The fuel consumption and greenhouse gas (GHG) emissions of medium- and heavy-duty vehicles (MHDVs) have become a focus of legislative and regulatory action in the past few years. Section 101 of the Energy Independence and Security Act of 2007 (EISA 2007), Pub. L. No. 110-140 §101, mandated the U.S. Department of Transportation (DOT) to promulgate fuel consumption standards for MHDVs for the first time. The statute requires DOT to provide 4 years of lead time between promulgation and enforcement of fuel consumption standards and also requires a period of 3 years of stability once the standards are in effect.
Section 108 of EISA also required the Secretary of Transportation to contract with the National Academy of Sciences (NAS) to undertake a study on the technologies and costs for improving fuel consumption in MHDVs. Within one year of the completion of the NAS study, the DOT was required to undertake its own study of the practicalities in promulgating fuel efficiency standards for MHDVs. Upon completion of that report, DOT was instructed to promulgate by rulemaking a fuel efficiency program for MHDVs that is “designed to achieve the maximum feasible improvement” in fuel consumption and to “adopt and implement appropriate test methods, measurement metrics, fuel consumption standards, and compliance and enforcement protocols that are appropriate, cost-effective, and technologically feasible for commercial medium- and heavy-duty on-highway vehicles and work trucks.” (49 U.S.C. § 32902(k)(2))
The present report is a follow-on to the National Research Council’s (NRC’s) Technologies and Approaches to Reducing the Fuel Consumption of Medium- and Heavy-Duty Vehicles (NRC, 2010; henceforth referred to as the “Phase One Report”). The NRC, the operating arm of the NAS, established the Committee to Assess Fuel Consumption Technologies for Medium- and Heavy-Duty Vehicles (henceforth the “NRC Phase One Committee”), which held its first meeting in December 2008 and continued with information gathering, deliberations, and report drafting before releasing its report on March 31, 2010. The Phase One Report provided a series of findings and recommendations on the development of a fuel consumption program for MHDVs; metrics for measuring MHDV fuel consumption; availability and costs of various technologies for reducing fuel consumption; potential indirect effects and externalities associated with fuel consumption standards for MHDVs; alternatives for the scope, stringency, certification methods, and compliance approach for the standards; and a suggested demonstration program to validate innovative certification procedures and regulatory elements.
Shortly after the release of the NRC report, President Barack Obama, on May 21, 2010, directed the National Highway Traffic Safety Administration (NHTSA), on behalf of DOT, to issue MHDV fuel consumption standards in close coordination with GHG emissions standards to be promulgated for the same vehicles by the U.S. Environmental Protection Agency (EPA). Given the connection between fuel consumption and GHG emissions, a coordinated approach to fuel consumption and GHG standards would reduce regulatory costs and burdens and minimize inconsistent regulatory requirements by allowing manufacturers to build one set of vehicles to comply with both sets of standards.
In October 2010, NHTSA released its report responding to the NRC report (NHTSA, 2010). The NHTSA analysis was generally consistent with the findings and recommendations of the NRC report, with some differences (see the next section), including issues (e.g., regulation of commercial trailers) that NHTSA deferred to future rulemakings.
On September 15, 2011, NHTSA and EPA, referred to hereinafter as “the Agencies,” jointly published a Federal Register notice (76 Fed. Reg. 57105) finalizing rules to establish a comprehensive Heavy-Duty National Program to reduce GHG emissions and fuel consumption for on-road medium- and heavy-duty vehicles. NHTSA adopted final fuel consumption standards under its statutory authority provided by EISA, and EPA adopted carbon dioxide (CO2)
emission standards under its Clean Air Act authority. (These are discussed in more detail in Chapter 5 of this report, on natural gas.) The coordinated rules were both tailored to the same three regulatory categories of heavy-duty vehicles: (1) combination tractors; (2) heavy-duty pickup trucks and vans; and (3) vocational vehicles. The EPA GHG emission standards commenced with model year 2014,1 whereas NHTSA’s fuel efficiency standards will be voluntary in model years 2014 and 2015 and become mandatory in model year 2016, in order to comply with EISA’s 4-year lead-time requirement.
Following promulgation of the initial standards, NHTSA and EPA have commenced work on a second round (Phase II Rule) of fuel efficiency and GHG emission standards for MHDVs. The current NHTSA fuel consumption standards take effect in MY2016 and must remain stable for at least 3 years under the statute. New standards must provide 4 years’ lead time. Assuming the Phase II fuel consumption regulation is promulgated in calendar year 2015, the earliest the new fuel consumption standards could go into effect is MY2020, owing to the 4-year lead time requirement.2
President Obama issued The President’s Climate Action Plan in June 2013 (White House, 2013, p. 8), which states that the administration plans to work with stakeholders “to develop post-2018 fuel consumption standards for heavy-duty vehicles to further reduce fuel consumption through the application of advanced cost-effective technologies and continue efforts to improve the efficiency of moving goods across the United States.”
The EISA anticipates that the NRC will update its report at 5-year intervals through 2025. Pursuant to that statutory timeline, NHTSA entered into a cooperative agreement with the NRC to issue a final report by 2016. The NRC formed the Committee on Technologies and Approaches for Reducing the Fuel Consumption of MHDVs (see Appendix A for member biographies) in January 2013. Subsequently, the cooperative agreement was modified (see Appendix B for the statement of task) to include a report to be issued in early 2014 that would inform a possible Phase II rulemaking such as that contemplated in the President’s Climate Action Plan.
This section looks back at the NRC report Technologies and Approaches to Reducing the Fuel Consumption of Medium- and Heavy-Duty Vehicles (2010), specifically the impact it has had on NHTSA’s and EPA’s rulemakings.3 In the preamble to the proposal of the Phase I Rule, the Agencies provided a response explaining their rationale for accepting or rejecting the NRC’s recommendations.4 In what follows, the committee provides its own views on the relationship between the Phase I Rule and the key findings and recommendations of the NRC Phase One Report that are of continued relevance.
The Phase One Report included the following recommendation:
Recommendation 2-1. Any regulation of medium- and heavy-duty-vehicle fuel consumption should use load-specific fuel consumption (LSFC) as the metric and be based on using an average (or typical) payload based on national data representative of the classes and duty cycle of the vehicle. Standards might require different values of LSFC due to the various functions of the vehicle classes, e.g., buses, utility, line haul, pickup, and delivery. Regulators need to use a common procedure to develop baseline LSFC data for various applications, to determine if separate standards are required for different vehicles that have a common function. Any data reporting or labeling should state an LSFC value at specified tons of payload. (NRC, 2010)
The Agencies (EPA and NHTSA) followed the NRC Phase One Committee recommendation to base the fuel consumption standard on the vehicle work accomplished, such as load-specific fuel consumption (LSFC). Class 7 and Class 8 trucks and vocational trucks have been addressed specifically in this manner, and Class 2b pickups are handled effectively as mentioned below. The Agencies also gave considerable thought and study to selecting representative drive cycles so as to ensure the regulation would reduce GHG emissions.
A further consideration is the gross vehicle weight assumed in the GHG Emissions Model (GEM) simulation, which for Class 8 vehicles is based on a payload weight of 38,000 lb, an intermediate load value. The Agencies adopted payload values for the GEM simulation calculations that are representative of real-world truck use, instead of merely
1 For purposes of this report, the term “model year” will be synonymous with “calendar year,” because unlike the light-duty vehicle sector, model years vary significantly among MHDV manufacturers, and so for the sake of simplicity and uniformity the calendar year is often used as the rough approximation for model year (MY).
