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US EPA issues ANPR for Cleaner Trucks Initiative

6 January 2020

Today, the US Environmental Protection Agency (EPA) released an Advance Notice of Proposed Rule (ANPR) soliciting pre-proposal comments on a rulemaking effort known as the Cleaner Trucks Initiative (CTI). The ANPR describes the EPA’s plans for new emission standards for NOx and other pollutants for highway heavy-duty engines. It also proposes to streamline engine certification procedures.

The EPA is considering implementation of new standards beginning in model year 2027, which is also the implementation year for the final set of Heavy-Duty Phase 2 GHG emission standards. The ANPR outlines several areas where regulatory changes are expected, however, it does not specify the emission limit values under consideration or other particulars of the future regulation.

The intended regulatory changes focus on the control of in-use emissions under real world operating conditions. The current heavy-duty engine emission standards reduced PM and NOx tailpipe emissions by over 90% for emissions measured using the specified test procedures, but their impact on in-use emissions during real-world operation is less clear, the EPA said. There are engine operating modes where SCR systems commonly used to reduce NOx are much less effective. For example, NOx emissions can be significantly higher during engine warm-up, idling, and certain other types of operation that result in low load on the engine or transitioning from low to high loads. Moreover, deterioration of emission controls in-use, along with tampering and mal-maintenance, can result in additional NOx emissions.

The main technologies and emission reduction strategies considered for the CTI include thermal management technologies that can be used to better achieve and maintain adequate catalyst temperatures, and next generation catalyst configurations and formulations to improve catalyst performance across a broader range of engine operating conditions.

The EPA intends to develop a heavy-duty engine emission program applicable to all 50 states. The agency said it is closely following the technical work initiated by the California Air Resources Board (CARB) to update their heavy-duty vehicle and engine programs under the CARB Heavy-Duty NOx Omnibus proposal.

Some noteworthy components of the ANPR include:

The CTI program focuses on engine-certified products—the proposed changes to the standards or test procedures are not applicable to chassis-certified heavy-duty vehicles.

Comments on the ANPR can be submitted at regulations.gov, docket ID #EPA-HQ-OAR-2019-0055. The EPA intends to publish a proposed CTI rule in early 2020.

Source: US EPA