Publication Detail

Air Pollutant Emissions and Electric Vehicles


Research Report

Suggested Citation:
Wang, Michael Q., Mark A. Delucchi, Daniel Sperling (1989) Air Pollutant Emissions and Electric Vehicles. Institute of Transportation Studies, University of California, Davis, Research Report UCD-ITS-RR-89-01

The introduction of EVs will affect emissions of HC, CO, NOx, SOx, and particulates. It will also affect emissions of greenhouse gases—carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), ozone (O3), and chlorofluorocarbons (CFCs). Greenhouse impacts of EVs are addressed elsewhere, and are not considered in this paper. The use of EVs may also reduce total emissions of benzene, but available data do not permit an analysis of benzene reduction. EVs reduce the noise from on-road vehicles because of their inherently quiet propulsion systems, but noise reduction has been estimated elsewhere, and shown to be small.

In this study, we consider five pollutants: HC, CO, NOx, SOx, and particulates. We use a comparative approach. We calculate emission factors of the five pollutants for both ICEVs and EVs, and estimate emission reductions for each pollutant. For ICEVs, we calculate fleet average emission factors in a target year by taking into consideration the mix of model-years, age, and mileage of vehicles. For EVs, we estimate emission factors of power plants, and then assign the calculated emission factors to EVs in accordance with their electricity consumption.

Emission factors of power plants are primarily a function of fuel mix of electricity generation and emission control technologies of power plants. We use fuel mix projections of electricity generation and establish scenarios of emission control technologies, and use sensitivity analysis to test the significance of fuel mix and emission control technologies. Since electricity consumption per mile of EVs is an important factor for EV emission factors, we design scenarios of EV electricity consumption in our calculation.

Over time, changes occur in emission control technologies, fuel mix of power plants, fleet average emission rates of ICEVs, and electricity consumption of EVs. The calculation of EV emission reductions therefore must be targeted to particular years. We estimate the emission impacts of EVs in four target years: 1995, 2000, 2010, and 2030. Since many factors are uncertain in the future, we use scenario analysis on power plant emission control strategies, energy mix of electricity generation, EV electricity consumption, and EV market penetration to calculate EV emission reductions in these four target years.

We calculate per mile emission reductions of EVs in California and the U.S., and tons-per-day emission reduction of EVs in California. The latter demonstrates the potential for EVs to help major air basins in California meet national ambient air quality standards (NAAQS).