Technology and Fuel Transition: Pathways to Low Greenhouse Gas Futures for Cars and Trucks in the United States

In this study, we investigate how potential changes in US light-duty and medium/heavy-duty vehicle technology and fuel mix from 2020 to 2050 may affect the transition to a very low-carbon future in the United States. Given US targets to reach 50% or more zero-emission vehicle sales by 2030, we consider new sales trajectories for battery-electric vehicles and hydrogen fuel cell vehicles, and rates of uptake across the country needed to reach these. We also consider biofuels use (ethanol and renewable diesel) in remaining internal combustion engine cars and trucks to minimize GHG emissions from those vehicles. Costs of all vehicles sold, and their fuel and other operating costs, are calculated and projected. To account for characteristics of specific vehicle types (e.g., weight, application, fuel economy, drive cycle, etc.), we disaggregate light-duty vehicles and medium/heavy-duty vehicles into ten subcategories. Relative to a business-as-usual case, we develop a series of low-carbon scenarios where three regions of the US adopt zero-emission vehicles at different rates. One is California, where the strongest targets and policies have been set. We also consider “Section 177” states that have agreed to adopt at least some California policies, and the third is the remaining states. Our findings suggest that even slower adoption scenarios can reduce greenhouse gas emissions in 2050 by 90% of 2015 levels. Greater reductions can be attained with rapid adoption cases. However, even a case with all US states adopting California-style policies with a five-year delay—for LDVs, essentially the equivalent of the April 2023 regulatory proposals of the US EPA—may not be quite sufficient to reach the apparent US targets. Despite significant upfront investments required to undertake transitions in the near-term, these scenarios all feature large net savings to consumers after 2030 (or sooner) as fuel and maintenance savings exceed higher costs in purchasing vehicles. Overall net savings from 2020 to 2050 (mostly accrued after 2030) are in the range of $1.7 to $4.8 trillion. However, achieving these full benefits could be challenging due to the need for a rapid rate of zero-emission vehicle adoption and possibly high production volumes of low-carbon biofuels.