The Potential Role of Plug-in Electric Vehicles in the U.S. and their Effect on Emissions through Mid-Century

Concerns about oil security and availability, greenhouse gas (GHG) emissions, and degraded air quality motivate interest in alternative fuels and vehicles. Plug-in vehicles (PEVs), which include plug-in hybrid electric vehicles (PHEVs) and battery electric vehicles (BEVs), have received significant attention from the government, research community, and automotive industry. These vehicles have the potential to increase the security of US fuel supply, improve air quality, and reduce GHG emissions by displacing some or all of the gasoline or diesel fuels with electricity and shifting emissions out of dense urban areas to more remotely located power plants.;Increasing PEV deployment will shift market shares in the light duty vehicle (LDV) sector, which can affect prevailing energy prices, technology deployment and utilization, and emissions throughout the energy system. The efficacy of using PEVs to reduce air emissions will depend on a broad set of underlying system-wide conditions that unfold over time. This research employs a bottom-up energy system model (TIMES), along with a U.S. dataset (NUSTD) I developed, to meet the following objectives: (1) identify the conditions under which electric drive vehicles (EDVs; which include PEVs and hybrid electric vehicles) achieve high LDV market penetration in the U.S. and quantify the associated change in CO2, SO2, and NOX emissions through mid-century; (2) quantify the incremental impact of PEV deployment on national U.S. CO2 emissions through mid-century under alternative electric sector scenarios; and (3) examine the potential impact of different time-of-day PEV charging scenarios on system-wide CO2 emissions, electricity prices, and technology deployment in the electric and LDV sectors.;To address future uncertainty and examine PEV deployment within the LDV market through 2050, varying assumptions related to crude oil and natural gas prices, a CO2 policy, a federal renewable portfolio standard, and vehicle battery cost were combined to create a large set of 108 scenarios. Furthermore, several policy options that could promote dramatic changes in the future electric sector mix were considered to quantify system-wide PEV emissions benefits and test the model response to different PEV charging patterns.;The model results suggest the following high-level insights. First, oil price and battery cost exert the greatest influence on EDV deployment across the modeled scenarios. Second, the model results do not demonstrate a clear and consistent trend towards lower system-wide emissions of CO2, SO2, and NOX in the U.S. as EDV deployment increases. Higher electric sector emissions associated with PEV charging and shifting emissions in other energy sectors can partially offset the lower tailpipe emissions from PEVs. Third, the incremental CO2 emissions benefit associated with PEV deployment largely depends on marginal changes in electricity generation mix required to charge PEVs. Fourth, time-of-day PEV charging does not produce a significant impact on electricity prices, PEV deployment, or total system-wide CO2 emissions in the U.S. through 2050. In summary, the net effect of PEVs over time on national emissions will depend on a variety of factors beyond vehicle deployment numbers, including the introduction of new energy and environmental policies, prevailing fuel prices, and technology innovation across the energy system. Policymakers should pay careful attention to prevailing system-wide conditions, as simply incentivizing the purchase of PEVs will not automatically lead to emissions reductions.