The International Council on Clean Transportation (ICCT) has released a report it commissioned from Sonoma Technology, Inc. (STI) that estimates the cumulative avoided nitrogen oxides (NO_x), fine particulate matter (PM_2.5) and well-to-wheel carbon dioxide equivalent (WTW CO₂e) emission reductions beginning in 2025 if 12 states plus the District of Columbia adopt California’s Advanced Clean Trucks rule, HDV Omnibus rule and enforcement of CA GHG Phase II Trailer standards.

The Advanced Clean Trucks (ACT) rule requires the sale of at least 30% zero-emission trucks by 2030; the HDV Omnibus rule requires a 90% reduction in NO_x emissions from Model Year 2027 engines; and the California Phase 2 greenhouse gas rule sets standards to improve the efficiency of tractor-trailers.

The 12 states and DC —along with California and Hawaii—signed a memorandum of understanding (MOU) calling for them to work toward a goal that 100% of new medium-duty (MD) and heavy-duty (HD) truck and bus sales will be zero emission by 2050, with an interim target of 30% by 2030. The signatories are California, Colorado, Connecticut, Hawaii, Maine, Maryland, Massachusetts, New Jersey, New York, North Carolina, Oregon, Pennsylvania, Rhode Island, Vermont, Washington, and the District of Columbia.

The ICCT is supporting the Northeast States for Coordinated Air Use Management (NESCAUM) with the implementation of the MOU. ICCT and the states are exploring a variety of regulations that mirror those adopted or that are under consideration in California.

The ICCT tasked STI with using the latest available version of the EPA MOVES3 (MOtor Vehicle Emission Simulator) model to generate calendar year estimates for the years of 2030, 2040, and 2050, based on MOVES3 default data and the 2017 National Emissions Inventory (NEI) data for representative counties in each state to characterize the air quality benefits associated with these regulatory options.

The ICCT defined six scenarios for analysis:

1. Business as Usual (reflecting current Federal programs only, and non-implementation of the GHG Phase 2 trailer requirements)

2. Dual Harmonization (California Advanced Clean Trucks Rule, Low-NOx Omnibus Rule w/urban buses) from model year (MY) 2025

3. Full Harmonization (Dual Harmonization plus implementation of the GHG Phase 2 trailer requirements) from MY2025

4. Advanced Clean Trucks Rule from MY2025

5. Low-NO_x Omnibus Rule w/urban buses from MY2025

6. Full implementation of the Phase 2 GHG Standard from MY2025 (benefits of Phase 2 trailer rule)

The resulting emission reductions for the California programs vary by calendar year, program Scenario, and state. Reductions ranged from 1%-53% for NO_x, 3%-23% for PM_2.5, and 1%-55% for well-to-wheels CO₂e.

Cumulative emissions avoided with 2025 implementation of ACT, HDV Omnibus, and CA Phase II GHG tractor-trailer standards (All EV Scenario). The ‘All EV’ scenario counts the emission reduction benefits of all new medium- and heavy-duty electric vehicles purchased in the state and does not count the benefits of electric vehicles operating in the state but purchased out-of-state. CO₂e emissions are given in million metric tons, while PM and NO_x emissions are given in short tons. Massachusetts, New York, New Jersey, and Oregon results reflect net-zero carbon goals for electricity generation.

Resources

• Benefits of state-level adoption of California medium- and heavy-duty vehicle regulations. Authors: Jeff Houk, Joey Huang, Shih Ying Chang, and Doug Eisinger for Sonoma Technology