2 If NHTSA adopted its standards in mid-2015 it could start applying those standards to vehicles certified after that equivalent date in 2019, creating a split model year. The statement of task therefore refers to the possibility of the Phase II standards beginning in 2019. For purposes of its analysis here, however, the committee will assume that the Phase II standards will begin to apply to the entire 2020 model year.
3 75 Fed. Reg. 74152 to 74456 (Federal Register/Vol. 75, No. 229/ Tuesday, November 30, 2010/Proposed Rules).
4 See also Factors and Considerations for Establishing a Fuel Efficiency Regulatory Program for Commercial Medium- and Heavy-Duty Vehicles (NHTSA, 2010).
using the maximum gross combination vehicle weight rating (GCVWR) for the vehicle weight class. This captures the situation that over half of trucks on the road are volume limited,5 meaning the trailer is filled up with containers without reaching the weight limit. In such a case the combined tractor trailer is not at full GCVW of 80,000 lb, the maximum allowed weight for un-permitted interstate transit.6 Appropriately, the Agencies indicated the need and intent to gather additional data on the weight/payload in actual service. They addressed the work-factor metric in Class 2b by accounting for the payload capability of these vehicles in the rule instead of setting a payload for evaluation, which overall addresses the Phase One Committee recommendations. The Agencies chose not to consider a metric for volume-limited freight, which might otherwise have been useful in the assessment of longer combination vehicles (LCVs). The NRC Phase One Report found that such vehicles “offer potential fuel savings for the trucking sector that rival the savings available from technology adoption for certain vehicle classes and/or types” (NRC, 2010, p. 176). Payload and its relationship to LSFC remain important considerations.
Recommendation 1.1: NHTSA should evaluate the load-specific fuel consumption (LSFC) at more than one payload to ensure there is not an undesirable acute sensitivity to payload by a particular truck power train and to reflect the fact that some states allow vehicles to operate with gross combination vehicle weight ratings well in excess of the values adopted for the simulation.
The Phase One Report included the following finding:
Finding 8-1. While it may seem expedient to focus initially on those classes of vehicles with the largest fuel consumption (i.e., Class 8, Class 6, and Class 2b, which together account for approximately 90 percent of fuel consumption of MHDVs), the committee believes that selectively regulating only certain vehicle classes would lead to very serious unintended consequences and would compromise the intent of the regulation. Within vehicle classes, there may be certain subclasses of vehicles (e.g., fire trucks) that could be exempt from the regulation without creating market distortions. (NRC, 2010)
The Agencies agreed with the NRC that regulating all MHDV classes at the outset of the regulation was important. As noted in the Phase One Report, if NHTSA were to regulate only Classes 2b, 6, and 8, this would encompass 90 percent of the fuel used by all medium- and heavy-duty vehicles. The Phase One Committee was quick to note, however, that uneven policy application may cause disruptions in the marketplace and create the potential for reclassifying various classes of vehicles, as has been done in light-duty vehicles (LDVs). Other unintended consequences might result, such as changes in market behavior to avoid higher prices due to regulation (e.g., if Class 2b is regulated but not Class 3, then buyers might buy more of the larger Class 3 trucks because they would become less expensive relative to 2b trucks). In view of these considerations, the committee believes regulating all MHDVs should remain the “agencies’ objective.” As the regulatory framework becomes more defined and comprehensive, additional effort needs to be applied to avoid unintended consequences, as addressed in the Phase One Report.
The Agencies adopted the general recommendation of using simulation to handle the wide range of vehicle configurations and equipment and drive cycles, while building on existing protocols of engine testing for criteria emissions. The use of simulation for the vehicle, with a separate engine test, generally followed the NRC Phase One Report recommendation to certify entire vehicles. The Phase One Report included the following recommendation:
Recommendation 8-4. Simulation modeling should be used with component test data and additional tested inputs from power train tests, which could lower the cost and administrative burden yet achieve the needed accuracy of results. This is similar to the approach taken in Japan, but with the important clarification that the program would represent all of the parameters of the vehicle (power train, aerodynamics, and tires) and relate fuel consumption to the vehicle task. (NRC, 2010)
The Agencies developed a relatively measured regulation in 2011 (EPA and NHTSA, 2011a) in that the fuel efficiency targets are modestly challenging for some vehicle classes, and the certification process builds largely on current methods. The exception where extensive engineering was required was the development of the GEM for Classes 2b-8 vehicle compliance (see Chapter 3 for more discussion of GEM). GEM, a MATLAB/Simulink-based model, uses the same physical principles as many other existing vehicle simulation models to derive governing equations that describe driveline components, engine, and vehicle. These equations are then integrated in time to calculate transient speed and torque (EPA and NHTSA, 2011b, p. 4-2). The development and benchmarking of GEM are found in EPA reports (EPA, 2011; EPA and NTHSA, 2011b). The Agencies reduced the engineering challenge by simplifying the model, excluding hybrid powertrains and several widely used component technologies (e.g., automatic transmissions).
5 Federal Register 57158 states that “These payload values represent a heavily loaded trailer, but not maximum GVWR, since as described above the majority of tractors ‘cube-out’ rather than ‘weigh-out.’”
6 GCVW of more than twice this weight is possible with special permits on certain roadways.
To capture fully the fuel consumption benefits of technologies in future regulatory phases, more engineering will be needed (and in fact is under way). The committee notes, however, that the selected drive cycles do not include external effects such as road grade or cross-winds (i.e., yaw angle), which are particularly significant for Class 7 and Class 8 vehicles. The simulations will thus not fully reflect the benefits of certain types of technologies for reducing fuel consumption. The NRC Phase One Committee had noted that road grade variations, for example, are absent from practically all widely used test cycles. A further example is adaptive cruise control, a subsystem actuated by radar systems to set a desired speed and offering the option of maintaining a set following interval from a vehicle directly in front. The longitudinal control this technology provides offers co-benefits for fuel consumption. These systems have full systems control. Further, as noted by the agencies, many of the vehicle specifications (transmission and final drive ratio) are left to the routine specification process (EPA and NHTSA, 2011a, p. 57158). The GEM simulation is based on a few user input parameters, including rolling resistance, aerodynamic drag coefficient, and vehicle weight reductions (EPA and NHTSA, 2011b, p. 4-10). Hence the question of expected change in performance is not fully answered and neither is the question of whether the Phase I Rule will have a favorable impact.
A lingering concern in GEM is the inability of manufacturers of Class 8 vehicles to take into account the engine choice, actual engine efficiency, and integrated power train design optimization, items that can provide as much benefit as some aerodynamic features.7 Also, the cooling system is neglected: It may be unfavorably affected by efficient aerodynamics yet not accounted for at the engine. The cooling system can represent 5 percent of the vehicle power demand during some operations.8
Both GEM and current test cycles are time based and may not accurately reflect fuel consumption to accomplish a mission. Improved productivity may not be recognized, yet it saves fuel because commercial vehicles will run until the mission (work, distance, etc.) is completed.
Finding: The current certification procedures rely on computer simulations that have only a few unbound variables that can be user-specified. Further, GEM specifically does not allow for synergy between components, the operation of components in a most efficient way, or the engendering of efficiency through operation of a smaller component at higher relative load. Vehicle designs that are optimized for the conditions of the simulation may not be optimized in the real-world operation.
Recommendation 1.2: NHTSA should conduct a real-world evaluation to validate the simulated fuel consumption outputs in light of the input data used. The evaluation should include a sensitivity analysis on key parameters, such as gross combination vehicle weight, to judge whether the variation in these parameters leads to a source of error in the simulation. NHTSA will need to test a reasonable number and variety of vehicles to further refine and validate the Greenhouse Gas Emissions Model (GEM) simulations.
