Yesterday, the U.S. Environmental Protection Agency (EPA) and the National Highway Traffic Safety Administration (NHTSA) finalized more stringent greenhouse gas (GHG) emission standards and fuel efficiency standards for medium- and heavy-duty engines and vehicles.  This “Phase 2” rule, applies to: 1) combination tractors; 2) trailers pulled by combination tractors; 3) heavy-duty pickup trucks and vans; and 4) vocational vehicles, such as buses, garbage trucks and concrete mixers, as well as engines that power combination tractors and vocational vehicles, and covers model years 2021 through 2027.  The Phase 2 standards also regulate—for the first time—emission and fuel efficiency standards for certain trailers used with heavy-duty combination tractors.  The greenhouse gas emission standards for these trailers take effect in 2018 and the fuel efficiency standards take effect in 2021.

While this Phase 2 rule does not include more stringent NOx standards for heavy duty on-highway engines, EPA reaffirms, in the preamble, its commitment to developing more stringent NOx emissions standards shortly, in a coordinated effort with the California Air Resources Board (CARB).  While caveating that it is not responding to Petitions for Rulemaking in this final rule, EPA sites petitioners’ request that EPA implement a new NOx standard by January 1, 2022, through a final rule promulgated by December 31, 2017.  Further, EPA foreshadows that significant emissions reductions are to come: “[p]rograms and research underway at CARB, as well as a significant body of work in the technical literature, indicate that reducing NOx emissions significantly below the current on-highway standard of 0.20 grams per brake horsepower-hour (g/bhp-hr) is potentially feasible.”

As we discussed in a blog earlier this summer, coupling a lower NOx emission standard with GHG emission standards can mean additional compliance challenges for industry.  As companies implement GHG controls to meet the Phase 2 emission standards, NOx emissions are expected to increase.  EPA and NHTSA state that the Phase 2 standards are based on emission control technologies that are still under development and under deployed, as well as currently available technologies.  It remains to be seen whether there will be enough time for industry to develop and deploy such emission control technologies to tackle GHG emissions, at the same time anticipating and addressing the not-yet-released NOx standards, and whether industry will be able to do so in an efficient, cost-sensitive manner.

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