. The proprietary results will be protected from public disclosure for five years. Therefore, the committee found it difficult to assess the scope and focus of OHVT's light-duty engine program. There was some indication, however, that one of the companies in the program is working on technologies that could be incorporated into hardware components for a Class 1 or Class 2 light-duty truck engine. The committee supports OHVT's promotion of industry research on promising, high-risk approaches to configuring engine emission-control systems that could facilitate the introduction of more fuel-efficient engines into the light-truck and SUV market. However, the committee does not endorse the use of OHVT funds to support specific engine or component development by industry.
Recommendation 5. The committee believes it appropriate for the Office of Heavy Vehicle Technologies (OHVT) programs to provide basic technical information (e.g., improved understanding of physical processes, new and/or improved system optimization and control techniques, etc.) that will promote more fuel-efficient engine-emission systems by the private sector for the light-truck and sport utility vehicle market. OHVT should evaluate the effectiveness of its 50/50 cost-share programs with industry to determine if they are creating needed basic information. OHVT should not support the development of a specific engine or component.
Some of the biggest improvement in the overall fuel efficiency of heavy-duty trucks can be achieved by improving aerodynamics, using lightweight materials, and decreasing rolling resistance. Aerodynamic losses for all trucks can be large (e.g., at 70 mph on a level road, roughly 65 percent of the power requirements are attributable to aerodynamic drag). For trucks limited by weight requirements (e.g., flatbed trucks), a decrease in vehicle weight would allow for an increase in payload weight. Therefore, large increases in material transport efficiencies, perhaps larger than can be made through improvements in engine performance, may be possible through decreases in aerodynamic drag, reductions in weight, and decreases in rolling resistance. However, new truck designs must also take into account the interaction of heavy trucks with the roadways (e.g., the rate of damage from a fully loaded Class 8 truck is equivalent to that of 5,000 cars), as well as congestion and disruption to the transportation system from road repair.
Several factors should be taken into account in a systems view of fuel economy. First, double trailers (sometimes even triple trailers, although not allowed in all states) have different aerodynamics than single-tractor trailers and also different cargo-carrying capacities. Because they are heavier than single trailers, they consume more gallons of fuel per mile; however, because they can carry more cargo weight, the appropriate measure for the fuel economy of trucks carrying cargo should be ton-miles/gallon (ton refers to the weight of the cargo being transported).
Second, the driving duty cycle should be specified for all vehicles targeted for improvements in fuel economy. Without specified driving cycles, fuel economy goals are not very meaningful. OHVT has done this for Class 7 and 8 vehicles by specifying constant-speed driving at 65 mph, a very simple driving cycle. Third, the performance level of the vehicle must be indicated because fuel economy improvements can be made by sacrificing vehicle performance, and this trade-off should be included in an evaluation of the improvement.
Finding 6. Engine efficiency is a significant, but not the only, factor in increasing the fuel economy of heavy vehicles. The overall Office of Heavy Vehicle Technologies (OHVT) program is focused too heavily on improving engine efficiency and not enough on other factors that affect fuel economy. The committee recognizes that some of these factors may be outside OHVT's mission and that addressing them will require interagency cooperation.
Recommendation 6. The Office of Heavy Vehicle Technologies (OHVT) should focus more on factors other than engine efficiency that affect on-road fuel economy, especially improving aerodynamics, reducing the use of accessory power, decreasing rolling resistance, and decreasing unloaded vehicle weight by innovative design incorporating high-strength, weight reduction materials (in keeping with
safety considerations, as well as highway wear and tear). OHVT, in cooperation with other government agencies, should conduct an analysis to clarify the trade-offs and opportunities among engine efficiency and other factors affecting vehicle fuel economy and reorient its programs accordingly.
To achieve a 10-mpg fuel economy in Class 7 and 8 trucks, OHVT should monitor trends in installed engine power and steps the commercial market is taking to achieve this. Trip time may be a more economically important parameter than fuel economy. OHVT's analysis should include vehicle systems models to identify opportunities for improving the vehicle system that could lead to improvements in fuel economy. For each truck classification, the driving duty cycle associated with each fuel economy goal should be specified. In addition, OHVT should evaluate which measure of fuel economy, miles/gallon or ton-miles/gallon, is most appropriate for each class of vehicle. The expansion of OHVT 's programs in this recommendation will require an increase in funding.
The most promising alternative to diesel fuel is natural gas. OHVT 's program is now focused on urban trucks and buses with hybrid electric power trains, especially configurations that use natural gas. OHVT plans to work with competitively selected industry teams of hybrid-vehicle system developers and vehicle manufacturers. Because of the lack of an extensive infrastructure for natural-gas fueling stations, the focus will be on urban trucks and buses, which can more easily be fueled at central stations than privately owned vehicles. When comparing compressed and liquefied natural gas, vehicle energy consumption should be measured on a “well-to-wheels” basis.
Finding 7. The goals of the Natural Gas Vehicle Program include demonstrations of two natural-gas vehicles by 2004 that are competitive in cost and performance with their diesel-fueled counterparts. One will be a Class 3 to 6 vehicle that operates on compressed natural gas (CNG); the other will be a Class 7 or 8 vehicle that operates on liquefied natural gas (LNG). Three types of natural-gas engines have been proposed: the SING (spark-ignition natural gas), the PING (pilot-injection natural gas), and the DING (direct-ignition natural gas). The size, weight, and cost of onboard fuel storage systems, as well as the limited availability and high cost of natural-gas fueling stations, are also being addressed. Completion of the demonstration program will help to clarify the position of heavy-duty, natural-gas engines relative to diesel engines in terms of compliance with future emission standards and fuel economy.
Recommendation 7. The Office of Heavy Vehicle Technologies should refocus its natural-gas research on meeting emission standards for 2007. Support for the PING (pilot-injection, natural gas) engine, DING (direct-injection, natural gas) engine and SING (spark-ignition, natural gas) should be continued until their performance and emissions characteristics are well understood. At that point, support for the SING engine should be discontinued unless it proves to have a substantial emissions advantage over the PING and DING engines. Research on onboard storage of natural gas should be focused on novel methods rather than on conventional compressed natural gas and liquefied natural gas storage technologies. A “well-to-wheels” analysis should be used to compare options for onboard storage. Research on refueling should be limited to the central refueling option.
The R&D programs in materials appear to be well managed. However, projects are not prioritized based on their importance to the success of the OHVT program as a whole and their likelihood of success.
Considering the myriad problems and opportunities in materials R&D, OHVT must develop a process for identifying the most significant materials-related barriers to improved performance and prioritize them according to need. Then, relevant technologies should be evaluated in terms of their probability of success, and the most promising technologies should be selected. Finally, OHVT should establish long-range research programs to address needs that cannot be addressed by current technologies. Unless a disciplined, systematic approach is adopted, almost any materials-related R&D can be justified as being relevant to the OHVT program. OHVT must ensure that the projects it supports are not just relevant but also (1) address a priority need, (2) have a reasonable chance of success, or (3) are long-term research projects that may have high risks but also have potentially large payoffs.
Finding 8. The Office of Heavy Vehicle Technologies has no systematic process for prioritizing high-strength, weight-reduction, materials-related research or for monitoring other relevant, federally funded materials R&D.
Recommendation 8. A systematic process should be developed and put in place to monitor relevant, federally funded, materials research and development (R &D), to prioritize materials needs, and to identify high-priority opportunities for R&D. This process should use vehicle-systems modeling analyses to set specific goals for vehicle, power train, and chassis weight to meet overall fuel economy goals.