The NRC Phase One Report included the following recommendation:
Recommendation 8-6. NHTSA should conduct a pilot program to “test drive” the certification process and validate the regulatory instrument proof of concept. It should have these elements:
- Gain experience with certification testing, data gathering, compiling, and reporting. There needs to be a concerted effort to determine the accuracy and repeatability of all the test methods and simulation strategies that will be used with any proposed regulatory standards and a willingness to fix issues that are found.
- Gather data on fuel consumption from several representative fleets of vehicles. This should continue to provide a real-world check on the effectiveness of the regulatory design on the fuel consumption of trucking fleets in various parts of the marketplace and in various regions of the country. (NRC, 2010)
It appears that the administration’s schedule for issuing a rule quickly was a key factor in not conducting a pilot program. It is recognized that the entire NHTSA regulation was on a mandatory fast track, as requested by President Obama (White House, 2010). The committee compliments the Agencies on getting a Phase I Rule in place quickly, to promote fuel savings as soon as feasible.
The recommendation that NHTSA conduct a pilot program had two broad purposes: first, the agency would gain experience with certification testing, data gathering, compiling, and reporting. The trial period was envisaged as a means for developing and refining the regulatory processes before the official start date of the program. Second, the pilot program would include gathering data on fuel consumption from several representative fleets of commercial trucks (e.g., long-haul, delivery vans, specialty vehicles, and large pickups). These data would provide a real world check on the effectiveness of the regulatory design on the fuel consumption of trucking fleets in various parts of the marketplace and in various regions of the country (NRC, 2010, p. 188).
7 David Kayes, Daimler Trucks North America, “Lessons Learned from FE/GHG Phase 1 Regulations, and Ways to Incorporate the Most Likely Future Technologies into FE/GHG Phase 2 and 3 Regulations,” Presentation to the committee, March 20, 2013.
8 Nigel Clark, West Virginia University, Morgantown, “Engine Models and Maps for Truck Certification,” Presentation to the committee, June 20, 2013.
The Agencies, however, declined to undertake a pilot program.9 Data gathering and comparing the performance of vehicles specified via the Phase I Rulemaking process versus current methods of specifying trucks for customers (using OEM specification tools) could nonetheless have begun in 2011 and been continued until now. Data gathering should be ongoing. At least some kind of demonstration programs could have been done, perhaps even with simulations.
Omissions that were due to the absence of a demonstration program include the following:
- The lack of baseline data from a few representative national fleets prior to the rulemaking, such as would enable comparison with post-rulemaking (after 2014) fuel efficiency. This would have also started to facilitate the comparison of real-world test data with compliance data. The committee nonetheless recognizes that NHTSA has begun the process of designing surveys and seeking the necessary approvals from the Office of Management and Budget10 to allow it to assemble a picture of the fleet characteristics.11
- Early assessment of the process, accuracy, and repeatability of both tire rolling resistance measurements and aerodynamic drag measurements—in particular of vehicles in Classes 7 and 8. These measurements rely on less proven methodologies than the engine fuel efficiency measurements, which rely on established emissions certifications procedures in a well-controlled test cell. The GEM model requires the insertion of drag coefficient and tire rolling resistance variables as two of the very few parameters in the model over which the manufacturer has control. It is important that all communities have confidence in accurate determination of these variables; otherwise, there may be a perception that GEM predictions and binning could be impacted.12 (GEM is discussed in detail in Chapter 3.)
The MHDV regulatory regime has had a short history relative to other fuel economy regulatory programs. There has not been the opportunity to benefit from numerous cycles of learning, development of regulatory measures, data acquisition, demonstrations, research and development (R&D), and modeling and simulation such as might be incorporated in periodic revisions to the rule. Many of these processes, such as R&D and models development, can take several years to reach fruition.
Finding: NHTSA can expect to benefit from insights and learning from technological advances and stakeholder dialogue.
Recommendation 1.3: NHTSA should allow the process of revising its regulations to be informed by the research and development cycle; advances in model development; and data collection, including its ongoing effort to develop surveys of the current fleet.
A further issue of importance is the need for data such as would permit regulators to evaluate regulatory efficacy. While the rejected Recommendation 8-6, quoted earlier, from the NRC Phase One Report assumed the “gathering of data from fleets” would occur prior to regulation, the NRC’s notion remains highly valid and is still required to improve the accuracy of the original promulgation program and, most certainly, the next phases. Even though the current program is structured as an incremental approach, both sides of the increment (with and without the program change) need to be auditable to validate the declared improvement.
There has been no action to restart the Vehicle Inventory and Use Survey (VIUS) or any similar survey. Using VIUS, researchers at Argonne National Laboratory found that during idle, Class 8 sleeper cabs use 7 percent of their fuel (Gaines, 2006; Capps, 2008). The data provided by such a survey would also be very useful for safety analysis, freight planning, and transport system analysis. This is discussed further in Chapter 4.
Interventions into complex systems inevitably produce unintended consequences. The American sociologist Robert Merton (1936) recognized that purposeful actions to try to change a system will often produce unintended effects that can be positive or negative. Some unintended consequences can be anticipated, while others cannot. An example of a beneficial unintended consequence is when cities started installing light-emitting diode (LED) lighting to save energy, accidents were also reduced because the lamps burnt out less frequently. An example of a detrimental unintended consequence is the water contamination that resulted from the addition of methyl tertiary butyl ether to gasoline as an oxygenate intended to reduce ground-level ozone. Sound public policy involves attempting to anticipate and reduce, when feasible and appropriate, the negative unintended consequences of policy interventions. Methods such as scenario
9 75 Fed. Reg. 74354.
10 The Office of Management and Budget’s (OMB’s) Office of Information and Regulatory Affairs is a statutory office created to administer the Paperwork Reduction Act.
11 See 77 Fed. Reg. 75257.
12 Binning is a method employed in model development to represent the real-world characteristics of a vehicle in a stylized, discretized manner. It involves the creation of a predefined set of notional categories into which real-world vehicles are sorted for purposes of carrying out the simulation. For example, GEM utilizes five bins to represent the aerodynamic characteristics of various vehicle configurations (EPA and NHTSA, 2011b, p. 2-46).
analysis or “red teaming” can be used to formally investigate potential unintended consequences (Lempert, 2007).
Fuel consumption regulations, in purposely trying to change product characteristics and mixes, could produce incentives and behaviors that may result in unintended consequences, either beneficial or detrimental (see, for example, Yun, 1997; NRC, 2001; and Harrington and McConnell, 2003). Some analysts have noted that original equipment manufacturers (OEMs) responded to the Corporate Average Fuel Economy (CAFE) standards by producing vehicles that counted as trucks for regulatory purposes (NRC, 2001, p. 10; Harrington and McConnell, 2003, p. 11).
Of note, two heavy-duty gasoline engine manufacturers (Ford13 and GM14) said that the Phase I Regulations are considerably more difficult to achieve for gasoline engines than they are for diesel engines in vehicle classes where both engine types are available (notably Classes 2b and 3). Both manufacturers have indicated that marginalization or elimination of gasoline engines from this segment is a possible future outcome based on present forecasts, and this feedback should be carefully considered when setting Phase II Regulations applicable to this segment. The Agencies may wish to consider whether such consequences are likely and, if so, to what extent they will be detrimental to the long-run health of the industry and the goals of reduced fuel consumption and GHG reduction, and if such second-order impacts can or should be mitigated.15
Finding: The avoidance of unintended consequences needs to continue to be an essential consideration during development of the MHDV regulations.
Recommendation 1.4: NHTSA should conduct an analysis, including methods such as expert surveys and scenario analysis or red teaming, as appropriate, to anticipate and analyze potential unintended consequences of its regulations and to determine whether additional actions are warranted to try to minimize such impacts. NHTSA should undertake this analysis concurrently with its next revision to its regulation.
