Heavy-Duty Low NOx

This page last reviewed December 12, 2017

Background

Nonattainment Map A key measure in the Mobile Source Strategy is the establishment of low oxides of nitrogen (NOx) engine emission standards that result in a 90 percent reduction in NOx emissions compared to the emissions of today’s diesel engines.  This measure is critical for attaining federal health-based air quality standards for ozone in 2023 and 2031 in the South Coast and San Joaquin Valley air basins, and fine particulate matter (PM2.5) standards in the next decade.  Under this measure, staff also plans to develop regulatory amendments to improve the certification requirements to better reflect emission control under low load urban driving operations, to improve engine and emission control system durability, and to expand and improve the in-use compliance testing program. These supplemental actions include:

  • Amending the warranty period;
  • Adopting a new low load certification test cycle;
  • Amending the useful life and durability demonstration provisions within the certification requirements for heavy-duty engines; and
  • Amending the Not-to-Exceed (NTE) in-use compliance program.
In 2013, California established optional low-NOx standards with the most aggressive being 0.02 g/bhp-hr, which is 90 percent below the current standard.  The optional NOx standards were developed to pave the way for mandatory standards by encouraging manufacturers to develop and certify low NOx engines and incentivizing the purchase of certified low NOx engines. As a result, four engine families have been certified to the optional low NOx standards, two by Cummins and two by Roush Cleantech.  The Cummins engines include the 2016 and 2017 model years 8.9 liter ISL G Near Zero compressed natural gas (CNG) engine certified to the optional 0.02 g/bhp-hr standard, and the 2017 model year 6.7 liter ISB6.7 G CNG engine certified to the optional 0.10 g/bhp-hr NOx standard.  Both engines are currently commercially available.  The Roush Cleantech engines include the 2017 model year 6.8 liter liquefied petroleum gas (LPG) engine certified to the optional 0.05 g/bhp-hr NOx standard and the 2016 and 2017 model years 6.8 liter CNG engine certified ot the optional 0.10 g/bhp-hr NOx standard.  The Roush Cleantech low NOx engines are also currently commercially available. 

Need for federal action:  As vehicles purchased outside the state account for a majority of the heavy-duty vehicle miles travelled in the South Coast on any given day, federal NOx engine emission standards are necessary in order to achieve emission reductions from vehicles operating in California that were purchased outside the state.  In the preamble to the Heavy-Duty GHG Phase 2 Final Rule, the U.S. Environmental Protection Agency (U.S. EPA) affirmed their commitment to consider developing low NOx emission standards for on-road heavy-duty engines.  California Air Resources Board (CARB) plans on coordinating its regulatory development efforts with U.S. EPA.  CARB Board action on a lower NOx standard for on-road heavy-duty engines is expected in 2019.

Research Activities:  CARB is currently funding several research projects, hereinafter referred to as the Stages 1, 2, and 3 Heavy-Duty Low NOx programs, to assess the feasibility of lower NOx emissions. The Stage 1 program is a $1.6 million research contract with Southwest Research Institute (SwRI) to assess the feasibility of lower NOx emissions on a 13 liter Volvo engine with turbocompounding through a combination of engine calibration, exhaust thermal management strategies, and advanced aftertreatment systems, as described further at: https://www.arb.ca.gov/research/veh-emissions/low-nox/low-nox.htm.  

The Stage 2 program is a $1.05 million follow-on project to the Stage 1 program with SwRI as the research contractor and the National Renewable Research Laboratory, or NREL, as a subcontractor.  The project was initiated in January 2017, and its objectives are to optimize diesel engine calibrations for low load duty cycles and to develop a low-load certification cycle.

The Stage 3 program is a follow-on to the Stages 1 and 2 programs.  It is a $1.325 million research contract with SwRI to demonstrate low NOx emissions on an alternative engine platform on certification cycles and the low load cycles developed in the Stage 2 program. The aftertreatment technologies to be demonstrated in Stage 3 may include technologies demonstrated in Stages 1 and 2 programs as well as other new technologies not identified in Stages 1 and 2.  The Stage 3 program is currently going through the contract approval process.

What's New


Posted December 12, 2017:

CARB invites you to participate in a public workshop to learn more about a potential regulatory measure to reduce NOx emissions from new on-road heavy-duty vehicles by amending the emission control system warranty periods. Additional details can be found in this public notice.

DATE:

Friday, January 12, 2018

TIME:

9:00 a.m. – 12:00 p.m.

PLACE:

South Coast Air Quality Management District
Auditorium
21865 Copley Drive
Diamond Bar, California 91765

Posted June 9, 2017:

CARB invites you to participate in a public workshop to learn more about potential regulatory measures to reduce NOx emissions from new on-road heavy-duty vehicles. Additional details can be found in this public notice.

Posted April 21, 2017:

The Heavy-Duty In-Use Compliance/Testing/Not-to-Exceed Workgroup and Heavy-Duty Low NOx Standard and Test Procedures Workgroup meetings were held on February 22, 2017 and March 6, 2017, respectively. At these workgroup meetings, CARB staff presented and solicited feedback regarding rulemaking timelines, status results of CARB-funded Heavy-Duty Low NOx research programs, analysis of in-use data to evaluate current NTE requirements and potential future revisions, and outside the box concepts and ideas. Staff presentations and summary of meeting notes have been posted on the "Meetings and Workshops" section of this page.

Posted November 1, 2016:

The agenda and presentations for the November 3, 2016 workshop, as well as the descriptions of workgroups have been posted on the workshops section of this page. The workshop is also available via webcast.

Posted October 5, 2016:

CARB invites you to participate in a public workshop to learn more about potential regulatory measures to reduce NOx emissions from new on-road heavy-duty vehicles.   Additional details can be found in this public notice.


Heavy-Duty Low NOx Program / Maintenance Provisions Meetings and Workshops

Date/Time Description Documents
January 12, 2018
9:00 am - 12:00 pm
Public workshop to discuss proposed amendments to the California emission control system warranty regulations and maintenance provisions for on road heavy duty vehicles with gross vehicle weight ratings greater than 14,000 lbs.
Workshop Notice

Webcast

Agenda - coming soon

Presentation - coming soon
July 12, 2017
10:00 am - 1:00 pm
Public Workshop to Discuss Proposed Amendments to the California Emission Warranty Regulations for On-Road Heavy-Duty Vehicles
Workshop Notice

Webcast

Agenda

Presentation
March 6, 2017
9:30 am - 11:30 am

Heavy-Duty Certification Standards and Test Procedures Workgroup Meeting:

Conference call meeting to discuss rulemaking timeline of the various Heavy-Duty Low NOx program elements, final results of the ARB-funded - SwRI Heavy-Duty Low NOx research program (Stage 1), and other outside the box concepts and ideas.
Meeting Agenda

CARB Staff Presentation
February 22, 2017
9:30 am - 11:30 am

Heavy-Duty In-Use Compliance/Testing/Not-to-Exceed Workgroup Meeting:

Conference call meeting to discuss rulemaking timeline of the various Heavy-Duty Low NOx program elements, CARB staff analysis of in-use data under NTE and moving average methods, and related research.
Meeting Agenda

CARB Staff Presentation
November 3, 2016
1:00 pm - 5:00 pm
Public Workshop to Discuss Potential Changes to the Heavy-Duty Engine and Vehicle Emission Standards, Test Procedures, Warranty, and Other Related Heavy-Duty Programs
Workshop Notice

Webcast
Agenda

Documents/Presentations

Email List

For more information on ARB’s heavy-duty low NOx efforts, please sign up for the Heavy-Duty Low NOx Email List

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