How clean are electric vehicles really considering they require electricity generated by powerplants, some cleaner than others? It’s an issue often brought up by those opposed to electric vehicles, and now it’s one addressed by the Union of Concerned Scientists in a new study, ‘State of Charge: Electric Vehicles’ Global Warming Emissions and Fuel Cost Savings Across the United States.’

Electricity created to power an electric vehicle varies widely by region. Still, UCS says that drivers can expect to reduce emissions compared to average gasoline powered vehicles regardless of where they live.

The analysis breaks the country into regions that are ‘good,’ ‘better,’ or ‘best’ for an EV, concluding that in every part of the country, EVs outperform most gasoline-powered vehicles when it comes to global warming emissions. According to UCS, 45 percent of Americans live in ‘best’ regions where an EV has lower global warming emissions than a 50 mpg gasoline-powered vehicle, with environmental performance in states like California and most of New York as good as an 80 mpg gasoline-powered vehicle.

UCS says that EVs are still ‘good’ when it comes to global warming emissions even in regions where coal dominates the electricity grid. For instance, in parts of the Rocky Mountains region, driving an EV produces global warming emissions equivalent to a gasoline vehicle with a fuel economy rating of 33 mpg, similar to the best non-hybrid compact gasoline vehicles available today.