The committee believes the Agencies were prudent in not establishing regulations for trailers in their Phase I Rule,16 given the additional time needed to develop and promulgate such regulations. In its report, the Phase One Committee found that “trailers, which present an important opportunity for fuel consumption reduction, can benefit from improvements in aerodynamics and tires.” Noting the synergies between tractors and trailers, that earlier committee recommended that “separate regulation of trailer manufacturers will be necessary to promote more fuel-efficient trailers, including integration of the trailer design with the tractor for improved aerodynamic performance, lower tare weight, and a requirement for low-rolling-resistance tires” (NRC, 2010, p. 189). Harmonization of tractor and dry van and refrigerated trailer aerodynamic features was not possible for 2014, but awareness would have been raised by requiring minimum semitrailer performance, even in select categories.
Finding: The omission of trailer regulations has led to suboptimal regulatory constructs when considering the combined tractor-trailer. The culture change in the tractor-van trailer fleet technical community has progressed but has done so absent clear signals on the cost-effectiveness of integrating trailers into the total vehicle. Separate regulation of trailers for fuel efficiency will have the beneficial effect of beginning integration of trailer design with the tractor for improved aerodynamic performance, lower tare weight, and a requirement for low-rolling-resistance tires.
Aerodynamic Test Method
The Phase One Report included the following recommendation:
Recommendation 5-1. Regulators should require that aerodynamic features be evaluated on a wind-averaged basis that takes into account the effects of yaw. Tractor and trailer manufacturers should be required to certify their drag coefficient results using a common industry standard. (NRC, 2010)
The Agencies understandably did not try to develop or implement a standard way of assessing aerodynamic drag coefficients of Classes 7 and 8 tractors in the Phase I Rule. Instead, they chose a reference method—an enhanced coast-down procedure—but at the same time included a process for manufacturers to calibrate results from their own test methods to said reference procedure.17 This eased the administrative and test burden on the industry for this initial Phase. The
13 Ken McAlinden, Ford Motor Company, “Heavy Duty GHG from a Full-Line Manufacturer’s Perspective.” Presentation to the committee, June 20, 2013.
14 Mark A. Allen and Barbara Kiss, “General Motors Comments: NAS Panel on Heavy-Duty GHG/CAFE Discussion,” Presentation to the committee, July 31, 2013.
15 The EPA faced a similar issue in its 2000 rulemaking on Tier 2 emission standards for light-duty vehicles. The Agency was concerned that its regulations would have unintended differentiated effects on diesel versus gasoline vehicles. EPA identified this potential concern in its rulemaking and proactively took measures to prevent any adverse unintended consequences by modifying the compliance schedule for diesel vehicles (EPA, 2000, pp. 6739-40).
16 75 Fed. Reg. 75354; 76 Fed. Reg. 57111.
17 76 Fed. Reg. 57148-57149.
Agencies announced plans to perform further assessments for future phases.
The Phase I Rule adopted test procedures that may not consider yaw angle; however, it was noted that “the Agencies are adopting provisions which allow manufacturers to generate credits reflecting performance of technologies which improve the aerodynamic performance in crosswind conditions.”18 Apparent wind yaw angles are certainly important in characterizing aerodynamic efficiency: They have a significant influence on the magnitude of aerodynamic drag. Some designs are likely to be more “yaw resistant” than others, so that a simple determination of the drag coefficient at zero yaw angle may not promote the best design in practice. The binning of data does not truly provide error margins, and misclassification relative to the real benefit can and will occur. The complexity of aerodynamic issues may exceed the ability of even a demonstration program. Findings in this area have been delayed by not having such a program.
The committee believes there are sufficient wind tunnel facilities in North America (including scale model wind tunnels with moving ground and yaw capability) to facilitate measurements of drag at varying yaw angles. Not accounting for the performance of aerodynamic drag in relation to apparent wind yaw angle keeps devices that perform better in yaw conditions from being given proper credit. These issues potentially exist with aerodynamic measurements and therefore are required to improve both the accuracy of the current program and (most certainly) that of the next phases.
Recommendation 1.5: NHTSA should create a dedicated program focusing on aerodynamics of the regulated categories of vehicles that would allow these factors to be more accurately considered in the overall fuel consumption reduction of commercial vehicles of different classes. This will entail a program of experiments and dedicated instrumentation.
The Phase One Report included the following recommendation:
Recommendation 8-5. Congress should appropriate money for and NHTSA should implement as soon as possible a major engineering contract that would analyze several actual vehicles covering several applications and develop an approach to component testing and related data collection in conjunction with vehicle simulation modeling to arrive at LSFC data for these vehicles. The actual vehicles should also be tested by appropriate full-scale test procedures to confirm the actual LSFC values and the reductions measured with fuel consumption reduction technologies in order to validate the evaluation method. (NRC, 2010)
NHTSA has sponsored a project at Southwest Research Institute (SwRI) that began in early 2013.19 Based on the SwRI representative’s status report on June 21, 2013,20 the committee concludes NHTSA is addressing Recommendation 8-5 of the Phase One Report.21 The committee is highly supportive of these efforts to quantify fuel consumption benefits.
Finding: In vehicle simulation, there is uncertainty about the effectiveness of particular aerodynamic devices, as well as other components like accessories, auxiliary power units, driveline parts, and tires. Some standardized test protocols are needed. This concern is elaborated in Chapters 3 and 6 as it relates to aerodynamic devices and in Chapter 6 as it relates to tires.
The committee believes some further points and recommendations from the Phase One Report are meritorious and still worthy of consideration. One issue was establishing the point of compliance or point of regulation. The Agencies have, in fact, partially implemented the recommendation on regulating the final stage manufacturer, but they retained a separate engine regulation based on a generic engine. The latter relies on simulation to streamline the certification process and accommodate the wide range of whole-vehicle configurations.
The points of regulation in the Phase I Rule are as follows:22
- Class 2b pickups and vans are regulated at the final vehicle builder.
- Vocational trucks are regulated at both the engine manufacturer and the chassis builder.23
- Classes 7 and 8 are regulated at both the engine manufacturer stage and the final-stage manufacturer.
As described on pages 190-194 of the Phase One Report:
18 76 Fed. Reg. 57149.
19 Thomas Reinhart, Southwest Research Institute, “Phase Two MD/HD Vehicle Fuel Efficiency Technology Study,” Presentation to the committee, June 21, 2013.
21 Recommendation 8-5 called for “a major engineering contract that would analyze several actual vehicles covering several applications and develop an approach to component testing and related data collection in conjunction with vehicle simulation modeling to arrive at LSFC data for these vehicles.”
22 76 Fed. Reg. 57110.
23 Regulating vocational trucks, such as dump trucks, refuse trucks, vacuum trucks, and so forth, poses unique challenges with respect to the high specification variation needed in order for a vehicle to perform its function and the added challenge that follows from the complexity of the bodies on these trucks, which can make up to 80 percent of the end-use vehicle content.
Finding 8-8: A certification test method must be highly accurate, repeatable, and identical to the in-use compliance tests as is the case with current regulation of light-duty vehicles tested on a chassis dynamometer, and for heavy-duty engine emissions standards tested on engine dynamometers.
Further, Finding 8-9 from the Phase One Report says that “to account for the fuel consumption benefits of hybrid power trains and transmission technology, the present engine-only tests for emissions certification will need to be augmented with other power train components added to the engine test cell, either as real hardware or as simulated components.” This led to Recommendation 8-4 in the Phase One Report, which says, in part, “Simulation modeling should be used with component test data and additional tested inputs from power train tests.” The need to account for the close interaction of the engine with other components/subsystems, such as the aftertreatment subsystem and the transmission, is greater now that hybrids and automated mechanical transmissions and aftertreatment algorithms have been improved. Therefore there is a need to use validated models of integrated power train components or actual power pack data operated over real-world drive cycles in the certification process.
