California emission regulations—Going forward

27 October 2016

California—the birthplace of vehicle emission regulations—and their clean air programs come again to the forefront in the aftermath of the Volkswagen emission scandal, and in the anticipation of a next round of emission standards for heavy-duty engines. The California Air Resources Board (ARB) played the key role in unveiling the VW dual calibration control strategy and in the development of the $15 billion settlement with the car maker over the VW 2.0 L diesels. It should be noted that these developments have been in stark contrast to the official response in the European Union, where—incredible as it may sound—it has not yet been determined whether the Volkswagen emission cheating software was in violation of EU emission regulations and the company has not yet been charged with any wrongdoing.

DieselNet talked about California air quality and future regulatory plans for vehicle emissions with Alberto Ayala, Deputy Executive Director of the California Air Resources Board (ARB). Dr Ayala emphasized that California has achieved significant reductions of diesel particulate emissions, but additional progress can be assured with newer, modern engines and well-maintained emission control systems. Emission standards have been driving the use of diesel particulate filters (DPF) on new vehicles, while in-use engine regulations require emission reductions from the existing diesel fleet. Under the provisions of the in-use Truck and Bus Regulation, by 2023 all heavy-duty vehicles in California will be 2010 models or newer—equipped with DPF and SCR technology.

With the solution for controlling diesel particulates widely recognized, the central emission issues for California remain diesel NOx emissions and CO₂/greenhouse gases. We asked Dr Ayala about his insights on the upcoming regulatory developments in California.

DieselNet: The planned low NOx standards and the recently finalized Phase 2 GHG emission standards for heavy-duty vehicles are in fact related and it would make sense to consider them together: a GHG standard that is easily achievable in combination with a NOx limit of 0.2 g/bhp-hr may be quite challenging if the NOx standard is tightened to 0.02 g. Last year, in the comments on the proposed Phase 2 GHG rule, the ARB said the EPA proposal misses opportunities to maximize GHG emission reductions and spur development of critical advanced technologies that can provide early climate benefits. Furthermore, the ARB had expected that the proposal would also include a commitment by the EPA to begin development of stricter NOx emission standards for heavy-duty diesel engines. The ARB stated that unless the EPA tightens the proposed Phase 2 GHG regulations, California will adopt their own, more stringent GHG standards for heavy-duty vehicles. Have you been able to reconcile your position with the EPA? Can we expect one set of federal standards for GHG/fuel economy and for NOx, or are California-only standards still an option?

Alberto Ayala: California is committed to a national GHG program for the heavy duty sector and, as the final rule now shows, the Phase 2 standards will provide some significant emission reductions from the sector to help California meet its climate targets. We achieved these standards by working collaboratively with EPA and NHTSA on the technical analysis underpinning the new requirements. Now, CARB is ready to proceed and adopt the California Phase 2 rule next year building from the final federal rule, which did address California’s stated concern on the proposal including the stringency of the standards. Equally important for California and other parts of the U.S. are new, lower NOx standards for HD engines. The sector is the largest source of smog-forming pollution in California and in order to attain the 2008 75ppb 8-hr ozone standard, we need aggressive NOx reductions. Our analysis also shows that a California-only standard will only get us approximately halfway to the needed reductions. Thus, we want to work with EPA as we continue our R&D to explore lower NOx, highly-efficient engine technology working in concert with the HD industry and other technology providers.

Can you comment on any measures concerning light-duty vehicles in the post-Volkswagen world? Are you considering EU-style PEMS testing? Do you intend to re-examine emission compliance in gasoline vehicles as well?

