Hybrids are an effective transitional technology for limiting US passenger fleet carbon emissions

Abstract

Human economic activity must be decarbonized within several decades to avoid dangerous levels of global warming, with the US passenger fleet a major source of CO2. Decarbonization likely requires an ultimate shift to completely electrified transportation, but given the current reliance of electricity generation on fossil fuels, the optimal deployment schedule of low-carbon vehicles is not known. A simple model is developed for the turnover of the vehicle fleet from the current conventional to an all battery-electric vehicle fleet, including the lifecycle emissions for vehicle production, fuel, and electricity generation. Hybrid-electric vehicles are included as a transitional technology. This model represents the US fleet and both the present and future electrical grid at the county scale, and a range of imposed vehicle market share transition scenarios are considered. To limit cumulative vehicle emissions over the 2017 to 2070 interval, an early, rapid adoption of low-carbon vehicles, either as hybrid or pure electric vehicles, must take place, with an ultimate transition to the battery-electric technology. However, hybrids are found to be an effective transitional technology, and even preferable over the short-term in many areas. Furthermore, some degree of behavioral change, in the form of reduced vehicle miles, must accompany this transition to fully meet climate targets.

Keywords

• hybrid
• electric vehicle
• transition
• global warming
• lifecycle analysis