Gasoline versus electric.

Which is the better choice for green-minded individuals? Turns out, it’s not so clear-cut.

It depends on what part of the country you live in and how electricity is generated there, whether from clean sources like wind and solar, or dirty ones like coal. CityLab.com has a detailed look at a study by the National Bureau of Economic Research that provides some clarity for how gasoline and electric vehicles really measure up in each state.

It found electric cars to be the greener choice in metro Atlanta, where toxic emissions contribute more toward an already more polluted area. But not so much for the more rural remainder of Georgia. That makes policy choices difficult for state legislators who as recently as this year weighed whether to keep in place a $5,000 tax credit to encourage purchases of EVs, or eliminate it, and whether to impose new fees on EV owners to help pay for road maintenance. (They ultimately nixed the credit and imposed a $200 fee for noncommercial, or $300 for commercial EVs).

The study suggests that in Georgia and many other states, the subsidies that were in place were not justified by the environmental benefits. Instead, a tax from $500 to $999 annually should be imposed on electric vehicle owners based on the overall environmental damage caused.

There’s a big BUT in all this data, though. The research does not take into account the “lifecycle” analysis of emissions, for example the environmental cost of how the car is manufactured, drilling for oil or transporting coal, according to CityLab.

Nevertheless, the study is worth a read.