by Dr. David Reinmuth, Senior Vehicle Engineer, Union of Concerned Scientists
One of the questions I’m most frequently asked about electric vehicles (EV) is: “Are they really a cleaner option?” While it’s obvious that a fully-electric vehicle eliminates tailpipe emissions, people often wonder about the global warming emissions from generating the electricity to charge an EV. The latest data affirms that driving on electricity produces significantly fewer emissions than using gasoline and is getting better over time.
Electricity power plant emissions data for 2018 has just been released and we’ve crunched the latest numbers. Based on where EVs have been sold, driving the average EV produces global warming pollution equal to a gasoline vehicle that gets 88 miles per gallon (mpg) fuel economy. That’s significantly better than the most efficient gasoline car (58 mpg) and far cleaner than the average new gasoline car (31 mpg) or truck (21 mpg) sold in the US. And our estimate for EV emissions is almost 10 percent lower than our previous estimate two years ago. Now 94 percent of people in the US live where driving an EV produces less emissions than using a 50 mpg gasoline car.
EV emissions are lower across the country
The mpg (miles per gallon) value listed for each region is the combined city/highway fuel economy rating of a gasoline vehicle that would have global warming emissions equivalent to driving an EV. Regional global warming emissions ratings are based on 2018 power plant data in the EPA’s eGRID2018 database (released January 2020). Comparison includes gasoline and electricity fuel production emissions estimates for processes like extraction, transportation, and refining using Argonne National Laboratory’s GREET 2019 model. The 88 mpg US average is a sales-weighted average based on where EVs were sold in 2011 through September 2019.
To compare the climate-changing emissions from electric vehicles to gasoline-powered cars, we analyzed all the emissions from fueling and driving both types of vehicles. For a gasoline car, that means looking at emissions from extracting crude oil from the ground, moving the oil to a refinery, making gasoline and transporting gasoline to filling stations, in addition to combustion emissions from the tailpipe.
For electric vehicles, the calculation includes both power plant emissions and emissions from the production of coal, natural gas and other fuels power plants use. Our analysis relies on emissions estimates for gasoline and fuels production from Argonne National Laboratory (using the GREET2019 model) and power plant emissions data released by the US EPA. The data, released in January 2020, tallied the emissions from US power plants during 2018.
When looking at all these factors, driving the average EV is responsible for fewer global warming emissions than the average new gasoline car everywhere in the US. In some parts of the country, driving the average new gasoline car will produce 4 to 7 times the emissions of the average EV. For example, the average EV driven in upstate New York has emissions equal to a (hypothetical) 231 mpg gasoline car. And in California, a gasoline car would need to get 122 mpg to have emissions as low as the average EV.
Compared to our last analysis that used 2016 power plant data, emissions from EVs are on average 10 percent lower. The reductions have come from two primary sources:
- The emissions rate from power plants in the US fell over 5 percent between 2016 and 2018. The drop comes from lower generation from coal and increases in natural gas, wind, and solar.
- The average efficiency of EVs sold to-date in the US improved since our last analysis (by about 6 percent). This was due to the sales of Tesla’s Model 3, one of the most efficient vehicles on the market. The Model 3 now makes up more than 20 percent of all EVs (and more than one third of battery electric cars) ever sold in the US, so its efficiency has a noticeable impact on calculation of average EV efficiency.
A decade of improvement
The change from our first analysis of global warming emissions from EVs and gasoline vehicles in 2012 (using 2009 powerplant data) is even more impressive. In our initial assessment, less than half the US lived where an EV produced fewer emissions than a 50 mpg car, while now nearly all of the US falls in that category. The improvement has been driven partially by increasing EV efficiency, but the major contribution has been from the reduction in electricity generation from coal power plants. Electricity from coal has fallen from 45% to 28% in less than a decade. At the same time, solar and wind electricity has grown from less than 2% to 8% in 2018.