Recommendation 1.6: NHTSA should consider the option of power train (power pack) testing and certification and of using, in GEM, verified models of the actual power train (power pack) shipped with the vehicle at the time of manufacture.
Recommendation 1.7: NHTSA, in coordination with EPA, should work toward requiring quantified baselines and improvements, achieved via recognized test protocols, especially for the “Vehicle Power Demands” parameters of the actual vehicle’s consumption of fuel process.
Further, NRC included in its Phase One Report the following recommendation for a study of dieselization of Class 2b through Class 7 vehicles:
Recommendation 4-2. Because the potential for fuel consumption reduction through dieselization of Class 2b to 7 vehicles is high, the U.S. Department of Transportation/ National Highway Traffic Safety Administration (NHTSA) should conduct a study of Class 2b to 7 vehicles regarding gasoline versus diesel engines considering the incremental fuel consumption reduction of diesels, the price of diesel versus gasoline engines in 2010-2011, especially considering the high cost of diesel emission control systems, and the diesel advantage in durability, with a focus on the costs and benefits of the dieselization of this fleet of vehicles.
Diesel engines present an opportunity for incremental fuel efficiency gains and, for some vehicles, may have the advantage of better durability. The Phase One Report also noted the high cost of diesel emission control systems and the price of diesel versus gasoline engines prevalent in 2010-2011 as factors that would prevent a move to a more fuel-efficient diesel power train. Since the Phase One Report was issued, natural gas engines have also become an option in some fleet applications. It remains relevant to determine the emission control strategy for NOx and CO2 emissions for Class 2b through Class 7 vehicles that would deliver the greatest reduction in fuel consumption and GHG emissions overall for this fleet, taking into account the cost of compliance.
Also in the Phase One Report was Recommendation 4-4:
Recommendation 4-4. NHSTA should support the formation of an expert working group charged with evaluating available computer simulation tools for predicting fuel consumption reduction in medium- and heavy-duty vehicles and developing standards for further use and integration of these simulation tools.
While NHTSA did not take such actions, EPA requested expert inputs, conducted an external peer review (EPA, 2011), and compared simulation packages in the course of developing GEM. As a result, the agencies have not fully addressed this recommendation.
A further recommendation in the earlier report, Recommendation 5-2, reads as follows:
Recommendation 5-2. There are numerous variables that contribute to the range of results of test programs. An industry standard (SAE) protocol for measuring and reporting the coefficient of rolling resistance is recommended to aid consumer selection, similar to that proposed for passenger car tires.
Although not specifically mentioned in the Federal Register notice promulgating the rule (EPA and NHTSA, 2011a), the International Organization for Standardization (ISO) published a standard practice in 2009 (ISO, 2009). This practice should be considered for inclusion in the future rulemaking.
The Phase I Rule had the effect of encouraging the adoption of technologies for reducing fuel consumption.24 Such reductions can be achieved through technological improvements to the vehicle as well as by improvements in operations, changes in behavior, and so forth. The Phase One Report considered nontechnology approaches such as intelligent transportation systems; construction of exclusive truck lanes; congestion pricing; driver training; and intermodal operations (NRC, 2010, pp. 159 et seq.). Also considered were market-based instruments such as fuel taxes.
24 The precise metric for measuring fuel consumption, the load-specific fuel consumption (LSFC) is measured in gallons of fuel per payload ton per 100 miles. The lower the fuel consumption (FC) of the vehicle and the higher the payload the vehicle carries, the lower the LSFC.
Another viable approach would entail adjusting size and weight restrictions on trucks. For example, this might include greater use of vehicles that have favorable load-specific fuel consumption—for example, LCVs, which have greater freight capacity than the notional tractor-trailer, which has a GCVW of 80,000 lb.25 Egress for LCVs from the network of roads and highways they are constrained to operate within might become an issue as the number of such vehicles increases. This must not be undertaken at the expense of safety and must operate with appropriate permitting. Lastly, Recommendation 7-3 of NRC (2010) called for training drivers to reduce fuel consumption. Training requirements for commercial driving licenses could be influenced by the U.S. Department of Transportation and NHTSA.
Recommendation 1.8: Recommendations 4-2, 4-4, 5-2, and 7-3 from the 2010 National Research Council report Technologies and Approaches to Reducing the Fuel Consumption of Medium- and Heavy-Duty Vehicles should be given further consideration in future regulations.
Finding: A number of strategies are available for reducing MHDV fuel consumption that do not involve changes to the engine or vehicle. While some nonvehicle alternative approaches for reducing fuel consumption and GHG may be beyond NHTSA’s delegated authority, the agency can and should work with other agencies with appropriate authority as well as to encourage private actors to consider such strategies to complement and support NHTSA’s standards.
Recommendation 1.9: NHTSA should consider additional strategies to encourage the adoption of measures that reduce fuel consumption. It should work together with EPA, the Federal Highway Administration, and the U.S. Department of Energy’s (DOE’s) Office of Energy Efficiency and Renewable Energy, as applicable, to realize such fuel savings in the real world and to create knowledge and incentives to capture the benefits of approaches other than regulating the vehicle, such as by changes to fleet operations and logistics.
This section briefly summarizes market and other regulatory background factors that are relevant to MHDV fuel consumption and GHG emissions that have significantly changed since the Phase One Report was completed. The Phase One Report reviewed the technologies that could practicably be considered for near-term and long-term fuel consumption and CO2 reduction, and in addition discussed a significant number of technology and market trends. For instance, there was already a move from diesel to gasoline direct injection technology at the middle of the MHDV range, as noted in the Phase One Report (NRC, 2010, p. 64). Likewise a shift to more fuel efficient, smaller displacement, greater power-density diesel engines was then becoming apparent and was expected to motivate continued downsizing, as with passenger cars. An analysis by Frost & Sullivan, a consultancy, indicates 15 liter (15 L) engines will continue dominating the Class 8 engine market through 2018 but then are expected to lose market share to 11 L to 12 L and 12 L to 14 L engines.26 While the consequences of these moves are reduced fuel consumption and reduced CO2 emissions, they may also have implications for the market as a whole and may influence factors such as supply chain and fuel choice.
Given that the previous Phase One Report was so comprehensive, only a few additional market and other background regulatory factors are identified in the current report as potentially affecting the efficacy of a future regulation. Some of these factors might counteract or complicate attempts to achieve improvements in fuel consumption or reductions in GHG emissions through the anticipated Phase II Regulations of NHTSA and EPA, while other factors might help to achieve those improvements and thus help to make the regulation more feasible. In addressing these factors, the committee focuses primarily on those that are likely to have a significant effect from 2020 to 2025, which is the likely implementation period of the Phase II regulations.
Of course the state of the economy will have a significant impact on MHDV vehicle-miles traveled (VMT), fuel consumption, and GHG emissions, particularly as macroeconomic trends affect growth and activity in the construction and manufacturing industry sectors. But in addition to the general economic health condition of the nation, the other potentially relevant factors discussed here include (1) the emergence of natural gas as a significant transportation fuel; (2) the role of biofuels; (3) the growing interest in the United States in dimethyl ether (DME) as a fuel; (4) the viability of electrification of the vehicles; (5) the development of automated and/or connected vehicles; (6) the implementation of green logistics; and (7) background regulatory developments.
The natural-gas-fueled engine, using either liquid natural gas (LNG) or compressed natural gas (CNG), is not a new technology. Natural gas engines were produced as early as
25 This follows from the observation that “weighing out” is better for load-specific fuel consumption than “cubing out,” with the latter referring to filling up the cargo area before reaching the GCVW limit.
