California Air Resources Board (CARB) staff has rescheduled the following meeting from September 27, 2024 to October 8, 2024, from 9:00 am - 4:00 pm. Staff invites you to participate remotely to discuss proposed amendments to the off-road new diesel engine emissions standards to reduce oxides of nitrogen (NO_x), particulate matter (PM), and carbon dioxide (CO₂) emissions from new off-road compression-ignition engines (Tier 5 rulemaking).

During the workshop, CARB staff will discuss proposed amendments to the off-road new diesel engine emissions standards including changes to the On-Board Diagnostics (OBD) and Tier 5 proposals since the October 2023 workshop. The workshop will clarify and update the diesel engine emission standards and OBD topics. Staff will release the Draft Proposed Regulation Order for the Tier 5 rulemaking prior to the workshop and will be seeking feedback from interested stakeholders.

Background

Currently, CARB’s regulations for new off-road diesel engines are largely harmonized with the United States Environmental Protection Agency’s for nonroad diesel engines. Off-road and nonroad refer to the same type of engine or equipment. The engines in this sector are land-based and range from less than 19 kilowatts (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 and selective catalytic reduction. As of model year 2020, more than half of all new off-road compression-ignition engine families continue to be certified in California to the Tier 4 final emission standards without diesel particulate filters. Exhaust aftertreatment technology has matured significantly in the last 20 years. Significant reductions in PM and NOx 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 amendments to the current Tier 4 off-road new diesel engine standards. Staff is proposing more stringent exhaust emission standards for NOx (up to 90% more stringent) and PM (up to 75% more stringent) than today’s Tier 4 standards. First-time tailpipe CO2 emission standards and OBD requirements for off-road engines are being proposed. CARB staff is proposing enhanced in-use compliance testing, more representative useful-life periods, and a new low-load test cycle. CARB staff’s proposal is scheduled for Board consideration in late 2025, with implementation beginning as early as the 2029 model year.

CARB is currently contracting with the Southwest Research Institute to investigate the feasibility of standards lower than Tier 4 standards. The Southwest Research Institute is demonstrating the feasibility of lower NOx and PM, and new CO2 emission standards.

This workshop is the eighth public event in CARB’s Tier 5 rulemaking. CARB staff invites industry, fleet owners, trade associations, representatives of non-governmental organizations, environmental groups, air districts, and other interested stakeholders to participate and provide feedback on the Draft Proposed Regulation Order for the Tier 5 rulemaking. Staff’s presentation and any additional webinar-related documents will be available on CARB’s website approximately one week before the workshop meeting.

Contact

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.