HomeGreen BusEPA Seeks Comments on Standardizing Heavy-Duty NOx Emissions Nationwide

EPA Seeks Comments on Standardizing Heavy-Duty NOx Emissions Nationwide

The U.S. Environmental Protection Agency is ramping up its efforts to target harmful emissions from heavy-duty commercial vehicles with an advanced notice of proposed rulemaking (ANPRM) for its “Cleaner Trucks Initiative” that was first announced in November.

EPA Administrator Andrew Wheeler signed the ANPRM on Monday. A proposed rule to clarify the level of oxides of nitrogen (NOx) emissions for all 50 states is expected to be published in the coming months. The last EPA update to NOx emissions standards was in 2001.

“EPA is following the technical work of the California Air Resources Board (CARB) to update their heavy-duty vehicle and engine programs under a Heavy-Duty NOx Omnibus proposal,” an agency spokeswoman explained in an email to School Transportation News.

Specifically, the ANPRM provides an opportunity for comment on the extent to which the EPA should adopt provisions similar to those in CARB’s proposal, which goes before its governing board later this year for final approval. The feds are also seeking public comments from engine and vehicle manufacturers, as well as other interested parties on potential regulatory incentives for reducing diesel and gasoline emissions earlier than required by the federal Clean Air Act.

Already, manufacturers such as ROUSH CleanTech with its Ford 6.8L V10 propane autogas and natural gas engines offer ultra-low NOx emissions of 0.02 NOx grams per brake horsepower-hour that meet the optional CARB standards and that surpass current EPA requirements.

The EPA is asking if it should adopt similar provisions. And if so, to what extent.

“For example, how important would it be to harmonize test procedures, even if we adopt different standards?” EPA asked. “Also, how might standards be aligned if stringencies are harmonized, but timing differs?”

Read the Full Advanced Notice of Proposed Rulemaking

For other manufacturers, the EPA said that it wants feedback on alternative approaches to traditional emission credit banking programs that would not necessarily work for the Cleaner Trucks Initiative. That’s because “it is unclear how those credits could be used to show compliance with respect to operating modes that are not reflected in the current cycles.”

The advance notice asks for comments on potential off-cycle credits that are designed to encourage manufacturers to continue early durability testing for new technologies that would reduce low-load emissions, despite not knowing the useful life mileages prior to a final rule being published.

EPA pointed out that any final rule should not “undermine” its and the National Highway Traffic Safety Administration’s joint Heavy-Duty Phase 2 Greenhouse Gases program to reduce carbon dioxide and fuel consumption. It should also leverage “smart” communications and computing technology, provide sufficient lead time and stability to OEMs to meet the new requirements, streamline and modernize regulatory requirements, and support improved vehicle reliability, EPA wrote.

A new EPA rule standardizing NOx emissions levels would also likely go into effect starting with model-year 2027 engines.

Related: EPA to Propose New Standard on NOx Emissions
Related: Widespread Support of EPA Proposal to Update NOx Rules
Related: University Study Claims Propane School Buses Outperform Diesel in Reducing NOx

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