As California moves its transportation sector to zero-emissions, new research looks at both progress and challenges

All over the globe, populations are feeling the environmental and health impacts of climate change, with excessive heat warnings, hurricanes, floods and wildfires growing ever more frequent and intense. But while no region is impervious to these challenges, the arid West contends with a unique set of environmental and jurisdictional hurdles that have necessitated ambitious greening goals. This is particularly true for California, where water is scarce, ecosystems are stressed by heat and drought, and urban growth means increased demand for energy, infrastructure, and dwindling natural resources. 

The transportation sector has been the locus of hefty policy initiatives to help the state mitigate impacts of a ballooning climate crisis. By 2045, California aims to achieve full carbon neutrality. Decarbonization will require a significant shift to electric vehicles, as transportation currently accounts for nearly 40% of carbon emissions in the state.

California has already begun ramping up its commitment to a clean energy future, and this means cities and counties across the state are now facing the complex task of transitioning their medium- and heavy-duty fleets to zero-emission vehicles (ZEVs). At the Bill Lane Center for the American West, student, faculty and staff researchers have spent the past year talking with local officials and analyzing state data to understand how public agencies are navigating this change under California’s new Advanced Clean Fleet (ACF) regulation. They recently released a report on their findings titled, "City and County Fleet Electrification under California’s Advanced Clean Fleet Regulations: Preliminary Findings on Progress and Key Challenges." The report is authored by Andrew Nevárez (Public Policy, ’25), Devika Madgavkar (Human Biology/Public Policy ’25) and Esther Conrad.

"California has one of the most ambitious plans for decarbonizing the transportation sector. Transitioning fleets to zero emission vehicles is an important part of this effort, but local governments face considerable challenges," said Esther Conrad, the Bill Lane Center's research manager who has been leading the project. "Our work examines the specific barriers that cities and counties face as they comply with the state’s Advanced Clean Fleet regulations. Amidst growing challenges on California’s path to carbon-neutral transportation, understanding and overcoming these barriers is all the more important."

California has one of the most ambitious plans for decarbonizing the transportation sector. Transitioning fleets to zero emission vehicles is an important part of this effort, but local governments face considerable challenges.

The Center's new report highlights where local governments stand and what support they’ll need to come into full compliance with the new rules. Conducted in partnership with the California Governor’s Office of Business and Economic Development (GO-Biz), the research surfaces both the early progress and the persistent barriers local agencies are encountering as they begin implementing the ACF.

Finalized in late 2023 by the California Air Resources Board (CARB), the ACF establishes a firm timetable for replacing nearly all medium- and heavy-duty vehicles with ZEVs. Most fleets were required to begin transitioning starting on January 1, 2024, and will be required to purchase ZEVs for 100% of ACF-covered medium and heavy-duty vehicles by December 2027. Small fleets and counties with lesser populations have until 2027 to begin complying.

Since the spring of 2024, a team of Stanford undergraduates — supported by Lane Center faculty director Bruce Cain and research manager Esther Conrad — interviewed staff from more than two dozen cities, counties, utilities, and Community Choice Aggregators (CCAs) to better understand what compliance looks like on the ground. The researchers also analyzed vehicle voucher data from California’s Hybrid and Zero Emission Truck and Bus Voucher (HVIP) program to identify trends in ZEV adoption.

Conversations with local governments

Interviews with city and county officials focused primarily on understanding the process of ACF compliance from the local government perspective. Student researchers probed the barriers that cities and counties have encountered, and in doing so, they uncovered the complex nature of understanding and meeting ACF standards. Compliance with these regulations is thorny and time-consuming — it requires the creation of a complete fleet inventory, the planning of future vehicle purchases and charging infrastructure, and securing necessary funding. 

Many agencies are just getting started. Some are still compiling their fleet inventories — a first and often protracted step toward compliance. Others have already begun purchasing ZEVs and planning infrastructure upgrades. But across the board, the same six challenges came up again and again:

• EV procurement challenges
• Funding availability and staff capacity
• Inadequate technical assistance
• Uncertainty/dissatisfaction with current EV technology
• Safety and charging logistics
• Grid capacity constraints

Even with state grant programs in place, many local governments lack the staff bandwidth to apply for funding or the upfront capital to invest in infrastructure and vehicle costs.

Opportunities for support

Importantly, researchers also heard from jurisdictions that are finding creative ways to move forward — often with help from regional partners. CCAs like Peninsula Clean Energy and Silicon Valley Clean Energy are already stepping up, providing hands-on support with fleet assessments, infrastructure planning, and funding applications.

Building on those models, the Lane Center team has recommended the creation of regional technical assistance hubs to achieve a three-fold purpose: expanding outreach and awareness around ACF requirements; providing in-depth, locally tailored technical guidance; and streamlining access to grant funding and financing tools.

These hubs could be hosted by CCAs, Metropolitan Planning Organizations, or other regional collaboratives, and would offer critical capacity for jurisdictions that are eager to act but constrained by limited resources.

Next steps

The Lane Center will build on this important work in the coming months. Says Conrad, "This summer, a new student team will continue the research, with a focus on informing the design of technical assistance programs to support local governments." Among other things, this will entail exploring how to scale regional support, better understand the needs of special districts like water and park agencies, and evaluate how the private sector might be brought into the fold — even in the absence of regulation enforcement.

As a hub for research and scholarship on the West, the Center sees this project as part of a broader commitment to understanding how public policy intersects with on-the-ground implementation —and how research can support local governments across the West in adapting to climate and regulatory change.

To learn more about these findings or to offer feedback, contact the Bill Lane Center's research manager, Dr. Esther Conrad, at esther [at] stanford.edu (esther[at]stanford[dot]edu).