EDVs have little impact on emissions, says study

North Carolina State University researchers have conducted a study into hybrid, plug-in hybrid and battery electric vehicles (electric drive vehicles, or EDVs) in order to predict their potential impact on emissions. Their paper was published in the journal Environmental Science & Technology.

The researchers ran 108 different scenarios, varying assumptions related to crude oil and natural gas prices, a CO₂ policy, a federal renewable portfolio standard and vehicle battery cost, to determine the impact of EDV use on emissions between now and 2050. “Across these scenarios,” the researchers said, “oil prices and battery cost have the biggest effect on EDV deployment.” That is, if batteries are cheap and oil is expensive, EDVs become more attractive to consumers.

However, they found that even if EDVs made up 42% of passenger vehicles in the US by 2050, there would be little or no reduction in the emission of key air pollutants such as carbon dioxide, sulfur dioxide or nitrogen oxides. The study’s senior author, Dr Joseph DeCarolis, said, “There are a number of reasons for this.

“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% of carbon dioxide emissions.”

Dr DeCarolis thus suggests: “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.”

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