Electric cars even cleaner if charged at night

Charging electric cars at night eases a smog problem caused by fossil-fuel plants that provide the power for these vehicles, according to a research paper that appeared in the journal Environmental Research Letters.

In the study, scientists in the US simulated the local impact from plug-in hybrid electric vehicles (PHEVs), which are cars that can switch from battery power to gasoline. Their computer model was based on predictions for 2018 of emissions of nitrogen oxides, the basic ingredient for ground-level ozone, in four major cities in Texas—Dallas/Forth Worth, Houston, Austin and San Antonio. The study compared likely pollution levels when 20 percent of mileage in the region was carried out either by PHEVs or by vehicles that were only gas-powered.