America’s high-carbon electricity grid is short-circuiting efforts to give consumers climate-friendly, electric-vehicle options. Depending on where you live, generating the electricity to charge an electric car can produce more greenhouse gas pollution than driving a fuel-efficient gasoline-powered car.
The good news is that there are lots of choices to reduce the carbon footprint from daily driving. Anywhere in the country, an electric car is much better for the climate than the average- mileage vehicle. But in many US states, popular high-mileage hybrid and conventional gas powered cars are climate-friendlier alternatives to electric cars today, and new fuel economy standards should lead to even more climate-friendly options in the coming few years.
A state-by-state analysis shows the contrasts in how climate-friendly cars can differ based on the grid. Cars are benchmarked to emissions associated with the Nissan Leaf and Chevy Volt because these are the top-selling all-electric and plug–in electric vehicles on the road today.
In 36 states, the hybrid electric Toyota Prius produces less greenhouse gas pollution than the all-electric Nissan Leaf, because when you plug in a Leaf to recharge, you are tapping into electricity generated largely by burning coal and natural gas in those states. (The Prius, which is the most efficient gasoline car sold in the US at this point in time, is called a hybrid electric vehicle, but it can be thought of simply as a high-efficiency gasoline car because it derives all of its power from gasoline: its batteries are recharged by running its engine and recovering braking energy.)
Coal is the largest contributor to the high carbon footprint of our electrical grid today. In states like Wyoming or Indiana, where 90 per cent or more of the electricity comes from coal, driving a Leaf is responsible for much more greenhouse gas emissions per mile (about 0.9 pounds) than a Prius (about 0.5 pounds).
The Leaf fares better in states that get a significant share of their electricity from natural gas, like Rhode Island or Nevada (about 0.6 pounds per mile), but typically still produces more emissions than a Prius. The Leaf does best in states that rely heavily on nuclear, like Connecticut (0.3 pounds), or on hydropower, like Idaho or Washington (0.1 pounds).
It isn’t only the Prius that out-performs the Leaf. In the 10 states with the most carbon-polluting electricity generation, there are 20 cars that are better for the climate than the Leaf; 13 of them are gas-powered vehicles with conventional engines. The rest are gas-powered hybrids.
The partially-electric Chevy Volt has a similar profile, depending on how often a driver engages its gasoline engine. A Volt, like a Leaf, plugs in to charge its battery, but when the charge is depleted during driving it switches to its onboard gasoline engine to keep going. If a Volt drives half its miles using gasoline and half using electricity from plug-in charging of its battery, it is a bigger carbon polluter than the Prius in 45 states.
But this doesn’t mean that electric cars are not an important option for fighting climate change. They can help address our oil addiction and save consumers thousands of dollars on gasoline over the life of a vehicle. And in the long-term, once the grid becomes low-carbon, electric cars, unlike gas-powered automobiles, could be a cornerstone of personal mobility in a world where carbon emissions are next to zero, which will be required to stabilise the climate.
In the meantime, as we work to shift much more of our electricity generation to low-carbon alternatives, there are many high-mileage hybrids, diesels, and other gas-powered cars available today that can offer substantial reductions in climate impacts.