UC Davis Institute of Transportation Studies

This study examines potential changes in car and truck powertrain technology and fuel mix that could enable a transition to low carbon futures, out to 2050, in California. We consider combinations of battery-electric and plug-in hybrid electric vehicles, hydrogen fuel cells, and advanced biofuels, including ethanol, diesel biofuels, and renewable natural gas, for internal combustion engines that could lead to 80% GHG reductions compared to 1990. We consider two main low-carbon scenarios—a high ZEV adoption case (ZEV) and a mixed (ZEV and Biofuel) adoption case (ZEV+B)—both relative to a business-as-usual (BAU) case. We find that achieving an 80% reduction in CO₂ from cars and trucks (separately and together) appears feasible at relatively low cumulative cost, and with eventual likely net savings (as fuel savings exceed vehicle cost, mostly after 2030). However, the required rates of increase in sales of ZEV cars and trucks, and production volumes of advanced, low-carbon biofuels, will be quite challenging. Regarding ZEVs, we expect the greatest challenge to be for long-haul trucks, and we reduce the rate of sales increase for these as a result. In the ZEV scenario, all vehicle types reach 100% ZEV sales shares by 2050 (except long-haul trucks, which reach 80%). In the ZEV+B scenario, these targets are lower, but a strong ramp-up in advanced biofuel use is needed to achieve the 80% target, with commercial scale cellulosic production of ethanol and renewable diesel dominant by 2050. The net costs or savings of the scenarios are relatively low—on the order of ±$10-50 billion over the next 30 years—in relation to $4 trillion total spending in the BAU scenario. However, the additional costs of vehicle purchase run as high as $110 billion in the ZEV scenario, which will likely require substantial purchase incentives to overcome. Future research should examine how costs translate into policy needs (including generalized cost factors such as driving range) and the potential role, sourcing, and cost of advanced biofuels.