How much more environmentally friendly is an all-electric car than a gas powered car?
Although all-electric vehicles (EVs) are in general more environmentally friendly than gas powered cars, the actual amount depends on a number of factors, but most importantly where the car is operated. To compare emissions for different vehicles it's important to consider all sources over the full life-cycle of the vehicle. This includes:
- Manufacture: because of the unique aspects of battery manufacture, an EV results in greater emissions than a gasoline vehicle during this phase.
- Power source: EVs must take into consideration the emissions associated with production of the type of fuel used to generate the electricity; transport of the fuel, if necessary; generation of the electricity; losses during transmission of the electricity; and losses during vehicle charging (see Figure 1). The vast majority of these emissions depend on the type of fuel used - renewable energy (wind, solar or hydroelectric) or nuclear the best, natural gas worse, and coal much worse. Correspondingly, ICEs must take into account drilling and production of oil, transport of oil, refining the oil to gasoline, and transport of the gasoline.
- Operation: an EV results in no tailpipe emissions, while an ICE generates emissions that are generally in line with the mileage efficiency of the vehicle.
- Disposal: there is little difference between EVs and ICEs at this phase.
A fascinating study from 2015
by the University of North Carolina, Greensboro and published in the National Bureau of Economic Research addressed the emissions produced by gasoline car tailpipes and the emissions produced by electricity grids that power electric vehicles (EVs) for every US county. The researchers focused on five major pollutants: carbon dioxide (CO2), sulfur dioxide (SO2), nitrous oxide (NOx), particulate matter (PM 2.5), and volatile organic compounds (VOCs). They considered 11 different 2014 models of EVs, as well as the "closest substitute" gas car. Whenever possible they used an exact equivalent, as with the Ford Focus, which comes in both electric and gas-powered versions. It should be noted that this study only partially addressed #2 above, as it did not attempt to include the emissions from producing the fuel source for either types of vehicles.
The results of the study were in the form of environmental cost of driving a mile with both types of vehicles, with damage costs ranging from 1 to 5 cents per mile. Figure 2 summarizes the results with gas powered vehicles plotted on the left and EVs on the right. Green is lowest damage; red is highest. Results are driven by two key parameters - how sensitive the region is to pollution and the amount of coal generated power in the region. It can be seen that gas powered vehicles perform the worst in large, congested cities, while EV performance is regional based and linked to the predominant fuel source used for generating electricity. If anything, the study appeared to show that EVs were actually worse for the environment than ICEs. Many in the fossil fuel industry used this data
to fight any policy changes in favor of EVs. However, at the time of the study, approximately 70% of electrical power generation in the US was from coal. Since then, electrical power production in the US has gotten significantly cleaner with the shuttering of older coal plants (such that in 2020 coal provided less than 20%
of US electricity generation), cleaner sources of renewable power, and increased pollution control equipment on existing plants. Updates to the study
by the same authors showed significant shifts in favor of EVs.
An evaluation in 2021 by Reuters
of an Argonne National Laboratory model that addresses all 4 phases of a vehicle's life-cycle showed that a midsize EV generates about 50% more CO2 emissions during manufacturing than a comparable ICE. It then takes approximately 1 year of driving using the average US electrical mix to overcome this deficit and begin to have a positive impact on the climate. Figure 3 shows results for when a Tesla Model 3 becomes cleaner than a Toyota Corolla for various electrical power mixes: about 1 year or approximately 15,000 miles for the US mix. The EPA provides a Beyond Tailpipe Calculator
to compare total GHG emissions for various EVs anywhere in the US. An example results from this tool is shown in Figure 4 for a Tesla Model 3 in Pierre, South Dakota, which is located in one of the dark green regions for ICEs (best) and dark red for EVs (worst) that was shown in Figure 2. Although the Tesla emits one-third more GHGs in Pierre than the nationwide average, due to the prevalence of coal power in South Dakota, it is still less than half that produced by a new gasoline vehicle. In a 2021 study
the International Council on Clean Transportation (ICCT) took into account not only the current electricity mix in 4 geographical regions - Europe, the US, India and China - but the projected improvements in electricity generation based on stated government policies to aling with the Paris Agreement. Figure 5 summarizes the results and shows that for the US total lifetime GHG emissions from EVs are less than half of those from ICEs.
In a similar result shared in USA Today
, Ian Miller of the MIT Energy Initiative states that, using the US average electricity mix, EVs produce roughly 100 grams of CO2 per mile, compared to 280 grams for a typical gasoline-powered car that gets 30 mpg, or just over one-third the CO2 emissions. Based on all the recent studies, an EV produces one-half or less CO2 emissions over its lifetime than an ICE, and this advantage will only grow in the future as the US electricity mix gets greener.