AA: CARB intends to take full advantage of the many valuable lessons we learned in investigating and solving the VW diesel scandal and to apply those lessons to improve what is already our robust and rigorous emission certification, in-use compliance testing, research, and enforcement program. It is no accident that CARB is the one that got onto the diesel issue originally and after extensive testing and process broke the case on the cheating. This shows that our program works. But we are now developing ideas for improvements. Some improvements are administrative in nature and we are already implementing them as part of the certification process. Some will require regulatory changes and new approaches and methodologies for making use of our new testing methods and other resources. PEMS testing is not a silver bullet, but it is one element in the toolbox that we intend to continue to use. Most importantly, there are aspects of dyno testing that were more important in the case and that we intend to put to use to make our program even better. We will continue our light duty diesel program and once complete we will turn our attention to gasoline engines, although for those, we have much more experience and a much deeper testing program which gives us confidence. These perspectives were recently clearly communicated to our European counterparts in a response to a request for information.

Alberto, you have emphasized the importance of OBD in unveiling the VW software strategy. Notwithstanding the role played by OBD in your investigation, one could argue that VW has beaten the OBD legislation—after all, the objective of OBD has been to reduce in-use emissions and get polluters off the road. In today’s implementation, vehicle OBD systems typically monitor emission related components, rather than emissions directly, and assume that if the components operate as designed, the OBD thresholds are not exceeded. If the components “fail by design” (e.g., due to inadequate catalyst volumes or urea dosing), the OBD system will not register a malfunction—a behavior that violates the idea of OBD. Are there any plans to change the way OBD systems are designed and certified, with more focus on direct monitoring of emissions?

AA: It wasn’t just the OBD system but the expertise we have developed in OBD and how we used that expertise coupled with other tools like unique dyno testing approaches that helped us in the case. The Board has already adopted new OBD requirements for real-time CO₂ monitoring which were developed even before the VW issue. But those new CO₂ monitoring requirements will come in real handy and compliment other activities to ensure in-use performance. We hope to continue to work with industry and develop approaches that take full advantage of the total potential that real time OBD monitoring can really offer. At the moment we have no further plans for more OBD changes as we need to let the new requirements take effect for model year 2019. But I think it’s plainly obvious that the question about monitoring for other pollutants will be a key question for regulators, industry, and society as we all strive to avoid a repeat of the VW cheating.

The concept of “remote OBD” or OBD III has been discussed for a number of years and studied through pilot programs, but never implemented. Under this concept, vehicles would have the ability to transmit OBD fault information to roadside receivers through cellular networks. In addition to emission faults, the system could transmit CO₂ and fuel consumption data, providing valuable information on fuel consumption by vehicles and fleets in real driving. Such systems could also generate reliable fuel economy and CO₂ data on hybrids and other advanced powertrains, where laboratory fuel efficiency measurement is a non-trivial task. Is there more political will to re-examine the implementation of remote OBD and related compliance tools?

AA: We will certainly be interested in exploring remote OBD again. As you said, it’s not a new concept but in the past concerns about privacy and now cybersecurity may keep us from taking full advantage of this feature. Today, California has already migrated to an OBD-based I/M program. The new real-time CO₂ monitoring will offer new opportunities for us regulators, but also for the auto industry such as a much better way for the real-world assessment of off-cycle technologies. I hope eventually we can resolve the ancillary concerns of remote OBD in order to realize its full benefit. I am interested in this discussion with the auto industry, but also with the heavy duty manufacturers. So stay tune, we will see where this goes. Who knows, maybe we will see remote OBD first in China or other places that California can look to for inspiration.

California has been very successful in controlling diesel PM emissions from both new and in-use engines, such as through DPF retrofits. However, nonroad engines remain a source of PM emissions. In spite of the intent on the Tier 4 regulation, some 50% of nonroad engine families are certified without particulate filters. Do you anticipate tightening of nonroad standards to force DPF technology on nonroad diesel engines?

AA: Yes, no question. We are very concerned about the market deployment of off-road engines that while fully compliant with standards, fail to adopt what we know is best available control technology. Our priorities for HD GHG Phase 2 and lower NOx have limited the resources available to focus on off-road. But we are obviously tracking closely Stage V and maintaining constructive dialogue with our European counterparts and the industry. As you know, diesel emissions are identified as a known carcinogen originally in California and now also by the WHO. Thus, we have a responsibility to re-examine the program to make sure that we have a plan for helping with attainment of ambient PM standards, but also with protecting public health from exposure to a known toxic air contaminant.

