EPA Finalizes Phase 3 Greenhouse Gas Emission Standards for Heavy-Duty Vehicles

EPA Phase 3 GHG Standards for Heavy-Duty

The Environmental Protection Agency (EPA) has published the final Phase 3 Greenhouse Gas Emission Standards for heavy-duty vehicles, requiring a 50% reduction in nitrogen oxide (NOx) emissions and a 25% reduction in carbon dioxide (CO2) emissions from new Class 4-8 trucks starting with Model Year 2028.

NOx Reduction Requirements

The new standards reduce the NOx limit from the current 0.20 g/bhp-hr to 0.10 g/bhp-hr for MY 2028 and to 0.05 g/bhp-hr for MY 2031. Achieving these levels will require significant improvements to aftertreatment systems, including the adoption of close-coupled SCR catalysts, electrically heated catalysts for faster light-off, and advanced ammonia slip catalysts.

CO2 Standards

The CO2 standards for Class 8 combination tractors tighten from the current Phase 2 level of approximately 80 g/ton-mile to 60 g/ton-mile by MY 2032. Manufacturers can comply through a combination of engine efficiency improvements, vehicle aerodynamic improvements, low-rolling-resistance tires, and electrification.

Industry Reaction

The American Trucking Associations expressed concern about the aggressive timeline, noting that the MY 2028 NOx standards will increase the cost of a new Class 8 truck by an estimated $8,000 to $12,000. Engine Manufacturers Association members indicated that while the technology to meet the standards exists, the compressed development timeline creates significant engineering and validation challenges.