California regulators are waiting for a green light from the EPA for a rule that would require an increasing percentage of medium- and heavy-duty trucks sold in the state each year to be zero emission.

The California Air Resources Board (CARB) adopted the regulation in June 2020. Known as Advanced Clean Trucks (ACT), the rule will require vehicle manufacturers to sell a certain percentage of zero-emission trucks starting in 2024.

The rule will help California meet its climate goals and clean up the air in the state’s most disadvantaged and polluted communities, CARB said upon adopting ACT.

The regulation is also a key component of a multi-state action plan released last week aimed at speeding the adoption of zero-emission trucks. States including Massachusetts, New Jersey, New York, Oregon and Washington have adopted the ACT regulation, according to the report from the Multi-State ZEV Task Force. The group was facilitated by the Northeast States for Coordinated Air Use Management.

“Regulatory requirements mandating [medium- and heavy-duty] ZEV sales establish a regulatory floor that provides market certainty needed to drive investments in zero-emission technologies and charging and fueling infrastructure,” the plan said.

Wavering on Waivers?

But EPA approval of the California regulation might not be a slam dunk. A recent report from E&E News said the EPA is considering partially denying a waiver to California for Advanced Clean Trucks and another regulation related to heavy-duty truck emissions. The denial would reportedly impact the regulations in their first years, according to the news story, which quoted an unnamed source.

The story noted that denial of a California waiver request would be a first under a Democratic administration.

The EPA Office of Transportation and Air Quality told NetZero Insider in an email that the agency is at the beginning of its process for considering CARB’s waiver requests.

“As such, no decisions have been made by EPA at this point,” the agency said.

A CARB spokesperson did not respond to a request for comment.

The EPA held a virtual public hearing on the regulations on June 29. The deadline for the public to submit comments is Aug. 2.

Three Waiver Requests

Under the federal Clean Air Act, California may set its own vehicle emission standards if they are at least as stringent as federal standards. The EPA issues a waiver to the state if the rules meet certain criteria. The state must receive the EPA waiver before it may enforce the rule.

Other states may decide to adopt California emissions regulations.

The EPA is currently evaluating three California waiver requests.

Advanced Clean Trucks requires manufacturers to sell a certain percentage of zero-emission trucks each year based on the vehicle classification. For Class 2b and 3 trucks, which typically include step vans and city delivery trucks, the rule requires 5% ZEV sales in 2024, increasing annually to 55% in 2035.

Truck classes 4 to 8, which might include bucket trucks, beverage trucks and buses, start with a 9% ZEV sales requirement in 2024, growing to 75% in 2035. The ZEV sales requirement for Class 7 and 8 tractors ranges from 5% in 2024 to 40% in 2035.

CARB is also seeking an EPA waiver for the Heavy-Duty Low NOx Omnibus Regulation, which aims to reduce emissions of nitrogen oxides from trucks. The rule sets new standards starting with the 2024 model year and tightens the standards further in 2027. The CARB board approved the regulation in August 2020.

The Multi-State ZEV Task Force report recommends that other states adopt California’s low NOx omnibus regulation to reduce emissions from heavy-duty trucks while the market transitions to ZEVs.

The third regulation awaiting an EPA waiver is an amended emission warranty regulation that extends emissions warranty periods for heavy-duty diesel trucks in model years 2022 and later.

In comments submitted to the EPA, CARB Chair Liane Randolph urged the agency to quickly approve waivers for the regulations. California needs to address the climate crisis and improve air quality as soon as possible, she said, and a delay would hurt other states that are adopting the California regulations.

“A partial or full denial of the waiver at this point would also have negative impacts on ZEV and diesel engine manufacturers who have been investing significant resources to comply with California’s standards,” Randolph said.