The timeline for federal NOx emission reductions for medium and heavy-duty trucks is uncertain, but expected in California in 2017. The California Air Resources Board (CARB) is expected to issue a NOx standard in 2017 that should reduce NOx emissions by up to 90 percent: the expected lower standard is 0.02 grams per brake horsepower hour (g/bhp-hr), a significant decrease for the current 0.2 g/bhp-hr. Under the Clean Air Act (CAA), California may issue emission standards that are more stringent than federal standards. While California is the only state with such authority, other states may adopt the more stringent emission standards promulgated by CARB.
California-only emission standards are often opposed by industry, as disparate standards across the country make compliance challenging for manufactures selling nationwide. A national emissions standard levels the playing field, and is often preferred by industry. EPA has not issued NOx standards for heavy-duty trucks since 2001; these standards took effect in 2007.
This summer, EPA is expected to release the final greenhouse gas (GHG) emission standards and fuel efficiency standards for medium- and heavy-duty engines and vehicles. In the preamble to this “Phase 2” rule, EPA will likely include a non-binding commitment to develop NOx emission standards for trucks. Many California regulators and environmentalists had urged EPA to include NOx emission standards with the Phase 2 rule. To drive a commitment from EPA, the South Coast Air Quality Management District (SCAQMD) is expected to petition EPA to develop lower NOx standards.
Coupling a lower NOx emission standard with GHG emission standards comes with trade-offs. As companies implement GHG controls to meet the Phase 2 emission standards, NOx emissions are expected to increase. Combining both emission standards in one rule may make compliance more challenging and more costly for industry. Yet complying with a California-only NOx standard, or a federal standard implemented much later, is challenging in its own way, as industry has to meet staggered emission reductions, often linked to the same emission reduction technologies and processes. This is a key issue to follow this summer for the trucking industry, as NOx standards—California versus federal, and the timeline for implementation of such standards, will have major implications for the development of medium- and heavy-duty engines and vehicles.
[View source.]
