truck convoy on highway

Understanding California’s Advanced Clean Fleet Regulation

What is ACF, who must comply, and what is required for compliance?

This article is part of a series designed to explain zero-emissions transportation regulations, who must comply, what is required for compliance, and more.

On April 28th, California legislators passed Advanced Clean Fleets (ACF), a groundbreaking regulation designed to phase out the sales of medium- and heavy-duty (MDHD) internal combustion engine trucks in California. The act aligns with the state’s long-term vision of transitioning the state’s transport system to zero-emissions vehicles by 2045. And other states are expected to follow suit in the coming years.

What is ACF?

ACF is designed to complement the Advanced Clean Trucks (ACT) rule and requires fleets to adopt an increasing percentage of zero-emissions vehicles (ZEVs) such as battery electric, long-range plug-in electric hybrids, and hydrogen fuel cell MDHD trucks. Compliance requirements differ based on truck type and use.

Who must comply?

Fleet operators that must comply with ACF fall into three categories:

  1. High-priority fleets are defined as fleets with more than 50 trucks or belonging to private companies that make more than $50 million in annual revenue.
  2. Drayage truck fleets are defined as fleets with trucks that operate at California ports or intermodal rail yards.
  3. Public fleets are defined as fleets owned by state and local government agencies that own, lease, or operate medium- and heavy-duty trucks.
What is required for high priority fleet compliance?

Fleets and private companies can comply with ACF by choosing one of two options:

ZEV model year schedule
  • Requirement: Any new truck fleet operators buy must be a ZEV starting in January 2024. Internal combustion engine (ICE) vehicles must be retired when they have been in use for 13 years, have traveled more than 800,000 miles, or are more than 18 years old.
  • Benefits: Compliance is relatively straightforward; this option is the default compliance option.
  • Challenges: This option is not as flexible as the ZEV milestones option; it does not allow for ICE truck additions after 2024 and treats all trucks equally regardless of size (it is generally recognized that it is easier to electrify smaller trucks today given battery size and charging needs).
ZEV milestones
  • Requirement: Fleet composition must meet specific percentage targets based on the vehicle size and model year (see figure below).
  • Benefits: Compliance can be achieved incrementally; fleet operators do not need to convert 100 percent of their new vehicles to ZEVs from 2024 onward (instead, they must hit ZEV fleet composition percentages).
  • Challenges: Fleet operators must meet their ZEV percentage targets, even if it means retiring ICE vehicles before they hit the end of their operational life.

What is required for drayage truck compliance?

Fleets with drayage trucks that operate at California ports or intermodal rail yards must:

  • Buy only ZEV drayage trucks starting in 2024
  • Report the mileage of trucks more than 12 years old by 2025
  • Remove a truck from the system if it reaches the earlier of 18 years or 800,000 miles, or a minimum of 13 years if the truck has more than 800,000 miles
  • Ensure that all fleet trucks are ZEVs by 2035, regardless of vehicle age or operating miles traveled
What is required for public fleet compliance?

State and local government agencies that own, lease, or operate MDHD trucks must ensure that:

  • 50 percent of new truck purchases between 2024 and 2026 are ZEVs
  • From 2027 onward all purchases are ZEVs

Specific counties and agencies with fewer than 10 vehicles are exempt.

Acceptable extensions and exemptions

The California Air Resources Board (CARB) recognizes that potential delays are outside of a fleet’s control, so ACF provides some flexibility regarding delays that fall into four categories:

  • Infrastructure delays: If a fleet begins to plan a project to comply with an ACF but is unable to do so due to construction delays, the fleet may apply for an extension delaying ZEV adoption for one year.
  • Electrical delays: If a fleet signs a utility contract and the utility needs more time to make the needed electrical upgrades, the fleet may delay ZEV adoption. To receive an electrical extension the fleet owner must submit additional documentation and use the load that can be supplied by the utility; all electrical extensions sunset in 2030.
  • Vehicle delivery delays: If a fleet purchases a ZEV but experiences a delay in delivery, the fleet may receive an extension, enabling the fleet operator to use an ICE vehicle until it receives a ZEV replacement.
  • Daily usage exemptions: If an operator can prove that available ZEV models on the market do not meet duty-cycle requirements, it can receive an exemption.

There are additional exemptions in the text, which can be found here.

How does ACF benefit communities and impact other stakeholders?

By implementing both ACF and ACT, California expects to accelerate MDHD ZEV truck adoption. CARB estimates that ACF can lead to a reduction in emissions of nearly 25 million metric tons of CO2 between 2024 and 2041.

ACF will also impact original equipment manufacturers (OEMs), utilities, and charging infrastructure providers.

To meet increased demand for ZEV trucks and charging:

  • OEMs will need to invest in research and development and produce more ZEV models;
  • Utilities will need to work with fleets and public utility commissions to develop and implement grid upgrades; and
  • Charging infrastructure providers will need to examine current trucking operations to plan and site charging infrastructure.