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Driving an electric vehicle may seem like the ultimate signal that you’re doing your part to save the planet. But just the ability to plug in a car doesn’t automatically make it climate-friendly if that electricity comes from a dirty source.
Figuring out how EVs actually stack up to gas-powered cars involves a heck of a lot of math and moving parts. There are nuances electric vehicle-curious folks should recognize before taking the plunge, from the materials used to make a car to the power source you’re plugging it into and how efficient your vehicle is at using that charge.
“You want to think about what we call life cycle emissions,” said Eric Larson, a senior research engineer at the Andlinger Center for Energy and the Environment at Princeton University. “If you’re talking about fossil fuels, like coal, there are emissions associated with mining it, and the combustion of fossil fuels gives you emissions. There are also emissions associated with manufacturing the electric vehicles and the batteries that go with it—those emissions have to be counted as well. Basically, all the emissions associated with getting from raw materials to the final miles traveled in the car have to be counted.”
The “most important step” in that equation, Larson said, was comparing how much electricity a vehicle is able to use to go a certain amount of miles versus going that same distance in a gas-powered car. “An electric car you put electricity in the battery, and you get a certain number of miles out of each kilowatt-hour you put into the battery,” he said. “With a combustion engine, you’re putting gasoline in and you’re burning it and you’re driving some number of miles. For the same number of miles you go on electricity versus what you go on gasoline, it’s a comparison of the amount of efficiency between those two.”
Why the Grid Matters So Much
In 2017, Climate Central, a nonprofit science and news organization, conducted an analysis of how the grid in each U.S. state informed what type of cars are actually the most “climate friendly”—in other words, which cars produced less emissions during their whole life cycle. (Larson was one of the authors of this report.) The researchers looked at the specifics of the energy landscape in the U.S., as well as the lifecycle emissions associated with manufacturing and driving 100,000 miles (160,930 kilometers) in 88 model-year 2017 cars. The cars included full-electric models like the Nissan Leaf and gas- and diesel-fueled cars.
In most states in the U.S., the analysis found, driving an electric car was kinder to the climate. But in 13 states, including places that relied heavily on coal like Kentucky, Missouri, and West Virginia, driving a fuel-efficient, gas-powered car was actually better emissions-wise.
The Climate Central report used data on states’ energy mixes from the Energy Information Administration that was gathered in 2015—the last publicly available data when the researchers were putting together the analysis. Renewables have expanded since then, the Biden administration is looking to grow their share even more aggressively while also pushing policies to create more charging infrastructure and electric vehicles on the road. Coal, meanwhile, is taking a steep downward turn. Analyses now project that half of the coal plants that were online in 2015 will still be around by 2035.
Climate Central had conducted a previous electric vehicle analysis in 2012 that found only 13 states had a green enough grid to make driving an electric car the most climate-friendly option, showing how rapid change is happening. That’s why a future-looking perspective is important to keep in mind when thinking about the emissions life cycle of electric vehicles. In July, the International Council on Clean Transportation released an analysis that found that driving an electric car was far and away better carbon emissions-wise in all areas of the world over about the next 20 years. Even using an EV in China, where coal still reigns, can result in 37% to 45% fewer emissions.
There are a couple of important points to consider in this analysis. In contrast to the Climate Central study, the ICCT study “includes the improvement of the electricity mix during the lifetime of the vehicles,” study author Georg Bieker said in an email. “This makes a big difference! In other words, we assess the emissions over the full vehicle life, not only the emissions of driving them right now.”
The ICCT report also assumes that the cars will be registered in 2021 and be on the road for the next 15 to 18 years, giving EVs a lot more time to reap the benefits of a changing grid over their life cycles. It also includes a different calculation for the battery emissions that Bieker said is based on recent research.
How to Ensure Your Electric Vehicle Runs on Clean Power
Even though there’s a lot of math to consider in figuring out the total lifecycle emissions of an EV and comparing them to gas-powered cars, and while advances in technology are making electric cars and batteries more efficient and their production less carbon-intensive, Larson said that “improvements in the grid will make all the difference” for seeing the full benefits of EVs in the future.
Decarbonizing the grid is a huge task. So get an electric vehicle, sure, but also turn up the pressure on policymakers if you want it running on carbon-free electricity. Among the possibilities are using a simpler dialer and script to pressure Congress to pass a Clean Electricity Standard as part of the budget bill, a proven way to clean up the grid.
And while the grid is getting cleaned up, it’s still worth it for the planet to transform how we get around—especially since research like the ICCT report shows that the benefits of electric vehicles take a long time to accrue. Right now in many places in the U.S., the basics of electric vehicle access, like charging, are only available to wealthy communities. Getting involved in efforts to increase equitable access is a great idea to ensure that when our grid is clean, everyone will have the ability to take advantage of it with their cars.