The National Academies have released a third review of the 21st Century Truck Partnership (21CTP); the review follows the Phase 1 and Phase 2 reviews by the National Research Council in 2008 and 2012 (earlier post) and assesses the progress the partnership has made. The report highlights goals that have been achieved and identifies remaining issues that the partnership should continue to address.
The 21st Century Truck Partnership is a cooperative research and development (R&D) partnership comprising four federal agencies and 15 industrial partners. The Partnership aims to “accelerate the introduction of advanced truck and bus technologies that use less fuel, have greater fuel diversity, operate more safely, are more reliable, meet future emissions standards, and are cost effective.” To do so, it supports research, development, and demonstration (RD&D) that can lead to commercially viable products and systems. Its strategic approach includes:
developing and implementing an integrated vehicle systems R&D approach that validates and deploys advanced technology;
promoting research on engines, combustion, exhaust aftertreatment, fuels, and advanced materials;
promoting research on advanced hybrid propulsion systems;
promoting research to reduce vehicle power demands;
promoting the development of technologies to improve truck safety;
promoting the development and deployment of technologies that substantially reduce energy consumption and exhaust emissions during idling;
promoting the validation, demonstration, and deployment of advanced truck and bus technologies, and improve their reliability to the point where they can be adopted in the commercial marketplace; and
researching, validating, and deploying technologies and methods that save fuel through more efficient operations of trucks and transportation systems.
The 21CTP was formed in 2001 to reduce fuel usage and emissions in trucks of Classes 3 through 8. Significant progress has made since the Academies issued its first report in 2008. While early R&D was largely component-based, as a result of US Department of Energy (DOE) American Recovery and Reinvestment Act (ARRA) funds in 2009, 21CTP was able to fund four SuperTruck projects.
The new report highlights a number of important accomplishments which have occurred since the earlier NRC reviews:
The engine systems Goal 1 of a 50% brake thermal efficiency (BTE) for an emissions compliant engine has been achieved. A pathway to achieve 55% is being developed.
The four SuperTruck projects jointly funded by DOE and the private sector are impressive projects that integrate a wide variety of engine and vehicle technologies to significantly reduce the fuel consumption of Class 8 tractor-trailer vehicles, which consume the greatest part of the fuel used in the United States for heavy vehicles. These efforts follow on the recommendations in the NRC Phase 1 report for the full system integration of technologies and away from component-only R&D. These projects have brought together a wide variety of companies, the national laboratories, and universities.
The SuperTruck projects incorporated a number of vehicle power demand technologies that accounted for about 56 to 74% of the total fuel consumption reductions, with 26 to 44% coming from engine efficiency improvements.
One truck has achieved a freight efficiency of over 175 ton-miles per gallon, compared to a 2009 model baseline efficiency of 99 ton-miles per gallon. In terms of fuel economy, the truck achieved 10.7 miles per gallon (mpg), compared to the baseline truck at 6.45 mpg. As for load-specific fuel consumption (LSFC), the truck achieved 5.7 gallons/1,000 ton-miles, down 43 percent from the baseline LSFC of 10.0 gallons/1,000 ton-miles. A portion of the improvement on a ton-mile basis came from weight reduction, which allows extra freight to be carried.
A second truck has doubled fuel economy from a 2009 baseline of 6.1 mpg to 12.2 mpg over one long-haul route, with a 120% increase in freight efficiency in ton-miles per gallon from a 2009 baseline of 94 ton-miles per gallon to 206 ton-miles per gallon. LSFC was reduced by 55% on one route and by 49% on a second, lower speed route. On the route that produced the 12.2 mpg result, the LSFC was 4.85 gallons per 1,000 ton-miles, compared to 10.6 gallons per 1,000 ton-miles for the 2009 baseline.
The 50% BTE and the 4.85 and 5.7 gallons per 1,000 ton-miles LSFC values are significant accomplishments, the review committee noted, and could not have been achieved without the ARRA funds since the overall DOE budget in normal years was not sufficient to take on a project like this.
Hybrid vehicle systems have demonstrated significant fuel consumption and emissions reductions in a number of MHDV applications, but their cost prohibits commercial deployment, especially at foreseeable fuel prices. In addition, the SuperTruck project results thus far show a limited potential benefit on long-haul duty cycles for hybrid systems using currently available technology. The 21CTP hybrid team is considering a proposal to restructure its mission and focus, which the committee supports.
The committee noted that there are still remaining issues that the Partnership should continue to endeavor to address, some of which have been of concern in the Phase 1 and 2 reviews as well:
The Partnership has identified particular areas to address but in some areas research funding has not been commensurate with the goals for those areas. In some cases, e.g., efficient operations or hybrid vehicles, funding has been insufficient to meet the goals. In those areas that have not received funding, adjustments to the goals should be made.
The Partnership needs to develop an ongoing and systematic approach to identify which projects fall under the 21CTP umbrella and how they contribute to the Partnership’s goals, as well as monitoring the results of the projects relative to the goals on an ongoing basis.
The Partnership has yet to develop a brief annual report but, is in the process of developing one.