26 Sandeep Kar, Frost & Sullivan, “Strategic Outlook of North American Medium and Heavy Commercial Truck Powertrain Market Megatrends and Industry Focus Indicate a Cleaner and Smarter Freight Movement Environment,” Presentation to the committee, March 21, 2013.
FIGURE 1-1 Illustrative pathway for vehicle fuels production and use.
1860 and now power about 120,000 vehicles on U.S. roads.27 The application of natural gas for MHDVs has been more recent, however, and earliest uses were for transit buses and municipal vehicles. Over the past two decades, the natural gas engine has served as a niche technology in the MHDV market, present in mostly urban refuse haulers and transit bus applications. Natural gas is often referred to as a “bridge fuel,” since it is a way to bridge the diesel-fuel dominance of the MHDV market to the next non-petroleum-based fuel—yet to be identified to the point of having a broad consensus. Common production pathways and uses for natural gas and other current and future MHDV fuels are illustrated in Figure 1-1.
The MHDV natural gas market developed slowly before circa 2010. Purchasers other than municipal fleets, which are subsidized by the government, had difficulty justifying the higher purchase price of the vehicle despite the lower cost of natural gas compared to diesel fuel. Furthermore, the cost of constructing fueling stations across the country ranges between $600,000 to over $1,000,000 per station for compressed natural gas and nearly twice that per liquefied natural gas station.28
Municipal vehicles, which run routes during the day and are centrally garaged at night, can be readily refueled at the garage, making them good applications for this niche technology.
In recent years, the gap between natural gas and diesel fuel prices has dramatically widened.29 Moreover, advancements in technology have enabled manufacturers to develop
28 TIAX (undated), “US and Canadian Natural Gas Vehicle Market Analysis—CNG Infrastructure: Final Report.” Prepared for American Natural Gas Association. Available at http://anga.us/media/content/F7D3861D-9ADE-7964-0C27B6F29D0A662B/files/11_1803_anga_module5_cng_dd10.pdf; and TIAX (undated), “Gas Vehicle Market Analysis—LNG Infrastructure: Final Report,” Prepared for American Natural Gas Association. Available at http://anga.us/media/content/F7D3861D-9ADE-79640C27B6F29D0A662B/files/LNG%20Infrastructure.pdf.
29 ACT Research, 2012, “The Future of Natural Gas Engines in Heavy Duty Trucks: The Diesel of Tomorrow?” August 10.
more natural gas engine options and attendant vehicle technologies to achieve reliability and durability similar to that of the diesel. Together these circumstances make natural gas a viable choice for future commercial over-the-road fleets.
A variety of natural gas engines suited to a wide range of MHDV applications will be available by 2015. As more OEMs are introducing natural gas options to their product line, the share of CNG/LNG MHDVs continues to grow. ACT Research predicts30 that the natural gas market share of MHDV truck and bus (includes municipal and refuse) could be as high as 36 percent by 2020. For these predictions to play out, the CNG/LNG infrastructure must be expanded. While there has been a significant increase in the number of natural gas fueling stations over the past years, the infrastructure is still nascent and will require large investments to provide enough stations to prevent disruption in routes and travel times for longer-haul trucks.
Another consideration in the future use of natural gas in the MHDV market is the rapid growth and output of hydraulic fracturing (“fracking”) in natural gas drilling. Fracking has greatly increased the supply and availability of natural gas while reducing its cost. EPA and some states are now exploring more rigorous regulation of fracking operations. Regulations are one of several factors that could significantly increase the cost or reduce the availability of natural gas. This would reduce the incentive to move toward natural gas fuels and technologies in the MHDV sector.
Affordable fuel prices and a growing infrastructure all bode well for the future of natural gas in MHDVs. However, if the price of fuel continues to be favorable vis-à-vis diesel, the transportation sector will have to compete with other sectors (e.g., electricity and heating) for domestic natural gas. (The exporting of natural gas could affect prices as well.) Predicting how this might affect the MHDV market is difficult. Analysts predict that as the economy improves, the price of natural gas will increase (AEO, 2013) but so will the price of petroleum-based fuels.
Another important issue raised by fuels such as natural gas is, on the one hand. the distinction between vehicle fuel consumption and GHG and, on the other, the life-cycle analysis of the fuel consumption and GHG using natural gas as a fuel (well to wheels). This issue is addressed in Chapter 5 of this report, which discusses the role natural-gas-fueled MHDVs will play in the reduction of fuel use and CO2 emissions in the future.
The current state of biofuel research, development, and production suggests that the biofuels produced in abundance over the next decade will likely be blends containing ethanol, gasoline, or biodiesel. In its 2013 Energy Outlook, the DOE’s Energy Information Administration (EIA) forecasts that the consumption of next-generation biofuels (including pyrolysis oils, biomass-derived Fischer-Tropsch liquids, and fuels derived from renewable feedstocks) by the transportation sector will increase to about 0.4 million barrels per day (BPD) from 2011 to 2040. This compares with 1.6 million BPD of diesel during the same period. Given this presence of biofuels, the future fuel consumption and CO2 reduction regulations for MHD trucks must take into consideration the effects of biofuels on the implementation of the future standards.
Ethanol has been used as a blend in gasoline engines for over three decades. Several federal regulations and programs have facilitated the use of ethanol as an oxygenate in the fuel to reduce air pollution (EPACT 2005 and EISA 2007). GHG emissions for E10 are 12 to 19 percent lower than those for pure gasoline (Argonne National Laboratory, 1999) at equal engine efficiency. Ethanol has the added benefit of reducing the U.S. dependence on petroleum, since it is made from plant materials, or “biomass.” In 2001, the production of ethanol as a share of gasoline volume was only 1 percent. By 2011, the share rose to 10 percent (EIA, 2012). This is largely due to the first Renewable Fuel Standard (RFS) program, which was enacted in 2006 as a part of the Energy Policy Act of 2005. As a result of EISA 2007, the Renewable Fuels Standard “RFS2” mandated renewable fuel consumption of 36 billion gallons (35 billion of ethanol equivalent and 1 billion of biodiesel) by 2022.
Although higher blends of ethanol are approved as a transportation fuel by EPA (E15 and E85), the majority of vehicles in the United States use E10. Higher blends can produce fewer GHG, but the higher blends usually exhibit less “tank mileage” (miles per gallon), because of the inherent lower energy content (i.e., enthalpy) of ethanol. Every 10 percent of ethanol in the fuel reduces fuel economy by approximately 3.5 percent (Knoll et al., 2009). Further, distribution infrastructure becomes more difficult at higher blends. Ethanol is a solvent, so its chemistry is prone to dissolving the hydrocarbon residue and water that are often found in the pipeline, which can render the transported fuel out of specification, especially if tanks and pipes are not properly cleaned before switching products. In some cases where other blends of ethanol are desirable, filling station pumps are modified to blend pure gasoline with E85 to produce the new blend. Note that in the mid-1980s heavy-duty diesel engines were developed and demonstrated using ethanol fuel with an ignition assist.
Studies by EPA and others indicate that the fuel consumption of B5, the most commonly used biodiesel, is about
2 percent worse than that for conventional diesel.31 However, vehicle CO2 emissions for B20 can be 15 percent less than that for diesel. The B20 pumps are available at a growing number of outlets throughout the United States.
