Across the United States, electric vehicles are more detrimental to the environment than petrol-powered vehicles thanks to the pollution created in generating electricity.

Stephen Holland at the University of North Carolina at Greensboro and his colleagues modelled air pollution from motor vehicles by region. Nearly all electric vehicles are less detrimental to global climate than petrol-powered ones, but the team found a significant variation in benefit across the country. For example, in the western United States, where a sizeable amount of electricity comes from clean energy sources, electric vehicles produce less air pollution than petrol-powered cars. But in the Midwest the situation is reversed, because electricity comes mostly from coal-fired power plants.

The US government pays a subsidy of up to US$7,500 to people who buy electric cars, but the authors say that this should take into account the regional variation in environmental impact.

Am. Econ. Rev. 106, 3700–3729 (2016)