Previous reviews have suggested that additional truck manufacturers and suppliers be recruited for membership to the Partnership but the members have remained the same. With the changes occurring in the industry, this should be revisited.
Given the expected constraints on future budgets, it will probably increasingly be important to identify the federal government’s role after assessing both domestic and overseas heavy-duty vehicle R&D, the review concluded. Assessing overseas R&D was recommended in previous reviews but it is not clear whether this was ever conducted.
The report makes a number of specific technology recommendations, including:
With the increased importance of advanced computational fluid dynamics (CFD) for developing the engines and operating scenarios necessary for minimum fuel consumption and in light of DOE’s role in the generation of new knowledge that gets incorporated into these CFD codes as submodels, a critical review of the Partnership’s program to develop the next-generation code (KIVA 4) should be performed. Feedback from participants in the high-performance computing workshop should be matched against the current code development activities, and the adequacy of the current program should be assessed. If necessary, the next-generation code development should be adjusted.
The fundamental diesel engine research program pursuing advanced technologies and combustion processes and engine architectures to achieve 55 percent BTE should continue to be a focus of the 21CTP engine activities. However, the experiments and modeling should maintain a focus on dynamometer R&D, as opposed to attempting to build a demonstration vehicle. The achievement of this goal should be extended from 2015 to 2020 in order to have sufficient time to carry out R&D on this stretch goal. Also, this activity should not be at the expense of efforts to reduce load-specific fuel consumption via system integration and road load reductions.
The DOE should develop specific aftertreatment goals for the 21CTP. These goals will serve as a focal point for researchers to submit proposals and for the DOE to assess them. The Partnership should also continue to fund work on improved SCR NOx efficiency (mainly low-temperature efficiency without compromising high-temperature efficiency) and aging and poisoning effects. California’s and, potentially, EPA’s move toward further heavy-duty NOx reductions to meet National Ambient Air Quality Standards for ozone will be critical. These new targets need to be set for the research efforts.
Technologies such as an SCR catalyst on a DPF or others that have the potential to reduce the volume, weight, and cost of the aftertreatment system should be a part of the program to develop a 55% BTE engine.
The DOE should continue to explore how the United States might use its abundant petroleum, natural gas, and biofuel resources in the most efficient manner. Studies, some of which are under way that contribute to this objective, should strive to answer questions such as what fuel properties (e.g., ignition characteristics, volatility, composition) of diesel fuel and gasoline provide for maximum efficiency of various advanced combustion engines? FACE and a common set of surrogate fuels should be utilized by all DOE facilities involved in combustion research programs in order to provide consistent fuel characteristics when evaluating laboratory experiments and engine test results. Based on well-to-tank analyses, what fuel properties and processing procedures result in the lowest GHG emissions for hydrocarbon-based and bio-based fuel components?
The 21CTP hybrid team is encouraged to use this opportunity to redefine its mission in a manner that will lead to vehicle efficiency and emissions reduction improvements via a range of technology options, including promising opportunities for electrification and other types of innovative drivetrain improvements. During the course of this restructuring, the six R&D stretch goals developed in 2011 for the MHDV hybridization program should be redefined as part of the development of strategic objectives of the restructured advanced drivetrain initiative. At the conclusion of this process, the 21CTP leadership, working together with DOE and the other 21CTP partner federal agencies, should make a serious effort to secure funding to pursue whatever goals emerge so that they have a realistic chance of being achieved.
Recognizing the advantages that hybridization can offer in trucks, 21CTP should support the development of new technology that offers promise for significantly improving the performance and cost-effectiveness of hybrid truck technology in the longer term. Project opportunities should be pursued to evaluate cost-effective vehicle electrification configurations for trucks, including hybrid drives with optimized component ratings to minimize their payback periods in different vehicle classes and applications. This future work should take advantage of technology advances originally made and commercialized for light-duty vehicles, including new battery technologies as well as opportunities for integrated micro-electrification of truck functions such as start/stop operation, idle reduction, waste heat recovery, engine starting, and accessory electrification.
21CTP should make it a priority to encourage EPA and NHTSA to accelerate their efforts to strengthen and finalize procedures for certifying the fuel consumption and emissions of hybrid MHDVs, including procedures for chassis dynamometer testing of complete hybrid vehicles and dynamometer testing of hybrid propulsion drivetrains alone. The 21CTP leadership is encouraged to work together with EPA and NHTSA to inform and educate the 21CTP stakeholders and the broader MHDV manufacturing community about the details of these procedures when they become available.
21CTP should assess future generation Forward Collision Avoidance and Mitigation (F-CAM) system development in order to identify barriers to development and establish incentives to foster commercialization.
Because of the great value demonstrated by the SuperTruck program, DOE should be working on at least one vehicle integration project at any given time. Owing to likely funding limitations, it will not be possible to have three or four similar projects running. A range of integration projects are possible, including a regional haul SuperTruck; a heavy-duty vocational SuperTruck (refuse, dump, etc.); a SuperTrailer program to help trailer manufacturers build engineering capability; and a delivery truck of Class 3, 4, 5, or 6.