Choosing to drive an electric car might seem like the most climate-friendly choice a consumer can make. But according to one report, in most states, it’s not.
A new report from Climate Central has found that in 39 states, an electric car actually produces more emissions from its manufacture to its 50,000th mile than a gas and electric-powered hybrid. The report compared the most efficient conventional (non plug-in) hybrid, the Toyota Prius, to the most efficient electric vehicle, the Nissan Leaf, and looked at emissions from all points of the car’s life — including manufacturing the car, charging the battery, and burning gasoline in hybrid cars. It found many states relied so heavily on fossil fuels to power their electric grids that they substantially reduced and even negated the climate benefits of electric cars.
“An electric car is only as good for the climate as the electricity used to power it,” the report states. “When all the carbon emissions associated with building and driving electric and high-mileage gasoline cars are included in the analysis, the all-electric advantage goes up in smoke.”
The manufacture of an electric car battery and other parts is carbon-intensive — as the report notes, the process produces more emissions than the manufacturing of a gas-powered car — and creates a 10,000 to 40,000-pound “carbon debt” that the electric cars can only repay after driving thousands of miles. Exactly how far they need to drive to repay that debt depends on the car and, more importantly, in what U.S. state the car is driven. In 18 states, including Kentucky, Michigan, Louisiana and Kansas, where fossil fuels are relied on most heavily to power the electricity grid, an electric car can never pay back its carbon debt, no matter how far it’s driven, making the Prius the more efficient choice.
An electric car can repay its carbon debt after driving 50,000 or fewer miles in only nine states — in four more, the car can repay its debt within 100,000 miles, and in 23, the debt can be repaid after 200,000 miles. For the most part, the states with the lowest mileage requirement for electric cars to pay off their debts are the ones whose power grids are fueled by sizable shares of renewable energy — Washington state, for example, gets 60 percent of its power from hydroelectric sources. And in Vermont, the report notes, where wind, nuclear and hydroelectric sources are most relied upon for energy, “a brand new Leaf needs to be driven only 22,000 miles before its total life-cycle emissions per mile are less than those of a Prius.”
The report makes clear that, in all states, buying a Leaf or Prius is still more climate-friendly than buying a traditional gas-powered car: the average fuel economy of new cars bought in 2012 was about 24 mpg, compared to about 50 mpg for a Prius. But it also highlights the need for states to adopt more clean energy sources if they want to reduce emissions and reap the benefits of electric vehicles. From 2010 to 2012, a shift away from coal and towards wind and natural gas led to an eight percent reduction in U.S. emissions per kilowatt-hour, according to the report. This reduction in turn more than doubled the number of states where driving an electric vehicle was less carbon intensive than driving a hybrid. The reductions were not enough to make the overall lifecycle emissions of an electric vehicle compare to a hybrid in most states, but they showed that, if states continue to shift away from fossil fuels and towards clean energy to power their grids, driving an electric car could be the climate-friendly choice it was meant to be in more parts of the U.S.