What if nearly half of the cars on the road today were replaced by the electric kind, those vehicles that environmentalists and electric vehicle marketing groups claim are "90% efficient" and worth the extra cost? How much better would our emissions scenario be?

It wouldn't make much difference. Even a sharp increase in the use of electric drive cars (hybrid, plug-in hybrid and battery electric) by 2050, up to as much as 42 percent of passenger vehicles in the U.S., would not significantly reduce emissions of high-profile pollutants like carbon dioxide, sulfur dioxide or nitrogen oxides.


At least not unless we switch to nuclear energy. And even then the impact due to cars wouldn't be meaningful. Cars make up a lot less emissions than they are portrayed as emitting.

The researchers ran 108 different scenarios in an energy systems model to determine the impact of electric vehicle use on emissions between now and 2050. They found that, even 42 percent of vehicles in the U.S. would not be an effective way to produce large emissions reductions. 

"There are a number of reasons for this,"
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.
"In part, it's because some of the benefits of EDVs 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 EDVs 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."

"How Much Do Electric Drive Vehicles Matter to Future U.S. Emissions?" is published in Environmental Science&Technology. Source: North Carolina State University