U.S. EPA Propose Stronger Heavy-Duty Vehicle Emissions Standards

The U.S. Environmental Protection Agency on March 7 proposed new emissions requirements for the medium and heavy-duty truck sector, to begin in model year 2027. The new standards are aimed at reducing emissions of nitrogen oxides (NOx) from heavy-duty gasoline and diesel engines and setting updated greenhouse gas standards for certain categories. The proposed action would reduce NOx emissions from trucks by as much as 60 percent in 2045. For the most robust option, it is projected that health-related benefits will be worth up to $250 billion between 2027 and 2045.

EPA noted that the proposals are the first step in its Clean Trucks Plan to develop regulations over the next three years to cut emissions from trucks and buses and to progress towards a zero-emissions transportation future. The agency said the proposal is intended to reflect shifts in the market it had not previously anticipated, including the early introduction of zero-emission technologies and more states pursuing ZEV mandates for trucks. EPA said the revisions would cut CO2 emissions by about 25 percent more than the current standards for the affected vehicle types.

The proposal aims to chart a path to advance zero-emission vehicles in the heavy-duty fleet and is consistent with an executive order from President Joe Biden. EPA said it is considering two approaches for the new standards for nitrogen oxide emissions. One would phase in new standards in 2027, followed by more stringent limits in 2031 that would be 90 percent lower than current restrictions once fully implemented. The other approach would set a single standard in 2027 and achieve less reductions compared to the first.

Transportation is the largest source of GHG emissions in the U.S., accounting for 29 percent of all emissions and heavy-duty vehicles are the second-largest contributor, at 23 percent. EPA last revised the NOx standards for on-highway heavy-duty trucks and engines in 2001. Those standards achieved notable reductions, but the agency said that new technologies can help achieve the additional reductions to improve air quality. Without further reductions, the heavy-duty vehicle sector is expected to become a major contributor to mobile source emissions of NOx, which is a precursor to ozone and particulate matter. The sector would contribute to 32 percent of the mobile source NOx emissions, and 89 percent of onroad NOx emissions, in calendar year 2045, according to EPA.

The Truck and Engine Manufacturers Association welcomed the proposed rule and committed to working with EPA to ensure the final rule is practical and effective. The group hopes to work with EPA to ensure that the final version of the rule is “practical, technically feasible, cost-effective, and will result in the necessary fleet turnover to achieve the nation’s environmental objectives.”

The American Trucking Associations said it will be working with the agency to ensure that the outcome builds on emissions reductions achieved so far without hurting the reliability of the trucks and trailers and imposing unreasonable or unworkable costs on the industry.

Environmental advocate Sierra Club said that the “proposal ultimately falls short of what environmental justice communities have been demanding” and urged EPA to move swiftly to strengthen the rule to get us on the path to 100 percent zero-emission sales of trucks and buses by 2035.

The proposal opens a 46-day comment period. EPA intends to finalize the rule before the end of 2022.