GDI engines are another growing source of PM emissions. Do you believe that the LEV III PM standards of 3 mg/mi and 1 mg/mi will trigger the use of gasoline particulate filters (GPF) on GDI cars? If not, would you consider the adoption of particle number (PN) limits for GDI vehicles? While PN limits have not been embraced in the United States, the EPA is currently working on aircraft engine standards that include a nonvolatile particle number limit—this could open the door for the adoption of PN limits for both diesel and GDI engines. In nonroad engines, the adoption of PN limits would allow harmonization with the EU Stage V standards.

AA: As you know, CARB has done a lot of work on PN and we have published extensively on the topic. Thus, I feel we are very well prepared and positioned. We have an extensive testing program of GDI vehicles for our midterm review of the California LEV III 1 mg PM standard coming up before the Board this December. We believe the GPF is a great solution, but it is not the only solution. We also believe that GDI improvements in combustion and optimization will allow for a non-GPF equipped GDI engine to meet the standards. If the interest was solely to force the use of GPFs, it is also not the case that a PN limit as done in Europe is the right or only approach to accomplish that. We welcome the opportunity to engage on these issues which, as you have extensively reported, are rich for discussion and ripe for constructive debate.

Summary: California regulatory developments in engine and vehicle emissions

Light-Duty Certification and Compliance—In the aftermath of the Volkswagen emission cheating scandal, a number of improvements can be expected in emission certification, compliance, and enforcement. In spite of arguably the most robust enforcement program, Volkswagen vehicles equipped with the illegal cycle beating strategy could operate on California roads for nearly eight years. The VW scandal created public pressures and a good political climate to improve and expand laboratory and on-road testing and to enhance requirements for certification, OBD systems, durability, warranties, and public disclosure.
HD NOx Emission Standards—The ARB plans to develop—together with the US EPA or alone—mandatory low NOx standards for heavy-duty engines, targeting a NOx limit of 0.02 g/bhp-hr—a 90% NOx emission reduction from the current standard of 0.2 g/bhp-hr. California plans to work closely with the Section 177 States who will have the choice of adopting the new California standards.
Phase 2 GHG Standards—California ARB, together with the US EPA and NHTSA, has been involved in the development of the Phase 2 GHG and fuel efficiency standards for heavy-duty trucks that were finalized in August. The ARB may consider adoption of California Phase 2 rule that would require higher, but targeted GHG emission reductions than the federal program.
Re-examination of NTE Criteria—The ARB intends to re-examine the Not-to-Exceed (NTE) window, with the intent of improving in-use performance of SCR-equipped vehicles. In 2015, the agency began in-use compliance testing using PEMS to enforce NTE limits. Some vehicles exceeded NTE limits and additional testing is currently underway. In addition to the potential broadening of NTE criteria or revision of NTE, the ARB is also considering a new general approach, including engine dynamometer test cycles.
HD Vehicle Inspection Program—A small proportion of high-emitting vehicles dominates the fleet-wide emissions inventory. Potential regulatory changes to the ARB’s Heavy-Duty Vehicle Inspection Program (HDVIP) and the Periodic Smoke Inspection Program (PSIP) include a reduction of the allowable opacity limit for heavy-duty diesel vehicles, which is currently set at 40%. The ARB is also considering a comprehensive I/M program for heavy-duty diesel vehicles with a GVWR > 14,000 lbs for implementation in the post-2020 timeframe. The new program would utilize the OBD capabilities in post-2013 heavy-duty vehicles.
HD Vehicle Emission Warranty—Inadequate emission warranty periods and limited recall ability remain an outstanding issue in heavy heavy-duty vehicles (HHD, GVWR > 33,000 lbs). The regulatory warranty period for emission components, such as DPF systems, in HHD vehicles is 100,000 miles or 5 years. This is significantly shorter than the regulatory useful life period for HHD vehicles of 435,000 miles, and their actual median lifetime of 800,000 miles.

California ARB