ACEEE report recommends steps toward international alignment of heavy-duty vehicle efficiency standards
A new report published by the American Council for an Energy-Efficient Economy (ACEEE) recommends the international harmonization of fuel efficiency and/or greenhouse gas emissions standards for heavy-duty trucks and buses.
Foundational steps toward such alignment would include a common set of test cycles and test payload weights, which would serve to define universal measures of vehicle performance. This in turn would permit a standardized calculation of cost-effectiveness of technology improvements as a function of regional conditions. This would also allow comparison of vehicles in a range of driving conditions, and in particular would allow buyers to estimate performance over their own duty cycles, the report suggests.
Aligning test methods would also reduce manufacturer compliance costs, and thus strengthen support for the program. Such basic steps regarding testing protocols should precede consideration of alignment of other regulatory elements, the authors recommend.
Japan, the United States, and Canada have adopted standards to reduce GHG emissions and/or raise the fuel efficiency of heavy-duty vehicles, and other countries and regions—notably China, Mexico and the EU—are headed toward doing the same.
Concurrently, manufacturers increasingly are developing global product platforms for the heavy-duty market. This offers an opportunity to accelerate the development and adoption of fuel efficiency technologies, the report authors suggest, noting that regulators could facilitate this outcome by coordinating the design of fuel efficiency and GHG emissions reduction programs across regions.
These regulatory programs have similar aims and share a number of features. There is also overlap in the vehicle models regulated, and the overlap is likely to grow rapidly in the coming years with increasing globalization of vehicle platforms and components. Yet the differences in the programs are fundamental. This report explores whether and how heavy-duty standards programs could be better aligned across regions.—“International Alignment of Fuel Efficiency Standards for Heavy-Duty Vehicles”
|Heavy-duty fuel consumption and/or greenhouse gas emissions standards by region. Source: ACEEE. Click to enlarge.|
One consequence of the differences among the regulatory programs is that they may drive different fuel efficiency technologies. For example, the basic test protocol for the U.S. does not capture transmission performance, while Japan’s program does not capture tire performance. As a result, the programs do little to promote optimal specification or fuel efficiency improvements in those components. In some cases, such features reflect the differing benefits of the various fuel efficiency technologies across countries. Often, however, the fuel efficiency technologies in question would yield benefits in all regions. In such cases, better alignment of regulatory programs could help to spread those technologies. Aligning programs across regions has potential benefits in terms of both fuel savings and the cost of complying with fuel efficiency regulations. Expanding the market for efficiency technologies spreads development costs over a larger sales base and helps to achieve economies of scale, expediting the adoption of these technologies. Increased alignment could also reduce manufacturer costs by allowing coordinated technological approaches to fuel efficiency improvement and by providing consistent testing protocols across regions.—“International Alignment of Fuel Efficiency Standards for Heavy-Duty Vehicles”
Although it might be tempting to seek standards that apply the same stringency across regions so as to be able to minimize the variations in vehicles across markets and to ensure the largest market for efficiency technologies, such uniform stringency appears not to be a feasible or even desirable objective, given the differences in operating conditions across regions, the report concludes.
A prime example of that is the reversal of urban and highway driving shares for large tractor-trailers in Japan and the US, a fact reflected in the very different fuel efficiency targets set for the two countries.
This suggests the need for a broader notion of alignment, which aims to increase the effectiveness of the individual programs by demonstrating the benefits of fuel efficiency technologies for the entire population of vehicles to which these technologies will bring real-world savings.—“International Alignment of Fuel Efficiency Standards for Heavy-Duty Vehicles”
The reports draws conclusions and makes recommendations in six specific areas:
Metrics. Program alignment will require the use of fuel efficiency or GHG emissions metrics that are readily convertible across programs. Liters (or grams CO2) per payload ton-kilometer or an equivalent appears to be the best choice.
Test payloads must be specified for the metric to be meaningful as well as to define equivalence with a liters-per-kilometer metric. Typical payloads vary from region to region, however. Hence testing should be done with multiple payloads, e.g., empty, full, and regionally appropriate payload.
Vehicle segmentation. Uniform segmentation across regions would be difficult. Nonetheless, for vehicle categories such as line-haul tractor-trailers that are important in many regions, it would be useful to develop global characterizations and weight thresholds to facilitate discussion and comparison of programs.
Test cycles. While various engine test cycles exist for criteria pollutant testing, and several have vehicle versions, fuel efficiency and GHG emissions programs will require additional data points and cycles. At a minimum, a complete engine fuel map will be needed. Additional information relating to engine cooling, transient operation, and response to ambient conditions may be required as well.
Two approaches to accommodating the variety of duty cycles for heavy-duty vehicles are: (1) developing a wide array of test cycles representing typical complete duty cycles, e.g., long-haul truck cycle or refuse truck cycle; and (2) choosing cycles to represent common driving modes, e.g., urban or highway, and defining vehicle performance as a weighted sum of the results over the modal cycles.
Either of these approaches could be used in an aligned program. This would involve either use-dependent certification of vehicles (first approach) or weightings that vary from region to region (second approach).
Testing and modeling methods. Alignment of test protocols for components, including engines, across regions would be relatively easy and could contribute substantially to both expanding the market for efficiency technologies and reducing manufacturer testing costs. Component testing is not, however, sufficient basis for a program of standards that seeks to recognize the full range of potential efficiency improvements. Full-vehicle evaluation will be required to capture the benefits of advanced technologies and the interactions of vehicle systems.
Simulation modeling will also be an important element of any heavy-duty test protocol. Any model adopted for this purpose should be fully documented and use open source software to allow for evaluation and improvement.
Some amount of physical testing will be needed to validate the results of simulation modeling and to capture the benefits of technologies not anticipated in the model.
Differing test methods do not preclude program alignment but may reduce the validity of cross-region comparisons. Uniform test methods also reduce manufacturer costs and hence will increase the appeal of standards to manufacturers.
Stringency. Due to cross-regional differences in driving patterns, fuel prices, typical payloads, and other conditions, it will not generally be feasible to set a given vehicle’s fuel efficiency or GHG emissions standard at the same level in all regions.
Data and research. Region-specific and cross-region analysis will both be needed; early efforts to coordinate could greatly reduce duplication of effort.
Development of modeling tools sufficient for evaluating heavy-duty vehicles’ fuel efficiency and GHG emissions will require detailed information on engines and other components and systems from manufacturers. A survey should be conducted of simulation models in use, with a focus on suitability for fuel efficiency and GHG emissions prediction.
For heavy-duty vehicle duty cycles and other information about driving patterns, participation of fleets will be essential. Data collection similar to that done by participants in EPA’s SmartWay program would be useful in all regions.
In view of these conclusions, we recommend approaching alignment of heavy-duty fuel efficiency and GHG emissions programs by establishing a common set of test payload weights and test cycles satisfying the requirements of one of the two approaches described above. This would result in universal, well-defined measures of vehicle performance. This information would permit a standardized calculation of cost-effectiveness of technology improvements as a function of regional conditions, which would help to establish a global market for efficiency technologies and thereby accelerate the rate of fuel efficiency increases. It would also allow comparison of vehicles in a range of driving conditions and in particular would allow buyers to estimate performance over their own duty cycles. Aligning test methods as well would reduce manufacturer compliance costs and thus strengthen support for the program.—“International Alignment of Fuel Efficiency Standards for Heavy-Duty Vehicles”
Therese Langer and Siddiq Khan (2013) International Alignment of Fuel Efficiency Standards for Heavy-Duty Vehicles (ACEEE Report Number T131)