Future emissions standards in the US for Heavy-Duty Vehicles

Future emissions standards in the US for Heavy-Duty Vehicles
15 September 2020

In November 2018, the US EPA (Environment Protection Agency) announced the Cleaner Trucks Initiative. According to the EPA, heavy-duty vehicles are the largest contributor to mobile source emissions of NOx. Current emissions standards for heavy duty diesel vehicles in the US have been in place since model year 2010; the current emissions limit for NOx is 0.20 g/bhph and for PM is 0.01 g/bhph. The EPA are currently reviewing Heavy-Duty Vehicles emissions standards with the aim of reducing emissions.

This initiative will see the preparation of a new proposed regulation that will include revised NOx emissions limits for heavy-duty trucks and engines, and in January 2020, the EPA issued an Advanced Notice of Proposed Rule (ANPR). This proposal is the first step towards the draft regulation containing updated emissions requirements for heavy-duty vehicles in the US. In this post, we take a look at the potential future emissions standards in the US and at the current optional programme California is already following to reduce NOx emissions from heavy-duty vehicles.

What is the Cleaner Trucks Initiative?

The Cleaner Trucks Initiative aims to make sure that emissions reductions occur in the real world in all types of truck operation - the updated legislation will establish new, more stringent emissions standards for NOx and other pollutants for heavy-duty engines. The Cleaner Trucks Initiative announcement followed on from a response in December 2016, when over 20 state and local government agencies sent petitions to the EPA requesting a revision of the NOX emissions standards for heavy-duty vehicles. The Advanced Notice of Proposed Rule (ANPR) identifies the need, in particular, to further reduce NOx emissions from heavy-duty vehicles at a federal level to improve air quality. The EPA examines several topics in the Advanced Notice with regards to the reduction of emissions and possible improvements in the certification procedure; these include the following:

  • Potential improvement for hybrid and other advanced technology vehicle certification
  • Lower emissions limits and possible changes to the test cycles used to determine emissions
  • Expansion of the in-use requirements to capture nearly all real-world operation (similar to the in-use programme in the EU).
  • The increase of mileage-based useful life values to be more reflective of real-world usage.

Manufacturers will be given sufficient lead time to meet new requirements and the legislation should not affect any manufacturers’ plan for meeting the CO2 and fuel consumption requirements of the Phase 2 heavy-duty programme. Further updates and explanation of US heavy-duty vehicle emissions legislation and CO2 emissions standards can be discovered by subscribing to EMLEG.

What is the California Optional Programme?

CARB, the California Air Resources Board, which regulates emissions requirements in California, developed options for voluntary low NOx certification from model year 2015. The low NOx voluntary programme allows certification to three levels of NOx emissions, the lowest being 0.02 g/bhph, which corresponds to a 90% reduction on the current mandatory limit. In 2019, several gas engines were certified to the optional low NOx standards.

In June 2020, CARB approved the Advanced Clean Trucks regulation which requires heavy-duty vehicle manufacturers to sell an increasing proportion of zero-emissions (ZEV) and near-zero emissions vehicles (NZEV) in California, starting from the model year 2024. The Advanced Clean Truck Regulation is part of an holistic approach to accelerate large-scale reduction of emissions.

CARB is working with the EPA on the updated emissions standards for heavy-duty vehicles. CARB also recently published a proposal for updated heavy-duty standards and test procedures named the “Heavy-Duty Omnibus Regulation”. The proposed updated standards cover both diesel and gasoline engines/vehicles and would also apply from model year 2024. One of the many aspects of the proposal is the introduction of lower NOx limits in two stages: from 2024 and then from 2027. Heavy-duty diesel vehicles of model year 2027 and after would have to comply with a NOx limit of 0.02 g/bhph, which is the same value required by the current most stringent optional low NOx certification. Discover more updates on recent developments in California’s heavy-duty vehicle regulations by subscribing to EMLEG.

Within EMLEG, you can discover the official EPA and CARB emissions standards as well as all updates or developments in the standards. EMLEG contains an explanation of emissions standards for all heavy-duty vehicles in over 50 countries. In addition to heavy-duty vehicles regulation information, you’ll also discover details of regulations for other market sectors including light-duty vehicles, motorcycles and more.

New details are added into EMLEG as they are published, which provides an easy way to keep track of and understand emissions standards by country and market sector. Discover more about EMLEG and request a demo.