Policy update

California’s heavy-duty omnibus regulation: Updates to emission standards, testing requirements, and compliance procedures

The California Air Resources Board (CARB) has adopted a new “Omnibus” regulation that updates standards, testing and compliance mechanisms for nitrogen oxide (NOx) and particulate matter (PM) emissions from on-road heavy-duty vehicles for model years (MY) 2024 through 2031. This new regulation will reduce per-vehicle heavy-duty NOx emission limits by 90% by 2031, leading to an estimated 30% reduction in overall heavy-duty NOx emissions by 2050. This policy update summarizes key elements of this regulation and provides information on technology pathways for meeting these new standards, the estimated costs and benefits of the omnibus regulation, and the international implications of this rulemaking.

The Omnibus regulation updates NOx and PM emission limits for heavy-duty vehicles starting in MY 2024 and updates them again for MY 2027 and 2031, ultimately leading to a 90% reduction in the NOx limit. In conjunction with these updates, in-use on-road testing protocols and evaluation are significantly revised to better simulate real-world conditions. Other emissions updates include revisions of useful life provisions and idling limits and updated emissions limits for PM. The regulation also refines in-use vehicle testing to more accurately capture the full range of conditions in which heavy-duty vehicles operate, including cold-starts, and it will require manufacturers to submit test plans for approval prior to testing. Finally, the new regulations resolve new discrepancies between California and EPA emission standards, through creation of a California-only averaging, banking, and trading program starting with MY 2022.

The Omnibus regulation is technology-neutral, meaning manufacturers can use any combination of engine and aftertreatment technologies to meet the emission standards. For diesel vehicles, some NOx curtailment can come from engine design, but most reduction will likely come from upgrades in the aftertreatment process. More substantial updates will likely be needed to meet the MY 2027 standards.

The projected benefits of this regulation are valued at $37.4 billion dollars between 2022 and 2050, largely in the form of avoided premature deaths and respiratory and cardiovascular hospitalizations. Additional benefits arise from increased length and coverage of warranties. The total projected cost of the new regulations is estimated to be approximately $4.5 billion. Most of these costs can be attributed to the additional technologies needed to meet the new NOx and PM standards. There are also significant costs to manufacturers to cover the extended warranty requirements.

California’s Omnibus rulemaking will have important implications globally for developments in technology and policy. In the United States, CARB and the EPA have historically aligned their respective criteria pollutant emission regulations for heavy-duty engines and vehicles, and several states have expressed interest in adopting California’s Omnibus regulatory package. Meanwhile, Canada is expected to commence a rulemaking process in the near-term, and CARB’s regulation will feature prominently as Environment and Climate Change Canada revises its criteria pollutant standards for heavy-duty engines and vehicles.

Outside of the U.S. and Canada, Europe is in the process of developing Euro VII, the next round of pollutant standards for heavy-duty engines and vehicles. A regulatory proposal is expected from the European Commission as soon as December 2021, and indications are that the required levels of NOx reductions will be similar in magnitude to the MY 2027 levels in CARB’s Omnibus regulation. Given that major manufacturers such as Daimler and Volvo are active in both the North American and European markets, it is likely that the technology advancements being developed to achieve NOx levels to meet California’s requirements will be very similar to those deployed as part of the Euro VII rollout.