A new study from North Carolina State University indicates that even a sharp increase in the use of electric vehicles by 2050 would not significantly reduce emissions of high-profile air pollutants carbon dioxide, sulfur dioxide or nitrogen oxides.
“We wanted to see how important electric vehicles may be over the next 40 years in terms of their ability to reduce emissions,” says Dr. Joseph DeCarolis, an assistant professor of civil, construction and environmental engineering at NC State and senior author of a paper on the new model. “We found that increasing the use of electric vehicles is not an effective way to produce large emissions reductions.”
The researchers ran 108 different scenarios in a powerful energy systems model to determine the impact of electric vehicle use on emissions between now and 2050. In a paper published in the peer-reviewed journal Environmental Science and Technology, the team reported that, even if electric vehicles made up 42 percent of passenger vehicles in the U.S., there would be little or no reduction in the emission of key air pollutants.
“There are a number of reasons for this,” DeCarolis says. “In part, it’s because some of the benefits of electric vehicles are wiped out by higher emissions from power plants. Another factor is that passenger vehicles make up a relatively small share of total emissions, limiting the potential impact of electric vehicles in the first place. For example, passenger vehicles make up only 20 percent of carbon dioxide emissions.
“From a policy standpoint, this study tells us that it makes more sense to set emissions reductions goals, rather than promoting specific vehicle technologies with the idea that they’ll solve the problem on their own.”
DeCarolis says what could affect U.C. emissions is the cost of oil, the cost of natural gas and the cost of batteries.
“If you charge a plug-in hybrid or a battery electric vehicle with dirty electricity, you’re just exchanging tail pipe emissions for upstream emissions from electric power,” said DeCarolis. ” I think we expected to see, though, some effect of an emissions benefit, some sub-set of the scenarios. It was just hard to find that.”
What the study doesn’t tell us is how much electric vehicles might be of help in a scenario where we do continue to phase out dirty coal power plants and move toward renewable sources of electricity.
The vast majority of studies have shown: electric vehicles are a key part of our longer-term strategy to cut carbon and smog-forming pollutants; and fueling our cars on an increasingly cleaner grid is a smart strategy to cut oil dependency and air pollution.
Some EV advocates are concerned that the new study might be misinterpreted, and used as ammunition against policies to encourage electrification of transportation. But they generally agree that efforts to cut vehicle emissions through deployment of cars have to go hand-in-hand with other policies to cut greenhouse gases, most notably, cutting emissions from power plants.
You can read the full paper in pdf here.