In 2001 biodiesel production was 9 million gallons. By 2011, it was nearly 100 times higher, at 967 million gallons. While this growth is significant, it represents only 1 percent of the total diesel production by volume. Consumption of biodiesel in 2011 was 878 million gallons (EIA, 2012). Similarly, RFS and EISA 2007 (RFS2) require consumption of 1 billion gallons biomass-based diesel. Tax credits and incentives through the RFS2 have had a positive influence on the production and consumption of biodiesel. Soybeans make up 57 percent of the biodiesel feedstock. Thus, droughts such as that the United States experienced in 2012 can cause the price of biodiesel to vacillate markedly, giving users little reason to purchase the fuel.
The use of biofuels is well established in the United States. The growth in production and consumption still relies in a large part on incentives and tax credits. Nonfood-derived cellulosic feedstock is another consideration in the growth of these biofuels, but large-scale production and consumption is years away (NREL, 2012). A further fuel not yet in widespread use is so-called renewable diesel fuel, which is bio-oil refined to remove oxygen and which resembles petrol-derived fuels.
Other alternative fuels, known as Fischer-Tropsch (FT) or gas-to-liquid (GTL) fuels, are available in the market but are currently produced in very modest volumes: only about 200,000 barrels a day, which is equal to less than 1 percent of global diesel demand a day (NYT, 2012). These fuels are produced via the FT chemical process, using natural gas, coal, or biomass as feedstock. FT fuels are interesting because they reduce dependency on crude oil and, depending on the feedstock used, may reduce the CO2 footprint as compared with petroleum-based fuels. The resultant fuel from the FT process is a high-quality fuel (NRC, 2009). Hydrocarbon, NOx, and particulate emissions all improve compared to diesel fuel when FT fuels are used (DOT-FHA, 2013).
These benefits notwithstanding, FT fuels are expensive to produce. Capital costs, the reliability of cost-effective feedstock, and the logistics of sourcing and transporting feedstock are all considerable. Analysts believe that FT fuels will be cost-effective only when natural gas and oil prices are out of balance. As long as natural gas and oil price differentials remain relatively aligned, the large investment in FT technology will be unsustainable (NYT, 2012).
Dimethyl ether (DME) may show promise as an alternative fuel. Synthesized from methanol, it can be produced from biomass, natural gas, or coal. Volvo Powertrain NA, the engine manufacturer for and supplier to Volvo and Mack truck brands, has announced it will produce engines operating on DME in 2015.
DME can have lower CO2 emissions than conventional diesel on a well-to-wheels basis, particularly if the feedstock is biomass. The clean-burning characteristics of DME result in virtually no soot production, making a particulate filter unnecessary. Its thermal efficiency and performance are comparable to those of diesel. According to the International DME Association, DME typically sells at a premium to energy value (i.e., costs more for the same enthalpy). DME is liquefied at 50 pounds per square inch (psi) (or 345 kilopascal (kPa)), so its use requires similar tankage to propane. DME is expected to have the same selling price as a diesel gallon equivalent.32 As with most alternative fuels, developing engine and vehicle modifications and the distribution infrastructure for the fuel are the most obvious obstacles to widespread use of DME in the near term.
DME currently has minimal transportation applications in the United States. It would be prudent, however, for the Agencies to consider its role in future transportation segments, given its growing popularity in Sweden and Japan and its forecasted presence in the United States.
The electrification of the light-duty fleet appears to be finally achieving traction after many years of false starts and slow progress,33 raising the potential for electric or hybrid medium- and heavy-duty vehicles to reduce CO2 emissions and fuel consumption. There are a number of technology alternatives for incorporating electrification into the MHDV fleet, including (1) hybrid-electric vehicles (HEVs); (2) electrified accessories; (3) fully electric power trains; (4) electrified power take-off (PTO); (5) plug-in hybrid-electric vehicles (PHEVs); (6) external power to electric power train for zero emission vehicle (ZEV) corridors; and (7) alternative fuel/hybrid combinations.34 In addition, there are so-called hotel load requirements to allow the driver of a Class 8 sleeper tractor to sleep in or otherwise occupy the
31 Petroleum diesel blended with 5 percent biodiesel.
32 Anthony Greszler, “DME from Natural Gas or Biomass: A Better Fuel Alternative,” Presentation at SAE Government/Industry Meeting. Washington, D.C., January 2013.
33 International Energy Agency, 2013. “International EV outlook.” Available at http://www.iea.org/publications/freepublications/publication/name,37024,en.html.
34 Tom Brotherton and Fred Silver, CALSTART, “Cal HEAT Research and Market Transformation Roadmap for Medium and Heavy Duty Trucks: Implications for the GHG/Fuel Economy Standards,” Presentation to the committee, July 31, 2013.
sleeper berth. Solutions include battery-operated HVAC and auxiliary power units (APUs), start/stop systems, and truck stop electrification.
Of course, given the range limitations of current vehicle battery technology, electrification is more feasible for some types and modes of MHD vehicles than others. For example, battery-powered motors are least feasible for long-haul heavy-duty trucks that usually travel hundreds of miles per day but may be very promising for service fleets where vehicles perform a number of local deliveries or other jobs per day and then are parked overnight at a centralized base, where they can be plugged in and recharged. One estimate is that up to 6.4 percent of power train systems in MHDVs (including buses) will be electric or hybrid by 2020.35 This represents slightly over 130,000 units, of which about two-thirds are projected to be hybrids and one-third pure electrics.36 Other analysts predict that electric and hybrid vehicles will represent only niche markets before 2030, when more significant market penetration is expected.37
Another important alternative-fuel technology involves hydrogen fuel cells as the power plant; such fuel cells are projected to significantly penetrate the MHDV sector by the early 2020s. Several light-duty vehicle manufacturers are developing fuel-cell vehicles (FCVs) for commercial introduction, including Hyundai in 2014 and Honda in 2015, with others planning introductions from 2017 to 2020.38 This will result in technology validation, hydrogen infrastructure development, and cost savings that will eventually benefit the commercialization of FCVs in the MHDV sector. California is supporting the introduction of FCVs through a partnership with vehicle manufacturers and other stakeholders that has developed a roadmap for installing the infrastructure needed for the commercialization of FCVs.39
Some MHDV manufacturers currently have active programs developing FCVs. For example, Vision Motor Company has developed the nation’s first Class 8 zero emission (tank-to-wheels) hydrogen/electric hybrid vehicle (the Tyrano), designed for local and regional short-haul trips.40
Hydrogen fuel cells are also being developed for buses in the MHDV category. For example, the Federal Transit Administration (FTA) has sponsored a cooperative partnership between industry and government to advance the commercialization of fuel-cell technology in U.S. transit buses (FTA, 2012). This program has launched demonstration and evaluation programs for fuel-cell buses in several U.S. cities. For example, AC Transit is currently operating 12 third-generation fuel-cell buses in its HyRoad demonstration program in Oakland, California, that are achieving significantly lower tank-to-wheels fuel consumption than diesel buses while emitting zero pollution.41 Fuel cells are also being developed to provide auxiliary power for trailer refrigeration, used in some 300,000 refrigerated trucks. The Department of Energy’s Pacific Northwest National Laboratory (PNNL) has launched a demonstration project with four trucks whose refrigerated trailers are powered by a fuel cell.42 According to the PNNL news release, “Industry officials estimate that approximately 300,000 refrigerated trucks with auxiliary power units are on the road in the United States. By replacing the small diesel engines with the more efficient fuel cell, users will see fuel savings of approximately 10 gallons a day per unit, in addition to reduced emissions of pollutants and significantly quieter operation.”43
The carbon dioxide and fuel consumption benefits of both electric and fuel-cell vehicles will depend to a significant degree on the emissions characteristics of the source used to generate the electricity or hydrogen fuel that powers the vehicle (Babaee et al., 2014).