|% of US population living in a “Best” region for EVs (>50 mpg equivalent)||45%||75%||94%|
|Fraction of electricity grid regions where an EV is lower emission than a 50mpg vehicle||9 of 26||16 of 26||22 of 26|
|fraction of US electricity from coal power plants||45%||30%||28%|
|fraction of US electricity from wind and solar power||2%||7%||8%|
Car buyers have options to be even cleaner by choosing a more efficient EV
The Tesla Model 3 is one of the most efficient EV models available. Efficient EVs help minimize the global warming emissions from driving. (David Reichmuth / UCS)
The average EV is cleaner than the average new gasoline vehicle everywhere in the US. But if you choose the most efficient EV available, your emissions reductions from switching from gasoline to electricity will be even higher. For example, driving the 2020 Tesla Model 3 Standard Range Plus (0.24 kWh/mile) in California has emissions equal to a 161 mpg gasoline car, or less than a fifth of the global warming emissions of the average new gasoline car and over 60 percent less than even the most efficient gasoline car. And in upstate New York, the emissions from driving an EV can be as low as one tenth those of an average new gasoline car.
As the grid continues to get cleaner, EVs, both new and used, will get cleaner as well. This is a distinct advantage EVs have over gasoline-fueled vehicles: their emissions get better over time as the grid gets cleaner. Gasoline vehicles’ fuel economy is fixed and therefore so are their emissions, as long as they rely primarily on petroleum for fuel.
Driving the most efficient EV available in the US means lower emissions than any gasoline car in nearly all of the US. In Upstate New York, emissions from driving the cleanest EV are one tenth that of the average new gasoline vehicle.
Larger EVs can still lead to lower emissions
The Audi e-tron is an all-electric SUV. It’s less efficient than many other EVs due to its size, but still has a global warming emissions benefit relative to the comparable gasoline SUV model. (credit:UCS/Reichmuth)
Larger EVs, like SUVs and pickup trucks are slowly becoming available, and more are promised soon, including an electric version of the Hummer SUV. Larger vehicles, whether gasoline or electric-powered, are less efficient. However, switching from gasoline to electricity still has an advantage.
Take for example the Audi e-tron EV SUV: using 0.46 kWh per mile, it is one of the least efficient EVs available. However, the most comparable gasoline model, the Audi Q8 gasoline-fueled SUV is also inefficient for a gasoline vehicle, with a fuel economy rating of 18 mpg. The Audi e-tron electric SUV will produce less emissions than the gasoline-powered Audi Q8 while driving, even on the dirtiest electric grids in the US. And on the cleanest grids, the electric SUV is responsible for less than a quarter of the global warming emissions of the gasoline SUV. For more than 90 percent of the population, driving the electric version of this vehicle will produce less than half the global warming emissions of the gasoline model.
|Audi e-tron EV SUV emissions compared to Audi Q8 gasoline SUV emissions||Greater EV emissions than gasoline||Up to 50 percent emissions savings with EV||50 to 75 percent emissions savings with EV||Over 75 percent emissions savings with EV|
|Fraction of US population||0%||8%||73%||19%|
|Population||0||26 million||232 million||61 million|
EVs are one part of reducing transportation emissions
Passenger cars and trucks are a significant source of global warming emissions in the US. Switching from gasoline to electricity is a vital solution for reducing emissions and avoiding the worst impacts of climate change. However, it’s only one of many solutions we need to use. Because many of the cars sold in the next five years will be gasoline-powered, it is important to make sure those vehicles are as clean as possible by having strong fuel economy and emission standards.
Additionally, actions we can take to reduce all driving (whether from gasoline or EVs) will help lower emissions. Sharing rides, using public transit, and making it easier to walk and bike are all important solutions to climate change. But for the personal vehicle trips that we can’t avoid today, switching to an EV can make a big difference in how much global warming emissions we produce and is one of the biggest actions a household can take to reduce their carbon footprint.
You can also use the UCS EV Tool to calculate your EV’s carbon emissions from charging, and compare that to gasoline powered vehicles. Learn more about transportation and other environmental issues at UCS’s website.
Reprinted with permission of the Union of Concerned Scientists