US EPA issues final rule on stricter emissions standards for heavy-duty vehicles

U.S. EPA issued its final rule Dec. 20 setting tougher standards for NOx and particulate-matter (PM) emissions from heavy-duty vehicles and engines starting in model-year 2027. The new emissions standards are 80-plus percent more stringent than current regulations. In 2045, this final rule will reduce NOx emissions from the in-use fleet of heavy-duty trucks by almost 50 percent, according to EPA.

“The rule establishes many new challenges for manufacturers and suppliers but also ensures diesel’s place in the future for trucking,” said Allen Schaeffer, executive director of the Diesel Technology Forum. “The current generation new diesel trucks are more fuel-efficient and emit less than 1/60th the emissions of 2000 models. They’re already near-zero emission for NOx and PM.”

The new emission standards also cover a wider range of heavy-duty engine operating conditions compared to today’s regulations and require these to be met for a larger portion of the time these engines operate on the road.

The rule requires lower NOx emissions over a much wider range of testing conditions, both in the laboratory and when engines are operating on the road.

This final rule provides a comprehensive approach to ensuring the new standards are met during more of the operating life of these vehicles by including provisions for 1.5 to 2.5 times longer useful life for engines and 2.8 to 4.5 times longer emission-related warranty periods for pollution-control equipment.

The new rule also includes maintenance and serviceability requirements that more clearly describe owner responsibilities for maintenance and use and provide more information on how to diagnose and repair emission-control systems.

“We expect the new maintenance and serviceability requirements for manufacturers would help operators keep in-use engines and emission-control systems working properly to maintain their certified emission levels in the real world,” the agency stated. “Data also show that tampering and poor maintenance of the engine’s emission-control system after the useful-life period is projected to result in NOx emissions that would represent a substantial part of the heavy-duty emissions inventory in 2045. To address this problem, as part of our comprehensive approach, the final rule requires manufacturers to design their engines to prevent operators from reprogramming the engine to bypass or disable emission controls (i.e., tamper). The final rule also includes a balanced approach to engine derates related to the SCR emission-control system (i.e., SCR inducements). The final SCR-inducement program requires engines to provide more advance notice for operators that their SCR system is not working properly, which we believe will encourage ongoing maintenance while limiting frustration due to unexpected engine derates. The requirements for electronic controls and SCR inducements are expected to reduce the risk of operators completely disabling emission-control systems and further ensure that the new emissions standards continue to be met during in-use operations.”

Scott Fenwick, technical director for Clean Fuels Alliance America, told Biobased Diesel Daily that while the organization continues to digest the rulemaking, Clean Fuels is working with its partner OEMs to help answer any questions on performance for their engines with renewable fuels.

“We’ve known for some time that this final rule was imminent, but the details are always of concern,” Fenwick said. “We are confident that biomass-based diesel fuels, such as biodiesel and renewable diesel, will fit well into this and future rules from the EPA. Clean Fuels has been working closely with a number of vehicle and engine manufacturers over the past few years to help identify solutions for these proposed [and now final] new limits. In addition to reducing the allowable limits for emissions of nitrogen oxides, hydrocarbons, carbon monoxide and other pollutants, the full useful life and warranty periods to demonstrate compliance are also being extended. Engine manufacturers are evaluating extended durability, compatibility and new onboard-diagnostic solutions to help develop new and improved emissions devices that will ensure compliance with these new limits. The hope is to quickly make decisions on new designs and equipment that will be able to be put into production in the next several years.”

The ruling is one of three major actions being taken under EPA’s Clean Trucks Plan, under which the agency intends to propose two additional rulemakings in 2023 that, when considered cumulatively with this final rule, would put in place stringent long-term standards to “reduce smog, soot, and climate pollution from heavy-duty vehicles and would include consideration of greater adoption of zero-emissions vehicle technologies,” EPA stated.

EPA intends to release the proposals for the remaining two steps in the Clean Truck Plan by end of March. These include the Phase 3 proposal for heavy-duty greenhouse-gas (GHG) standards for model-years 2027 and later, and the multipollutant standards proposal for light- and medium-duty vehicles for model-years 2027 and later.

“Biodiesel and renewable diesel help offer benefits with lower particulate matter and other emissions that will help reduce the burden on emissions-aftertreatment hardware while providing greater than 50 percent reductions in greenhouse-gas emissions as advanced biofuels,” Fenwick said. “Although compliance for heavy-duty vehicles will certainly be dependent upon new-vehicle sales with new technologies, low-carbon renewable fuels will continue to play a part, with potentially growing implications, as the U.S. looks toward decarbonizing the transportation sector while maintaining the economy with the movement of goods and services via heavy-duty trucks.”

Schaeffer added, “The further improvements in diesel engines anticipated in the outcome of this final rule and the ability of truckers to invest in new trucks will be fundamental to ensuring progress toward meeting both local clean air and national climate goals. Without continued turnover in the fleet, older generations of technology with relatively higher emissions will stay in service longer, thereby delaying benefits to disadvantaged communities and contributing to worse air quality all around the country. This is underscored in a recent study, which found that in the next 10 years three times more GHG reductions can be achieved by accelerating the turnover of older trucks to the newest generation of advanced diesel and utilizing low-carbon renewable biodiesel fuels as compared to an all-electric truck option.”

The final rule issued Dec. 20 does not include final action regarding the proposed targeted updates to the existing heavy-duty GHG emissions Phase 2 program. “We intend to consider potential changes to certain heavy-duty GHG Phase 2 standards as part of the Phase 3 GHG rulemaking,” the agency stated.

EPA also intends to issue final decisions in early 2023 regarding several California waiver requests for California’s heavy-duty vehicle and engine emission standards.

To read the final rule, click here.