NHTSA and EPA’s Phase I Rule, following President Obama’s rulemaking request (White House, 2010), considers the fuel consumption of the vehicle and the tailpipe CO2 emissions that need to be achieved, on average, by the mix of vehicles sold each year by each manufacturer. Manufacturers are likely to achieve these vehicle standards using the variety of different energy fuels and technologies discussed above—including diesel, gasoline, ethanol, natural gas, electric batteries, and fuel cells—each of which will have varying implications for overall GHG emissions and energy demand considered on a life-cycle basis.
While energy consumption and GHG in the end-use phase (onboard fuel consumption and tailpipe emissions) may be the largest contributor in some cases, energy consumption and emissions associated with fuel production, distribution and processing, vehicle efficiency, and end-of-life may contribute to a substantial share of overall vehicle emissions and energy consumption. The committee notes that the 2010 memorandum also states that “[NHSTA and EPA should] propose and take comment on strategies, […] to achieve substantial annual progress in reducing transportation sector
35 Sandeep Kar, Frost & Sullivan, “Strategic Outlook of North American Medium and Heavy Commercial Truck Powertrain Market,” Presentation to the committee on March 21, 2013.
37 Eelco den Boer, Sanne Aarnink, Florian Kleiner, and Johannes Pagenkopf, “Zero emissions trucks: An overview of state-of-the-art technologies and their potential,” CE Delft, July 2013.
38 A. Webb, 2013, “Auto makers renew interest in fuel-cell vehicles: Despite cost, political hurdles.” Available at http://wardsauto.com/vehicles-amp-technology/auto-makers-renew-interest-fuel-cell-vehicles-despite-cost-political-hurdles.
emissions and fossil fuel consumption consistent with my Administration’s overall energy and climate security goals.” However, not considering well-to-wheel emissions may lead to regulations that do not achieve the anticipated energy and GHG savings. The committee recognizes there are complexities, uncertainties, and limitations to the feasibility of a regulatory framework such as would expand the scope to such a life-cycle approach from the current end-use approach.
Recommendation 1.10: NHTSA, in coordination with EPA, should begin to consider the well-to-wheel, life-cycle energy consumption and greenhouse emissions associated with different vehicle and energy technologies to ensure that future rulemakings best accomplish their overall goals.
Significant progress is being made in developing “connected” or “automated” vehicles that can operate more efficiently and safely using advanced telematics technology. To date, most of the progress in this area has focused on light-duty passenger vehicles, with Google and most light-duty vehicle manufacturers actively developing such vehicles for commercialization within the next decade.44 Although at a slower pace, these technologies will inevitably also be applied to MHDVs. For example, Caterpillar Inc. is currently building 45 automated, 240-ton mining trucks to operate at an Australian iron-ore mine without an onboard operator (Berman, 2013). The most optimistic estimates are that the first automated long-haul trucks (ALHTs) may be commercially viable by the mid- to late-2020s, and could decrease fuel consumption by 15 to 20 percent compared to today’s traditional fleets through more efficient driving patterns (Conway, 2013). It is likely that more limited semiautonomous systems with various driver aids (e.g., adaptive speed control) and enhanced communications (e.g., vehicle-to-vehicle or vehicle-to-infrastructure) will be installed before fully autonomous vehicles are available, and these may provide fuel consumption savings even sooner (Clancy, 2013). Perhaps the most promising technology in the short term is vehicle platooning, in which a set of two or more vehicles is operated closely spaced using semiautonomous intervehicle and navigational communications technologies to reduce aerodynamic drag. Demonstration programs for such vehicle platooning are already under way in the United States,45 Europe,46 and Japan.47 If trucks with semiautomated technologies become available during the compliance period for the Phase II regulations, they may help achieve compliance with the standards, depending on how the standards are structured.
“Green logistics” refers to innovations in infrastructure, organizational initiatives, or traffic management that can result in more sustainable transport. It may also include increased driver training and other behavioral initiatives. These approaches can result in significant and cost-effective reductions in transport emissions and fuel consumption (Hyard, 2013). Examples of such measures that could impact MHDVs are access control (including lane restrictions), urban traffic control measures, road pricing, smart traffic lights that provide more information to drivers on road conditions and traffic, ramp metering, and other fleet and fuel management approaches. Many U.S. cities and municipalities are actively exploring such programs, which to date have been more widely adopted in Europe and Asia. These, along with operational changes that companies are making to reduce their environmental footprints and improve their bottom lines, may contribute to improved MHDV fuel consumption and reduced CO2 emissions by the 2020s when the Phase II regulations are in effect.
As NHTSA and EPA move forward with the Phase II regulations, it is likely that other federal and/or state regulations will be promulgated that may directly or indirectly affect fuel consumption, GHG emissions, or attempts to control fuel consumption and CO2 emissions. While the committee has not fully investigated these other regulations, it recognizes that in some cases, they may pose a positive or negative confounding effect on the implementation of Phase 2 MHDV fuel consumption and CO2 regulations. For example, a more stringent NOx standard in California may reduce the fuel consumption potential of an MHDV, making compliance with the Phase II Rule more difficult to achieve. A short list of such possible regulations that might interfere with or alternatively assist with compliance with Phase II regulations on fuel consumption and CO2 emissions is provided in Table 1-1.
44 KPMG and Center for Automotive Research, 2012. Self-Driving Cars: The Next Revolution.
46 Safe Road Trains for the Environment (SARTRE), available at http://www.sartre-project.eu/en/Sidor/default.aspx.
47 Steven Ashley, “Robot Truck Platoons Roll Forward,” BBC Online, April 10, 2013, available at http://www.bbc.com/future/story/20130409-robot-truck-platoons-roll-forward/print/slide/0.
TABLE 1-1 Possible Non-Fuel-Efficiency Regulations in the 2020-2025 Period That Could Affect Fuel Consumption of MHDVs
|Possible Regulation||Impact on Fuel Consumption and CO2 Emissions|
|California Air Resources Board considering further NOx emission standards for heavy-duty engines||May increase fuel consumption unless aftertreatment becomes more efficient.|
|Specifications for new and alternative fuels—e.g., CARB establishing regulations identifying new alternative diesel fuels||Expected not to negatively impact fuel consumption and will improve CO2 emissions control.|
|California AB32 (California Global Warming Solutions Act)||Requires statewide plan to reduce GHG emissions by 2020, including provisions that will have direct and indirect benefits in reducing MHDV California emissions relating to fuels, traffic control, and other measures.|
|Highway speed limits for heavy-duty vehicles||Lower speeds will generally have a significant beneficial impact on fuel consumption, although size of impact will depend on other power demands of the vehicle.|
|State regulations on fuel exploration, extraction, production, or distribution (including fracking)||Depending on the regulation, natural gas pricing and availability may be negatively affected, which may increase the cost of reductions in fuel consumption.|
|Wireless roadside inspection programs||Eliminate idling from vehicles having to wait in inspection lines, thereby reducing fuel consumption.|
|Restrictions on driver distraction and hours||Will promote more efficient trips; beneficial indirect impact in reducing fuel consumption.|
|Highway funding changes—e.g., VMT fees, fuel tax, weight limits||Many such measures are likely to reduce fuel consumption.|
|International Harmonized Heavy-Duty Certification Test||Due to the complexity of matters considered in harmonizing regulations (e.g., test cycle, fuel specification, compliance expectations, fuel taxes), the effect of harmonized regulations is uncertain.|
Finding: A variety of factors, including alternative fuel technologies, non-fuel-consumption regulatory programs, and other developments will affect the fuel consumption and GHG emissions of medium- and heavy-duty vehicles manufactured and operated in the 2020s.
Recommendation 1.11: In its regulatory analysis, NHTSA should carefully consider and attempt to quantify the impacts of nontechnological factors on the costs and feasibility of future fuel consumption improvements.
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