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The California Air Resources Board (CARB) staff invites you to participate remotely in a public workgroup meeting on June 27, 2023, at 9AM - 12PM PST to discuss possible concepts and strategies to reduce oxides of nitrogen (NO_x) and particulate matter (PM) emissions from new, off-road compression-ignition (CI) engines. During the workgroup meeting, CARB staff will discuss concepts for the off-road new diesel engine Tier 5 rulemaking including a useful life, warranty, and selective catalytic reduction (SCR) inducement strategies.

The regulatory useful life is the period in years or engine operation hours during which manufacturers are liable for emissions compliance. The emission warranty period is specified in years or engine operation hours during which the manufacturers shall warrant to the purchaser that the engine is free from defects in materials and workmanship which cause the failure of a warranted part to be identical in all material respects to the part as described in the engine manufacturer's application for certification. Manufacturers are required to track the information on possible defects and submit reports following the federal requirements. CARB staff will discuss the potential amendments in useful life/warranty periods and defect reporting requirements.

Currently, CARB requires offroad diesel engine manufacturers to demonstrate that engines equipped with selective catalyst reduction (SCR) systems utilize inducement strategies that encourage equipment operators/owners to perform proper SCR maintenance by derating engine performance when diesel exhaust fluid (DEF) has not been replenished in a timely manner, or when tampering of the SCR system has occurred. CARB staff is considering incorporating additional inducement strategies for other critical emissions control devices such as diesel particulate filters and exhaust gas recirculation systems to incentivize prompt repairs and prevent noncompliant engine performance. Staff will introduce these additional concepts at the workgroup meeting and is requesting feedback on the concepts.

The workgroup meeting will be held via Zoom webinar at the following date and time:

Date:                 June 27, 2023
Time:                 9:00 am – 12:00 pm (Pacific Time)
Location:           Zoom Webinar/Teleconference

Register

After registering, you will receive a confirmation email containing information about joining the workgroup meeting. Please use the link and password to join the workgroup the morning of the meeting. If you are using a tablet or smart phone, please download the Zoom app. Ensure the latest version of Zoom is installed on your device.

During the workgroup meeting, if you wish to provide comments or ask questions on the potential regulatory concepts, please use Zoom’s “raise hand” feature. The “raise hand” button can be found on the Zoom webinar window. For those who are joining via a conference call, press #2 to raise your hand. The “Q&A” feature on Zoom will also be available to provide comments and ask questions. This workgroup meeting will be recorded for future viewing.

Background

Currently, CARB’s regulations for new off-road diesel engines are largely harmonized with the U.S. Environmental Protection Agency’s for nonroad diesel engines. Off-road and nonroad refer to the same type of engine or equipment with off-road being used exclusively in California. The engines in this sector are land-based and range from less than 19 kiloWatt (kW) to well over 560 kW in rated power. The existing Tier 4 emission standards were adopted in 2004 and were based on the capabilities of the best available technologies at that time: diesel particulate filters (DPF) and SCR. As of model year 2020, more than half of all new off-road CI engine families continue to be certified in California to the Tier 4 final emission standards without DPFs. Exhaust aftertreatment technology has matured significantly in the last 18 years. Significant reductions in PM and NO_x  are now feasible beyond the current Tier 4 standards of 0.02 grams per kilowatt-hour (g/kW‑hr) and 0.40 g/kW-hr for 56 – 560 kW engines, respectively.

CARB staff is working on potential amendments to the current Tier 4 off-road diesel engine standards for the Tier 5 rulemaking. Staff will likely propose more stringent exhaust emission standards for NO_x (up to 90 percent more stringent) and PM (up to 75 percent more stringent) than today’s Tier 4 standards. First-time tailpipe carbon dioxide (CO₂) emission standards for off-road engines will also likely be proposed by CARB. CARB staff is considering proposing possible elements such as enhancing in-use compliance testing, proposing more representative useful-life periods, and developing a low-load test cycle. CARB staff will also propose to update the test procedures and consider first-time off-road OBD requirements. CARB staff’s proposal is tentatively scheduled for Board consideration in the 2025 timeframe, with implementation beginning as early as the 2029 model years.

CARB is currently contracting with the Southwest Research Institute (SwRI) to investigate the feasibility of standards lower than Tier 4 standards. SwRI is assessing the feasibility of lower NO_x, PM, and CO₂ emission standards.

Contacts

If you have questions, please contact: Tier 5

If you require a special accommodation or need this document in another language or in an alternate format (i.e., Braille, large print), please contact Isabel Guerra as soon as possible, but no later than 15 business days before the scheduled webinar. TTY/TDD/Speech to Speech users may dial 711 for the California Relay Service.

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Clearing California Skies for Over 50 Years

CARB is the lead agency for California’s fight against climate change,
and oversees all air pollution control efforts in the state to attain and
maintain health-based air quality standards.

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