California Air Resources Board

Amendments to the In-Use Off-Road Diesel-Fueled Fleets Regulation

Introduction

The recent amendments, approved by the California Air Resources Board (CARB) in 2022 (2022 amendments) to the In-Use Off-Road Diesel-Fueled Fleets Regulation (Off-Road Regulation or regulation) incorporate new requirements to use renewable diesel. This fact sheet reviews key elements of the renewable diesel requirements as well as the limited exemptions.

Background

Renewable diesel is a transportation fuel produced from non-petroleum renewable sources – specifically, vegetable oils and animal fats. The chemical and structural properties of renewable diesel are similar to petroleum-derived (conventional) diesel, and renewable diesel meets the federal registration requirements for fuels and fuel additives and the ASTM D975-21 Standard Specification for Diesel Fuel. Therefore, renewable diesel can be used as a direct substitute for conventional diesel (up to 100% or R100). Blends of renewable diesel and conventional diesel are labelled with an R followed by the percentage (by volume) of the renewable diesel content.

It is common to confuse biodiesel and renewable diesel. While both originate from vegetable oils and animal fats, the processes used to produce the two fuels are very different. Therefore, they have different chemical properties, physical properties, and environmental attributes. Biodiesel is used as a diesel blend stock in limited volumes (up to 20% or B20) rather than as a direct substitute for conventional diesel. Biodiesel can increase oxides of nitrogen (NOx) emissions in some engines – a characteristic that limits its blend level in diesel fuel and that requires the mitigation of excess NOx in accordance with CARB’s Alternative Diesel Fuel regulation.

Of these two fuels, only renewable diesel complies with the requirements of the 2022 amendments to the Off-Road Regulation.

Requirements [Section 2449.1(f)]

Beginning January 1, 2024, all California fleets subject to this regulation are required to procure and only use R99 or R100 renewable diesel fuel in all vehicles subject to the Off‑Road Regulation, with some limited exceptions.

Recordkeeping, Reporting, and Affirmation [Section 2449(h)(10) and Section 2449(g)(2)(D)]

Fleet owners must maintain documents that demonstrate compliance with the renewable diesel fuel requirements, including the date and volumes of fuel purchased. Records must be kept for three calendar years from the date the transaction is completed. Also, fleet owners are required to comply with all reporting requirements in the regulation, including any additional reporting requirements for exemptions, and affirm annually as, as part of the annual reporting requirements due to CARB by March 1, that they are in compliance with the renewable diesel fuel requirements and that the reported data is accurate and complete.

Unable to Procure [Section 2449.1(f)(3)]

A fleet may be exempt from the renewable diesel fuel requirements if they are unable to procure R99 or R100 renewable diesel fuel as defined by the regulation. However, fleet owners are required to keep records describing the normal refueling methods, their documented attempts to procure renewable diesel fuel and proof that shows they were not able to procure renewable diesel (i.e., correspondence or contractor bids).

Exemptions [Section 2449.1(f)(2)]

There are several potential exemptions to the renewable diesel requirements:

Operations in Captive Attainment Areas: Any fleet or fleet portion that is designated a captive attainment area fleet is exempt from the renewable diesel fuel requirements. This includes fleets where the equipment exclusively operates in designated areas as defined under 2449(c)(6). This exemption also applies to any vehicle while operating in one of the counties listed under 2449(c)(6).

Tier 4 Final Fleets: Any fleet or fleet portion that are entirely comprised of vehicles with Tier 4 final off-road engines, model year 2010 or newer on-road engines, or zero-emission vehicles are exempt from the renewable diesel fuel requirements. The use of renewable diesel fuel has less of an emissions reduction impact when used in engines with advanced emission control technologies, such as selective catalytic reduction and diesel particulate filters.

Cold Weather Exemptions: There are two types of low temperature exemptions that provide flexibility to mitigate potential performance issues when using renewable diesel at cold temperatures. In both cases, the temperature threshold is 20 degrees Fahrenheit (20⁰ F), and both exemptions require additional reporting.

1. Winter low temperature exemption: Any fleet, fleet portion or vehicle is exempt from the renewable diesel fuel requirements from November through February if it is located or operates in a location where the tenth percentile January low temperature is below 20⁰ F. The analysis may consider historical low-temperature data from the ten years prior to the request. Historical temperature data may be found through several commercial and governmental weather programs such as the National Weather Service.

   For example, a fleet owner uses ten years of recorded January low temperature data for their location, that would total 310 data points given there are 31 days in January and provided each day has one data point. The data is sorted by temperature and the tenth percentile, in this case it is the 31st data point, must be below 20⁰ F for the exemption to apply.

   There are additional reporting requirements for fleets that use the winter low temperature exemption. Fleet owners must report to CARB by April 30 of the year and reports must include the fleet, fleet portion, or vehicle location, the tenth percentile low temperature used, as well as the volume of renewable diesel and conventional diesel procured during October through February. Reports may be submitted electronically to DOORS@arb.ca.gov or mailed to CARB at:

   California Air Resources Board
   Mobile Source Control Division (In-Use Off-Road Diesel)
   P.O. Box 2815
   Sacramento, CA 95812

2. Intermittent low temperature exemption: This exemption is for intermittent cold temperature events where the temperature drops or is expected to drop below 20⁰ F. This exemption allows fleets to use the appropriate cold temperature fuel when they operate vehicles in an area that does not meet the requirements of the winter cold temperature exemption (above) or if a cold weather event occurs outside of the months that the winter cold temperature exemption applies. The forecasted temperature must be within 14 days. Examples of valid weather forecasts include, but are not limited to, those made by the National Weather Service, local television or print news, The Weather Channel, and other weather apps. During these low temperature periods, any fleet or fleet portion may procure and use conventional diesel in its vehicles. Once the cold snap has passed, vehicles may use the remaining conventional diesel in the vehicle fuel tank, until the vehicle is refueled. In other words, fleet owners do not have to drain the tank. This exemption is necessary to allow fleets to use the appropriate cold temperature fuel when they operate vehicles in an area that does not meet the requirements in section 2449.1(f)(2)(C) or if a cold weather event occurs outside of the months of November, December, January, and February.

   Fleet owners must report to CARB within two weeks of the last exemption date. Reports must include each day conventional diesel was used, the fleet location, the high and low temperature record, including a printout or screenshot for each day of the exemption, and provide the date and source of the temperature record. The report must also provide the volume of renewable conventional diesel fuel. Reports may be submitted electronically to DOORS@arb.ca.gov or mailed to CARB at:

   California Air Resources Board
   Mobile Source Control Division (In-Use Off-Road Diesel)
   P.O. Box 2815
   Sacramento, CA 95812

Rental Vehicles [Section 24491(f)(4)]

This requirement applies to rental vehicles that operate in California:

• Rental fleets must include language in their rental contract that the recipient of the rented vehicle (renter) must comply with the renewable diesel fuel requirements.
• Rental fleets that include this contract language will not be held liable if the rented vehicle is not compliant.
• Fleets, vehicles, or operations that are exempt from the renewable diesel fuel requirements, or from the Off-Road Regulation entirely, do not need to use renewable diesel in any vehicles that they rent. There is no requirement that the rental company drain fuel from these vehicles.

While this document is intended to assist fleets with their compliance efforts, it does not alter or modify the terms of any CARB regulation, nor does it constitute legal advice. It is the sole responsibility of fleets to ensure compliance with the Regulation for In-Use Off-Road Diesel‑Fueled Fleets.